Automatic 12V Lead Acid Battery Charger


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This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged.

Schematic

Schematic of the 12V automatic battery charger

Parts

Part
Total Qty.
Description
Substitutions
R1, R32330 Ohm 1/4W Resistor
R21100 Ohm 1/4W Pot
R4, R5, R7, R8482 Ohm 2W Resistor
R61100 Ohm 1/4W Resistor
R911K 1/4W Resistor
C11220uF 25V Electrolytic Capacitor
D11P600 DiodeAny 50V 5A or greater rectifier diode
D211N4004 Diode1N4002, 1N4007
D315.6V Zener Diode
D41LED (Red, Green or Yellow)
Q11BT136 TRIAC
Q21BRX49 SCR
T1112V 4A TransformerSee Notes
F113A Fuse
S11SPST Switch, 120VAC 5A
MISC1Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output, Fuse Holder

Notes

  1. R2 will have to be adjusted to set the proper finish charge voltage. Flooded and gel batteries are generally charged to 13.8V. If you are cycling the battery (AGM or gel) then 14.5V to 14.9V is generally recommended by battery manufacturers. To set up the charger, set the pot to midway, turn on the charger and then connect a battery to it's output. Monitor the charge with a voltmeter until the battery reaches the proper end voltage and then adjust the pot until the LED glows steadily. The charger has now been set. To charge multiple battery types you can mount the pot on the front of the case and have each position marked for the appropriate voltage.
  2. Q1 will need a heatsink. If the circuit is mounted in a case then a small fan might be necessary and can generally be powered right off the output of D1.
  3. T1 is a transformer with a primary voltage appropriate to your location (120V, 220V, etc.) and a secondary around 12V. Using a higher voltage secondary (16V-18V) will allow you to charge 16V batteries sometimes used in racing applications.
  4. If the circuit is powered off, the battery should be disconnected from it's output otherwise the circuit will drain the battery slowly.

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Comments

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Abid Ali
Automatic 12V Lead Acid Battery Charger
Saturday, April 12, 2014 2:20:05 AM
hi! if 18 AC volts Can we use this circuits And one battery charge from solar and other battery fit in running circuit, the solar battery can connect to the running circuit battery. can you help to design a circuit for this. thank x
kc
Automatic 12V Lead Acid Battery Charger
Thursday, March 06, 2014 8:07:17 PM
Hello. Just thinking what is the output power of this circuit? And how long will it take to fully charge the 12V battery? :) Thank you.

(Editor's notes: As I'm sure the notes say, the output is dependent on the size of the transformer up to 5A. And the time it takes to charge the battery depends on the size of the battery.)

Chris
Automatic 12V Lead Acid Battery Charger (how can I increase the Ams to 12-14amps?)
Thursday, January 30, 2014 10:57:00 AM
Hi, Thank you for sharing this knowledge. Can you please help me with an information? I need a 12 volt battery charger with 12-14 amps capacity. From the schematic above, what are the components I need to change to achieve this? and what exact specs of the components? Many Thanks. Chris
jay
Automatic 12V Lead Acid Battery Charger
Tuesday, January 28, 2014 6:19:49 AM
i have a question. what if there is no available BRX49, is there any option that this circuit work? or what would i do of this problem?? please help me, i need an answer.. you are part of our project.. please reply asap. Godbless
sushil
Automatic 24V Lead Acid Battery Charger 150 mAh batt. each
Sunday, January 05, 2014 3:22:18 AM
thanks for your above chart it is clear but I really need 24 volts to charge 2 batteries at same time so plz can you just replace the required parts only on Description table or whole image itself. Actually I got 220 ac to 24 volt ac transformer i want to use this transformer for charging by converting into DC line..i n past I did lot but always some thing blows off..so plz if possible contact my email add..
Solartech
Automatic 12V Lead Acid Battery Charger
Sunday, December 29, 2013 12:38:57 AM
can this circuit diagram suitable for ups charger?
hafiz g
Automatic 12V Lead Acid Battery Charger
Wednesday, October 23, 2013 12:08:11 PM
asalamualaikum bro i have one prob on this circuit please tell me what is the substitute of BRX49 SCR ,,,,this ic is not available on my area so please guide me what can i use for its substitute.???
soundar
Automatic 12V Lead Acid Battery Charger
Monday, May 20, 2013 5:17:23 AM
hi..... how to add 2 or 3 batterys to this same circuit........???
faz
Automatic 12V Lead Acid Battery Charger
Monday, April 01, 2013 6:36:41 AM
i can't found the TRIAC BT136 but can i use TRIAC BT139 instead of TRIAC BT136? and can i use BC548 or BC558 instead of BRX49 SCR? and can i use IN4004 diode instead of P600 Diode? please help me. i need to complete my project urgent.
anonymsamaduSAloussa
Automatic 12V Lead Acid Battery Charger
Monday, April 01, 2013 5:24:52 AM
i assembled a 12v charger only using 1no center tap 12-0-12 transformer 4amp and 8nos of power diode 4nos for each side and charged 120AH BATT WITHIN 8HOURS. CHARGING CURRENT FOUND 10AMP. NO MORE COMPONENT USED. WHAT WILL BE THE DEMERITS ON IT .
anonymous
Automatic 12V Lead Acid Battery Charger
Wednesday, December 12, 2012 8:07:15 AM
pls how can this circuit be reconfigured to charge two 12V/15Ah sealed lead -acid batteries using a 27 or 28 volts AC/DC converter
kimura
Automatic 12V Lead Acid Battery Charger
Thursday, November 08, 2012 4:46:08 AM
i made that cct n its working good, used full wave rectification coz D1 introduce high resistance, n BT151 for brx49,
Dileep Naik
Automatic 12V Lead Acid Battery Charger
Wednesday, November 07, 2012 6:21:09 AM
Dear sir, We try to make the circuit but at the output we are getting voltage between 6.3 v to 7.38v only. Connected LED D4 is not glowing. We are connected 3v red LED. Please guide us how to get complete 12 v for charging the battery. We also connected 12v chargable battery at output but we are not getting 12v at the output.
anonymous
Automatic 12V Lead Acid Battery Charger
Wednesday, July 11, 2012 2:31:03 AM
hi been wondering whether Vac or Vdc is used to power the device? i tried making it but it failed to power up. please send me an email. thanks!
emmanuel
Automatic 12V Lead Acid Battery Charger
Friday, May 18, 2012 4:26:23 AM
Dr. thanks for the good work, Please how long will it take to charge 12V 200AH battery and how will i change the design to charge the battery within 5hrs Please send me the reply if possible with the circuit diagram to my email
tjolle62
Automatic 12V Lead Acid Battery Charger
Tuesday, May 08, 2012 5:45:05 PM
Hello, I'm going to build this nice gel charger and i womder what values and components do i need to change for a 24V feed ?
wempire
Automatic 12V Lead Acid Battery Charger
Saturday, April 28, 2012 4:48:55 AM
third class circuit dont try to assemble otherwise you will loos your mony and time
anonymous
Automatic 12V Lead Acid Battery Charger
Wednesday, March 21, 2012 12:32:03 PM
Does this circuit really works? What is the charging time for a fully discharged battery? What will be the approximate cost(in Indian rupees) of building this?
E.L. Gabriel
Automatic 12V Lead Acid Battery Charger
Thursday, March 08, 2012 11:42:49 AM
Hello, and thanks for a good circuit, it is easy to build and to modify' I've made two of these and two of my friends are very happy. For starters, I substituted the 4x2 watt resistors,for 5watt ceramic type, added adjustable fan cooling using separate power supply. Next time I make another I'll add volt and amp gauges. Thanks once again
Ryn
Automatic 12V Lead Acid Battery Charger
Tuesday, March 06, 2012 11:44:16 AM
can i know , how the triac in this circuit operate? And the overall operation for the circuit ? TQ
mj
Automatic 6V Lead Acid Battery Charger
Thursday, February 02, 2012 4:23:05 AM
hi sir Can this circuit be modified using 6V battery?
Jimmie
Automatic 12V Lead Acid Battery Charger
Wednesday, January 25, 2012 11:44:22 AM
How long does it take,n how much in $
ATH
Automatic 12V Lead Acid Battery Charger
Sunday, January 22, 2012 4:47:07 PM
Can I use BT138 or BT137 instead of BT136 ?, (75 ohm 4w) instead of (82 ohm 4w) resistors ?, are there any equivalents to brx49 ?
alby
Automatic 12V Lead Acid Battery Charger
Monday, January 16, 2012 9:50:23 AM
Would like to have a go at this one & was wondering if anyone has the layout for the PC board
Lynne
Automatic 12V Lead Acid Battery Charger
Monday, November 07, 2011 4:02:35 PM
Then 2 330 Ohm 1/4 watt resisters burnt seems it should have been closer to 2 watt . . I am replacing them with 2 1k 1/2 watt in paralllel which means it will be 500 ohms of resistance and 1 watt of power disapated . . will find out in a bit if it holds
Bates
Automatic 12V Lead Acid Battery Charger
Friday, October 28, 2011 3:30:20 AM
Thanks author!. I've just finished building this project within 3 days. My output volt from charger unit terminal without connected to battery was 6.92v but as i connect the output terminal to the car battery terminal, i've got 12.94v (increasing, but LED not yet ON) please tell me is it normal for the different volt reading (from the output charger unit) when connect & disconnect from the car battery terminal. Btw, can't find P600 diode so I use A610 instead.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, October 18, 2011 10:08:59 PM
i read all the comments and decided not to try this...hehehe do not waste money..lol
Rey
Automatic 6V battery charger
Tuesday, September 27, 2011 5:37:07 AM
Can this circuit be modified using 6V battery?
hussain shaikh
Automatic 12V Lead Acid Battery Charger
Monday, September 19, 2011 11:47:10 AM
HI MY ANOTHER QUESTION HOW CAN I REGULATE THE AMPS eg: i want to charge 7 amp and 14 amp battery in one time or 7amp and 7amp and i have a charger of 14 amps or only 7 amps.
hussain shaikh
Automatic 12V Lead Acid Battery Charger
Monday, September 19, 2011 11:35:18 AM
hi i like your project and i want to charge more amps battery what's my question is how can i charge 35amp battery FROM 220V DC.
Joynal
Automatic 12V Lead Acid Battery Charger
Thursday, September 01, 2011 6:52:01 AM
Hi. Can i charge my battery 12v 250amp.
ZUGO
Automatic 12V Lead Acid Battery Charger
Wednesday, August 31, 2011 8:11:48 AM
let me build this circuit and find out hw results will be.i real like to deal with challenges like these at a very early stage so that i can see where am i going with electronics.
Ramesh, K. B.
Automatic 12V Lead Acid Battery Charger
Friday, July 29, 2011 1:48:28 AM
Dear friend I am an ameture in electronics. I am interested in using the circuit for charging my 12V battery. Can you please provide me some check points to make sure that what I have wired is correct. Thanks in advance Ramesh
populas
Automatic 12V Lead Acid Battery Charger
Friday, July 08, 2011 5:03:47 PM
can i use a 12v 20a transformer with this charger
Dylan Eave
Automatic 12V Lead Acid Battery Charger
Wednesday, April 20, 2011 7:47:35 AM
Hi there... I built this circuit about a year ago but I think I have done something incorrectly. The highest voltage the circuit can achive is 13.4V... and the LED never ceases to flash when the pot is set to this, the highest possible charging voltage. Is my battery being adequatley charged at 13.4V? Time to charge is not an issue at all. Perhaps my question should be: What is the minimum charging voltage for a 12V SLA battery? Thanks
kris
Automatic 12V Lead Acid Battery Charger
Thursday, April 07, 2011 10:56:54 AM
what will be the amp rating in the transformers secondary core and if i use a 2 amp transformer will it charge a 7 amp battery.
anonymous
Automatic 12V Lead Acid Battery Charger
Monday, April 04, 2011 1:13:28 AM
very confused wit the connections of the triodes( Q1 and Q2) . unable to detect which terminal to connect...... Please help....
Kelven Chang
Automatic 12V Lead Acid Battery Charger
Wednesday, March 02, 2011 11:32:38 AM
What component should i change if i wanna charge 24V AGM battery
GeoIL
Automatic 12V Lead Acid Battery Charger
Tuesday, February 15, 2011 5:28:19 PM
I build this project exactly like in description. I did not make any change of the parts. I tried to charge my battery car (12V/35Ah) and I did not have succes. The charging current was about 20mA. My battery was not dead she have 12,7V. But with an battery witch indicate 10,7V the cahrging current was 16,7mA. Wat is wrong. The circuit is good or what?? Excuse my bad english!!
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, February 03, 2011 12:43:13 AM
Is this charger can charge also SEALED Lead Acid Battery? please answer me.. tnx
Hashim
Automatic 12V Lead Acid Battery Charger
Friday, January 07, 2011 12:35:19 PM
Can I use 12v 5Ah transformer instead of 4Ah ? I have it in my handmade car battery charger which is a basic charger (just simple rectifier and nothing else) and wanted to add your circuit to it.
chilo
Automatic 12V Lead Acid Battery Charger
Tuesday, December 07, 2010 9:41:47 PM
how could i run this off a 12 volt dc like cigar lighter chargers or jus a 12v source of a car?

(Editor's notes: No.)

peter
Automatic 12V Lead Acid Battery Charger
Saturday, December 04, 2010 9:47:00 AM
can this charger charge 12v 200ah deep cycle battery
cetot
Automatic 12V Lead Acid Battery Charger
Tuesday, August 10, 2010 12:55:39 PM
This project is interesting...but how to modified the schematic to become the Automatic variable battery charger 0-24VDC with the cutoff switch when the battery is FULL loaded? If better to add meter and display to indicated the charge voltage and current...Any idea to done this?
ali raza
Automatic 12V Lead Acid Battery Charger
Wednesday, July 14, 2010 9:04:50 PM
hi i have to install battery charger for my ups so if i have to increase current of charger i.e 4amps to 10 or 20amps what i have to do??
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, June 29, 2010 8:38:47 AM
I am surely interested to build this project, however my great problem is how to find replacement for SCR- BRX 49. Do you have any suggestion? Can I add a relay switch to an inverter to switch to it during power brownouts?
namnp2007
Automatic 12V Lead Acid Battery Charger
Tuesday, June 22, 2010 8:41:34 PM
Why we need R5 and R8 here? I thing it the same as R4 and R7.
rounak
Automatic 12V Lead Acid Battery Charger
Friday, June 04, 2010 3:31:52 PM
hi, can i use TYN612 instade of BRX49 SCR? because BRX49 SCR is unavailable only TYN612 available.please hurryup sir i m on line...
anonymous
Automatic 12V Lead Acid Battery Charger
Wednesday, June 02, 2010 4:13:38 AM
So this circuit can charge any sealed 12V battery? What about higher voltages? Would this design work to maybe charge electric scooter batteries?
anonymous
Automatic 12V Lead Acid Battery Charger
Monday, May 31, 2010 11:29:24 AM
To avoid battery discharging in event of mains faiIure, fit a relay whose (230v) coil is energised by the input supply, and switch the charger output + via the N/O contacts of the relay. clsed when power present, open when not. Simple, cheap.
Steve Quah
Automatic 12V Lead Acid Battery Charger
Sunday, May 16, 2010 7:07:11 PM
You can avoid discharging the battery when the power is off by adding a diode at the output +ve. By the way the circuit does not work with Full-wave rectification right?

(Editor's notes: Adding the diode would prevent this circuit from working.)

Ajin vishnu A.S
Automatic 12V Lead Acid Battery Charger
Tuesday, May 11, 2010 10:09:32 AM
This circuit is a good one. I can easy understand it.
JPL
Automatic 12V Lead Acid Battery Charger
Monday, May 10, 2010 9:05:57 AM
Would leaving the battery connected to the circuit while not plugged in be cured by putting a diode between the charging circuit and the battery on each terminal? If so, what should be used
Tanveer
Automatic 12V Lead Acid Battery Charger
Thursday, May 06, 2010 1:15:29 PM
what if i connect the same p600 diode at the positive of output.... i think this will solve the problem of discharging the battery when there is no power! is it so??? :)
gopalagowda k
Automatic 12V Lead Acid Battery Charger
Wednesday, May 05, 2010 1:19:46 AM
hi sir, i want to know how much time the battery takes to get fully charged...
Brendan
Automatic 12V Lead Acid Battery Charger
Sunday, April 25, 2010 12:34:21 AM
Hey, 2 questions about this circuit. 1) if i were to put diode on the 12Vout and -12Vout in the direction of the output would this prevent the battery from discharging if there were a power outage? 2) if i were to try and split the Vout's in parallel, how many batteries would this circuit be able to re-charge? ( theortically it shouldn't matter, but in reality? ) - yes i am aware this would drastically change my charge time ( factor of half? for each successive battery) This circuit looks like a great alternative for me looking into making an electric vehicle =) Thanks
zad
Automatic 12V Lead Acid Battery Charger
Tuesday, January 12, 2010 9:14:58 PM
i need to powered up a 12V 4A load, at the same time charge up a back up battery of 12V.can this circuit works for my application?
anonymous
Automatic 12V Lead Acid Battery Charger
Saturday, January 09, 2010 4:28:35 PM
please how can i adapt this circuit to a 6 v lead acid battery ??
anonymous
Automatic 12V Lead Acid Battery Charger
Saturday, December 26, 2009 3:59:21 AM
i want to use 40 amt triac for bigger AH battery pls is it possoble?
jeffreywong
Automatic 12V Lead Acid Battery Charger
Friday, December 11, 2009 5:32:53 AM
1) For the 12V lead acid battery charger, can i use a 240V- 12V / 2A transformer instead of 120V transformer ? 2) Can i use this charger in my 12V 25A battery ? 3) If so, how long i need to charge it until full ? Thanks...
phermsin
Automatic 12V Lead Acid Battery Charger
Thursday, December 10, 2009 3:17:56 AM
AC source only
Matthew Schembri
Automatic 12V Lead Acid Battery Charger
Wednesday, October 28, 2009 3:48:17 PM
Hi, can the circuit be run from a 12V dc source or does it have to be AC ?
swisskid
Automatic 12V Lead Acid Battery Charger
Saturday, October 17, 2009 5:39:13 PM
i av found the substitute for brx49 i actually used BT169 its difference is that BRX49 can accommodate a max voltage of 200v while BT169 can accommodate up to 400v but they both do pretty much the same work. i av used it in my circuit and it worked. the only problem that i av is that i need a modification for 24v charging system.
user
Automatic 12V Lead Acid Battery Charger
Monday, October 12, 2009 4:10:48 PM
You can try 2N6565 for BRX49. See http://www.classiccmp.org/rtellason/transdata/2n3001.pdf Notice the authorship of the schematic is not known. Please stop posting comments hoping someone will write you back. If you don't want this circuit to drain your battery if it's connected and unplugged, buy one more D1, and stick it between Q1/R1 and the battery, with the cathode connected to the battery side, and the anode connected to the component side. If you drew it on the schematic its symbol would be thus: Q1 & R1 ->|- to 12V battery.
Alan Mann Sr
Automatic 12V Lead Acid Battery Charger
Saturday, September 19, 2009 9:17:56 AM
I have put together this charger with these parts, DigiKey part # R1,R3= OD33IJE-ND R2 =100OHM 1/2W 3329P-101LF-ND pot R4,R5,R7,R8= 82W-2-ND R6= 100XBK-ND R9= OD102JE-ND C1= P13477-ND D1= SB550-E3/54 GICT-ND D2= 1N4004 DICT-ND D3= 1N4734A DICT-ND D4= LED Q1= 568-3651-5-ND Q2= EC103M-ND T1= TRIADMAGNETICS P#= F219X 115/12VAC 4A Now out put of transformer is 13.65VAC and out of D1 is 8,95VDC. On Q1 pin 1, 8.95VDC Pin 2, 1.05 which is the 12V + bat out put. Pin 3 Gate, 8.96. Q2 is Pin1, 8.3-V Pin 2 .41V Pin 3 -.2V, which is the -12V bat out put. So what have I done wrong? Any Help would be appreciated. I am trying to make a charger for my robot which has 4 6V SLA batteries 2 in series and then in parallel for 12V.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, September 08, 2009 12:32:38 PM
There is a problem, if you leave the charger at an unattended location and the power goes out, it will discharge the battery.

(Editor's notes: Yep.)

Sachin
Automatic 12V Lead Acid Battery Charger
Tuesday, September 08, 2009 11:36:32 AM
can i know the actual pin configurations of the triac and the scr used in the circuit?plsss.... PLEASE GIVE ME THE SUBTITUDE OF BRX49 scr i am from india and it is not aviable plz give me the another subtitude for it. I used tyn604 but LED is glowing Countinusly. please send me details and please send pcb layout. thank you.
Garouda
Automatic 12V Lead Acid Battery Charger
Thursday, August 20, 2009 6:03:16 AM
Why do you use a triac in a DC circuit? What about replacing D1 by a rectifier and Q1 by a thyristor?
cedric
Automatic 12V Lead Acid Battery Charger
Tuesday, August 11, 2009 9:45:34 AM
what other equivalent can one use to replace the thyristors if not found?
chandrashekar g
Automatic 12V Lead Acid Battery Charger
Wednesday, July 29, 2009 10:46:50 AM
sir i need brx49 scr but in local market not avilable in this number scr plase help me this scr eqlenet numer send my mail your sinci chandrashekar
Rachael
Automatic 12V Lead Acid Battery Charger
Monday, July 20, 2009 7:10:20 AM
Ya. its nice. i request you to kindly explain for me how it works. Theory and procedures used. Use my email please. Thank you.

(Editor's notes: Search the forum for this explanation.)

neil wright
Automatic 12V Lead Acid Battery Charger
Sunday, July 12, 2009 3:16:52 AM
l have this charger in my off road camper trailer and it has stop workingcan you help me out wiht it l live in perth is there a dealer here;
meto
Automatic 12V Lead Acid Battery Charger
Monday, June 22, 2009 2:55:52 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger with Transformer 24 volt 5A
Richard Hale
Automatic 12V Lead Acid Battery Charger
Saturday, June 20, 2009 6:24:24 PM
have yoy done anything with desulfators.I've biult 2 and I'm not convinced they do anything

(Editor's notes: They don't.)

umair
Automatic 12V Lead Acid Battery Charger
Friday, June 05, 2009 3:48:29 AM
sir plz give a substitute for BRX49.i cannt find it anywhere
caeser
Automatic 12V Lead Acid Battery Charger
Thursday, June 04, 2009 6:10:21 AM
the designer of this circuit has been used the half wave rectifiering .which performs that D1. without controlled rectification voltage so that the a.c voltage of secondary T1 must be within a stable range (12.5--13.5) volt .without widely shiffting. otherwise less than 12.5 volt there is no complet operation charging (full charge ) and more than 13.5 volt for long time may damage the battery .because you know the main a.c source that feeds the primary T1 is unstabl . do you know what is the equivalent circuit of a batte
Pedro
Automatic 12V Lead Acid Battery Charger
Saturday, May 16, 2009 11:43:47 AM
This shows that a lot of curious people that know zero about the principles, still try to build things. It is very elementary knowledge that what charges here is the peak current/voltage, not the RMs values, so it really does not matter if is half or full wave.
Philip Wadham
converting 24v charger to 12 volt
Sunday, May 10, 2009 5:59:43 PM
I have a 24 volt charger no longer used to charge power wheelchair batteries. I want to change this to a 12 volt charger for a car battery. Seems like it should be reasonably straightforward. How will I go about this.
Chris Van Der Westhuizen
Automatic 12V Lead Acid Battery Charger
Sunday, May 10, 2009 4:12:12 AM
I have 4 x 105 Amp 12v sealed solar batteries being charged off solar panels during the day. At night I would like this charger to come in via a day night switch and check the batteries are full, if not it must come in and fully charge these batteries, so that they are full at all times. However I do not want to overcharge or damage these batteries in any way. i ahve built this suggested circuit and tested it on various 9aH 12v sealed alarm type batteries with various shelf voltages (Battery Voltage as they are on my workbench and have not been charged for some time). However I have had to take my seconadary transformer voltage to 16v Ac to get anywhere near + 13v required to charge this type of battery, but I get a maximum of 100mA charging current. Am I doing something wrong. Please advise as soon as possible. Thank you for your kind assistance and keep up the good work. Chris
mfg
Automatic 12V Lead Acid Battery Charger
Wednesday, April 29, 2009 9:42:31 AM
12v , 7ah : what will happen if he battery is charged for 24/7 hours , charge voltage 13.5v , with out any cutoff circuit Is this the right way of charging pls help
alomgir
Automatic 36V -40A SMF Battery Charger
Tuesday, April 21, 2009 11:59:42 PM
dear sir, i need a auto charging circuit which will be 36VDC auto charger. can i get such type of circuit diagaram with parts list.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, April 14, 2009 5:26:39 PM
All the circuits this person has are failures. I have built a few and none of them seem to work.This circuit shows that when 12v AC passes through D1 straight away you will only get half the voltage which is 6 volts dc so how is it going to charge a 12 volt battery? Shame on you for putting stuff like this on the net.

(Editor's notes: This charger works fine. You are making mistakes.)

Gary Hardman
Automatic 12V Lead Acid Battery Charger
Sunday, April 12, 2009 6:47:59 AM
If only it was so simple ... Unfortunately, due to the circuit having no smoothing whatsoever, any battery would be subject to so much 'ripple' current that it would be destroyed in a short space of time!

(Editor's notes: Been using this circuit to charge batteries for nearly 10 years. No issues.)

onesmus
Automatic 12V Lead Acid Battery Charger
Sunday, April 05, 2009 7:30:12 AM
instead of using ac supply ,can i use solar panel with output voltage 13.8v what regulating component can i use?
anonymous
Automatic 12V Lead Acid Battery Charger
Friday, March 13, 2009 4:43:23 AM
if i need to charge the 12V/9ah battery and simultaneously run a dc fan, how do i protect the battery getting discharged when there is a low sun light(can i use zener diode if so what could be the value i need to use?)
indi
Automatic 12V Lead Acid Battery Charger
Thursday, March 12, 2009 12:12:05 PM
can this charger, charging the lead acid battery 6V? If this can do it, what needs to be change?Thanks for the information
Jamey
Automatic 12V Lead Acid Battery Charger
Sunday, March 08, 2009 12:50:34 AM
I have two 24 volt industrial chargers, can i convert these for charging 12 volt automotive batteries? These chargers originally were charging four six volt gel cell batteries. I have another 24 volt charger that was charging four six volt deep cycle batteries.
purwanto
Automatic 12V Lead Acid Battery Charger
Thursday, March 05, 2009 6:38:29 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger. what component should i change ? thanks
purwanto
Automatic 12V Lead Acid Battery Charger
Saturday, February 28, 2009 6:13:48 PM
Sir,How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger with Transformer 24 volt 5A . what component should i change ? thanks
shalom
Automatic 12V Lead Acid Battery Charger
Friday, February 20, 2009 2:58:29 AM
Pretty nice circuit you got, but please i am in need of an Automatic 12V-120Ah battery charger circuit diagram.
anonymous
Automatic 12V Lead Acid Battery Charger
Monday, February 16, 2009 7:00:06 AM
Q1 is that a triac or an scr? i think Q1 Is an scr .
shola
Automatic 12V Lead Acid Battery Charger
Saturday, February 14, 2009 10:11:14 AM
how can i make the 12v lead acid battry charger to a 24v charger.
anonymous
Automatic 12V Lead Acid Battery Charger
Monday, January 12, 2009 12:49:45 AM
Hi, if you can provide a charge controller which is charger will automatically turns off the transformer when it reach 13.8V and it will be turning on automatically when the voltage goes down to 11V to avoid battery discharge. Thanks & regards
BUFF
Automatic 12V Lead Acid Battery Charger
Saturday, January 03, 2009 3:27:07 PM
TO PREVENT BATTERY DISCHARGE WHILE AC POWER IS SHUT OFF, WHILE BATTERY IS STILL CONNECTED CAN BE PREVENTED BY INSTALLING A DIODE ( 5 amp @50 volts) AT THE JUNCTION OF Q1 AND R1 WITH THE ANODE TO THE JUNCTION AND THE CATHODE TO THE POSITIVE TO THE BATTERIES POSITIVE POST .
O. Sewtohul
Automatic 12V Lead Acid Battery Charger
Monday, November 17, 2008 1:09:52 AM
How can the charger supply 4A at >12V when the transformer secondary voltage is limited to 12V? Shouldn't the transformer secondary be at 15V.
waqar
Automatic 12V Lead Acid Battery Charger
Sunday, November 16, 2008 11:04:00 AM
very good circuit
sudeep
Automatic 12V Lead Acid Battery Charger
Monday, October 27, 2008 2:58:10 AM
sir i want Automatic 12V Lead Acid Battery Charger.but the specification is when the battery is full (14v) the circuit is cutt off the charging trans former .i think it protect battery as well as transformer.so kindly send this types of circuit
rocketman221
Automatic 12V Lead Acid Battery Charger
Saturday, October 25, 2008 10:22:35 PM
how can i modify this to run off of a solar panel
mehul
Automatic 12V Lead Acid Battery Charger
Tuesday, October 21, 2008 10:03:47 PM
Is your circuit have over charging protection and it is continuous rated? can i use it for parmenantly connected on mode.? what changes if i want over charging protection.
Nwokeji St Martins
Automatic 12V Lead Acid Battery Charger
Sunday, October 19, 2008 1:13:16 PM
To modify the automatic 12V lead Acid battery charger to become a 24V lead Acid charger, do U need to recoil the transformer?
Ajmal Hussain
Automatic 12V Lead Acid Battery Charger
Thursday, October 09, 2008 5:04:04 AM
If input voltage varies from180v to 240v (At transformer primary) Then can I use a Zener Diode (Paralell with transformer secondary) for taking 12V output from transformer,if i can do then what are the specification of that Zener Diode.
Guilherme Guebur
Automatic 12V Lead Acid Battery Charger
Monday, October 06, 2008 4:34:50 PM
Sr.; Can I use 100ohms/2W resistor in R4,R5,R7,R8 ? I need a substitute of BRX49?, I don't find this component here in Brazil. Thanks!!!
michael uson
Automatic 12V Lead Acid Battery Charger
Monday, October 06, 2008 3:08:52 AM
instead of using ac supply, can i use solar panel with output voltage 13.8v what regulating component can i use?
GandhiGandhianonymous
Automatic 12V Lead Acid Battery Charger
Thursday, October 02, 2008 4:49:56 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger. what component should i change ? thanks
Bob Dole
Automatic 12V Lead Acid Battery Charger
Friday, September 26, 2008 1:08:18 PM
I need help determining what to use for the BT136 Triac and the BRX49 scr. I am trying to find suitable replacements for both. Which BT136 specifically is required? There is an entire series of BT136 Triacs. Do you have any suggestions for more common components that will work as replacements (for both)? Many thanks!
OME
Automatic 12V Lead Acid Battery Charger
Sunday, August 24, 2008 7:14:16 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger. what component should i change ? thanks
Jay Lorenzo
Automatic 12V Lead Acid Battery Charger
Sunday, August 10, 2008 8:32:52 PM
Dear Sir, can i use a 6A 12V instead of 4A 12V? Is there any part should i relaced and if there is what components and value it is?
RODNEY LAMAY
Automatic 12V Lead Acid Battery Charger
Thursday, July 24, 2008 11:47:40 PM
Sir I have a 18 volt output solar cell.I would like to have your charger to put out 5 to 600 ma. For my place in the desert.What if any resister changes do i have to make please? Thank You Rodney LaMay P/S i have a 12 volt battery
Uagbae Izzi
Automatic 12V Lead Acid Battery Charger
Wednesday, July 23, 2008 8:58:23 AM
Please i would like to know what modifications i could make to the circuit to enable me charge 6-8 12v 100amps battery at a time. Ps you are doing a great job. Many thanks. Izzi
Alex
Automatic 12V Lead Acid Battery Charger
Sunday, July 13, 2008 3:39:27 PM
Can we use this charging circuit for charging battery in motorcyle ? I mean where power supply is from stator windings which is variable ? Any response will be appreciated. Thanks.
m a raza`
Automatic 12V Lead Acid Battery Charger
Thursday, July 03, 2008 3:24:00 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V/80A Lead Acid Battery Charger.
Sudhindra
Automatic 12V Lead Acid Battery Charger CHanging circuit for 6volt Battery
Sunday, June 22, 2008 8:27:53 AM
Sir, I am using a 6 Volt battery. How can I convert this circuit for charging my 6volt Battery?
umair
Automatic 12V Lead Acid Battery Charger
Monday, June 09, 2008 3:01:45 AM
it will charge but charging current is very low approx. 0.6-0.9A,can i increase.
DWI
Automatic 12V Lead Acid Battery Charger modify
Tuesday, June 03, 2008 2:29:44 AM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger. what component should i change ? thanks.
metador
Automatic 12V Lead Acid Battery Charger
Thursday, May 29, 2008 4:08:47 PM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, May 27, 2008 3:12:32 PM
I would like to charge 3 batteries (12V 12 Amp/h each) in serial connection totaling 36V. What resistance values should I change to? Best regards.
joseph nabhan
Automatic 12V Lead Acid Battery Charger
Friday, May 16, 2008 5:45:36 AM
dir sir how do i modify automatic 12 v lead acid battery charger to automatic 30 v 7 A lead acid batery charger
BAKARE OLUFEMI
Automatic 12V Lead Acid Battery Charger
Tuesday, May 13, 2008 9:23:44 AM
yeah i need to know how i can improve or simply step up my charger capacty cos 4A is very small to charge my device so i can i step it up i have built my inverter but i need to incorporate the charger circuit into it and the battery i used is 200Ahx 6 so help me out on how to get a suitable charger
frank
Automatic 12V Lead Acid Battery Charger
Saturday, May 10, 2008 8:24:47 PM
Can i use my 6A 12V transformer on this circuit? I need your advise sir, and reply me, Thank you.
Alejandro Bemporat
Automatic 12V Lead Acid Battery Charger
Monday, April 28, 2008 2:44:48 PM
Hi i will like to make a 36VDC charger 20AMPs if you can help me TKS
TAUQEER
Automatic 12V Lead Acid Battery Charger
Monday, April 28, 2008 2:32:15 PM
Sir Thanks a lot of your its a very helpful circuit.
mohy
Automatic 12V Lead Acid Battery Charger
Sunday, April 27, 2008 12:05:57 PM
it's very good inormations and design . what do you mean by U1? in last raw of part table
Alfred
Automatic 12V Lead Acid Battery Charger
Sunday, April 27, 2008 5:40:14 AM
Dear sir i am designing solar charger to charge a 12V Acid Battery with 185 AH (Amp per hour). the solar cell is 12V, i can run 12V energy saver with the cell. what kind of modifications will be done in above circuit to charge battery thanks
ashimas
Automatic 12V Lead Acid Battery Charger
Friday, April 25, 2008 1:40:54 AM
Sir, I am using this circuit for 6V battery.but the current flowing through the circuit is not as per our requirement.Please give the circuit diagram and working for 6V battery with current less than 0.2A.
GOPAL
Automatic 12V Lead Acid Battery Charger
Tuesday, April 22, 2008 6:22:47 AM
OK THIS CIRCUIT IS OLD TYPE.NO PROTECTION.
jawad
Automatic 12V Lead Acid Battery Charger
Monday, April 21, 2008 3:33:24 PM
Is this circuit workable for batteries from 50 to 175AHr? if not what changes required to do so, also how much harm this circuit can does to battery, is it reliable to work as first part of UPS.
Benjamin Naworio
Automatic 24V Lead Acid Battery Charger
Monday, April 21, 2008 10:29:20 AM
How do I modify automatic 12v lead acid battery charger to Automatic 24V Lead Acid Battery Charger.
ghanem
Automatic 12V Lead Acid Battery Charger
Saturday, April 19, 2008 5:22:57 PM
after building the circuit i found the outpot V less than 10V ,so added 2200 mic F capacitor after D1 which raises to 12V ; but the led before and after adding did not putoff although removing the VR.please help .
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, April 15, 2008 9:23:36 AM
Hi, How can we add the 12v battery charger to the inverter to continue to charge the batteries while converting power from the battery to 240v
Nelita
Automatic 12V Lead Acid Battery Charger
Sunday, April 06, 2008 6:53:35 AM
sir how do i modify the circuit to charge a 12V battery but for a different current?
bryan chua
Automatic 12V Lead Acid Battery Charger
Friday, April 04, 2008 10:23:21 AM
sir's do i have to modify the circuit for a 20A 12V transformer? pls reply... thanks...
gps
Automatic 12V Lead Acid Battery Charger
Wednesday, April 02, 2008 7:41:35 AM
Thanks for schematic boss.. Will try it soon... Joel www.apobae.com www.garmin.co.id www.gps.co.id
afaq
Battery Voltage Correction
Sunday, March 30, 2008 5:42:06 AM
In this circuit you suggested 12V ac Transformer, not to mention that the diodes will lower the output voltage also lead acid battery isn't at 12V even when discharged, its around somewhat 12.2~12.3 , and at fully charged its at 12.8 volts. So i wonder how this circuit gonna charge battery ???

(Editor's notes: The output of a 12V transformer is somewhat higher then 12V.)

KAYODE KEHINDE ABAYOMI
Automatic 12V Lead Acid Battery Charger
Tuesday, March 25, 2008 9:56:49 AM
what are the possible precaution that need to be followed to prolonged the live of the battery charger
Ed Borstel
Automatic 12V Lead Acid Battery Charger
Monday, March 24, 2008 11:34:16 AM
You mentioned in the notes that the transformer could be changed to 18V output for charging larger batteries. Is this also true with 24 volt batteries? I need to charge 24 volt aircraft batteries. Will this ciucuit work for this application?
anyoka
Automatic 12V Lead Acid Battery Charger
Friday, March 14, 2008 9:24:03 AM
sir, how do i modify this charger to get it charge a 24V still with 4A.THANKS
Juzar Gandhi
Automatic 12V Lead Acid Battery Charger
Monday, March 10, 2008 11:44:55 PM
Can I use circuit for three phase delta connections : 110V to 200V AC inout to charge 24V : 40 amps lead acid batteries: please comment with alternative
rocketman221
Automatic 12V Lead Acid Battery Charger
Monday, March 10, 2008 2:59:21 PM
can a i make this so that i can use just as a charge controller with my own power supply
AKINOLA GABRIEL
Automatic 12V Lead Acid Battery Charger
Sunday, March 09, 2008 5:23:06 AM
the site has given me an important clue which i think will help me execute my projet
Michael
Automatic 12V Lead Acid Battery Charger
Saturday, March 08, 2008 8:31:29 AM
It would be kind of you if you can help to design a charger to charge 120AH lead-acid battery via solar cell and alternatively main power line.
meline fereira
Automatic 12V Lead Acid Battery Charger
Friday, March 07, 2008 12:42:11 PM
PLEASE GIVE ME THE SUBTITUDE OF BRX49 scr i am from india and it is not aviable in mumbai plz give me the another subtitude for it
Amrit Kharel
Automatic 12V Lead Acid Battery Charger
Friday, February 29, 2008 11:32:09 AM
Can i charge 80 Ahr battery or more with the help of this charger or will i have to increase the value of the components used. Please help me out.
kalyan kumar.b.r
Automatic 12V Lead Acid Battery Charger
Saturday, February 16, 2008 4:24:03 AM
Sir, I need to know the working principle of circuit diagram since i wanted the charger for 48V system with 4A. How do i modify this circuit. Thanks.
toto garcia
schematic diagram of automatic 24 V, 15A battery charger
Sunday, February 10, 2008 5:35:04 AM
Can we use this diagram in 24v transformer?
herry parwatha
Automatic 12V Lead Acid Battery Charger
Sunday, February 03, 2008 9:39:47 PM
If I want to use 10A transformer, did the rest of part will remain the same or must be use the bigger amps.? Thanks
dasari
Automatic 12V Lead Acid Battery Charger
Thursday, January 31, 2008 11:42:35 PM
we need description of the circuit and operation........... what is need for AND gate to the input of transformer.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, January 29, 2008 11:55:55 AM
PLEASE GIVE ME THE SUBTITUDE OF BRX49
alex jagal
Automatic 12V Battery Charger
Thursday, January 24, 2008 10:46:33 AM
I need a 12V 35A/20Hr car battery charger please do send me.
P Bunyan
Automatic 12V Lead Acid Battery Charger
Saturday, January 19, 2008 9:20:08 PM
Can a 12 volt center tapped XFMR be used with this circuit to charge both 6 or 12 volt batteries by switching the cener tap and the bottom XFMR leg? Thank You.
Senior Design
Automatic 12V Lead Acid Battery Charger
Friday, January 18, 2008 1:14:36 AM
Is their a way to make the charger work using 25VDC rather than the 120VAC. I need a battery charger that will run off of 25VDC. Any comments will help.
vishal monga
Automatic 12V Lead Acid Battery Charger
Thursday, January 17, 2008 5:40:43 AM
Respected Sir, Can u plz provide me the ckt diagram for a microcontroller based batterr charging ckt Waiting for a positive reply
emmanuel
Automatic 12V Lead Acid Battery Charger
Tuesday, January 15, 2008 6:05:53 AM
it is good, but i need something more of automatic. keep up your good work.
LINH
Automatic 12V Lead Acid Battery Charger
Monday, January 14, 2008 10:45:30 PM
It is good, but i have a 12V-7AH battery. According to theory, We have to charge it by 7/10= 0.7A. So 4A is too high, do you have any idea to decrease it to around 0.7-1A.
madhu
Automatic 12V Lead Acid Battery Charger
Monday, January 14, 2008 4:18:48 AM
Please send me the functioning of each components(description). URGENT!

(Editor's notes: I'll save you the trouble of searching the forum: http://www.aaroncake.net/forum/topic.asp?TOPIC_ID=5954)

vince
Automatic 12V Lead Acid Battery Charger
Monday, January 14, 2008 1:37:12 AM
i would like to know that if this circuit will able to charge up to 12v 7ah batttery simultaneously?
sampurna
Automatic 12V Lead Acid Battery Charger
Wednesday, January 09, 2008 12:49:00 AM
This is good but can u give me the circuit description and cant this be implemented even more simply?
dinojoy
Automatic 12V Lead Acid Battery Charger
Tuesday, January 08, 2008 1:16:21 AM
respected sir, can i charge 18ah12v batterry with this ckt, can do it , which input powersupply require,this ckt make over voltage cut off ?
anonymous
Automatic 12V Lead Acid Battery Charger
Wednesday, January 02, 2008 3:04:40 PM
ENGINEER AYO HELP? Pls give me a circuit diagram that can be use as low battery cut-off and full cut-off e.g when a battery is working with inverter and when it runs down to 9v or 8.5v the circuit should cut-off and when it start charging immediately 13.5v or 14v and 14.5v is gained the circuit should also cut-off, and pls i also need a battery back up. e.g when a 12v battery is been used on inverter , the circuit will make it last at least two,three,four,five days or a week.
madhu
Automatic 12V Lead Acid Battery Charger
Saturday, December 22, 2007 12:44:57 AM
Sir, can we replace the lead acid battery by an SMF battery in the same circuit?
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, December 18, 2007 5:38:40 AM
can i up this to a output of 24VDc
sujan
Automatic 12V Lead Acid Battery Charger
Monday, December 17, 2007 2:40:47 AM
This is great but for 12v 120Ah battery it does not work? please can i upgrade this circuit?
komala
Automatic 12V Lead Acid Battery Charger
Wednesday, December 12, 2007 5:21:24 AM
hi, sir can you please give me the detailed description about the circuit operation and working of each component in the circuit. thank you

(Editor's notes: Search the forum.)

bbsoftck
Sunday, December 09, 2007 4:05:23 AM
Good site!
diva
Automatic 12V Lead Acid Car Battery Charger
Friday, November 30, 2007 5:51:25 AM
i would request you to tell me more about this circuit. plz send me an email about the design procedure and woking principle of automatic 12V Lead Acid Car Battery Charger Thank you

(Editor's notes: Search the forum, or read previous comments.)

Ben
Automatic 12V Lead Acid Battery Charger
Saturday, November 03, 2007 1:08:19 PM
Can you provide me the most simple design for a battery charger? Thanks
Budiono
Automatic 12V Lead Acid Battery Charger
Wednesday, October 31, 2007 3:56:26 AM
Sir, Can you please tell me how to make battrey charger with POWER MOSFET MTP3055,Autoshut-off, Polarity Protection,Short Circuit Protection? Thanks You
Andy
Automatic 12V Lead Acid Battery Charger
Tuesday, October 30, 2007 7:09:10 AM
is it possible to use this circuit on a 12v 45Ah 300A car battery?
anonymous
Automatic 12V Lead Acid Battery Charger
Monday, October 29, 2007 11:44:41 PM
Nice design. I believe I can answer a couple of the questions, in that you need to know what the allowable high rate charge can be for your application. If you have a big battery (e.g. 19Ah) you can drive a higher current to begin with like this design shows, but if you have a smaller battery (e.g. 2500mAh) you need to drive a lower initial current or you will probably create a toaster or an IED. Simply use a lower current output transformer and your high rate charge current will be lower too. Some component adjustments may be necessary to get the right threshold voltages. Idea: Add diodes (large enough to handle the current) on the output to prevent battery drain in the event of a power disconnect.
KAUSHLENDRA KATIYAR
Automatic 12V Lead Acid Battery Charger
Tuesday, October 23, 2007 6:06:34 AM
Dear sir, I REQ 12V 10Amp BATTERY CHARGER CIRCUIT WITH FLOT AND BOOST CHRGING ATOMATICALY CHANGE KINDLY SUGGEST ME
steve y.
Automatic 12V Lead Acid Battery Charger
Saturday, October 13, 2007 12:04:56 PM
much better if the whole assembly (picture of the circuit's assembly) must shown in this site together with the schematic diagram. well, this site is very good, i learned from it... thanks a lot...
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, October 11, 2007 11:24:46 PM
can i also use this charger to charge a 12v motorcycle(dry cell) battery?
h2n
Automatic 12V Lead Acid Battery Charger
Friday, October 05, 2007 9:32:19 PM
How about 12v 7A 10hr Sealed Acid batteries ? may I use that schema too? please reply me. thanks
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, September 27, 2007 4:21:10 AM
This project is helpful to the students who wanted to learn the basic concept of designing. R4 and R5 are connected in parallel may be replaced by a single resistor if the desired resistance value is available. R7 and R8 also have the same situation with R4 and R5 as they are connected in parallel. Being a half-wave rectifier circuit, the charging current is smaller compared to the fullwave rectifier circuits. Fullwave center-tapped or fullwave bridge type may be used as an alternative rectifier to this project.
Attilaus
Automatic 12V Lead Acid Battery Charger
Thursday, September 27, 2007 12:05:33 AM
Please tell me if this charger can be left to charge a battery for indefinined time,or it need other circuits? Regards
Patricio
Automatic 12V Lead Acid Battery Charger
Wednesday, September 26, 2007 11:48:00 AM
Thanks a lot fot the circuit, i have a question: can i use a full wave rectifier (4 diodes) instead half wave (1 diode). Thanks gg.
ryan
Automatic 12V Lead Acid Battery Charger
Tuesday, September 25, 2007 2:58:41 AM
i cant find BRX49 SCR,... can you give an equivalent componet that is widly avelable; thank you...
anonymous
Automatic 12V Lead Acid Battery Charger
Sunday, September 23, 2007 1:23:48 AM
Can I use 500mA transformer? And can I use TYN612 SCR instead of BRX49?
ANIL CHANDRA GHOSHymous
Automatic 12V Lead Acid Battery Charger
Saturday, September 22, 2007 1:02:31 AM
Sir , Can I use this circuit to charge 24 V battery ? Please suggest the componenent value changes. Thank you.
anonymous
Automatic 12V Lead Acid Battery Charger
Friday, September 21, 2007 7:06:58 AM
can u please show the whiole specification about the circuit? kindly sir. thanks
lkryzhijchertfd
Wednesday, September 19, 2007 1:03:10 PM
Good site!
MABILA SAKHI
Automatic 12V Lead Acid Battery Charger
Saturday, September 15, 2007 4:48:02 AM
Can I use a UPS to make it to power to a Computer power supply without the Mains for quite a long time
nagi reddy
Automatic 12V Lead Acid Battery Charger
Saturday, September 08, 2007 8:47:59 AM
can i use this circuit perminently to the battery because when power is gone to load automatically i want to conect this battery to load that means like backup battery. if any modifications required pl.give the additional circuit
ALADELOYE SILAS
Automatic 12V Lead Acid Battery Charger
Thursday, September 06, 2007 10:28:42 AM
sir, is there any substitute for the following: Q1-:BT136 TRAIC Q2-:BRX49SCR
ALADELOYE SILAS
Automatic 12V Lead Acid Battery Charger.12v-120 inverter
Thursday, September 06, 2007 10:21:44 AM
thanks to almighty for finding out such a site enhance students especially the young tech- with there career. I say a BIG weldone to the site management
CHETHAN
Automatic 12V Lead Acid Battery Charger
Wednesday, September 05, 2007 1:58:26 AM
IS THIS CIRCUIT REALLY WORKS
zzz
Automatic 12V Lead Acid Battery Charger
Thursday, August 30, 2007 3:20:09 AM
Can you also let me know about a UPS and how I can make it to power my Computer without the Mains for quite a long time.
Rock
Automatic 12V Lead Acid Battery Charger
Friday, August 24, 2007 4:39:01 AM
Thank you very much for this circuit
anonymous Tunde Ilesanmi
Automatic 12V Lead Acid Battery Charger
Tuesday, August 21, 2007 2:29:32 PM
Dear Sir, thanks a lot for all that you are doing for technological improvement and humanity in general. Please Sir,kindly help me with the full circuit diagram of automatic 12v lead acid battery charger capable of charging 12v 200ah battery automatically..Thanks in advance.

(Editor's notes: It's on the page about 8 inches above this comment.)

harold
Automatic 12V Lead Acid Battery Charger
Saturday, August 18, 2007 5:14:59 PM
can i use 5 amp transformer instead 4amp transformer?
HapTrail
Automatic 12V Lead Acid Battery Charger
Thursday, August 16, 2007 1:57:29 PM
This looks useful. It appears to be the half wave equivalent of a full wave battery charger from Harb.Frieght ~ $20 which is 6v/12v 2A/6A. Item 45005 very nice.
Nicholas
Automatic 12V Lead Acid Battery Charger
Wednesday, August 15, 2007 8:06:01 PM
I need to charge a 18v 1.2 amp lead acid battery. Also, can I use a 18v 1.2 amp dc power supply, it measures over 22v at no load.
khalili
Automatic 12V Lead Acid Battery Charger
Sunday, August 12, 2007 10:54:23 PM
Thank you for this circuit design
anonymous
Automatic 12V Lead Acid Battery Charger
Friday, August 10, 2007 12:35:32 PM
very good
Joseph Atsu
Automatic 12V Lead Acid Battery Charger
Wednesday, August 01, 2007 5:48:09 AM
HI, I WILL LIKE TO ATTACH THIS CIRCUIT TO AN INVTER CIRCUIT TO ENSURE THAT ANYTIME THERE IS A DROP IN THE BATTERY VOLTAGE, IT WILL AUTOMATICALLY BE RECHARGED. DO YOU THINK IT WILL WORK OUT?
julber
Automatic 12V Lead Acid Battery Charger
Thursday, July 26, 2007 9:24:04 PM
I am very thank u to the person who create this circuit but i am little bit pointed because it does not complete with the process of work, i have a question for you that can you explain me please, how the circuit of atutomatic Lead Acid 12volt charger can work????
Munsaf Munir
Automatic 12V Lead Acid Battery Charger For Pakistan
Wednesday, July 25, 2007 2:26:16 PM
I feel I will be cheating on myself if I don't thank you people for this great and wonderful work! THANK YOU Very Very much to let us easily get and learn this information. Can you also let me know about a UPS and how I can make it to power my Computer without the Mains for quite a long time.
sanwel
Automatic 12V Lead Acid Battery Charger
Sunday, July 22, 2007 10:08:28 PM
thank u
jawid
Automatic 12V Lead Acid Battery Charger
Thursday, July 05, 2007 6:09:28 AM
while looking for above circuit. I found this site and found very helpful. I hope you will maintain it. ok.
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, July 05, 2007 12:30:58 AM
good for the proffessional and the greens alike
wireless
Automatic 12V Lead Acid Battery Charger
Saturday, June 30, 2007 6:09:44 AM
Quite good for me.
Cobra
Automatic 12V Lead Acid Battery Charger
Tuesday, June 26, 2007 2:37:08 PM
It's a good design, however, using it in a smaller type of lead acid battery might blow the battery itself. using it on a bigger one like 2SM is good, and I appriciate the performance. thanks
adewale raji
Automatic 12V Lead Acid Battery Charger
Monday, June 25, 2007 10:26:48 AM
pls i need more xplanation on this project and how to design one for a bigger battery
Dmk
Automatic 12V Lead Acid Battery Charger
Friday, June 15, 2007 7:32:36 AM
I feel I will be cheating on myself if I don't thank you people for this great and wonderful work! THANK YOU Very Very much to let us easily get and learn this information. Can you also let me know about a UPS and how I can make it to power my Computer without the Mains for quite a long time.
LOZ
Automatic 12V Lead Acid Battery Charger
Thursday, June 14, 2007 7:32:11 PM
Hi, can you use a higher amp transformer for say a 12AH battery without changing other components ?
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, June 14, 2007 7:23:41 PM
Thanks for the diagram but what type of electrolite cap is needed
lekan
Automatic 12V Lead Acid Battery Charger
Wednesday, June 13, 2007 7:43:16 PM
i want to know how it work authomatic
lekan
Automatic 12V Lead Acid Battery Charger
Wednesday, June 13, 2007 7:35:35 PM
please kindly send me manual for the troubleshooting for in case of any problem
dinesh
Automatic 12V Lead Acid Battery Charger
Sunday, June 10, 2007 11:56:05 AM
It is a Very use fulfor the students like me.
Yuccabeth
Automatic 12V Lead Acid Battery Charger
Thursday, May 24, 2007 9:50:20 AM
pliz I wanna get some analysis of a battery charger that is to be used for the ups to supply 12 volts. Thanks.
anonymous
Automatic 12V Lead Acid Battery Charger
Thursday, May 24, 2007 5:04:36 AM
Can it be a risk of the gates on the circuit board can be burned off, because of the high current?
anonymous
Automatic 12V Lead Acid Battery Charger
Friday, May 18, 2007 3:15:03 AM
can you please send me the principle of operation of this battery as i want to build one for myself. Thank you.

(Editor's notes: http://www.aaroncake.net/forum/topic.asp?TOPIC_ID=5954)

gm_karutz
Automatic 12V Lead Acid Battery Charger
Sunday, May 06, 2007 7:54:05 AM
Can u send me,the pcb layout of this project....please send me also some substitution af BRX49 SCR..because i cant buy here in our area...
ken roux
Automatic 12V Lead Acid Battery Charger
Saturday, May 05, 2007 5:01:11 PM
Is it possible to charge multiple 12V 3Ah SLA batteries in parallel at once with this circuit? would anyone be able to recommend any circuit modifications to do so? thanks.

(Editor's notes: Yes.)

cyprian odhiambo
Automatic 12V Lead Acid Battery Charger
Saturday, May 05, 2007 1:40:51 PM
pliz sir,kindly e-mail to me the design calculations for the Automatic 12v lead acid battery charger.i interested in making the project and presenting it to the panel.Thanks in advance yours,cyprian.
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, May 01, 2007 2:59:48 AM
First, thank you for your diagram. How can I use a 12vdc input to charge a 12vdc battery?
FANNY
Automatic 12V Lead Acid Battery Charger
Sunday, April 29, 2007 11:44:18 AM
CAN YOU SEND ME PLEASE THE PCB OF THIS CIRCIUT
anonymous
Automatic 12V Lead Acid Battery Charger
Saturday, April 28, 2007 10:25:36 AM
Is it possible for you to supply the design calculations?
murali
Automatic 12V Lead Acid Battery Charger
Friday, April 27, 2007 12:24:27 PM
dear sir, i want clarify about 12 v battery charger , how much for the max amps battery will be conected, thankyou, murali.
fedfray
Automatic 12V Lead Acid Battery Charger
Tuesday, April 24, 2007 11:10:39 AM
can that circuit use for 24 vdc and 10 A? aand 12 Vdc 10 Amp? what component should change?
benard okidia
Automatic 12V Lead Acid Battery Charger
Monday, April 23, 2007 9:20:41 AM
i highly appreciate your notes they have been of great help to me.
Torben Holmelund
Automatic 12V Lead Acid Battery Charger
Monday, April 23, 2007 7:32:35 AM
Hi. Great design. Currently I'm looking for at charger to small motocycles, as it is over charging the battery. So I want to know if Q1 can be changed with a TIC 263M? (to increase the current) Best regards, Torben
izhk baqish
Automatic 12V Lead Acid Battery Charger
Friday, April 13, 2007 3:08:36 PM
HI THENK'S FOR AGRAET CIRCIUT CAN YOU SEND ME PLEASE THE PCB OF THIS CIRCIUT. thank you.
Peter
Automatic 12V Lead Acid Battery Charger
Tuesday, April 10, 2007 2:10:55 AM
Hi, Have you had any posative comments from whom have built this charger ? Would I be able to use these on Marine type GEL batteries? Does the current self limit in case the battery is flat ? kind regards Peter

(Editor's notes: Works great. I use it all the time.)

preety sharma
Automatic 12V Lead Acid Battery Charger
Sunday, April 01, 2007 12:48:22 PM
worst charger i have ever seen i can make it more effecient
anonymous
Automatic 12V Lead Acid Battery Charger
Saturday, March 24, 2007 2:37:08 AM
Can this be modified for 24 Volts
anonymous
Automatic 12V Lead Acid Battery Charger
Tuesday, March 20, 2007 8:05:34 AM
a relay can be added to the circuit in order not to drain the the battery if the circuit was unpluged. the coil of the relay can be connected after D1 or a bridge and its normally open switch can be connected in series with the +ve of the battery
Ani
Automatic 12V Lead Acid Battery Charger
Saturday, March 17, 2007 4:06:16 AM
drawing such a huge current with a half wave rectifier continiously will destroy trafo. a bridge rectifier may be used instead.
james dede
Automatic 12V Lead Acid Battery Charger
Friday, March 16, 2007 10:10:52 AM
i need the above diagram in my box
oderinde taoreed
Automatic 12V Lead Acid Battery Charger
Wednesday, March 14, 2007 5:30:42 PM
is it possible to use a bridge rectifier instead of D1?.Please I will be glad if my question is answer as soon as possible.THANKS
sajid
Automatic 12V Lead Acid Battery Charger
Wednesday, March 14, 2007 6:21:23 AM
Please explain briefly circuit function of lead acid battery charger .

(Editor's notes: See this forum topic)

islam
Automatic 12V Lead Acid Battery Charger
Tuesday, March 13, 2007 5:05:35 AM
its nice
George Lobastov
Automatic 12V Lead Acid Battery Charger
Sunday, March 11, 2007 2:27:42 PM
Which of suppliers could I used to get parts for that your Charger?
jodelou
Automatic 12V Lead Acid Battery Charger
Thursday, March 08, 2007 12:00:03 AM
can i know the actual pin configurations of the triac and the scr used in the circuit?plsss....

(Editor's notes: Datasheet...)

wongalethu
Automatic 12V Lead Acid Battery Charger
Tuesday, March 06, 2007 4:21:32 AM
My name is wongalethu, i just want to know how long or how many minutes is the charger will it take to charger a battery. thank you.

(Editor's notes: Depends on the size of the battery.)

anonymous
Automatic 12V Lead Acid Battery Charger
Friday, March 02, 2007 12:34:23 AM
Ibuilt this circuit but LED not working voltage accross the LED is very very low 0.09v -0.06v what would be the problem
George Lobastov
Automatic 12V Lead Acid Battery Charger
Thursday, March 01, 2007 12:34:28 PM
Could you tell me how can I buy the parts for both Chargers - #1 and #2, please.
oti ogah
Automatic 12V Lead Acid Battery Charger
Wednesday, February 28, 2007 1:39:14 PM
please i need a circiut diagram for 12V/5A battery charger
oti ogah
Automatic 12V/5A Lead Acid Battery Charger
Wednesday, February 28, 2007 1:35:13 PM
i need a circiut diagram for the above.please send to my box
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