| rafoster |
Posted - Sep 11 2008 : 3:25:17 PM
Hi there. I am interested in building a circuit that when triggered will close one relay immediately, another relay one second later and a third relay 2 seconds later
The application would be to provide a soft start for childrens electric powered ride-on vehicles which have been upgraded from the stock configuration of 12V to 18V or 24V. In most vehicles this is a straightforward operation and simply involves boosting the power supply to the appropriate voltage. However the modification can result in reduced gearmotor life due to the full on/off acceleration. Some manufacturers include a simple circuit board which controls the output, giving 1 second of 6V then allowing 12V to the motor circuit. Vehicles with this circuit board cannot be upped in voltage without frying the board.
Many enthusiasts are advocates of installing PWM controllers from electric scooters because this provides the soft start and variable speed, and they are reasonably priced, however these generally also have a voltage constraint in that they must run at 24v or 36v.
My goal here is to produce an easily assembled circuit board that can be separately powered by a 9V battery and used to control the output of any 3 battery array using dpdt relays... basically when the throttle is depressed, adding the second battery and then third battery to the circuit in series at 1 second intervals.
The output would look like this - when the NO throttle switch is closed the first relay would be closed, providing power only from the first 6v battery. one second later a second relay would close, adding the second 6v battery to the battery array in series, upping the voltage to the motor to 12V. After another second the last relay would close, adding the last battery to the array in series and providing 18V to the motors. When the throttle switch is opened again, the circuit should reset.
Does this sound feasible or worth the time? Or should we all just stick to the $15 PWM scooter controllers?
Thanks! |
