My voltage readings are opposite of what I'd expect!!

[chuckycheese]

I just checked out my voltage readings on my GS1100 and find them to be just the opposite of the way you'd expect them to read on a running bike.

These voltages are measured indirectly from the battery (well-connected BatteryTender cables) and are as follows:

0 rpm with engine off 12.6V

1500 rpm 13.45V

2500rpm 12.82V

5000rpm 12.5rpm

This bike's battery is nearly new and is not boiling out. Also, the bike can sit for a couple of weeks and still start easily. The R/R is OEM, has been replaced recently by the guy I bought it from and does, indeed, look like new. What could possibly be going on. By the way, I know I'm checking it out correctly because my GS750 checks out just the way it should. I welcome your thoughts!!! It must be something simple but I'm baffled.

[Nessism]

Time for the Stator Papers baby!

http://www.thegsresources.com/garage/gs_statorfacts.htm

Good luck.

Cut and paste from Stator Papers.

My bike seems to charge OK on idle and slightly up, but when the revs rise up to, say, 4000 RPM, the voltage on the battery poles starts to drop down. What's wrong here?

It seems at this point as if your stator doesn't have a complete shortage, but the insulation has deteriorated enough to cause a leak under load, as is the case when the revs rise, since the stator would then generate more power.

If the rectifier/regulator is still okay at this point, you will probably want to replace your stator right away, since when the stator blows, it'll probably fry the diodes in the rectifier. But on the other hand, this might, on a GS, well be caused by the phenomenon as described in the theory story, so this might be a very bad omen. Check your commonsense (and

[bonanzadave]

I would check out the POs R/R connections. Also check the R/R ground and do the ground direct to the - battery post everyone does. Those readings tell me you have a good battery and a bike thats not charging. Stator ?

[chuckycheese]

Thanks

Yeah, I need to check out all the connections and really go through the whole thing. The section from the stator papers sounds exactly like what's going on. I don't remember seeing that when I rebuilt the charging system on my GS750 but....it didn't sound like a problem I had with that bike. With the GS1100, it sounds like that's it, for sure. The fact that the voltage would go down as the revs go up sounds almost paradoxical and I find it hard to understand.

I didn't get the part about the 'phenomenon discussed in the theory story' as I didn't sift through the flowery entertainment but I'm guessing that I'll end up with a new stator. I'll check all my connections and work through the problem...and report back!

Thanks to both of you for the information!!:-D

[posplayr]

Voltage inversion

I have not seen it on my bike, but I have described this before. If you have a poor connections between your positive R/R out and the battery (i.e. resistance of a few ohms in an inline corrector which should also probably be changed) then there will be some voltage dropped between the battery and the R/R.

You will measure it as a positive drop from R/R to battery (R/R out is higher than the battery voltage relative to battery negative; put the plus VOM lead on +R/R out and the negative VOM lead at + bat). That is because the R/R is generating current that is going to the battery. The more current the R/R puts out the lower your battery voltage gets.
Another member here GS Zealot (??) described the same effect. It was something like 0.5 volts at idle and probably closer to 2 volts at 5K rpm.

Simply measure the voltage difference between the R/R out and the battery. As RPM's increase the more current will flow to the battery and the lower the voltage will get. Clean the positive lead to the battery and it should go away. I think that the Honda regulator partially solves this as it uses a separate sense point and not the same place that it is trying to charge.

Posplayr

[BassCliff]

Yep, I'd say that stator is suspect Mr. chuckcheese. Have you tried the AC voltage test?

Thank you for your indulgence,

BassCliff

[posplayr]

May I beg your indulgence

I understand that the stator papers are time tested but there seems to be a possible oversight requiring further elaboration. At least I don't understand why the test for positive and negative connections between the R/R and the battery are not tested at both idle and 4000 RPM.

This decreasing battery voltage phenomenon will be readily identified in this step. Of course there is a possibility that the stator could be shorting at higher voltage/currents but I don't think this is really a stable condition like the observed measurements. If the stator is shorting then it is likely to be on a one way trip to "smokes ville" and a quick trip at that.

Easiest thing to do is rev the motor while doing the two tests below and make sure you have less than 0.2v or so at 4000 RPM. That will most likely give you a stable charging system and without it likely to cause major problems. Remember at 10 amps it only takes 0.1 ohms to make a 1 volt difference. to get to 0.2 v you need less than 0.02 ohms resistance between the R/R and battery connections.

Bottom line is I think it is much more likely that a GS has more than 0.02 ohms resistance in the connections than the stator is intermittently shorted at higher load currents.


Let the engine idle, and connect the black multimeter lead to the battery(+). Connect the red multimeter lead to the RED output wire of the RR. Leave the RR connected to the bike. Check the reading on the meter. Leave the engine idling!more than
0.2 V
Bad connection in the positive lead from RR to battery(+). Check the entire lead (suspect the connectors as well as the fuse-box and fuses). Good connections are extremely important in this high current lead. Solve the problem and return to STARTLess than 0.2 V
Connect the red multimeter lead up to the battery's negative pole (-) Connect the black multimeter lead up to the negative output of the RR (BLACK/WHITE), but leave the RR connected up to its leads on the bike. If you can't find a negative output wire, then the casing of the RR is normally the negative lead to the frame. Check the reading on the meter. Leave the engine idling !more than
0.2 V
Bad connection in the negative lead from RR to battery(-). Check the whole lead to the battery(-). If the RR doesn't have an output lead but uses the case as connection to the frame, clean the area where it is bolted and use new screws. Also check the connection between battery(-) and frame. Also suspect the plate on which the RR is mounted (sometimes it is rubber mounted and uses an extra cable from this plate to the battery(-) or frame). Disconnect all suspect terminals and clean. Best solution: connect the RR straight up to the battery(-) with an extra lead. Solve the problem and return to START


Posplayr

[chuckycheese]

No yet!

Yep, I'd say that stator is suspect Mr. chuckcheese. Have you tried the AC voltage test?

Thank you for your indulgence,

BassCliff

Thanks, Clifford! I just recently bought the bike and have had such fun riding it (my GS750 feels a little sad at the moment) that I haven't done much of anything....except order some parts to rebuild the carbs. I'm going to check it all out and get to work on it.

[chuckycheese]

Thanks

Posplayr, your knowledge of electricity is 'light years' ahead of anything I know about the subject. I'll take your advice and check the things you mentioned....and report back what I'm able to find out.

Several years ago, I went through the stator papers and ended up changing both the stator and R/R. Since then, I've often wondered if only the R/R was bad...I'll never know for sure.

[BassCliff]

To wrench or to ride? That is the question.

Thanks, Clifford! I just recently bought the bike and have had such fun riding it (my GS750 feels a little sad at the moment) that I haven't done much of anything....except order some parts to rebuild the carbs. I'm going to check it all out and get to work on it.

My Mom calls me "Clifford", but only when she's mad at me. :-D

Definitely clean all the electrical connections and make sure the ground wire from the r/r is connected directly to the negative terminal of the battery, then retest. If the voltage at the battery is still low when running at 4000 rpm, test the stator output (active) and continuity (passive) both between the legs and to ground. It's all explained in the Stator Papers.

Feel free to have a look at my stator replacement adventure on my little BikeCliff website. I know what you mean about wrenching time cutting into your riding time. I need to slow down for a day or two so that I can install my new front brake lines, rebuild the calipers, and install my Progressive springs.

Thank you for your indulgence,

BassCliff

[posplayr]

Basscliff

I can't do it now, but I just got done drawing a schematic of the charging / battery system on paper and I think I now understand the issues more fully. It also explains why the Honda regulator is such an improvement over teh stock Suzuki.

The bottom line is for OEM R/R's it is critical to minimize the voltage drop from the R/R + to the battery positive terminal just as much as it is to get the ground right.

With just a little resistance in the + supply wire, the bike with kick start or bump start run fine all light/accessories work and the harder you ride it the more dead the battery will get and other than a little resistance everything (including the stator) is fine. Bad design!!!!!!

More later.

Posplayr

[bakalorz]

Yeah, I need to check out all the connections and really go through the whole thing. The section from the stator papers sounds exactly like what's going on. I don't remember seeing that when I rebuilt the charging system on my GS750 but....it didn't sound like a problem I had with that bike. With the GS1100, it sounds like that's it, for sure. The fact that the voltage would go down as the revs go up sounds almost paradoxical and I find it hard to understand.

<snip>

The voltage going down with increasing RPM is not really unusual.
Its a side effect of the type of trigger in the shunt regulator.
Usually the voltage to RPM will start low at 1000 rpm, rise till 1500 or 2000 and then start dropping again.

I'll try to explain what happens, although I'm going to gloss over and really simplify some parts.
The output of each stator is an AC sine wave. The rectifier section of the R/R changes it to DC, but it still has ripple.
At low RPM, the stator does not generate enough voltage to trigger the regulator, and all the voltage it can generate is passed on to the battery.
As the RPMs rise, the stators voltage rises, and so does the charging voltage.
When you get to about 1500 RPM, the stators peak output voltage is just below the R/Rs setpoint trigger voltage. This will be the highest charging voltage you will get.
As the RPMs increase a little bit more, the stators peak output voltage rises above the R/Rs setpoint trigger voltage. So for part of each stators cycle, the stators voltage is shunted to ground. So the average charging voltage drops
As the RPMs increase even more, the stator voltage rises faster, so that a larger part of each cycle is shunted to ground. So the average charging voltage continues to drop as the RPMs increase.


So the dropping Voltage with increasing RPM probably isn't a problem by itself.

However, your overall voltage readings do seem low.
The first step would seem to be cleaning and checking all your connections.

Read my Sig for more advice ...\\/

[posplayr]

Well I dont get it

When you get to about 1500 RPM, the stators peak output voltage is just below the R/Rs setpoint trigger voltage. This will be the highest charging voltage you will get.

As the RPMs increase a little bit more, the stators peak output voltage rises above the R/Rs setpoint trigger voltage. So for part of each stators cycle, the stators voltage is shunted to ground. So the average charging voltage drops

As the RPMs increase even more, the stator voltage rises faster, so that a larger part of each cycle is shunted to ground. So the average charging voltage continues to drop as the RPMs increase.

For the 1981 GS750 Suzuki manual, says that the charging voltage across the battery should be between 14.0 and 15.5 volts at 5000 RPM. While at idle it will be much closer to 13 v if not discharging a little (less than 12.8 v). So while there may be an inversion of the voltage output as some RPM short of redline, the voltage should not reverse and decrease the voltage substantially if the output is going to be within this a controlled range.

I have been analyzing a schematic of the charging system and I have another engineer is going to simulate the Suzuki manual schematic. The more we look at the control mechanism the less we like it.

The objective is to explain the following phenomenon by simply adding excess resistance.

a.) Over charging voltage on the battery (+15.5-17V)
b.) Under voltage inversion of the battery voltage (12.5-12.8v)
c.) smoked battery ground strap (who knows how much current went through a 12 Gage wire with no insulation; I guess i can try and calculate it)

From my own personal experience I started out with a bike that was over charging and had smoked a ground strap from side plate to battery support (daisy chained to the harness). By cleaning connections I got an old stator, and two old OEM regulators to charge with no more than 0.2 volts difference between battery and R/R terminals at 4000 rpm, and contain the max voltage to about 14.5 v. Both old OEM R/R's performed to within about 0.1 v of each other. After changing to the Electro sport stator I also saw the same thing and have never swapped to either a Honda regulator or the new Electro sport regulator. Not saying that I wont just that I went from broke over charging to spec function with just diligent cleaning all of my connections (including the fuse box). That tells me that the failures should be reproducible and natural consequences of deteriorating connection with the poor Suzuki design.

Posplayr

By the way Bakalorz, I posted several copies of the same schematic. If you think it is different could you provide the correct one(s)? TIA

http://www.thegsresources.com/_forum...551#post789551

[bakalorz]

When you get to about 1500 RPM, the stators peak output voltage is just below the R/Rs setpoint trigger voltage. This will be the highest charging voltage you will get.

As the RPMs increase a little bit more, the stators peak output voltage rises above the R/Rs setpoint trigger voltage. So for part of each stators cycle, the stators voltage is shunted to ground. So the average charging voltage drops

As the RPMs increase even more, the stator voltage rises faster, so that a larger part of each cycle is shunted to ground. So the average charging voltage continues to drop as the RPMs increase.

For the 1981 GS750 Suzuki manual, says that the charging voltage across the battery should be between 14.0 and 15.5 volts at 5000 RPM. While at idle it will be much closer to 13 v if not discharging a little (less than 12.8 v). So while there may be an inversion of the voltage output as some RPM short of redline, the voltage should not reverse and decrease the voltage substantially if the output is going to be within this a controlled range.

I agree that Chuckycheese's voltages are too low.

What I was trying to explain is that it is not uncommon for the voltages to rise from idle to 1500 or 2000 RPM and then to start slowly dropping as the RPMs are increased more.

Something I would consider likely to be typical would be:
1000 RPM 12.8 volts
1500 RPM 14.5 volts
5000 RPM 14.0 volts
9000 RPM 13.5 volts

My bike does it, but it may not be good test, since has a homebuilt R/R on it.
However, my trigger is conceptually similar to Suzuki's (with addititonal amplification and overvoltage protection)

I have read quite a few times on the GSR that other people's bikes do that to a greater or lesser extent.

If the Suzuki regulator schematics are accurate, it is how you would expect it to behave.

I have been analyzing a schematic of the charging system and I have another engineer is going to simulate the Suzuki manual schematic. The more we look at the control mechanism the less we like it.

Nooooooooooooooooo ........... you can't mean that.

(note for the humor impaired: the above contains sarcasm)

Although Suzuki's trigger is primitive as heck, I suspect it would be adequate (just barely) if it was overvoltage protected. Read the other thread.

By the way, I (more or less) simulated the above in LTC switchercad when I did my regulator. To get any kind of meaningful results you have to do the alternator coils and the loads as well.
(and the simulation showed the same kind of rising then falling voltage fwiw):-D

The objective is to explain the following phenomenon by simply adding excess resistance.

a.) Over charging voltage on the battery (+15.5-17V)
b.) Under voltage inversion of the battery voltage (12.5-12.8v)
c.) smoked battery ground strap (who knows how much current went through a 12 Gage wire with no insulation; I guess i can try and calculate it)

From my own personal experience I started out with a bike that was over charging and had smoked a ground strap from side plate to battery support (daisy chained to the harness). By cleaning connections I got an old stator, and two old OEM regulators to charge with no more than 0.2 volts difference between battery and R/R terminals at 4000 rpm, and contain the max voltage to about 14.5 v. Both old OEM R/R's performed to within about 0.1 v of each other. After changing to the Electro sport stator I also saw the same thing and have never swapped to either a Honda regulator or the new Electro sport regulator. Not saying that I wont just that I went from broke over charging to spec function with just diligent cleaning all of my connections (including the fuse box). That tells me that the failures should be reproducible and natural consequences of deteriorating connection with the poor Suzuki design.

Posplayr

By the way Bakalorz, I posted several copies of the same schematic. If you think it is different could you provide the correct one(s)? TIA

http://www.thegsresources.com/_forum...551#post789551

I replied in that thread, but the short answer is that I thought all the GS's were like the last one you showed. My mistake.

[chuckycheese]

Not yet!

Well, I spent quite a bit of time today going over my bike and looking for my problem. I performed just about every test on the stator papers and almost everything looked just fine. Nearly all of my connections looked like new (the stator and R/R have very few miles on them). The tests seemed to indicate that both the R/R and stator work perfectly. One test that didn't work out was this one:

Let the engine idle, and connect the black multimeter lead to the battery(+). Connect the red multimeter lead to the RED output wire of the RR. Leave the RR connected to the bike. Check the reading on the meter. Leave the engine idling!more than
0.2 V
Bad connection in the positive lead from RR to battery(+). Check the entire lead (suspect the connectors as well as the fuse-box and fuses). Good connections are extremely important in this high current lead. Solve the problem and return to STARTLess than 0.2 V

My bike exceeded 0.2V and registered between 0.5V and 0.6V. I am hoping that's the problem; is that likely???

I had 'high hopes' that it was but I disconnected the R/R and measured the voltage between the battery posts with the bike off; it read 12.6V....then I measured the voltage between the negative battery post and the power source to the R/R....the reading was nearly identical. So the connection seemed compromised with one test but not with the other. I'm dejected and don't know what to do next. Thanks for your help!!