Topic: Charging Issues - Holy Fried Wires, Batman!

[brycegp]

My rider is having charging issues.  1971 cb500.

I headed out for a ride on Sunday and it was AMAZING!  Started with a fully charged battery.  BUT...after about 40 miles, it started dying at stop signs.  The electric start didn't work cuz the battery was dead.  But it would kick start first kick.  So I kept going.  After 70 miles, it died at a stoplight and wouldn't even kick start.  The battery was DEAD, lifeless, kaput!  So I gave it a quick trickle charge, it started right up and I got it home.  It died pulling into my driveway.

I charged the battery overnight last night.  And this morning I tested the battery.  Below are the mulitmeter test results from the battery terminals.


Bike off.  Key off.  Steady reading.


Bike off. Key ON. Voltage reading dropping.


Bike at idle. Steady reading.


Bike at 2000 RPM.  Steady reading.


Bike at 4000 RPM.  Steady reading.


Thoughts?

[Deltarider]

Or am I just an idiot?

Well, how can I put this?... Maybe you want to switch to DC instead of AC.

[brycegp]

ha.  i knew i was an idiot...   So this electrical shizzz...is new to me.  I'm learning.

RETESTING...standby.

[TwoTired]

Yes you should be using the DC scale to measure battery voltage...But...
No way should you be reading 28V AC on a DC output.

You better state the probe points and conditions under which you measured that 28V AC.  If probes were on the battery terminals while the bike was running, you have serious rectifier problems.

Applying AC to a battery will screw up the the battery.

Cheers,

[brycegp]

retested...see above.  New DC results....

[TwoTired]

If you have 28VAC on your battery terminals, it doesn't really matter much what the DC voltage is.  IMO

[brycegp]

If you have 28VAC on your battery terminals, it doesn't really matter much what the DC voltage is.  IMO

Your post doesn't really give me any information.  Can you explain?

From what you're saying and what little I know so far about the system in general...the rectifier is converting the AC current to DC current that can actually charge the battery.  Because there is such a high AC reading, the problem must be the rectifier NOT rectifying.  Which might be why the DC reading isn't increasing much when under higher RPMs??

Is this what you are saying?

[TwoTired]

If you have 28VAC on your battery terminals, it doesn't really matter much what the DC voltage is.  IMO

Your post doesn't really give me any information.  Can you explain?

From what you're saying and what little I know so far about the system in general...the rectifier is converting the AC current to DC current that can actually charge the battery.  Because there is such a high AC reading, the problem must be the rectifier NOT rectifying.  Which might be why the DC reading isn't increasing much when under higher RPMs??

Is this what you are saying?

Pretty close.  You never did say where your probes were for the AC reading, or if the bike was running or not.  This matters.  It is important data for a proper diagnosis.

[brycegp]

In the post, I mentioned I was testing the battery.  So thought it would be implied the probes were on the batt terms.  Sorry for not being clearer.

I reported the readings at each of five different conditions...as identified in the original post.
1. Bike off. Key off.
2. Bike off. Key on.
3. Bike on @ idle.
4. Bike on @ 2000 RPM.
5. Bike on @ 4000 RPM.

I'll get back to you after I take an electricians class and learn to read your charts.   

[TwoTired]

If you got 28 VDC at the battery terminals with the engine not running, then your meter is faulty/ lying.  The only source of AC on the bike is the alternator, and it only makes any power when the engine is turning.

Could be that the AC measuring section is broken and the DC is still working.  But, until you know, the meter can't be considered reliable.

A fully charged, rested battery should read 12.8-12.6VDC, no load, no charger.  It can have a "surcharge" just after removal from the charger, but that actually interferes with a proper charging system evaluation.

Since the bike doesn't normally charge the battery at idle speed, the bike's load makes a difference in battery voltage. I.E if the headlights are on or not.
If you noticed in the shop manual, they give a chart with different readings for light on and lights off.

The battery is no longer at full charge when the electric starter (50 amps or more load ) is used, or the bike operates at idle with lights on for a while.  These events reduce the battery from full charge.  Even if the charging system is working, the battery can't be instantaneously recharged when the engine is revved.  It takes some time to put the energy back in, which means the voltage can rise slowly depending on the state of discharge in the battery.
That's kinda what the battery is for, a reservoir which neither depletes quickly or recharges quickly. And the stock alternator doesn't ever recharge it quickly, although you can put loads on the battery to make it discharge rapidly.

FYI, when describing electrical tests, don't rely on "implication" to relay conditions.  Electricity conforms to very precise physics.  Any added variables only allow for confusion and conjecture.

Cheers,

[brycegp]

Awesome!  thanks for spending the time to explain. 

I have an aftermarket regulator/rectifier 2-in-1 unit laying around.  Should I put it on in place of the regulator and rectifier units to see if my issue is resolved? 

First I'll get a proper multimeter.  my next door neighbor is an electrician.  I'm gonna get him to help me conduct the next round of tests.

Starting with a fully charged, rested battery, no charger. Probes placed on battery terminals for a VDC reading.
1. Ignition key off with no load = TBD
2. Ignition key on, motor NOT running, headlight ON =  TBD
3. Motor running @ idle, headlight on = TBD
4. Motor running @ 2000 RPM, headlight on = TBD
5. Motor running @ 4000, headlight on = TBD

Anything else I should test and report on?

[TwoTired]

I'd like to see the running voltages with the lighting off, too.

[Roach]

what coils are you running

[brycegp]

what coils are you running

stock coils...

My neighbor with a pro multimeter tested this with me.  And YES...he said my VAC scale is defunct.  Damn $10 Harbor Freight special!!

Starting with a fully charged, rested battery, no charger. Probes placed on battery terminals for a VDC reading.
1. Ignition key off with no load = 13.8 VDC
2. Ignition key on, motor NOT running, headlight ON =  12.65 VDC and dropping
3. Motor running @ idle, headlight on = 12.6 VDC and steady
4. Motor running @ 2000 RPM, headlight on = 12.6 VDC and rose to 13.0 VDC in just a few seconds
5. Motor running @ 4000, headlight on = 13.0 VDC and rose to 13.2 VDC in just a few seconds
6. I didn't test with headlight off cuz I just came in from doing these tests and saw your post asking me to.  
But the /neighbor electrician says "Its charging."  Thoughts?

Maybe something was vibrating loose???  Or by disconnecting and reconnecting some things I fixed the disconnect??

[TwoTired]

It does look like it is charging.  But, I'd like to see at least 13.8 V, if not 14.5V when revved.

What regulator are you using?

Is there a difference between the actual battery voltage and the voltage at the black and green of the Vreg?

Have you checked that all six diodes in the rectifier are operating correctly?  Are all the alternator yellows correctly attached to the rectifier?

[brycegp]

What regulator are you using?

Is there a difference between the actual battery voltage and the voltage at the black and green of the Vreg?

Have you checked that all six diodes in the rectifier are operating correctly?  Are all the alternator yellows correctly attached to the rectifier?

Using stock regulator. Stock rectifier.

Haven't tested the black/green Vreg.

Don't know how to test the rectifier diodes.

Alternator Yellows are all attached as they have been for 3 years.  Nothing has changed there.

[brycegp]

it may interest you to know that i swapped on the Reg/Rect 2in1 unit that I mentioned above and there was no change in the same 5 VDC readings tested above.

I did test the green/black Vreg...black to black and red to green...but the VDC reading was a negative (-) number.  So I thought I must be doing something wrong.  What was I doing wrong?

I took the bike out for a 10 minute ride around the neighborhood.  Pre-ride, batt term, no load VDC reading was 13.3.  Post-ride, batt term, no load VDC reading was 13.0.

In the morning, I'll pull off the left side engine cover and see if any of the wiring connections exiting the stator have come loose or are grounding out.

[stueveone]

Negative reading means you have the probes crossed Ie the black test lead probe is on the positive leg/or side when it should be on the negative leg. Test a battery to wee what I'm talking about. You'll get 12.3v got I stance one way, and -12.3v the opposite way. The negative sign is not important in any practical sense

[scottly]

Quick test:
Neg (Black) lead on meter to neg battery terminal, with ignition switched on, motor not running. Check the DC volts with the red meter probe on:

1) plus term of the battery (this number will be dropping, so move on quickly to steps 2 and 3)

2) black term at reg

3) white term on reg

4) green term on reg

[dave500]

just out of interest auto alternators are also tested while running for ac output,rectifiers arent perfect and some trickles through,like perhaps .01-.1 volt ac or similar,this can interfere with modern cars computers and sensors and what not if its too high,each model alternator will have an acceptable spec for this.

[brycegp]

ummm...i think I found the issue.  I'm charging off of only 2 (maybe only 1) phases of the alternator.  

There was an exposed connection on the green wire that was periodically grounding on the motor casing (see black tape on green wire, temp fix just to shield it for now).  It fried the insulation on the yellow wires.  As you can see one yellow wire was burnt and severed, one is barely attached and the other is crispy.

so if I patch these three yellow wires and properly insulated the exposed connections, it should be charging at 14.5VDC (HOPEFULLY)...

[bollingball]

The green is a ground anyway? The yellow is the problem now. But I do not think it could have been like this during your test. Hope you didn't fry something else. Now ohm the alt. out retest every thing wouldn't hurt if your friend had a Megger ask him he will know what I am talking about. Is the other wire white to Reg. check it too. I am not a expert but TT and some others will see this

[TwoTired]

The yellow wires are the three phase power outputs from the alternator.  The low charging Voltage is expected when only two phases of an alternator are providing power

Can you see evidence of those wires being soldered together?  If not, you are the victim of shody repair work.  You can thank the PO for this headache.  Someone did just enough work to get by, instead of thinking long term repair.

If the wires WERE just twisted together, then they slowly corrode over time and become high resistance connections.  This eats power and converts it to heat at the connection points.  They don't have to touch the case for this to occur.

I don't recall if there were bullet connectors at that location originally.  But, you either need to put the connectors back or make clean soldered connections to restore the yellow wire connectivity.  Coat the junctions with liquid vinyl AND then heat shrink tubing.

Probably should unwrap the white and green and give them the same treatment; connectors or solder.

BTW, I don't like solderless connector for a weather exposed repair.  These will produce the same failure you've experienced, eventually, at the join between wire and terminal.  If you can get the wire as new clean, have the proper crimping tool, and then coat with liquid vinyl it can last a good bit of time, though.

Cheers,

[brycegp]

TT you rule!!

Connections soldered.  VDC reading at batt terms @ 4000 rpm 14.4!!

thanks for the help, guys!!

[TwoTired]

Glad you got it sorted.  Now you can go on and get those electrician credentials!