Originally Posted by ehaughn
Is there something that is causing a drain? I heard the CD changer has constant power, but I removed this years ago. I have MotoLights and PIAA lights, that are on a switched power source.
I read this post a few days ago and remembered something from my own experience I'll pass along. Some years ago I had several bikes. A few weren't ridden at all in the winter. I had three of the batteries on Battery Tender chargers over the winter. Two got through just fine.....one battery was shot come spring. Next winter....same thing. It finally dawned on me that one of my chargers might be bad. The lights were acting normally on the unit, showing what seemed to be normal function, but I got rid of the charger I knew had been on the failed battery the second winter. Problem solved.
Also, it's possible, as you mentioned, that you could have too much residual current draw on the battery when the bike's shut down. I've seen LT owners unknowingly have the radio muted and turn the key to the R position, thinking the bike's shut down, but leaving the radio energized. They didn't hear the radio, and thought it was off. Over a few days that would pull a battery down. You can prevent that any time by turning the key past the R always which turns off switched radio power.
One way to test for residual current flow with the key off is to disconnect a battery lead, put an ammeter between the lead and the battery terminal, ...and see if there's any current draw. A "bad" way to check the same thing, but one I've been known to do a few times is to disconnect a battery lead from it's terminal, and with the key in the off position touch the lead to the terminal. If you see a noticeable spark....there's current flowing....i.e. something pulling power with the key off.
My guess though is either you've gotten an unlikely batch of bad batteries.....or something's not right with your charger.