Bucking and sputtering--battery related?

[kongjie]

Came out of work and battery was D - E - D dead. This time I don't think I stupidly left the key on the park position--I'm thinking the battery is old, perhaps the original one that came with the bike. The first and original owner kept it on a tender. I checked the charging with a meter and it seemed to be adequate, but maybe now that the bike is getting daily use the battery has given up the ghost.

I park on the top level of a parking garage and so the one good thing is that I can push start by going down a level. I got it started but it was running REALLY rough, bucking and sputtering. I almost gave up on it but after 5 minutes or so it was back to normal and I was able to ride home.

When I got it home, out of curiosity I tried starting it after turning it off, and it was dead. I plugged in the battery tender and after just a minute or two the red light was one and the green light was flashing, which normally indicates 80% charged. So I think the battery must be so shot that it's not even charging properly.

I'm going to get a new battery, charge it up, install it and then check the charging system. My one question for now is this--was the bucking and sputtering the result of the battery being so low that the bike could barely run? It's my understanding that this bike needs a charged battery to run, so I'm guessing the juice was so low that it was on the verge of stalling, until there was enough charge.