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Alternator isn't charging the battery.

pen

CB750 Member
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Location
Bunker Hill, WV
To start, I'll say I don't have the "proper tools" the manual wants you to have to test the alternator, the best I've got is a multi-meter that reads AC, DC, and resistance. I've gone through and checked what I can on the alternator itself: the resistance. the field coil reads about 7 ohms, and all the stator whatevers read about 0.4-0.7. That's all up to spec as far as I'm aware. After checking the actual hardware, I decided to see if I could get a reading directly from the alternator while it's running. I set my multi-meter to ac, and starting probing the connector. I'm not exactly sure which thing I should be checking, theoretically they should all give a reading of some kind. And they do. 0.2 volts AC That can't be right, right? This is supposed to charge the battery, how in the world is that enough. Maybe I'm reading it wrong, maybe it's impossible to actually get a reading directly from the alternator. If all of that is correct and how it should be, the only other culprit for it not charging is the regulator/rectifier.
 
I've gone ahead and ordered a new regulator/rectifier unit. I "tested" the old one the only way I know how: check for continuity where I believe there should be continuity according to some wiring diagrams. I found none. So, if it were never going to charge, I suspect this is the culprit.
 
I’m really hoping some sees this and gives me some comfort. The new parts arrived and I wanted to test the wiring harness a little bit to make sure there wouldn’t be any shorts. I ended up finding continuity from the field coil wire (white) through the hot/12v wire (black). It read 12 ohms, and it is very worrying.
 
Try cleaning the points on the inside of the voltage regulator, then adjust the regulator. That solved my problems of the battery not charging.
 
I've gone ahead and ordered a new regulator/rectifier unit. I "tested" the old one the only way I know how: check for continuity where I believe there should be continuity according to some wiring diagrams. I found none. So, if it were never going to charge, I suspect this is the culprit.
Hi Pan, have you actually installed the new regulator/rectifier unit? I have the same issue as you and am looking for pix/instructions as to how to do it...
 
Hi Pan, have you actually installed the new regulator/rectifier unit? I have the same issue as you and am looking for pix/instructions as to how to do it...
Hi! I did install the new unit and it seems to have mostly fixed my problem. In your case it could entirely fix it as long as you're certain the alternator itself isn't faulty. If you can, do the proper tests on the stator and field coils and check for correct resistance. They are in the manual somewhere, or online. As long as you're certain the alternator parts aren't grounded, then I would say go ahead and replace the regulator/rectifier. In my case, I'm not getting the 14 volts I believe I should be, but I am getting enough to keep the battery at ~12.6v and keep the lights on.
 
The sohc puts out very little charge. Only time you will see charging will be at higher rpm. At idle with the headlight on you will more than likely see the battery draining......they charge next to nothing at idle.
 
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