First, I want to say that I have read the charging system diagnosis/mod post and some other related threads, but electrical issues are not my strong suit. I have a friend who is good with such problems, but not real familiar with motorcycles. So I wanted to post a description of exactly what's going on and see if I could get some opinions of where to start. OK--I have a 2001 DRZ400. I have only had it a couple of months and supposedly a new battery was installed last summer and was kept on a battery tender. I did not put it on a battery tender initially, due to it being in a garage and the weather being fairly warm. The first couple of times I rode it it started right up with no problems. Then, after sitting maybe a week and a half, we had to push start it, but that day it started right back up anytime it was shut off. I hooked it up to a battery tender and let it charge. The next time it was ridden it started with no problems. Hooked back up to a battery tender and did not ride for 3-4 weeks--It wouldn't start. It initially turned over and then weakened (the headlight dimmed, etc.) So we're thinking bad battery. Push started it and rode for a while, but if you cut it off it would not start back. Hooked it up to a battery tender overnight (it showed to be fully charged the next morning) but it didn't even turn over, as if the battery were completely dead. The headlight came on though. Any help is appreciated.