Max charging voltage

I noticed the battery on my KZ900 is approaching the end of time. After sitting for 3 or 4 days it will be down around 12 volts or high 11s. My concern though is when checking the voltage at 4 T rpm it will climb up to 16 volts. The manual states normal charging voltage at 4 grand should be between 15 and 20 volts. I'm guessing a sick battery will prompt the voltage regulator to throw more voltage at it but this seems really high. Would anyone else be freaking at 16 volts charge on a tired battery?

That's too high. The early regulators were notorious for boiling the battery. It should be 14.5 max.
Steve

Too high. Stick in a good battery, then check it. If' it's still too high with a good battery, your charging system is cooking too hard.

At least the alternator is working well. Looks like a candidate for a R/R upgrade to me.
Steve

I just replaced it.

Robb2018 wrote: ............... The manual states normal charging voltage at 4 grand should be between 15 and 20 volts. ...............

Holy cow! What manual says that? Below is a clip from the 1981 KZ650 Kawasaki Service Manual. Ed

That's with the regulator unplugged.
Steve

Thanks, I missed that part. The good news, Z1 Parts is sending me a new RR on warranty. Great people over there.

So obviously this test is meant to be done if you have a separate regulator and rectifier.

That is good on them. Most vendors will not accept returns, nor replace electrical parts. NAPA will not return a part that has been installed. They can tell if it was installed by looking at the terminals looking for scratches. No one knows what was done to the part. . Poof! Oooops! :S LOL

Z1 in one of mine, and a lot of other old-kaw enthusiasts, is one of their preferred vendors. IMHO, they set the gold standard for old kaw parts vendors. (other makes also)

I agree... Z1Parts is aces. Got the new RR today and it's putting out 13.5 V at 4K. I have no idea why the other one went out so soon, or if it never was right in the first place. Battery was never accidentally reversed and only had an hour or two tops riding since it was new. I didn't check it for over voltage when I first installed it, just checked it at 2 to 3 K and was fine. (Didn't start over charging till RPM got over 4). I don't know why I even decided to check it for over voltage in the first place as it had been running fine and wasn't giving me any indication there was a problem.. Lucky I did before I started toasting things. When I first hooked this one up it wasn't putting out at all and I thought... here we go again! Had it grounded to the battery box, which I thought would be good since it shows good continuity to the frame, but it didn't charge until I got a better ground.

What's the voltage at 5000 rpm? You should be getting 14 volts DC if your stator is strong.

I'll check that today thanks. I think a volt meter is a good addition to any of these old bikes. Electrical problems can often be symptomless up to the point where they become a serious problem... like a fire under your ass or a dead electrical system out in the middle of nowhere.