Battery Problem

[Vince]

Any motorcycle mechanics can help me with this one. Put a brand new battery in my Harley after winter. Ran fine for a few times and then the battery went dead. Ok, I thought maybe just a bad battery. Got another new battery. Today I went out to the garage to put a meter on it to see if the charging system was working and it read 3.04 volts. Tried to start it and...viola...another dead battery. Only thing I can think of to do is put another new battery in it and immediately check and see if the charging system is working....but 2 bad batteries in a row from 2 different places? I don't think it's coincidence. Anybody think of something I'm missing here? And no, nothing was on while it was sitting in the garage.

 

[GURPS]

check the Alt output ...

for cars it should be around 14.7 v with the lights on .....


also maybe a parasitic drain killing the battery

 

[GWguy]

Newer bike with security system? Pulls power even when turned off.

Sounds like you may have a charging issue. Probably not the battery, at least not 2 in a row. Take it out, charge it on a known good charger. Put it back in, start the bike. If your meter has an amperage/current setting, disconnect the battery while it's running and put the meter in series with the battery. Note if it's charging or discharging. If it's discharging, the bike has an issue. Turn off the bike, but leave the meter in amp mode in series. You should see a minimal discharge. If it's anything significant, you have a bad drain on the bike. DO NOT TRY TO START THE BIKE WIRED THIS WAY. YOU'LL BLOW THE METER OUT.

 

[Larry Gude]

Anybody think of something I'm missing here? And no, nothing was on while it was sitting in the garage.

I'm sure you've already considered the obvious; there is a short somewhere. Either rob a bank and take it to Harley or, next battery, see if you can hook up the negative first and then add, one by one, with the switch off, the hot side (or put in fuses one by one) until you can see what is making it spark. I don't know HD electric systems. On my bike, it's pretty easy to isolate all the hots and go one by one.

 

[Vince]

Older Harley. Not much on the electrical system except lights. Once the ignition is off, there shouldn't be anything draining it. Going to try to charge the battery. Fully charged it should be around 13.2 v after engine start it should read around 14.8 v if the charging system is working correctly. I'll go from there. Yeah, I kept a batter tender on it all winter for all the good it did. Guess I need a new one.

 

[Larry Gude]

Older Harley. Not much on the electrical system except lights. Once the ignition is off, there shouldn't be anything draining it. Going to try to charge the battery. Fully charged it should be around 13.2 v after engine start it should read around 14.8 v if the charging system is working correctly. I'll go from there. Yeah, I kept a batter tender on it all winter for all the good it did. Guess I need a new one.

Once charged, make sure key is off and take off the positive side, leaving the negative hooked up. Tap the positive post with the positive wire. If it sparks a little, something is pulling juice. If you have no accessories, no clock, there should be no spark at all. Either you got back to back bad batts or you got a short.

 

[Vince]

Once charged, make sure key is off and take off the positive side, leaving the negative hooked up. Tap the positive post with the positive wire. If it sparks a little, something is pulling juice. If you have no accessories, no clock, there should be no spark at all. Either you got back to back bad batts or you got a short.

Thanks Larry. I'll give it a try as soon as the battery is charged.

 

[GWguy]

Thanks Larry. I'll give it a try as soon as the battery is charged.

Make sure you don't have any gas leaks.... :boom:

 

[garyt27]

Do you leave the key in the ignition? I had a scoot that would kill the batt when I left the key in although turned to off position.