pic: Team 358's Backup battery

[JesseK]

Where did your negative wire go?

We need to figure out *why* this happened. 1885 has a backup battery charger circuit that keeps charging our batteries to 8.5-9.0 volts and we're worried the batteries will explode. We now have to keep replacing the batteries in between matches anyways (what we were trying to avoid) and also have to run them down. Changing the battery causes us to (even with the utmost care) pull out or dislodge a sensor or pwm wire, which has devastating results elsewhere on the bot.

I didn't design our circuit, but our electrical mentor says we are using the standard FRC backup battery charger circuit and have mounted it on a PCB in such a way that we can also power the IR board off of it (separate circuits, same PCB). I showed the circuit to an EE at work and gave him a description of our problem. He said that at first glance, using a different-spec'ed zener diode may help to not overcharge the battery.

Any thoughts on this?