I use Idec for controlling everything, you don't need any charger to keep the batteries up, and you can change the program to suit the way you want it set up.
I just don't under stand it. OFF MEANS OFF.
I run 2 plcs on my car, one for motor management the other for lights, horn, blinkers, brake and tail lights etc. There is no draw when the E STOP is on. It has a EPROM so you don't loose memory, I have several options the way I set it up, crank, no spark, fuel pump only, ignition only, crank only any combination you want.
Blinkers each side blink at a different rate, just to be different, brake lights flash 3 times then stay on for 5 seconds, then flash 3 times until the brake is released, I have a remote mode then when away from the car, each light will flash in a circle around the car, do this 3 times, then in another 5 minutes goes the opposite way, people will see them flash with nobody around, then stare at the car wondering, then they start to walk away and it does it again the opposite way, screws with peoples mind. Now thats fun.