Help with Kz750 charging issues

My custom 1983 kz750 is having issues with charging. I have a lithium ion battery from anti gravity. A new stator from ricks and a sh775ab R/R but it doesn’t seem to be holding itself. Can y’all help me diagnose what’s up and why it’s not charging or at least keeping its charge? The only thing I can think of is that the R/R is bad or something. Can y’all walk me through a diagnostic process to find out what’s wrong? I have the bike on a trickle charge and she fires right up in the morning. Runs well and starts up for about 40 minutes to an hour of riding. But if I stall out on a hill she won’t even turn over so I have to jump start her down a hill.


Thanks!

How did you wire the charging system? Please draw a schematic, take a photo, then post here.

This is the method I like to use.

To check charging you need a fully charged battery, then set your volt meter on DC and put the probes across the battery while reving the engine to 5000 rpm. Lithium batteries like 14 VDC and lead acid types 14.5 VDC.

SH775 Install by nessism , on Flickr

do you have an extra draw somewhere? had a similar issue on a bike where a wire was loose in the handlebar switches and was grounding out. after about 45 min the bike would die and be impossible to start.

I have it wired exactly the way you did. 3 yellow to stator. Red positive to a constant 12 volts and negative to ground. And I made sure that it has a good ground and a good positive 12v.

With the bike sitting. There isn’t any draw in the battery. It will hold its charge. But my guess is after riding something is grounding out somewhere. Idk where though. Plus if I try test the voltage with my meter it won’t stabilize. If it was an analog meter it would probably spin in circles. Not sure why. Like I said. It has a new stator. The battery holds its factory charge of 13.2v or so.

It’s currently idling at 12.70v and with revs charging at 13.2-13.5v. Something is wrong and I don’t know what it is. Is my battery bad? Or my R/R????

I’m sure your local auto parts store can test the battery... a very non Scientific way to test it is, on a fresh charged battery turn the ignition on but run/stop off so the headlight is on. Leave it for about a minute, turn ignition off and watch the battery voltage. It should return to a minimum of 12.6 fairly quick. If it doesn’t hit 12.6 the battery is likely bad.

JohnLuke wrote: It’s currently idling at 12.70v and with revs charging at 13.2-13.5v. Something is wrong and I don’t know what it is. Is my battery bad? Or my R/R????

What rpm to get 13.2-13.5? And did you buy a real deal SH775 or one of the China cheepies that advertise "SH775 replacement?" Reason for asking is because I've bought more than a dozen used SH775's off ebay and tested them before reselling and I've never found a bad one.

Idk. 13.2v was right off idle and even reving it high like it won’t go any higher or closer to 14v. Yes it’s real on the back it says sh775aa. But my guess is it’s bad. So I’ll probably buy another sh775ab or as r/r. But idk if it could be the battery too. Like I’ve drained it where it won’t crank. Multiple times. But by the time I get home and charge the battery on my lithium ion battery charger. By morning she’s back at spec volts and if I stop charging it she will hold voltage for awhile . But she still could be bad. Idk

If you post the 775 to me I'll test it on my bike. USPS small flat rate box is about $8 these days. I've never seen a bad SH775... Oh, and I've got two units in the garage so if yours is bad I'll make you a good deal.

Just a real quick observation.
You mentioned the bike is good till you stall out then you can't get it started.

Sounds like your charging system is fine.
But your battery is not accepting the charge.

I notice this when I jump start people's cars.
If i can jump it and the car continues to run after I pull the jump starter, then the charging system is working.
If they shut off their car and can't start it again then the battery is suspect.

If I jump it and the car dies after I pull the jump starter, then the charging system is faulty.



I want you to check something.
Grab your meter.
DC V
Start the bike

One probe on the battery's positive battery post( post will be the metal part of the battery do not put the probe on the terminal for the battery cable)
Put the other probe on the red wire coming off of the reg/rec connector. Do not disconnect the connector from the reg rec. You can back probe the connector.
Your voltage should be less than 0.5V (don't worry if it's negative or positive. The number is what you are interested in)
If it is higher than .5 V then you have a bad connection between the battery and the regulator.
It can be a crimped wire, corrosion, loose connection.

Now put your probe on the negative battery post and the other probe on the black wire coming off of the reg rec connector. Do not disconnect the connector.
Same thing...any voltage over .5V is bad.

If you find you have over .5 volts, move one of the probes closer to the other probe along that wire.
Once your voltage drops below .5 you have found your problem.

You mentioned your voltage is jumping a lot.
Can you be more specific?
Is it jumping 1 volt, 5 volts, or 12 volts?

I’m thinking it’s the battery. Honestly.