What procedure would you use to test the reg/rec on a bike engine? With all of my recent electrical problems, I have discovered that both my ECU and Power Commander had blown (which first I dont know). The Power Commander was causing some very odd voltages at the ECU pins, and as soon as I stripped it out, and replaced the ECU, everything has fired up and seems to be behaving (thank you Andy Bates for the parts, and your knowledge - you are a bloody legend!).

The final test Andy suggested was to test the reg rec, as this is the most likely cause for the electrical issues. Andy suggested starting the engine with the output from the reg rec disconnected, but hot wired so that I could read the output voltage. The wiring is as follows:

5 pin plug:
- brown wire (feed from ignition switch) - this turns on the reg/rec
- 2 x black - earths
- 2 x white/red - output from the reg rec

3 pin plug:
- 3 x yellow - wires from the generator

I wired up the reg rec so that I was applying 12V to the brown wire pin (turns on the reg rec), I joined the two earth wires together, and I joined the two output wires together. The earth wires were fed to the -ve terminal of the battery. I put my multimeter between the -ve terminal of the battery, and the combined two output wires (white and red). Andy said I was looking to see if the voltage fluctuated when the revs rise....

The problem is, I got a reading of ~45V....! I switched the reg/rec for another, and got the same result.... Why is this? The repair manual states an output voltage of 14-15V, but it suggests testing this at the battery with the engine running - I dont want to do this as it might blow my ECU!

So why is my voltage so high? Is my test procedure bogus?Please help! It has been 2 months since I drove my car, and tonight, with the sun shining, and the car mostly back together, I cant take it out as I cannot be sure I wont blow up another ECU. Please help LCBs!

I suspect it may be all over the place with no battery connected.
can you borrow another battery and jump onto it to avoid hooking up to the main circuit and blowing your ecu?

quote:

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Originally posted by ReMan
I suspect it may be all over the place with no battery connected.
can you borrow another battery and jump onto it to avoid hooking up to the main circuit and blowing your ecu?

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I suspect the electronics in the regulator which will vary the output voltage as appropriate, will struggle to do so in a no load situation, we'll soon see :-)

From yahoo mate.

Electronic voltage regulators and rectifiers have no internal moving parts and must be replaced if found to be bad. the main symptoms of a bad voltage regulator are:

1. The battery will discharge.

2. The battery will be over-charged.

3. The light in the electrical system will start to burn out quicker than they should.

In most normal cases, inspecting a voltage regulator, just simply run the engine at the recommended engine speed and check the DC current at the battery. If it is overcharging, it's the regulator that has gone bad and should be replaced. If it is undercharging, and all the other charging components are working right, then it is the regulator that is probally bad.

Rectifiers are somewhat easy to test. Just use an ohm-meter, and connect the ohmmeter to the ends of each of the diodes and check the resistance in both directions. The resistance should be low in one direction and very high in the opposite direction. The exact specs are usually given in most shop manuals. A general guideline for testing most diodes is to have 5 - 40 ohms of resistance in the forward bias direction (where the current is allowed to flow), and infinite resistance in the reverse bias direction (where the current isn't allowed to flow).

Testing the rectifier involves attaching the black probe of the meter to the ground side of the rectifier and the red probe of the meter to each of the three contacts. Record the numbers. Then swap around the meter leads (red and black are swapped) and take the readings again. You have thus measured the ground side of the rectifier.

Testing the battery side of the rectifier involves attaching the meter probes to the battery side of the rectifier and testing the doides in the same way as just described. Once that is done, you should have about twelve readings that are the forward and reverse bias measurements for each of the doides.

A bike regulator won't work properly without a minimum load on it. You could try wiring an old 21watt indicator/brake lamp across the output.

Also the brown wire is likely a feedback signal to the regulator (i.e. the regulator adjusts it's output to achieve 13.8v or so on the brown wire), so should be connected to the regulator output if testing it in this manner.

[Edited on 25/9/13 by MikeRJ]

i take it you dont have a piggy back alternator on your bike engine?(small version of car one)
if not
with engine stoped! first check that your stator windings in your engine are not conected to earth in any way! (use meter in ohm and conect one lead to the engine case and other to each one in turn of the 3 gen ouput wires you shouh have no or very high resistence of its good) discnected from rec/reg

if you get good reedings then check between any 1st of the 2nd output wires, note reading in ohm, then test between 2nd and 3rd take reading and then 3rd and 1st.
you shoud get a simmular low'ish restence of its good

also check wiring of thease wires you get about 90V ac with the engine running (more revs more v's)

if above is ok then start looking into reg/rec unit this is basicly a 3phase full wave rectifier (6 diode type) with an V regulator on output.
a haynes or genuine workshop manual may tell you how to bench test it for your orignal bike model
only other way is to replace it or run engine and check battery v's dont go over 14.8v

note it needs a way of dissipating heat so you shoud have it bolted to something to absorb its heat like chassis or alloy plate with some heat transfer pase/gel or you will kill it by over heating


by the sound of your problem i woud say you have had some high stray voltages and most likely to be ac, high dc v's usualy just boil the battery.

Thanks Baz - I wasn't combining the 'feedback' wire with the reg/rec outputs, so the reg/rec had no way to adjust the voltage. Once I changed the setup last night, and ran the test again, I got the result I was expecting - 13.5-14.8V, rising with the revs...

I still dont know what caused my issues in the first place - it must be either the ECU, the Power Commander or the rec/reg - I cannot find any evidence that incriminates any of these items....

I have found the trouble shooting PDF from Electrex World to be invaluable. Click on the "Bike battery charging problems" in red, very easy to follow and understand.