Topic: Charging woes

[savannahcafe]

Where to start. I have read all through the FAQ and it seems like there is allot of good info, but light on what to do if something doesn't register right. I have a new battery and I rewired my electronics. Everything is soldered and I did the one wire at a time method. I have wired my headlight on constantly. I had a few problems so I replaced the battery and all was fine. My system showed 14+ volts at 2500 RPM. I have a new rectifier and I adjusted my regulator today. Still, after a full charge, there is no voltage change while revving. So, where do I start. I have tested the regulator and from the findings, it seems to be working. While the bike is running, the regulatpr heats up a bit. All my grounds are good and I'm not using the starter button on the handle. Any suggestions? What is the best way to track this down in the proper order? Once again, I have read the FAQs and tons of other stuff. The only thing I havnt soldered is the rectifier. It has the factory connector and I checked continuity and it seems fine.

[TwoTired]

Can we assume you have an SOHC4?

If your rectifier output does not go higher than static battery voltage, then check the voltage going to the field of the alternator.  For the alternator to make power, there must be voltage there.  The closer to battery voltage the more output it should make.

[savannahcafe]

oops,sorry. Yes, a 75 cb550. OK, I went out and traced the wires I extended from the alternator to under the seat where I mounted the electronics and I found a few of them had broken right past the solder joint. I skimped out and used a small gauge wire and thats what I get. I'm at my house so I will have to wait till tomorrow to grab some decent wire and re do it. I'm guessing that during the bundling and wire tying process they must have broken. Sorry I didn't check this out before posting, I'm a newb. Ill fix those known problems and see what I come up with tomorrow. Like I said, it was charging fine after the new battery.

[TwoTired]

It may not be the gauge of the wire but the strand count or termination technique.

Post a pic of where it broke.  Maybe we can help avoid a recurring problem?

Cheers,

[savannahcafe]

OK, I have the wires all sorted out. Everything is connected and I have the charger on the battery. The battery still had enough charge to start the bike, but it still wasn't showing more than a half volt increase at 2500rpm. I pulled the black wire and white wire from the regulator and connected them then revved the engine while testing voltage at the battery and no difference. Im guessing this means it is something other than the regulator. What should I test next? It is a brand new rectifier on the bike but who knows, maybe its bad.

[savannahcafe]

OK, I also checked the rectifier by setting my meter to ohms I placed one lead to green and tested the 3 yellow wires. The 2 yellows on the outside showed between 6 and 7 ohms but the one in the middle showed no reading. Could this be the problem with no charging?

[TwoTired]

I pulled the black wire and white wire from the regulator and revved engine while testing voltage at the battery and no difference.

To an electrical technician this is parrallel to saying "I took the pistons out of the engine, and it still won't run right!" 
Did you connect the black and white wires together bypassing the regulator?

Im guessing this means it is something other than the regulator. What should I test next? It is a brand new rectifier on the bike but who knows, maybe its bad.

Guessing is what I call the "shotgun approach" where you just keep replacing components until the circuit works again.  This is fine if you have the parts/money.
Was reply #1 not clear about what to test check?

OK, I also checked the rectifier by setting my meter to ohms I placed one lead to green and tested the 3 yellow wires. The 2 yellows on the outside showed between 6 and 7 ohms but the one in the middle showed no reading. Could this be the problem with no charging?

You sure you read the FAQ?

VI.   Check the five leads on the rectifier.
A.   To perform a forward bias test first connect the red tester lead to the green ground lead.
B.   With the black tester lead test all three yellow wires.
C.   Resistance must fall between 5 and 40 ohms.
D.   To perform a reverse bias test connect the black tester lead to the green ground lead.
E.   With the red tester lead test all three yellow wire.
F.   Resistance must be greater than 2000 ohms.
G.   Connect the black tester wire to the red and white rectifier lead.
H.   With the red test lead test all three yellow wires.
I.   All three must have between 5 and 40 ohms.
J.   Connect the red test wire to the red and white rectifier lead.
K.   Test all three yellow wires with the black tester lead.
L.   Resistance must be greater than 2000 ohms. 

[savannahcafe]

Heres where I get frustrated. Am I to assume the rectifier is plugged in still, or do I need to unplug it? EVerything I read leaves something out.

[savannahcafe]

With the rectifier unplugged
VI.   Check the five leads on the rectifier.
A.   To perform a forward bias test first connect the red tester lead to the green ground lead.
B.   With the black tester lead test all three yellow wires.
C.   Resistance must fall between 5 and 40 ohms.   
first yellow wire 4.0 ohms
second yellow wire 118. k ohms and counting
third yellow  1.012 ohms

DO i need to go on with the rest of the testing on the rec, or can I assume its shot?

[TwoTired]

With the rectifier unplugged
second yellow wire 118. k ohms and counting

DO i need to go on with the rest of the testing on the rec, or can I assume its shot?

This indicates and open circuit or a bad diode. If you can verify wire/connection integrity within the unit, then another rectifier is a good choice.

Cheers,

[savannahcafe]

I contacted the owner at Oregon Motorcycle Parts with my results of testing the rectifier and he says its fine.

I said=  Yes Im using a digital multi meter, and yes it does have a diode check function. In the diode check
> > function, the diodes seem to be doing there job. I show roughly .500 on
> > all three wires one way but when I reverse the leads, it shows nothing.
> > What is my next step?
>
>His reply=  Assuming you did this test from both green to yellows and black to
> yellows, the next step is to test the stator and field coil. The
> rectifier is fine. A standard resistance test from a digital meter
> cannot be used on a rectifier or single diode.
>
> Tony

This was his response after I told him my findings

With the rectifier unplugged
VI.   Check the five leads on the rectifier.
A.   To perform a forward bias test first connect the red tester lead to the green ground lead.
B.   With the black tester lead test all three yellow wires.
C.   Resistance must fall between 5 and 40 ohms.   
first yellow wire 4.0 ohms
second yellow wire 118. k ohms and counting
third yellow  1.012 ohms

DO i need to go on with the rest of the testing on the rec, or can I assume its shot?

Here is what I e mailed him.
There is no black wire on the rectifier. 3 yellows, a green and a red. I posted my results on a forum and was told the rectifier is bad with the results I provided. Im not arguing I just keep getting different answers. On my first e mail to you I stated that while checking resistance on the yellows using the green, I got 4.00 ohms on the first, no reading on the second and 1.012 on the third. Is this ok? Everywhere else I have read says that is a bed rectifier?

So I feel like Im getting 2 completely different answers. What gives?

[TwoTired]

I assumed you were using the diode function on the first set of numbers you gave us.  118K ohms indicates an open.

The diode test function uses a higher voltage injected into the circuit, necessary to activate a good diode.  The newer meters inject such a low voltage on normal ohms scale that diodes may not activate and this gives a high ohm reading because the diode is not conducting.  This comes under the heading of "know your test equipment capabilities".

There are 12 tests to perform on the rectifier using the diode test function of your meter.
Green to yellow (3) with one test probe polarity.
Green to yellow (3) with opposite test probe polarity.
Red to yellow (3) with one test probe polarity.
Red to yellow (3) with opposite test probe polarity.

Each of these tests isolates a single diode of the six contained in the rectifier module.  Each should conduct in one direction of current flow, but NOT in the other, as determined by the test probe polarity.

What are your results?

[savannahcafe]

Awesome, thanks for clarifying that. I will test sometime tomorrow and let you know. I think you should submit that to the FAQs because it isnt very clear in there. Thanks again, Ill let ya know soon.

Mark

[savannahcafe]

Alright, using the diode test function on my multimeter,
red lead on the red wire and black lead testing 3 yellow wires I had no reading
I put the black lead on the red wire and tested the 3 yellows and got .450-.480 on all 3

red lead on the green wire and black lead on each yellow meter showed .450-.480
black lead on the green wire and red lead on each yellow meter showed no reading.

SO I see the diodes are doing there job, is this the only test to check for a bad rectifier? What should I check next. I did take the white and green wires off of the regulator and connected them together and still at the battery while running showed no voltage increase at any RPM range.

[TwoTired]

SO I see the diodes are doing there job, is this the only test to check for a bad rectifier?

I did take the white and green wires off of the regulator and connected them together and still at the battery while running showed no voltage increase at any RPM range.

Small wonder.  Connecting both ends of the field coil winding together doesn't help make any current flow through it.

Measure the resistance across White and Green.  About 5 ohms is good.

By pass the regulator by disconnecting White and Black and then connect White to Black.  This should activate the alternator and it should make power.  Check the voltage across the rectifier green and Red when the you rev the engine, as it should be charging the battery then, provided the rectifier is attached to the battery terminals.

[savannahcafe]

Alright, resistance across white and green was 5.8 ohms    I connected the white and black wire from the regulator and metered voltage at the rectifier red and green and when I revved the engine to 3000 rpm the voltage did increase but only to about 13.5 volts.

[savannahcafe]

took it up to 4000 rpm still the same. I checked the resistance  between the white wire and ground with all regulator wires disconnected and resistance was 6.2 ohms meaning the field coil is good. Tested stator yellow wires with rectifier unplugged 1 and 2=1.8ohms, 1 and 3=1.7ohms, 3 and 2=1.8ohms

[TwoTired]

The battery charge level dominates the voltage reading there.  If the battery was discharged, the alternator will charge it slowly, and 13.5v is on the way toward 14.5 V (where the Vreg will cut back the alternator power out).
When the lighting is on, it diverts/absorbs power from charging the battery.

The starter motor draws 150 amps per second and if the alt. is only putting an amp into the battery, it will take more than 150 seconds to recharge the battery.  And, even longer to peak surcharge it to 14.5V.

Test process:
peak charge battery without using the bike.
Let rest about 2 hours.  The voltage reading s/b 12.6v, or very nearly so.  Make a note of the voltage.
Kick start bike.
Make a chart of voltage at 1000, 2000, 3000, and 4000 RPM.
Anything higher than 12.6v at battery means it is charging.

Note that the field coil on the 550 is supposed to be 4.9 ohms +/- 10%.  What does your meter read when you place the probe tips together on the lowest ohms scale?  You must subtract this amount from your measurements, as that is test lead error. 
Poor connectors and wire can also add resistance to the measurement.
The higher the resistance, the less current flows to field coil, weakening the magnetic strength, and causing the alternator to reduce power.

Cheers,