genikz

Battery tenders are the key. My Odyssey 680MJ knock-off (can't recall the name off the top of my head) lasted 2 years. About 1.5 years in, I forgot to put the tender on after one event and the battery completely died. I did a full charge with a full-size charger, but the battery was never the same. I had trouble starting the car even with only removing the tender the morning of an event. It still lasted another 6 months though...but I was having to jump the car by the end of the day after letting it completely die.

As long as the battery has enough CCA to start the car when it's new, and you use the battery the way it was intended...fully charged most of the time, a small motorcycle battery is fine.

You could probably run a car until it runs out of fuel with a completely dead battery, once it's started. When I had to jump my racecar using my tow vehicle, and the car ran just fine once it was started. The alternator does all the work when the engine is running.

trackdaycareracer

Thanks for a lot of really good answers!

I've already got a battery tender which is being used off-season, maybe I'll carry along a couple of jumper cables or one of those emergency starters while we're being instructed around the track - and put it in the pits when the instructions are over and it is time for some action.

For regular track days I'm not that worried (anymore)