6 or 12 Volt Tractor Pulls 6 Volt Trailor

Bad idea, for two reasons: 1. Very inefficient: lots of energy used for heating up the resistors, and 2. resulting voltage will not be constant 6 Volt, but depend on the load: braking lights turn on, voltage drops. Direction indicators will flash - all other lights will reciprocate. You'd be rather looking for a switching regulator, as those don't suffer from the problems above.

For the ballast resistor (required to reduce 12 volts to 6 volts for the ignition coil), use a generic Chrysler style (NAPA #ICR13 ) or equivalent.

Beware of lenzrulz. He is the most notorious liar, spammer and hypocrite on EveryCircuit. lenzrulz projects himself as victim, while he's creating resentments by his very own actions, and has been doing so for years. Be wary when he presents himself as tech-savvy individual - his incompetence in the field of electronics is striking. But don't take my word for it, see for yourself. Should you engage into debate with him, keep a hardcopy or screenshots of what was said - he may manipulate his comments. He continuously reposts his crappy spam under the pretext of "cleansing of defamatory comments", but has been observed doing so with crap which didn't even contain a single comment at all. As self-declared master of debates (rather, master of hot air and moronic "Lol"s) he doesn't hesitate to fabricate fake "evidence" to support his lies. He is not interested in Electronics, but in provocation.

The alternator will not charge the 6 volt battery.

@Imccoig, ignore @Bushmills comment, the admins are looking into his deplorable behaviour.

Shown as two six volt batteries in series but it is one 12 volt battery in truck with extra post on battery cells to make 6 volts to power trailer lamps. Truck charges the 12 volt battery.