Topic: checking my non-charging charging system

[Buffo]

I have to check my charging system out. I bought a yelow multimeter from walmart but I must confess that I dont know how to use it...i really didnt even understand the directions it came with...

Can you guys give me some pointers...

[TwoTired]

Oh, a yellow multimeter.

Perhaps you could tell us the brand and model number?

Or, describe the knob settings and scales offered.

Post a pic?

Must be a zillion multimeters out there.  Perhaps only a million are yellow, though.

[Buffo]

I thought the yellow was a good discription. 

[Bodi]

Just about any meter will measure volts pretty well.
There's DC volts (like on almost all of your bike) and AC volts like in your house - and in the alternator circuit between the stator and rectifier. Some meters adjust the scale automatically, some have knobs to select the maximum voltage displayed. Exceeding the "knob" value should not do any damage, up to some absolute maximum allowed.
Amps (or MA, milliamps, 1/1000 of an amp) measure electrical current, probably both DC and AC as well. The meter will have a maximum allowable current, more than that and it will probably pop an internal fuse or be damaged. You must not try to measure voltage using the amps scale or terminals on the meter, you will probably overload the meter. Cheaper meters have low maximum current as a rule, better ones should have a 20A scale which covers most bike needs.
Then there's ohms - resistance measurement. This measurement requires the meter to supply a bit of DC electricity to the leads, and it measures the resulting current. With inexpensive meters very low ohms measurement tends to be wildly inaccurate although over about 100 ohms it should be pretty close.
Some meters have a diode test setting, this shows the voltage drop across a semiconductor junction. Good diodes will be about 0.3 to 0.5V forward and read "max" or something similar reversed. Bad ones read zero or max forward and may be either reversed also.

So... as an example: for battery voltage, hook the leads to the red and black meter terminals, red goes to positive and black to negative on the battery. Select the DC volts or a range around 20VDC to take a reading. If there are separate amps terminals, do not use them; if there is one set of terminals and a dial, do not connect to the battery with the knob selecting a current (A, MA, uA) range. It should display the battery voltage!

The stator and field coils can be measured, disconnect all their wires first. The field coil should have a pretty low ohms reading, but don't compare it to the spec as your meter is likely way off. If it's a few ohms higher than with the meter leads just touched together it's likely to be fine. The stator wires should have almost exactly the same low reading between any 2 (ie 1-2, 2-3, 1-3 should be the same). An odd reading indicates a bad coil section.

Oh, don't try to measure the spark plug voltage. That will fry the meter pretty instantly!

[TwoTired]

Oooooo pretty yellow.

You will probably need a 9V battery installed in it to make the display do something.  Plug test leads into the "COM" Black, and "V ohm m A" Red.  Rotate the dial to DC V 20 scale.

Put the leads, red on battery + post, and black on battery minus post.  Notate reading.

Check your charging system with a fully charged battery.   Use battery tender/charger, whatever.  A smart charger will charge the battery until it gets to 14.5 V and then cut back the charge rate to maintain voltage at 13.2 or 13.8 V.  Your new toy will tell you what's goin on.

Remove charger connection, the battery should stay around 13.2 v, at least, if it is a good battery.

Start the bike (kick start is best) and make a chart of measured battery voltage vs RPM.
Report your findings and we'll proceed with checkout from there.

Your resistance scale has two settings, you'll find handy.  The 2K setting should be used if you want to check the diodes in your rectifier later.  And, the 200 setting will beep when you have continuity between probes.  This will be handy when you want to verify a wire has a connection between two points and you won't have to look at the display for a reading.

Cheers,

[Buffo]

thank you TT.

I will do this and report back...

Buffo

[Buffo]

ok here we are. Tests were done with headlight turned off, a cold engine and measurements were taken with engine at said rpm for at least 2 seconds with the mulit-meter set at DC V 20

off: 13.06

Idle: 11.97

2000: 12.00

2500: 12.01

3000: 12.02

3500: 12.02

4000: 12.03

[TwoTired]

Well, no doubt about it, your bike isn't charging the battery.

Is your wire harness stock? If I use the stock wire diagram will you be able to locate the correct reference points?

Find your regulator. With ignition on, 20V scale, black test lead on green terminal, what is measured on black terminal and white terminal respectively with the red test lead?  Both terminals should have whatever the battery voltage reads across its terminals.  These two terminals (white and black) can be shorted together temporarily if the white wire reads low or no voltage.  If your charging output suddenly reappears, get another voltage regulator.

The white wire powers the alternator.  Full battery voltage there should make the alternator put out as much power as it can for any given RPM.
If still no charging output:
Next is the rectifier output check and to verify the wire between rectifier and battery is intact.  Locate your rectifier.  Measure the green (com or black meter lead) and red/white wires from the rectifier (red test lead 20V DC scale).  If you read a higher voltage there than at the battery terminals (Engine running above 2K RPM), find the wire fault between there and the battery connections.  If it reads the same low battery voltage below 13 V. then check the rectifier.

Unplug the rectifier.  The connector has 3 yellow wires, a green wire and a red/white wire.  These connect to six diodes, and you will take 12 measurements on these six diodes to evaluate there functionality.  Set your meter to 2K resistance scale. (The one with the little diode symbol next to it.)  Place the red test lead on the red/white wire connection.  Then place the black lead on each of the yelow wires in turn.  Reverse the test leads and repeat the measurements again.  You should get a very high reading with one polarity and a very low reading with the other polarity.  Record these readings and then measure from green wire to each yellow wire with both polarities for a total of 12 measurement recordings.  Report back what you have recorded.

If all this checks out, the last thing is the alternator itself.  Find the connector from the alternator and disconnect. It will have white, green, and three yellow wires in it.  Ignore the others for this testing.  The white and green field coil wires should read about 7.2 ohms. (set your meter scale to the lowest resistance scale.)   The green wire may also read zero ohms or nearly so to frame or another green wire on the bike.  The yellow wires are your stator connections and should read 0.2 ohms between any two yellow wires.  Check them all.  This will be difficult for your meter to read acurately because the value is so small.
With your meter set to the lowest scale, place both test lead tips together.  The reading on your instrument scale is your measurement error, as it should be zero.  But, the test leads and internal components have some small resistance.  Remember this number and subtract it from any resistance readings you take with the instrument.
It is probably most important to note a very low resistance value between any two yellow wires, and very very high or infinite resistance between any yellow wire and frame ground or any green wire on the bike.

If all this has check out, then the only thing left is a wiring interconnect issue between components.

Lets us know what you find or if you have further questions.

Good luck!

[SCJIM]

hey buffo,

if it turns out that its your rotor, theres a guy that rebuilds them in alabama "Tim Parrot"

ill look for the email address.   its around here somewhere

[SCJIM]

here ya go buffo,

the ad on ebay is :

It comes with a 1 year warranty .The rotor was know to be the cause most of the charging failures in those bikes .have built and sold hundreds over the years. we also carry the stator and the reg/rectifier if needed . you can e-mail me with any question you might need to diagnose your problem. any questions please e-mail tim@tpe-usa.com . You must send your rebuildable core up front to be built to get this deal.  free ground ups return shipping.   we also carry the correct puller for $15.95    Always best to use the right tool to remove. It helps make sure your core can be  rebuilt.   I have seen to many rotors damaged by using jaw pullers or took a hammer and just beat it off. Quick way to turn the rotor in to a 5 pound paper weight. This is being offered so that there is no core return lag time for us and to save the customer money. By not having to charge the $75.00  refundable core charge.   Rotors are hard to keep in stock this time of year due to demand .This way helps the rebuilder and customer  both

[TwoTired]

The rotor in your pic sure look like it has slip rings.  I can believe the Cb650 has this type.

The Cb750 has no windings in the rotor and therefore no slip rings.  It's rotor is just shaped chunks of metal.
It does have a stator and a field coil, both stationary that come off attatched to the left engine cover.

Cheers,

[Buffo]

as far as I know the harness is stock.  And I should be able to find the correct wires.

I will do all of this and post my findings...

[Buffo]

Ok...I am doing this the best I can...I had to ride my biek to work and took the readings with a not fully charged battery...If I have to do it with a fully charged batt I will re-do it tomarrow morning...

Batt with ignition on...12.24
reading at black wire on regualtor...  -12.04
reading at white wire on regulator.. it flashes between  -0.01 and -0.00

"Both terminals should have whatever the battery voltage reads across its terminals. These two terminals (white and black) can be shorted together temporarily if the white wire reads low or no voltage. If your charging output suddenly reappears, get another voltage regulator."[/color

when I short the white and black wires do I use a jumper and do it with them still connected to the regulator or do I unconnect them from the regulator and then tie them together?

Buffo

[Buffo]

Ok...I checked the voltage at the battery with the black and white wires tied together and the head light off...

I checked the readings at the battery terminals...as the bike Idles the voltage drops a bit every few seconds...if you turn the idle up to 2500 or so the voltage climbs rather quickly...I didn't know how high I could let the battery charge so the highest I let it go was 13.33.

Should I have let the bike run at a higher rpm too see how high the voltage would get...
to let it "top out" if you will.

the readings ot the rectifier at about 2300rpm was: at the battery: 14.55, at the rectifier: 14.88
I tried to take the readings at the exact same rpm and as quick as I could  because the voltage risies at that rpm

The readings for the rectifier are as follows:

looking at the harness the red/white wire on the top, left corner and the green in the top, right corner.

lower left yellow wire readings in the order described in your post: 1.  /  .492  /  .495  /  1.

center yellow wire readings in the order described in your post: 1.  /  .509  /  .508  /  1.

lower right wire readings in the order described in your post: 1.  /  .491  /  .499  /  1.

[Buffo]

I tried to check my alt. but I really did not understand the directions. I have a dark green and a light green wire in that harness. when I test the white and green wires do I test them to each other or to something else? what is the lowest resistance setting on my meter? would it be the 200 setting?

I am sorry that I am retarded. 

[TwoTired]

Looks to me that your regulator is not working and the rest of your charging system is.

When you jumper the black and white wires, you are bypassing the regulator.  It's job is to keep the battery from charging up past 14.5 volts by controlling the power going to the alternator field on that white wire.  The battery is full when 14.5 volts is acheived, and continued charging will eventually cook the battery.  So don't do this long term.

Your charging system worked when you placed voltage on that white wire.  Ergo your regulator is faulty as it isn't doing its job.

If you have a spare regulator, use it.  Otherwise look for a replacement. 

Uh, these things can be fixed.  Though I'm not sure I can explain how over the internet.  There are a lot of variables to contend with.  Instruction would turn into a small booklet.

You have nothing to lose by popping the cover off the regulator and checking the contacts for carbon buildup.

Do you have the Honda shop manual?  On page 95, they have a diagram of the internal circuits of the regulator.  You would have to figure out why the white terminal isn't getting connected to the black terminal.

Cheers,

[Buffo]

thanks 2Tired...I will just look for a new regulator. I have also heard that some people change the seperate regulator and rectifier to an modern single R/R unit. How do I find out which one I would need and how to intall it...

Buffo

[TwoTired]

I've always been able to get the originals to function and could probably make my own, anyway .  So, I don't have any direct experience with replacement reg/rec.
I did an online search for motorcycle regulator rectifier, and found these offerings from Electrex and Oregon Motorcycle Parts that ought to work. 

http://oregonmotorcycleparts.com/vregulators.html

http://www.bikebandit.com/partsbandit/productlist~section_dept_id~1170244~terrain_dept_id~1173708~cat_dept_id~1264784~product_dept_id~1264923~selection_Path~3.asp

I have no first hand information with either of these products or companies.

I suppose you could send me your old one.  I could probably fix it if the contact coil is still good.  I would expect you to pay postage both ways and any internal parts I'd need to replace.  It is a very simple device, really.  I've seen them need adjustment/cleaning, but never fail outright like yours aparently has.
Cheer,

[Buffo]

Thanks again TT. I will remove mine today and open it up...maybe there is something I can find in there foiling the works... 

[Buffo]

Ok TT, I took the cover of of the regulator and it looks pretty clean. The only thing tht I saw tht looks strange is (forgive my descriptions)on the top of the cylindrical thing with the windings(?) there is a piece of wire that comes out of the side near the top, just under the black plastic "insulating pad" and is pointing twards a circular thing that attaches a thin strip of metal to the only moving part on the regulator(a "L" shaped metal piece on the top of the regulator. The thin metal strip is resting on a "setting screw" and seems to be putting resistance on the "L" shaped contact maker...

Anyway, that wire comiing off of the cylnidrical winding thing is not attached to the "L" shaped opiece of metal....is it supposed to be?

Buffo

[TwoTired]

Flying ends of unattatched wires are not normally found inside working electrical devices.

The round cylinder of wire you've located is an electromagnet.  When the voltage gets high enough its strength increases and pulls the upper contacts appart of the "L" thingy.

The round cylinder has two connection wires at the base of the cylinder.  No wires connect to the moving "L" bracket.

Since you're in there.  Check the contacts.  At rest, the L thing should be pushed up and the upper contacts should be "made".

Use your ohm meter (resistance scale, lowest setting) and check for continuity across these contacts while they touch each other.

Sometimes, the contacts will corrode if the gasket seal has been corrupted or if arcing has formed a carbon layer over the contact surfaces.

If the contact resistance is not near zero, take very fine emery cloth or paper (or 600 grit paper) insert between the contacts and wear away some of the surface of each contact.  Then burnish the contacts with the BACK of the paper to polish.  This should restore the connection between the contacts and continuity between the black a white terminals of the regulator.  If so, put it back in the bike and check your charging system again.

Cheers,

[Buffo]

the top contact points were very dirty and but now read a resistance of zero. and that is the same for the bottome contact  points...

however when checking the lower contact: with one lead on the "L" thing and the other on the lower contact point: when pressed down and contact is made the meter reads zero (with proper subtraction) but if you lighten up on the "L" thing to let it rest on the upper contact point you still get a reading of 36.8

I would think that no current should pass without the points touching

Buffo

[Buffo]

Hey!!! I put it back on the bike and with the headlight on at 4000 rpm it read 14.25 to 14.38...it kinda flashed at different numbers inbetween those two...

is that too high? voltage that is.

I just set the rpm at 4000 it started charging at a lower rpm but I didnt note what rpm.

Buffo

[Buffo]

I forgot to mention that when I cleaned the contact points the plastic block that holds the upper and lower points was a little losse and kinda moverd around...I tightened it up in the possition that looked right. (the contact points all lined up and square with each other....does this matter?

[TwoTired]

My Comcast internet connection only seem to work during daylight hours these days...  I guess that's the extra service they provided along with the 8% fee increase.

Really, the voltage regulator's primary job is to keep the battery from overcharging.  It is fully charged at about 14.5 - 14.6 volts measured at the battery.

You had earlier indicated a voltage loss between rectifier and battery of 0.33V.  Add that to 14.25 and 14.38 you are reading now and well what do you know  14.68 - 14.72 V.  There will be some voltage loss in the wire and connectors between charging system and battery.  So, it sounds like your vreg and charging system are okay now.  But, to get things peachy, I'd go through the all the connections between bat and rectifier and vreg, clean them to reduce or minimize losses, so the vReg can "see" as near as true voltage of the battery, and the charging system can deliver full power to the battery.

When you measure the battery voltage, it is really important that it be at full charge.  A good partially discharged battery cannot read 14.5v while it is being restored to full power.  However, once it has reached full charge, the regulator will cycle the alternator between full and partial output to keep the battery at or very close to the full 14.5-6 volts.  Your meter is a sampling meter.  It takes tiny snapshots of what it measures on the probe tips.  The display changes because the vreg is switching on and off.

Congratulations on your Voltage regulator repair!

Cheers,