CBR 900RR 1993 - 1999 Honda CBR 900RR

1998 Bad battery? Bad starter? Something else?

Old 10-03-2018, 05:47 PM
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Default 1998 Bad battery? Bad starter? Something else?

I've been chasing this problem with my '98 for several months, and it's completely baffling me: I can't tell if I have (two) bad batteries, a bad starter, a bad charging system, or some other voodoo electrical problem.

With a fully charged battery, the bike starts and runs totally fine. After about two trips out and back to work (~23 miles round trip), the battery appears to be dead, and the bike either turns over very slowly or doesn't turn over at all.

If I get it home and drop it on the charger, it appears to charge fully in anywhere from ten minutes to two hours. Mostly, checking it on the charger shows that it charges in about ten minutes. The charger shows "25%" for like two minutes, the "50%" for about two minutes, then "75%", then "100%". It *can't* possibly be fully charging a dead battery that fast.

Most recently, I rode about ten miles for lunch and the bike ran fine. I parked in the parking lot and turned the key off, then, just to test, turned the key back on and hit the starter button and got nothing but clicks from the starter.

Not trusting my bike any more, I had started carrying the second battery with me and the tools to change it. Went and had lunch (I was already there, after all), then changed the "dead" battery out with the charged spare, and the bike started right up and ran fine all the way home. Checked the "dead" battery with the multimeter when I got home and it read 12.5V. IDGI.

The smart charger indicates that the battery is healthy, (The guys at the battery shop indicated the same thing -- The battery tests "healthy". I bought a second battery just in case the first battery was somehow mysteriously actually bad, despite testing as healthy.)

If I hook up a multimeter to the battery in the bike, I get the followup voltages at the indicated stages:

- Key off: 12.54V
- Key on, not started: 11.96 V
- Idling: 13V
- 5K RPM: 13.5V

As far as I can tell, this indicates a charging system that's working correctly. Except the battery doesn't appear to actually be charging.

The batteries I'm using are made by "XTreme", and are "AGM Tech" batteries. The model is a "XTAX9-B5" battery, rated as 12V and 8.5Ah.

The smart charger is a NOCO "genius G3500 v2" charger.

Any ideas what's actually wrong, or what tests I can do to figure out what's wrong? I'm stumped, can't think of anything that gives this behavior.
Old 10-04-2018, 07:37 AM
TimBucTwo's Avatar
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Join Date: Jun 2006
Location: NY,The Land of Taxes
Posts: 4,064

Sounds like a bad R/R.
The diodes in the R/R get weak and let power flow backwards, discharging the battery.
If the battery holds a charge when disconnected from the bike, I would suspect a bad R/R.
Old 10-04-2018, 09:22 AM
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Put your meter on the battery and do your usual ride. Keep an eye on what the voltage is doing and see if it drops off or discharges.
Old 10-04-2018, 11:03 AM
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TimBucTwo: Sounds good. My next step was going to be to replace it anyway, just out of a sense of "Well, what *else* can I replace that might be it?", but this gives me a plausible understanding for *why* it fixed it. Thanks -- I'll let you know how it goes once the r/r gets here and I swap it.

74demon: Good idea -- Do you know of any good bluetooth-capable meter units I could mount to the battery and check with my phone? Thanks for the suggestion.
Old 10-04-2018, 12:02 PM
74demon's Avatar
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Just hook up your meter and tape it to the tank. You're just doing it for testing.
Old 11-13-2018, 10:18 PM
Join Date: Aug 2018
Posts: 34

"Electrical"? have fun, or not? C.W
Old 12-08-2018, 02:22 PM
Join Date: Apr 2014
Location: Black Hills, SD
Posts: 52

I had a issue with similar symptoms but mine resolved with a new starter relay switch. Adding for others who may have similar issues not tied to the regulator/rectifier.
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