When I bought my 08WR450, the sales guy said that I’d need to use a battery tender to keep the battery charged, he said that the system only has the juice to keep itself charged and did not have the power to recharge a drained battery. Anyway, I ignored him. And since then my battery was fine until I rode Rubicon, the battery didn’t have the power to start the bike when I stalled it numerous times on Cadillac hill (right when I actually needed e-start the most). I ended up charging it off a jeep with a pair of jumper cables. Fast forward a month, and this weekend at Downieville the e-start/battery starts slowing down right as I’m entering the nastiest river bank climb I’ve ever seen. If the e-start won’t work in the nasty I’d be better off with a YZ. Anyway…. After the Rubicon experience, I had decided to check my charging system. Reading thru the manual, I discovered that it said to check the system voltage at 5K RPM. And it occurred to me that the WR charging system might not be very powerfull at low RPMs, and its probable that my dead battery was due to the low RPMs I was running while putting thru hours of tight single track. Anyway, back to last weekend, after my battery died, I wrung the bike out a bit more and the charge came back on the battery.