Weird battery problem

[geeker]

I have two pairs of Tenergy LiFePO4 3v batteries used in the Prodigy. One pair works great, the other pair barely works at all. What could be the reason for this? They are the same age, and have been charged about the same number of times.

What would happen if I took one from the good pair and one from the bad pair and used them together? Would this be dangerous somehow?

[Jim Davis]

One of the batteries may be pooping out. I had a batt that registered 4 volts, but dropped to 2 volts when a load was put on it. If the bad batt is used with a good one, it may be pulling the other one down.