Electrical experts - Odd total loss of electrical power...

[Sci85]

Hey guys, I've always valued the expertise this group provides so hoping you can help me with one of my other projects, a 1989 ZX7 I've owned for a few years now. Anyway, bike has always run very good. No real issues. However, the other day when I went to take it out for a ride, it kept dying after a few minutes during warm up. The battery seemed low so I didn't troubleshoot it at the time and instead hooked it up to the battery charger overnight and let it be. A couple days later, with a full charge, I took her out for a test ride to see what was up. She ran flawlessly for about 10m and then completely lost power and died. Other than a faint glow from the oil pressure warning light, nothing electrical worked. I got her home and checked the battery voltage and it was only showing 8v!

So, I put it back on the charger and it took a full charge overnight no problem. Everything works, lights, starter, etc. So now I'm wtf?

Any idea what might cause something like this or where to start troubleshooting?

Thanks for the help.

[LAB3]

Sounds like a charging system issue, a bad battery or both. Go ahead and get it restarted and test the voltage while running, get it up to 3-4000 rpm and see what you've got.

[Sci85]

Ok I will check the charging voltage and report back. Thanks.

[Sci85]

BTW, I should make clear she died while I was riding. Just out of nowhere. It was after I trailered it home that I checked the voltage and it was 8v.

[bccap]

Sounds like your charging system failed while you were on that ride and it ran on the battery until it ran out of power. The same thing when you charged it and it ran again until the battery was drained. Do the quick charging test in posplayr's signature after you recharge the battery... Just look up posplayr's name in the members list and you'll find him......

[Redman]

Sounds like bike is not charging the battery, and bike running only as long as the battery last, and battery not lasting very long either.

good that you have volt meter.

charge battery back up.
take off charger for half hour or so.
measure battery volts.
start bike, take reading again at idle , and 2000 , and 4000 rpm.
and report here.

also, start looking for the wiring (3 wires) between the stator and r/r. That is probably where need to check next, but for now..... tell us those battery voltages.

[Sci85]

Ok, the battery was sitting at 13.3v key off. I started her up, let her warm for a bit then took a reading at 4K rpm...12.4v. Reading at 1K rpm, 12.4 volts. This was with the red lead on the + batt and the black lead on the chassis ground of my volt meter. After the test, batt voltage was 13.1v key off, 12.96v key on.

[fastbysuzuki]

12.4v at 1K & 4K is to low at 4K you should be getting close to 14.5v ideally. Do the quick test here and report findings

https://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page9

[Brendan W]

Hmmm.
Full charge battery is good for a lot more than ten miles.
What's the bet you have a short in the r/r that is not only preventing it charge properly but draining the battery?

[TxGSrider]

If the battery is starting out at 13+volts and going to 12+ volts while running, Im thinking its doing the opposite of charging....

[LAB3]

Hmmm.
Full charge battery is good for a lot more than ten miles.
What's the bet you have a short in the r/r that is not only preventing it charge properly but draining the battery?

Brendon has a good hunch here, pretty much what my impression is. We can keep giving out our impressions here but perhaps a forum that's specific to your bike can give you some better advice on sorting it out.

[Sci85]

That's a probably a good guess. I was honestly thinking it might be something up with the r/r. Thanks guys. I'll run through the service manual checks on the r/r and see if it checks out then go from there.

[Redman]

not charging at all.

disconnect the r/r from the stator and all.
see if battery charge last longer.

check output if the stator at 4000 rpm. will need to have meter set on AC scales.

[Sci85]

Just to close out the thread, it turned out to be the generator belt let go.

[Redman]

Just to close out the thread, it turned out to be the generator belt let go.

Tell us more.

Generator Belt.....?
something other than a BMW boxer has a belt? A Kawasaki has a belt?
A modern bike has a generator?


In addition to that, seems that once you charge the battery, it should runn longer than you said it did.