Charging issue/question

The new regulator arrived and I promptly installed it. Of course it wasn't a perfect fit but it was close enough. Fired it up and tested the charge. At idle, 12.6. Rev it up to 1200 and its pushing 13.6-13.8. Rev it up to 4k and its pushing 14.8-15.0. What the hell?

That may be just a little high at 4000 rpm, but it doesn't sound too bad. The Kawasaki Service Manual for the KZ / GPz750 shows the spec at 4000 rpm as "about 14.5 V". The spec for the KZ650 at 4000 rpm is "about 15 V". If yours exceeds 15 volts you may want to deal with it; otherwise I would not think there is a problem. Ed

On a warm day, you'll be boiling the battery at 15v. In summer you really want to max out below 14.5v... closer to 14.2 is better.

If you do a search, you'll find that the overcharging can be the result of dirty fuse holders and other bad connections.

loudhvx wrote: On a warm day, you'll be boiling the battery at 15v. In summer you really want to max out below 14.5v... closer to 14.2 is better.

If you do a search, you'll find that the overcharging can be the result of dirty fuse holders and other bad connections.

Ugh. The bike has been swapped over to blade fuses and the holders are brand new, all connections checked and double checked.
I've been over the bike several times to see if there were any bad connections so it's pretty good from what I can tell.

The bike really went to 15 one time, but that's all it takes. The rest of the time, it hovered at about 14.5-14.8. I haven't ridden it yet because the weather has been shit here the entire day.

My luck...from undercharging to overcharging.

If your regulator has a brown wire, I believe that is the sense wire used to determine the output voltage. Trace this wire through your harness and ensure that there is no resistance in it or the circuit it measures. You might consider the possibility of manipulating the voltage that the sense wire sees...

jackleberry wrote: If your regulator has a brown wire, I believe that is the sense wire used to determine the output voltage. Trace this wire through your harness and ensure that there is no resistance in it or the circuit it measures. You might consider the possibility of manipulating the voltage that the sense wire sees...

Yes, as Jackleberry says, it's the voltage on the brown wire that the regulator uses to determine whether or not to decrease output. If the regulator has the brown wire, you should measure the voltage on the brown wire relative to ground on the regulator. If that voltage is above 14.5v, then the regulator is letting the voltage get too high. If the voltage is closer to 14.3v, then the regulator is ok, and if the battery is higher than that, then there is a bad connection somewhere you will need to find.

If there is no brown wire (or separate sense line), then the output wire of the reg/rec is the sense line. In this case, itcan only be the regulator causing the problem.

Also, if you have access to one, you may want to try using another meter to confirm yours is reading true.

loudhvx wrote:

jackleberry wrote: If your regulator has a brown wire, I believe that is the sense wire used to determine the output voltage. Trace this wire through your harness and ensure that there is no resistance in it or the circuit it measures. You might consider the possibility of manipulating the voltage that the sense wire sees...

Yes, as Jackleberry says, it's the voltage on the brown wire that the regulator uses to determine whether or not to decrease output. If the regulator has the brown wire, you should measure the voltage on the brown wire relative to ground on the regulator. If that voltage is above 14.5v, then the regulator is letting the voltage get too high. If the voltage is closer to 14.3v, then the regulator is ok, and if the battery is higher than that, then there is a bad connection somewhere you will need to find.

If there is no brown wire (or separate sense line), then the output wire of the reg/rec is the sense line. In this case, itcan only be the regulator causing the problem.

Also, if you have access to one, you may want to try using another meter to confirm yours is reading true.

I do have two voltmeters actually. I checked iit just now before doing any work and starting with a 12.6v battery charge, I fired it up. It idles at 1k rpm and was giving me 13.5. Within a moment or two, it rose to 14.5 at idle. At 4k it was giving me 15 to 15.2 consistently. I looked at the regulator and sure enough, my old one did not have the brown wire but the new one does.

How do I check the voltage on the wire? Or rather, what am I grounding to when I check the wire? I traced the wire all the way to the binnacle where I pulled it apart and saw the wiring was good and unmolested other than a load of spider webs in the binnacle itself.

Any ground should work, as long as it is a good ground. The "brown" wire tends (should be) a switched full battery lead. It should be indicating what the full electrical system is demanding. I know this is not always the case with 30+ year old wire, switches and connections. Sometimes all of that has to be replaced or bypassed.

But IMHO the systems that make use of the sense wire provide a truer sense of what demand is being place on the entire system. When that occurs the charging system has a better chance of keeping up so to speak and providing what is required.

So I've traced the brown wire as far as I dare. Where does it terminate or rather, I'm assuming that it goes to the binnacle. Provided I'm unable to find the issue, what are my options?

Shabba wrote: So I've traced the brown wire as far as I dare. Where does it terminate or rather, I'm assuming that it goes to the binnacle. Provided I'm unable to find the issue, what are my options?

Well, if you shorted the brown wire to the red/white wire (the one that goes to the positive terminal of the battery), then it would be like your old regulator which didn't have the brown wire. The idea with the brown wire is that you can connect it to the place where the load is, so that the regulator can put out a higher voltage to overcome whatever voltage drop there is in the system. (I think they usually wire these at the headlight--you'll have to check a wiring diagram for your bike to know for sure if you can't trace it through the harness). If there's a drop in the sense wire circuit, then it will cause the regulator to increase the output voltage unnecessarily, which could explain your 15.2V reading at the battery.

jackleberry wrote:

Shabba wrote: So I've traced the brown wire as far as I dare. Where does it terminate or rather, I'm assuming that it goes to the binnacle. Provided I'm unable to find the issue, what are my options?

Well, if you shorted the brown wire to the red/white wire (the one that goes to the positive terminal of the battery), then it would be like your old regulator which didn't have the brown wire. The idea with the brown wire is that you can connect it to the place where the load is, so that the regulator can put out a higher voltage to overcome whatever voltage drop there is in the system. (I think they usually wire these at the headlight--you'll have to check a wiring diagram for your bike to know for sure if you can't trace it through the harness). If there's a drop in the sense wire circuit, then it will cause the regulator to increase the output voltage unnecessarily, which could explain your 15.2V reading at the battery.

I can't find anything causing the drop. I've tested the wire as far I can trace it and tested it at the binnacle. Nothing. I might just go ahead and short it at the wire you mentioned. I'll be ordering a quality r/r next week, one that should handle this without all the issues. I hope.

Sooooooo.... I decided to just remove the new r/r and replace it with the old one simply because the old one was charging enough for me to ride to work and back. My thinking is that I'd rather undercharge or just barely charge enough to get some saddle time in without ruining the battery and possibly other parts of the charging system.

Upon removal and inspection, I noticed that the ground cable from the old r/r, where it attaches to the connector, was loose. As I looked further, it came out completely. No corrosion, no breakage, just where the cable and the metal connector divorced. I pulled the plug out of the plastic, carefully crimped it and put it all back together.

Charging? 13.5 at idle, 13.9-14.2 at 4k rpm. Everything is working too. I checked with the high beams on and as soon as I flicked the high beam on, charging dropped to 12.9 and immediately built back up to 14.0.

Does this sound like it's doable until I can get a high quality r/r?