Topic: CB650 charging problems

[erckx]

Hi! My 1980 CB650 has been struck by the oh-so-familiar charging problem. I've so far had a lot of help from forums such as this one taking me to the point where I am now, but I've kind of run out of ideas what to do next.

How it stands now: The bike runs for 60-80km (with lights), but when killed, won't start over, the battery will be dead. If I jump start the engine and ride the bike for a while with no lights, the battery start charging. I can then kill the engine, and start it again with the start engine.

I've since replaced the old charging rotor with a new aftermarket one, along with a new rectifier unit. But still with the same result.

The battery reads as follow:
   
1500RPM with lights        12.10 (seems low)
1500RPM without lights   12.60 (seems low)
5000RPM with lights        14.10
5000RPM without lights   14.20

Any thoughts on where too look next?

[calj737]

The voltages you post indicate the bike is charging, perhaps lower than optimal, but charging. What you have not indicated is what changes from stock have you made to the bike? Especially the headlight or other electrical components?

Also, fully charge the battery overnight. Let it rest off the charger for a mimunim of 2 hours. Measure its voltage. Then, compare that voltage with the bike running at idle, 2k revs, 4k revs, and 5k revs. You may find that your battery is bad, or that you simply need to perform some maintenance on your charing system wire harness and grounds.

"I've since replaced the old charging rotor with a new aftermarket one, along with a new rectifier unit. But still with the same result."

I'm going to assume you meant to say "replace the stock regulator/rectifier" with an aftermarket unit. Yes? If so, which do you buy?

[erckx]

Thanks for your reply calj. I have not made any changes that would affect the electrical system, except replacing mentioned parts. I am charging the battery as we speak, and will check the voltage the coming week.

Yes that's correct, both the regulator/rectifier and the rotor are from Electrosport Industries.

[calj737]

And why did you change the stock components? Did you test them to verify they were bad, or were you having charging problems and replaced them believing they were bad?

[erckx]

Yes, made measurements on both the rotor and the regulator/rectifier and none were working properly.

[calj737]

You keep saying "rotor". Did you actually replace the stock rotor? With... aftermarket? Used Stock? It is extremely unusual for all 3 components to fail simultaneously. In fact, absent of accident damage, I'd venture the odds to be 1:100,000,000 or thereabouts....

So at this point, why don't you use this flowchart and examine your entire charging system to see if you can isolate what is, and what isn't working properly?
http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

[TwoTired]

The 650 has slip rings and brushes.  What is their condition?

What is the field coil ohms measurement when testing from the connector at the rectifier?

Were the voltage measurements in the o.p., made with a fully charged, known good battery?  Discharged batteries (good ones) change their charge state/voltage slowly.

Yes, made measurements on both the rotor and the regulator/rectifier and none were working properly.

Given you can't fix this yourself, you need someone to check and corroborate your work.  Please post your findings/measurements on the components you have determined "bad".