Battery not maintaining a charge

[Tapartacus]

So my 89's battery would not hold a charge. Finally decided it was toast. Bought a new one after a couple days of riding now bike won't start. Sounds like it wants to turn over but battery is just too weak. Sorry for sounding dense but is there an alternator or regulater that might be to blame?

Thanks
Andrew

[fj1289]

Yes.  Easiest way to check it is to put a volt meter across the battery terminals with the bike off and then again with it running. 

[Zwartie]

Check the voltage at the battery when the bike is at idle and also with it revving at 3,000 or 4,000 RPM. Should be something like 13.8 V when the revs are up as I recall.

Zwartie

[markmartin]

Yes to what's been said so far, and also check out the end of this thread http://www.fjowners.com/index.php?topic=13982.15  and the infamous red connector.

[Tapartacus]

Thanks for the reply's gentlemen. Checked red connector all looks good. Tested battery with volt meter and 12.5 when not running drops off to 11 or so idling. Blip throttle brings it up to 12 or so again. Now what?

thanks Andrew

[FJmonkey]

Thanks for the reply's gentlemen. Checked red connector all looks good. Tested battery with volt meter and 12.5 when not running drops off to 11 or so idling. Blip throttle brings it up to 12 or so again. Now what?

thanks Andrew

When you checked the connector, did you pull it apart to see inside? Mine looked fine from the outside, but was quite cooked inside. Your voltage seems low. Did you check it at 3 to 4 K RPM? I would expect to see 13 to 14 volts

[Tapartacus]

Hey Mark, I did take the connector apart and it looked good. 12.45 at 4000 RPM. 12.11 at Idle

Andrew

[FJ_Hooligan]

Hey Mark, I did take the connector apart and it looked good. 12.45 at 4000 RPM. 12.11 at Idle

You're not charging.  It's got to be in the 13s to low 14s (volts) in order to charge.  Start looking at the alternator.

[FJmonkey]

Hey Mark, I did take the connector apart and it looked good. 12.45 at 4000 RPM. 12.11 at Idle

Andrew

What FJ_Hooligan said, I get 13.8 to 14.5 at 4000/5000 with short spikes to 14.9. See if you can borrow an alternator before you buy a new/used one...

[markmartin]

This is an interesting link.

http://www.electronicamotos.com.ar/technical-resources/library/known-issues/street_65700.html