The processor is based on a ATmega8 micro controller connected to 20 MOSFETs and an Accelerator Potentiometer. Each MOSFET switches a solenoid for 100 ms if activated by the ATmega8. The processor can put a switch in the bypass position or in the position where the battery is switched in series with the other batteries. Two solenoids are used for the two positions of each switch. The main spring in the switch keeps the middle switch arm in the required position after it has been activated for a 100 ms. (Therefore no excessive power dissipation in the solenoids.)
5V supply is provided via a standard 7805 regulator circuit from the 12 V vehicle utility battery.
The controller circuit diagram is shown in the figure below.
The program is written in Basic Language. The listing is given below.
The program was created and compiled with BASCOM AVR and the programmer used is the USB-ISP programmer, both available from www.mcselec.com
The processor can be constructed using breadboard and installing it into an enclosure