I see there are a couple similar topics, but my situation is unique. I went to start up my bike ('91600F2)to ride to work this morning and it barely cranked. So I assume my battery is dead/weak. However, I rode it yesterday to and from work, (and to and from lunch) it cranked strong and started fine every time. Why would a battery get so weak over night? Any ideas?

 

Age.. it happens..

How old is the battery?

 

I put a new battery in last June ('06).

 

hrm.. that's odd.. Unless you got the battery from Wal-Mart, I'd say the battery wouldn't be the cause of the problem.

Take the seat off and check the battey terminals with a good multi-meter. With the bike off, key off, it should be no lower than 12.3 volts. With the bike running, it should be around 14..

 

12.3 wopuld be an almost dead battery. The Yuasa instructions I just got say that 12.8 or above is normal 100% full, 12.6 or about is 75%, and 12.3 would be at about 25% to 50% 12v or lower is almost dead.

 

You're right, of course.. dunno what I was thinking

That's what I get for hurriedly typing a response while at work

 

Thanks guys, I haven't even been able to get at the battery yet, because I can't find my damn allen wrenches. Just wondering if anyone has any ideas about something, other than the battery, that could be causing this.

 

OK, I just got to the battery and hooked a jumper box up and the bike cranked right up. I let it run for a few minutes, shut it off and triedagain (w/out the box)and now it doesn't even cranky weakly...it just ticks. Does this mean anything to anyone? I don't have a voltage meter to check it w/. Would you guys suggest just throwing a new battery in or do you think it's more likely a R/R problem, which I've seen mentioned in other similar posts?

 

Could be either. If you are using one of those chargers that put more than 2 or 3 amps of charge, then you may have destroyed the battery when charging. Also, during the winter, if you don't keep the battery charged, it will lose capacity. Heat also destroys batteries, so it could be that. Without a good multimeter you'll never know because you'll need one to test the battery and the R/R.

In any event, my old battery did the same thing you describe. Cranked really slow or not at all and it still read 12.8v sitting there. Then I would rev the bike I was getting about 14v output from the R/R. Replaced the battery and it cranks better than it ever has before and starts right up. I don't know old the last one was, so I can't comment on how long they should last. I do know that I have a trickle charger that I will be using this winter or when the bike will be sitting for any period more than a few days.

 

yes the batt is dying, is it from a faulty r/r or a bad battery, or a bad stator...hmm.lol without a volt meter i can offer this advice. if you jump it, take off the jumper cables offand rev up to about 7k, if it begins to sputter most likely its the batt. also if your neutral light is sorta dim and goes bright when for instance you hit the front brake. batt need replacing. plus if the batt is fine and its just the r/r, after you let it sit for about 5 min the battery should self recover to about 85 percent. enough to start it i believe.