1 battery or 2, 12V

[voltdr]

Always remember that heat is the enemy to EVERYTHING......... When your starter is cranking over for 30-45 seconds, it is building a lot of heat inside the starter itself. More heat equals more friction. As someone mentioned, as the voltage drops the amperage goes up. It can be a snowball effect. I run the same size (as the positive) ground wire from the battery directly to the block. Chromemoly is not a good electrical conductor. Soldering your connections is good IF done properly. Not everyone knows how. A fully charged 12V battery should read 12.6V after the surface charge is dissipated. If your battery is reading 12.1V. It will take approx. 10 hours to charge the battery using a 10A charger. I'm going from memory, I used to have a chart from AC Delco but not anymore. The point is that it takes longer than you think to charge a battery. Charging for 20-30 minutes between rounds is NOT adequate. Buy a good battery charger that is made for your type of battery and keep it on your car anytime the car isn't running. I've never seen anyone lose a race because their car started but a lot because it didn't.
Dan