1980 gs1100 - diode test for regulator - charging ISSUES

[Steve]

Cars have their rectifiers and regulators built into the body of the alternator, so that, by the time there is a wire that you can put a clamp around, it's a DC current. The equivalent wire on our bikes is between the R/R and the battery. (Funny, it's the same thing on a car.)

Clamp-on amp meters work by measuring the strength of the magnetic field that is generated by the current going through the wire. DC meters rely on steady current, and are confused by the constantly changing field of AC current. Essentially, it sees current going one direction, then the oposite direction, and says to itself 'one cancels the other, so there is no current here'.

An AC meter does not care what direction the current is traveling, and ignores the fact that it is constantly reversing. Some will work with DC, others will not.


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[Hap Call]

Actually, if you are using the amp clamp on the stator wires, don't you want AC? :-|

Yes, you do want a DC clamp if you put it on anything downstream of the regulator, like the battery wire. 8-[


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I would think he would clamp on at the positive battery lead (or negative) to get total current draw. If he clamped on the leads coming from the stator he would have to clamp on to each phase one at a time, maintain the same RPM, then sum the three currents. If he tried to clamp around all three phases at the same time, due to phase angle, the current would equal zero or some inaccurate number. Also, if he is not using a quality meter like a Fluke 37, the RMS values may be out of wack due to frequency not being a standard 25, 50, 60, or 400 Hz.

Hap

[Steve]

Hap,
You are quite right about having to sum the phases of the stator. I understood his original intent was to check the DC side for current draw. Most of the amp clamps I have seen were for industrial use on AC, so I merely raised the caution to make sure that he had a clamp that would measure DC. Seems the thread has digressed into technicalities, but the idea is still the same. 8-[

ps. I was not aware that the RMS meters were frequency-dependant. I was under the impression that the RMS qualification assured accurate numbers regardless of frequency. I am, though, under the impression that its calculations are based on a sine wave, so other shapes will yield innacurate numbers.


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[Hap Call]

Hap,
You are quite right about having to sum the phases of the stator. I understood his original intent was to check the DC side for current draw. Most of the amp clamps I have seen were for industrial use on AC, so I merely raised the caution to make sure that he had a clamp that would measure DC. Seems the thread has digressed into technicalities, but the idea is still the same. 8-[

ps. I was not aware that the RMS meters were frequency-dependant. I was under the impression that the RMS qualification assured accurate numbers regardless of frequency. I am, though, under the impression that its calculations are based on a sine wave, so other shapes will yield innacurate numbers.


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The key words are RMS qualification. While I normally deal only with Flukes, I've been told by other engineers (and some calibration techs) that not all clamp-ons will read accurately at non-standard frequencies. I could not begin to tell you why. That is one reason I stick with Fluke meters and have them calibrated at regular intervals.

[hotdergs07]

Well after putting on some new connectors, attaching my regulator to battery ground terminal, and solving my battery light problem by jumping the sensor wire to power I think i've got a marginal pass of my charging system. I have been getting anywhere from 13 to 13.9 V it kind of jumps around non related to RPM...so I am guessing the regulator is working and that is why my voltage is jumping around a little bit...(is that a correct assumption??)

Also, out of the stator there are three wires...two of which go directly to my regulator/rectifier and one that ataches to a green wire somewhere in the wiring harness...where does this green wire go/do...is it some type of voltage sensing circuit?

thanks for all the feed back, I am getting about 9 amps out of the
rectifier/B + cable

[Steve]

The third stator wire disappears into the harness to show up again at the headlight switch (that Suzuki so thoughtfully disabled for you), then returns back to the rectifier/regulator. Hopefully you did find a third wire somewhere that connects to the third input wire of the R/R? The theory behind that was based in the days that you could turn off the headlight. Why generate the power if you are not going to use it? By removing that leg of the stator from the circuit when the lights were off, the regulator did not have to work quite as hard. Made sense then, but does not matter now that the lights are on all the time.


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[hotdergs07]

yeah that makes sense, there is a third wire, red/white tha comes back into the regulator, now that i know that I might take the voltage drop over that wire, or check the resistance...that could be eating a little bit of my charging voltage too.

[Steve]

You can also bypass that wire entirely.

Take the third wire from the stator and connect it directly to the third input on the R/R.


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[hotdergs07]

Another good point!