Topic: Charging tests "where are you TT?

[Hush]

OK so my bike (1979 CB650Z)has charging problems and battery runs flat even after being ridden all day.
Consulted Clymer bible and conducted tests as per their instructions.
I'm just not sure how to interpret what the results are?
EDIT, IGNORE REGULATOR RESULTS AS WAS USING WRONG RANGE ON MULTIMETER.
Tested regulator plug: 3 yellow wires 4.20, 2.65, 5.95, so none the same!
                                Reversed leads and only the middle yellow wire has any reading 8.88!
According to Clymer, all should test either high or low but should be exactly same...what is this telling me?

Tested stator wires: 3 yellow wires show low continuity to each other (that's good I think)
                              3 yellow wires also show continuity to earth (that's bad I believe)

Battery test: attached multimeter in 20v range across battery terminals with bike running, even at high revs (6-7000) only got 13.2 volts....Clymer says should be 14.5 volts.

Tested rotor as per Clymer, all tests OK.

OK which parts do I throw over my shoulder? I think at least a new regulator is called for, do I also need a new stator?

[GammaFlat]

when you say regulator, do you mean rectifier.  If those are the tests from the yellow leads of the rectifier, then throw the rectifier over your shoulder.  Consider making your own.  I did.  Very cheap.  Awaiting awesome heat sinks to make it a very nice, neat package (instead of a little rube goldberg right now).  Good luck.

[Hush]

Fished through bin and found regulator, apparently there was some user error involved...we won't go into that at this point.


Hi Gammaflat, the CB650 has a combined regulator/rectifier so you test one you test both, am using TT's recommended range for retesting (Clymer actually expects some form of expertise in this field obviously).

I should have listened harder in my basic electronics classes.

OK re-did tests in the correct range for diodes, all tested 8.55 one way and infinity 00.00 the other so guess that rules out the diodes being coozed.
Retested stator and still get grounding somewhere which I'm not supposed to, this would indicate shorted stator I assume.

[Spanner 1]

Hush, when you tested the 3 yellow wires was their plug disconnected ?, i.e. needs to be...

[Hush]

Yep Spanner, had unit completely disconnected when I tested, looking like stator problem.
Might cheat and drop the regulator and stator into an auto electrician for checking.

[bryanj]

There are 3 yellow wires to the stator and with the plug disconnected there should be equal resistance (OHMS) reading (Low) between any pair and a high reading any one to ground. If youre readings repeat first check would be for wire chaffing where thet go through any casing

[Hush]

Exectly what I was thinking BJ, it makes a ton of sense that the wires are rubbing on the engine casing.
I did fit a thick plastic pipe around them when I put the motor back in but it may have worn through again.
I'll remove the stator from the bike, unkink the wires, clean it up and retest on the bench.

[TwoTired]

Hush You have regulator and a rectifier built into the same unit.  But, I don't think there is much electrical connectivity between the two functions inside.

The rectifier connections are yellow(s) red and green.  This enables you to isolate the rectifier diodes for testing.

The regulator connections are white and black (outputs) to alt. rotor, and a separate Black to power the regulator in concert with the green. (the green is probably the only terminal shared by the two internal functions of the R/R.)

As noted, the yellow stator wires should have continuity (less than 1 ohm) between each other but not to the engine case.  This is a fault condition, if you are measuring correctly.
Infinity, by the way, is a very high number, not Zero.  However, some meters will display zero but flash the display or have some other display indicator representing an "over range" condition.  Different brands can communicate to the operator differently, but that should be explained in the owners manual that you read when you obtained the unit.    The reality is that you can't really measure infinity, as by definition, it is not finite.  How the meter displays this inability to measure varies among brand and model of instrument.  Just as motorcycles are different beyond having two wheels and a motor, so are test instruments different, even though they have test leads and a display.  With the function know set to a resistance scale the probes touching together, you should get very near zero on the display.  With the probes not touching anything (especially not each other), should be pretty close to an infinite reading on the meter display.

Er, It is rather surprising that a grounded stator would produce 13.2 V at the battery.  You have the lights off or something? You might wish to review your tests, before condemning components.

Cheers,

[Hush]

Yes totally agree that seems strange that system can create 13.2 volts at battery and still be faulty?
Will keep testing (in frustraition) before condeming any parts.

[Hush]

Retested: 12.6 volts at idle......12.4 volts with headlight on full beam.....13.2 volts when held at over 5000rpms didn't matter if light on or off.
Bike runs well, starts easy?
Why does my battery die???

[TwoTired]

Could be weak charging, I suppose. 12.4V is discharging.  At what RPM does the voltage climb start to climb back above 12.6v?

How confident are you about your stator resistance measurements?  A grounded phase would make the alternator about 2/3 strength, and probably increase the RPM needed to begin charging.

Can you take AC measurements of the stator output?  Set meter to ACV, prod across yellow and green at rectifier while running.  They should all be about 60v-ish.

I suppose I'd start prodding about the system taking measurements, regulator input at regulator (compared to battery terminals), regulator output to rotor, rotor resistance, and so on.  With enough accurate data points, the problem should point to itself.

Cheers,

[Hush]

Yeah i see where you are going with this TT, if say one field coil was grounded it would lessen the charging output of the stator but I might still get some charge happening.

[Hush]

Been running some more tests on the charging system with my little brother, he's a linesman so is more used to Kilovolts than DC12 volts but he has been most helpful.
We retested the stator wires and it still shows a ground somewhere and is way past specs so maybe this is the fault I have been looking for.
Also noticed some grinding on the rotor, not sure how this could have occured as it is a tight fit in there and only if the outer casing was left loose and the bike run would this sort of damage happen so it wasn't me!
Stator shows internal shorting under close inspection, little bro says definitley as sign of shorting and would explain the 12.6 volts I get when i should be getting 14.5, as you said TT part of the stator possibly not working.
Second photo is of normal part of stator to compare with shorted bits.
Stator wiring also hows continuity to ground across all yellow wires so again possibly the fault.
Bike is ridable and if I don't use the headlight the battery will restart bike after riding so may have to leave it in that condition until I source another stator.

[750goes]

Hush,

why it is scraping is because the bike has possibly been dropped on that side - are there any telltale marks/scrapes on the engine casing ?

I did the same with mine - dropped it doing a turn in the carpark and then the mtor would not turn over... found out the rotor casing was dented on the bottom a bit too much (it must have been dropped at least once or twice before) and it came in contact with the rotor and jammed it. Also check your stator for marks on the inside - if it is held on by three screws like the 750 they may be slightly out of alignment..

[bryanj]

OK I admit that that is the first ever stator i have seen that LOOKS like it has failed electricaly BUT I recom its overheated due to the rotor rubbing

[Hush]

Hi 750goes, could well be that the PO dropped it hard and replaced the whole engine case cover on that side as it doesn't seem to match the rest of the engine in colour, it's like battleship grey and rest of engine is more silver?
When I got the bike it was in boxes so the stator was in one and the casings in another.
Just got a call from my ex wife's bro-in-law, he has 2 650's and says he can give me a spare stator so this could true test the rest of the charging system if the new stator is any good, will see if I can borrow a regulator/rectifier as well to do some swapping around testing.
Oh to have a whole spare engine to play with.

[Hush]

We'll know soon enough Bryanj, can't wait to get my hands on a spare stator, regulator/rectifier to see which is the dud.

[bryanj]

No problem Mate, as this is an ex police the generator will have done more work than a normal one as the bike will have done more miles with a higher electrical load, I'm always willing to be proved wrong and will add youre expereience to the data in the nogin if you post back with final results.

Best of luck

[SteveMcQ]

Gang: I had a similar problem. Restoring an '81 CB650 Custom bought for $200. Ran but kept killing my battery. First checked/replaced the fuses; then cleaned the starter motor (which was taking a lot of juice) and replaced its brushes; then, replaced the stator's brushes and then replaced the stator. Was actually considering replacing the rotor until I saw the cost of a new one or even a refurbished one. Then a funny thing happened....

Rotor had a kind of varnish on its outside, making it look kind of gold or beige. After running well for a half hour, it looked shiny and clean, slip rings looked pretty good, and brushes were definitely making contact. No obvious "opens" with poor insulation either on the rotor or stator.

So next I replaced the old ignition switch with a bottom (contacts) piece I found. The old switch was corroded, old, ugly. Still no luck charging.

Thought since it was dying at high speed maybe it was my coils - apparently these models, the original coils separate under heat and return to make proper connection when they cool. Found  a pair on EBay.

Not it. Still not charging.

Ordered a Rectifier/Regulator I got for about $30 on EBay. Bingo, bongo, we have a winner.

Tested my original R/R tonight. Guess what? Even with accurate yellow wire readings, we were way off on red/white and white readings.  Clymer does tell you how to test, you just have to be patient. And take good careful measurements and notes. And know how to read an ohmeter/voltmeter. And it says if your r/r "fails any of these tests" - meaning you have to go through all of them until any failures - "your rectifier must be replaced."

So, advice for SOHC/4 folks with charging, "hot start" and other related charging issues: Start with the battery, and work your way to the rotor/stator, not the other way around...

And by the way, cleaning the contacts on the starter solenoid always a good idea.

I touch the button on my Candy Universal Blue '81 CB650C now, and it starts like it's brand new.

So, on to other issues...

But  I must say reading your forums has been a huge help, which is why I've decided to finally stop lurking and report my bike is nearly fully restored, and running like I just went to a Honda shop and bought it new.

Allbest,
Steve McQ

[Hush]

Welcome SteveMcq, your comments helpful.
OK so re-ran all my battery tests with the old setup before changing anything.
At Idle 12.25 volts  At 5000rpm 12.38v At 5000rpm plus headlight on fullbeam 12.09v.
Replaced stator with borrowed one and reran tests.
At idle 12.75 volts  At 5000rpm 13.18v  At 5000rpm plus headligh on fullbeam 13.18.

Borrowed stator looked better than my one but still had minor signs of burning at a few points.
Now to replace my regulator with the borrowed one and see if anything changes....back soon.

[Hush]

OK with my regulator replaced with borrowed one results are:
At idle 12.80 volts
At 5000rpm 13.65v
At 5000rpm with headlight on fullbeam 13.60v

Now what have I proved?
Improved idle from 12.25 to 12.80
Improved charge at 5k from 12.38 to 13.65
Improved charge at 5k plus light from 12.09 to 13.60

While this is overall improvement it doesn't quite narrow my search down to any particular faulty part!?
Guess I'll ride it a bit with the borrowed parts in and headlight on to see if that makes any difference.

[TwoTired]

Did you measure the replacement stator (ohms) before the swap?

[Hush]

Yes TT it gave better results than my own stator.
I'm kicking myself for not grabbing a rotor off bro to swap out my one as there is definite scrape damage to rotor.

I'm pretty happy with my regulator now too, it tests out as being OK and has comparable readings with the borrowed regulator, good job I didn't throw it away eh TT.
Will put my own reulator back on bike and ride it to see if battery takes a charge even with headlight on, this will eliminate regulator once and for all from suspicion.

So that leaves me with stator or rotor, the common factor being the rotor which I did not replace with a borrowed one, might do that on Tuesday when I have to go back to the prison to chair a union meeting and pass my bros' work place where his bike parts are.
I think someone once told me that I could use my rear axle as a rotor puller if need be.
That obvious damage to it is starting to bug me....could my problems all stem from a coozed rotor hmm???

[bryanj]

If youre battery isnt charged,or dying, that 13.6 volts could be all you will get

[TwoTired]

Bryan is right.  The battery doesn't charge instantaneously.  It climbs up slowly if it is not already at peak charge.  On it's way to getting to peak charge, it will measure all voltages up to 14.5 V.

This is a good thing.  If the battery would peak charge to 14.5 V rapidly, it would also go the 0 volts rapidly, too.

Cheers,