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CB900C charging problem

13K views 13 replies 5 participants last post by  stroknsmokngt 
#1 ·
I have an 1980 CB900C that is not charging the battery. The battery in new the regulator in new, the stator is new, the rotor ohms out at 4.6 and I checked all the wires. What am I missing?

What is this? is it part on the charging system? I can't find it in any diagrams.
 

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#3 ·
I disconnected it and did a diode test on it and it test OK. I also for I have 13.8 volts going to the battery when running. The battery will hold a charge just sitting for a few days. The problem I had was after riding for about 4 hours today the battery went dead and I had to catch the bike in gear to to get it started. Maybe a bad battery or loose connection. It wasn't charging before and I went through all the connections with WD40 and it started charging again. I am lost as to why my battery is going dead.

vanman250
 
#4 ·
Maybe a bad battery or loose connection. It wasn't charging before and I went through all the connections with WD40 and it started charging again. I am lost as to why my battery is going dead.
You just answered your own question. Just stick with it.....and check the voltage more often (which you should have done before replacing ALL those expensive parts !!).

If you never catch the charging voltage down below 12.6 (assuming your meter is right), then you are back to bad connections or a bad battery......which can have bad connections inside.

You probably should carry that meter with you until you get things ironed out.

Maybe you should now go thorough those same connections again......only blowing the WD40 OUT this time !!

P.S. Don't count on the bike to recharge the battery. If it is so weak that the bike dies.....or the starter won't turn....then it needs an complete external charge.
 
#6 ·
Well I ran through all the wires again. at 2500 rpm I was at 13.6 Volts at 5000 I was at 13.9 volts. I couldn't get it to go below those numbers no matter how much I jiggled the wires or the bike. I made sure the battery had a full charge and if it goes dead again I am going to have the battery tested.

vanman250
 
#7 ·
I made sure the battery had a full charge and if it goes dead again I am going to have the battery tested.
Good plan.

One more thing: If you haven't already, you should disconnect and inspect and clean (scrape) the connections at both ends of the main battery cables. Corrosion sometimes hides inside the connections where you can't see it. Disconnect the negative cable at the battery first and reconnect it last. :thumbsup:
 
#11 ·
i think with it being an '80 model the charging system might be a bit before my time so to speak. but if you have a manual, have you a picture/diagram of the rectifier/regulator. the manual should maybe have a test for this part.:confused: you obviously have a voltmeter to test for continuity, i.e broken connections:confused:
:)
 
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