Over charging issues ?

[AshishNJ]

I am using the Kawasaki alternator on my custom that replaced the stock unit a while ago. Problem seems to be with overcharging at rpm’s higher than 2500 or so mark.
I am seeing voltage at battery exceeding 15 volts.
Battery indicates a voltage of 13.25 between two poles and between -ve and the charging output of alternator. Resistance among three stator poles shows consistent .25 ohm
The key switch is sending a signal from battery to field coils (red wire) and the voltage at that reads 12.2v.

That is a full 1 volt difference and seems to my issue. It is an aftermarket switch . Wondering if voltage drop is expected.

D0F1C199-9499-4E6C-9F74-DE91105BDDE6.jpeg

[512tr]

Does this alternator have a built in Regulator Rectifier?

[AshishNJ]

Yes.

[Larry Zimmer]

I don't know much anything about using these alternators. However, the first thing I would do is check resistance across all pertinent connections. It appears to me that something is getting a wrong signal telling the rectifier to putout more. Doesn't take 0.1 ohm to do that. Connectors should show 0.0x max. Remember, the ignition switch itself is a connector.

[512tr]

Most likely the regulator, check out this Nippon Denso regulator upgrade video.
https://www.youtube.com/watch?v=M-G9t9mAYOc

[AshishNJ]

I don't know much anything about using these alternators. However, the first thing I would do is check resistance across all pertinent connections. It appears to me that something is getting a wrong signal telling the rectifier to putout more. Doesn't take 0.1 ohm to do that. Connectors should show 0.0x max. Remember, the ignition switch itself is a connector.

On it… thanks

[AshishNJ]

Most likely the regulator, check out this Nippon Denso regulator upgrade video.
https://www.youtube.com/watch?v=M-G9t9mAYOc

I have seen those as well. However I have another alternator and showing exact signs . That makes me wonder if it is something in switch . That switch is losing 1 volt and is directly in between battery and alternator.

[512tr]

Why are you not connecting the charging wire from the regulator directly to the battery (via a 30A)?

[AshishNJ]

That will keep the field coils energized all the time. Oem setup also goes via a switch

[512tr]

Is that a problem? If so a 30A relay activated by the key switch in on position, could be used?

[NobleHops]

Ashish, I went through something similar on my bike, and it turned out that excessive resistance in the wiring harness from a really crappy repair that some asshole did (me) was causing the alternator to go full field, overcharging the battery and eventually destroying it. J.R. worked with me to eliminate the R/R on my unit by sending me his own to test. I replaced the wiring harness and it was perfect thereafter.

In my case it was the bad repair, but I have seen excessive resistance created at the small red plug under the right side cover, in the key switch base, at the rotary kill switch, and just though really cruddy connections.

N.

[AshishNJ]

Problem solved . I pulled out the switch and sprayed electrical contact spray in it. Removed battery and put it on a charger outside of bike. Reassembled and rechecked all wiring and now the charger would keep the battery at exact 14.4V :).

Nils and others, thanks for providing some wisdom and helping resolve it. Today I did a 90 mile loop and had a big grin during my entire ride . It was fun , bike has great brakes , I can really lean it and not worry about tires giving in :)

[NobleHops]

Which switch, Ash?

[AshishNJ]

An aftermarket ignition switch

[512tr]

An aftermarket ignition switch

Hi AshishNJ,
I saw on your project tread that you are using the M-unit. Another way to wire the Regulator/Rectifier is to take the battery 12V+ sending signal from the M-unit.

The AUX 2 or AUX1 output can be used, it can be configured to gives 12V+ when ignition on, or when engine is running, doing it this way it minimizes the potential fault sources compared to wiring via the key lock.

I also saw in your project tread that you planned to use Lithium battery, is that what you are using? If so, how is that working with your current Regulator/Rectifier?