Charging System or Dead Short???

[copperhead25]

Greetings all,
1979 xs1100 special, New battery and replaced Voltage Regulator..., Cleaned all accessable connectors.....vehicle starts and runs like a champ. Lights don't dim or brighten with RPM change and I believe that the stator and field coil meet specs.
After riding for about 90 minutes, I stopped for Gas and my battery was dead. Recently, I left the battery hooked up and all fuses in place and the battery went dead after sitting for 3 days.....I believe I have a dead short, I welcome any other opinions/ theories. Also if anyone knows where these beasts most commonly develope shorts or any other helpful information, I would appreciate it.
Thanks.......

[randy]

copperhead25;

Do you have anything connected to the "ACCESSORY" terminals? If so, I'd check there. Those terminals are live even when the key is off. Don't ask me how I know!

Other than that the best way to find your 'short' is:

First, make sure your battery is charged.

Key OFF

Disconnect the positive battery terminal.

Connect a voltmeter between the positive battery post and the positive lead. If you see a voltage, you've got a drain somewhere.

Leave the meter connected and begin pulling fuses one by one. When the meter goes dead, you've found the faulty circuit.

Then you can re-connect that fuse and make your way down that circuit and pull connectors to find the offending part.

Good luck and let us know what you find.

[mro]

When nothing obvious, what randy says is the best way to narrow it down.

Few weeks ago bought new battery. Added the acid and charged it for 9 hours at two amps to "activate" it. Two days later had to get a jump start to get back to shop. New batt was bad. Took back and got another one

Another time went and locked the forks with the key. Did not notice the running lights had come on. Drained batt in short time.


mro

[copperhead25]

hey randy

Thanks for the info...I hooked up voltmeter as directed and found that the system is drawing voltage with key OFF. 3-5 volts.....when I disconnected the main fuse this dropped to .5 volts.
I also noticed that when the turn signal is engaged with the beast in neutral...the neutral indicator light seems to pulse.
The wires coming from the alternator to the fuse box area (Wh-Wh-Wh-Yellow) whe getting warm/hot with the machine running, but I thinks I fixed that.....bad connector.
I don't know if it fixed the entire problem or not, because I'm afraid to ride more than 40 minutes!!!
I'm going to check the wiring into the fairing etc and check the charging system as directed in the manuals with a ammeter and voltmeter.....I'll let you know what I find out.
Thanks so much for your advise and if you think of anything else...let me know!

[copperhead25]

Another Follow-up.....
Voltmeter actually shows 1.8- 2 volts when the system is off.
Disconnecting wires from circuits one at a time narrows it down to the voltage rectifier (which did not test out when removed) and the alternator.
As the alternator was only kicking out 12.2 volts on a good day, and it had a hot lead coming from it...and....the tachometer kicked out after about 30 minutes of riding (tach runs off the alternator)
I figure a new alternator and voltage regulator will cure the beast.

I welcome any other opinions, thanks

Dave

[skids]

I am betting a new volt regulator will cure it if the connectors behind the fuse panel are good.

Originally posted by copperhead25
Another Follow-up.....
Voltmeter actually shows 1.8- 2 volts when the system is off.
Disconnecting wires from circuits one at a time narrows it down to the voltage rectifier (which did not test out when removed) and the alternator.
As the alternator was only kicking out 12.2 volts on a good day, and it had a hot lead coming from it...and....the tachometer kicked out after about 30 minutes of riding (tach runs off the alternator)
I figure a new alternator and voltage regulator will cure the beast.

I welcome any other opinions, thanks

Dave

[TopCatGr58]

Hey Copper,

Skids is probably right, the Alts rarely go bad, no actual moving parts, just the large rotor on the crankshaft, but it doesn't touch anything!! The reg/rects are known weak spots. In the Products review, Geezer sells a great aftermarket unit guaranteed for life, made with heavier duty parts than OEM, and plug and play.
T.C.

[copperhead25]

next chapter

checked voltage regulator with meter as described in manuals, found to be out of spec.
Checked Alternator with meter as described in the manuals...should be .4 ohms +/- 10%.... metered out at 1.2 ohms...little high, huh.......

Any ideas on where to pick up an alternator...have been watching E-bay......
Thanks All,
Dave

[randy]

Dave,

Forget your alternator, as T.C. said, there's nothing there to go wrong except the connectors. If I were you, I'd check all of the plugs for burnt connectors. BTW, there's a hidden connector behind the fuse panel. I'll bet you a beer it's fried.

P.S. USPS willl accept beer for shipment!

[skids]

Also clean the contact where the VR mounts to the frame. It is a frame ground...that is why the black wire goes nowhere. The bolt/VR/frame must all have electrical contact.

[trbig]

Copperhead...

I was having charging problems in the past and Geezer (Tony) was a tremendous help. Here's the steps he told me to take to see what was wrong. I think they were a little easier to follow.
--------------------------------------------------------------------------
"With the meter in hand, unplug the wires from the alternator. There should be about an ohm resistance between the white wires and infinite to ground.

Next test the resistance between the green and brown wires from the alternator. This is for the field coil and should be around 5 ohms. (This step should actually be 3.5 +/- 10%) I don't have my manual on had at the moment but these numbers should be very close.

Assuming you've gotten good news from the previous 2 tests, make sure the terminals are clean and plug the connectors back together. Turn the ignition on but do not start the engine yet. Place a .002" feeler gauge flat against the center of the alternator cover. If it is magnetically attracted to the cover, you're half way there.

Fire up the engine, put the volt meter on 25 volts DC, insert the positive probe of the meter into the back of the plug on the reg/rec unit (still plugged in) and the negative probe to ground. Rev the engine and you should see the voltage rise to around 15 volts at about 4000 RPM.

If it’s not charging at this point, the regulator is probably good but the rectifier is probably bad. Unplug both plugs to the reg/rec, set the meter to ohms x1, touch the positive lead of the meter to the red wire and the negative probe to each of the white wires. At this point you will either get continuity or not but it should be the same on all 3 white wires. Reverse the test leads and do the test again and now you should get the opposite results but again the same on all 3 white wires. Now you’re half done, do these to test with the black and white wires. "
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You can probably find a cheaper Reg/Rect unit off of Ebay, but like TC said, the ones Tony builds are guaranteed for LIFE and are made from better parts than originals. I'd hate to see anyone buy a 20+ year old electrical part and depend on it, but I also understand that sometimes money is the deciding factor. Tony is a heck of a nice guy and knows his stuff about the electrical side of these bikes... not bad on the other parts of it either!

If you want to see all the stuff that took place, the link is here..
No Charge

Tod

[posthuman]

Interesting...

my XJ1100 Tachometer suddenly died while on a ride, I noticed the turn signals getting slower, the headlight getting dimmer...

and ALL the "computer" indicators were all lit up, and the red trouble light came on.

drove home on battery power

checked for dead short with key OFF from positive battery terminal to ground

saw nothing wrong

I figured it must be the regulator rectifier

Bought a reg/rec and replaced it, and when I turned the power on, the computer indicators weren't lit anymore, but the tac still didnt werk.

so. good for a few minuts, then suddenly ALL the "computer" indicators were all lit up again.

I took the cover off the alternator and there seemed to be some bits of that plastic looking amber colored stuff that came loose in the bottom on the housing.

After detached them from the reg/rec, The 3 white wires have 0 ohms (no resistance) between them from the "alternator" (the wire wound coils), but infinite to ground.

Any ideas?

[LoserShoes]

That amber colored stuff is probably the insulation from the field or stator coils. Your meter readings pretty much confirm that one or the other is shot. Take the them off and examine them.

Steve

[randy]

posthuman,

Interesting...


"checked for dead short with key OFF from positive battery terminal to ground"

--The correct way to check for shorts is to disconnect the positive lead from the battery and connect your meter between the battery and the positive lead. There should not be any voltage reading with the key off. If you do see a reading then there is a drain. Pull fuses to find the offending circuit.




"After detached them from the reg/rec, The 3 white wires have 0 ohms (no resistance) between them from the "alternator" (the wire wound coils), but infinite to ground."

This is in fact the correct reading. The white wires are the STATOR. Have you checked the FIELD coil (brown/green or green black, not sure of XJ colors). Your XJ also has brushes and commutator? - they can be bad. (someone help here).

[Snow]

+1 about checking behind fuse panel for the hidden connector...mine had melted and had gone to bare wires...