A 12-0-12 volt transformer rated at 5 amp output may charge a low battery enough to start vehicle. I figured 13.5 volt in simulator.
The DC 0 to 5 amp meter in front of battery positive terminal is not shown. As 8 volt battery charges the current goes down which would show on ampmeter.
Do not confuse the positive and negative terminals connecting to battery.
Two diodes are 1N4007.
One capacitor is 2200uF/25V.
