[orange4boy]

If you have the extra juice the inverter-charger works well. It's a bit of a pain though because most chargers are not designed to be power supplies. but you have to turn on the ignition, turn on the inverter, turn on the charger then hope the charger does not decide that the batteries are full and stop charging.

I think you may need to have an extra battery. I'm not sure how it would work to try to charge a battery with itself. Will it become a black hole, sucking up the universe? we do not know... Will it work as a power supply with no battery attached? I have not tried that yet... There is also the problem of efficiency losses because with each conversion you lose some power to heat. So if you have the extra capacity, fill your boots. I suppose if you are just powering the coil and the fuel pump you could get away with a small, cheap dc-dc converter. I'm considering this myself. It saves the pain of turning those suckers on and off every time you use the car.

There are chargers out there that are both a dc-dc and a charger. Can't remember the name right now...brain. not. working... error... error...does not compute.