00 and 01 1100 zxi battery pro blems
 

I just bought a set of 2000 and 2001 1100 ZXI skis. One had a bad battery, so the guy I bought it off of bought a new one. Then the other didn't start so I bought a new battery. I have two new batterys, charged and ready. Got the skis running, ran fine. Let them sit for two weeks, now neither will start. I know for sure the ignition was off. When testing with a volt meter, the batterys read about 3 volts. I tried to charge them, and it still only reads 3 volts. I'm not sure what is wrong.

One part, besides the positive and negative wires there is a third smaller wire. I think it goes to the ignition or, at least leads up there, could be KATS possibly too. Any idea what that wire is? I connected it to the positive terminal, and am wondering if it should've went to the negative. But I can't imagine any wire going to the negative, at least I have never seen a wire goto a negative on any other battery in car/truck etc.

Part two, when the skis were running I couldn't get the KATS system to really do anything. No lights came on, and manually trimming didn't seem to do anything.

Any help or suggestions would be appreciated.