[Al Skierkiewicz]

Seth,
We use the CBA II battery analyzer from West Mountain Radio. If you look earlier in this thread you will see actual curves from actual batteries.

Pikat,
I know that this will sound weird but teams who draw lot's of current during driving can easily draw the battery below 5 volts during those high current demands. The internal resistance of the battery is 11 mOhm so a 400 amp draw will drop the terminal voltage of a fresh battery by 4.4 volts. At the end of a match where the internal resistance rises, this resistance will cause a further voltage drop.

Everyone,
A voltmeter only tells you the "open circuit" voltage of the battery. A voltmeter does not draw current (not enough to change the reading) to cause a drop across the internal resistance of the battery and therefore is not a good indicator of battery health. A current tester will show what the battery is capable of delivering under a load. The CBA II will draw up to 7.5 amps and West Mountain makes a high current device as well. However, one must know what the data tells them. It is possible that the battery has reduced capacity in that it can only deliver current for a fraction of the time a good battery can, the battery cannot supply current at full voltage or a combination of the two. A battery that cannot supply current for a normal length of time has some internal condition that prevents correct operation. I know that this is a foreign concept, but the data sheet specifies these batteries to have a 400 charge/discharge cycle life. It is very easy for a team who only keeps a few batteries in their inventory to run 400 cycles in a season between practice,demos and events. Charge when the battery is hot, store at temperatures near or below freezing, or deplete a battery in just one two minute match will shorten that 400 cycle life by half or more.