[DougHogg]

Originally Posted by Denman

the best thing to do, is to get a battery reader thing. We borrowed one that tells you the voltage, the amp hours left and the temperature of the battery. it means you can tell which re the most charged...

We bought two different types of battery tester this year, but neither of them shows the "amp hours left". What was the make and model of the "battery reader thing"?

I suspect that your tester was basing its amp-hours-left reading on the battery voltage. One possible problem: if you start charging a battery and then test it part way through the charging cycle, the battery will have a surface charge which would throw off the tester.

What I am saying is, watch out for half-charged batteries. The voltage on a battery will register high if you take the battery off a charger in the middle of the charging cycle (as the charger was putting a high voltage on the battery to charge it and thus creating a surface charge on the battery), but the charging process won't be complete, so the battery could die during a match if your robot uses more current than the battery got from the partial charge. (We experienced this first hand in the third match of the finals at the S. Calif. Regional this year.)