Leaking Voltage on R100RT

[GTDOUG]

Any help would be greatly appreciated in my search for a voltage leak on my 1983 R100RT.

When measuring this leak, battery voltage is 13.82 volts. With the ignition off, voltage measured is 12.82 between the negitive lead and negitive battery terminal. Voltage steadly drops until reaching 10.65 volts measured at this same location. I am wondering if this is an indication of where to start looking for this voltage leak?

A while back I took the R100RT into my local mechanic who had been maintaining this bike for quite some time. After a great deal of testing his only recommendation was to replace the wiring harness. This work was done, however volt leak still remained.

To me this might be an indication of a capasitor with the slow voltage drop. BTW all wiring connections in the charging system appear to be sound.

 

[carlo]

I've never had this problem with my 1982 model, but a friend had a similar thing happen to his 1984 model. He went through the entire system, replaced the alternator, regulator, diode board, nothing seemed to help.
It was finally traced to a pinched wire somewhere in the headlamp shell.

The only way to find it is disconnect everything, everywhere, then start looking for a path to ground in the wiring harness.

It might be easier to just buy a new wiring harness, including the part that's inside the headlamp shell.

 

[bombayduck]

A positive wire or pathway must be making ground somewhere. I wouldn't know where to start looking but I suspect that wire is getting very warm as the current flows through it.

 

[GTDOUG]

Thanks, the temprature maybe the key to finding this issue. I have an infrared camera. I hope I can find it that way. The camera is out on a job right now. I will have to wait till tomorrow or the next day to find out.
Thanks again for the info/help.
GT DOUG

 

[carlo]

Thanks, the temprature maybe the key to finding this issue. I have an infrared camera. I hope I can find it that way. The camera is out on a job right now. I will have to wait till tomorrow or the next day to find out.
Thanks again for the info/help.
GT DOUG

How rapidly is the voltage falling? If that was a dead short, you'd be blowing fuses. I'm not sure how it happened in my friend's case, but he said there were no obvious signs of burned wires indicative of a dead short, just a slow steady loss of voltage over time.

 

[GTDOUG]

The voltage does not drop that fast. Its about a 100th of a volt every 2-3 seconds. Thanks Carlo
GT Doug

 

[skiteach]

Try connecting a test lite between neg term and cable. It will glow if there is a draw, disconnect various things until it goes out- that circuit will be at fault. This method will not work with computerized systems as they require a 12v feed to the ECM at all times. It's much easier to do this with vehicles with more than 2 fuses! I would probably start with the fuses and then move on to connectors and relays. Infared camera is interesting idea, however if it generated enough heat you'd know by the burned section of wiring.

 

[20774]

between the negitive lead and negitive battery terminal.

I'm not sure what you mean here...where are you measuring? But in general, using a voltmeter to measure leakage or loss of amps is not the way to use the meter. You really need an ammeter. Skiteach has a good idea...that sounds like a crude ammeter to me.

 

[carlo]

I'm not sure what you mean here...where are you measuring? But in general, using a voltmeter to measure leakage or loss of amps is not the way to use the meter. You really need an ammeter. Skiteach has a good idea...that sounds like a crude ammeter to me.

He was probably using the word "voltmeter" generically.

I like the idea of using a bulb between the ground wire and the negative terminal on the battery.
Only problem is that if it's a very weak short, there may be only a few milliamps of current flowing, and the light may glow too dimly to be of much use.

A careful inspection of the wires at any location where pinching can occur (mainly inside the headlamp shell, and near the steering head) might be the first troubleshooting step to take.

 

[lkchris]

If that was a dead short, you'd be blowing fuses.

Nah, the bike only has two fuses.

I'd start at relays under the tank. Then maybe starter. Then maybe diode board.

 

[donbmw]

For me the diode board has always been the cause of a drain on the battery.

Don

 

[carlo]

Nah, the bike only has two fuses.

I'd start at relays under the tank. Then maybe starter. Then maybe diode board.

Ok, blowing fuses or having insulation go up in smoke.

 

[skiteach]

With a bulb in circuit you'll know if it's circuit board or not. I have found MANY "shorts" this way; heated mirror relays that were stuck on, glove box and trunk lites to name a few. An old German mechanic taught me this trick, before they were called Techs. As I remember, you can see the filament in a test lite pulse, due to clock mechanism.

 

[GTDOUG]

I think I found the issue. Disconnected the clock power and the lamp (voltage leak gone) went out (Thanks Skiteach for that suggestion) Now the question is should the clock be replaced. Its not nice to have a hole in the dash.
GTDOUG

 

[carlo]

I think I found the issue. Disconnected the clock power and the lamp (voltage leak gone) went out (Thanks Skiteach for that suggestion) Now the question is should the clock be replaced. Its not nice to have a hole in the dash.
GTDOUG

You mean the clock lamp was on? That would cause a drain on the battery.

Why not just remove the bulb?

 

[mneblett]

You mean the clock lamp was on? That would cause a drain on the battery.

Why not just remove the bulb?

The bulb in the test line at the battery, not the clock's.

 

[skiteach]

The lite should "pulse" as the auto wind feature works. If it was a working clock, it shouldn't drain the battery in a short time. If the clock is defective it might drain. It's hard to imagine that that is issue. How old is battery? They will sometimes drain themselves- weak cell(s). Now if the dealer or I could fix my '07 Silverado- interior lites kill my battery, they claim the draw is in spec. I really HATE jumping it after banging nails all day!

 

[GTDOUG]

Carlo...
I am not sure why the clock is draining the battery. The clock light is not on when the ignition is off. When I disconnect the power supply to the clock the voltage leak is gone. This clock works except for the voltage leak. Any suggestions would be greatly appreciated in tracking down the cause.
GTDOUG

 

[GTDOUG]

BTW, I priced a new clock (Not from BMW). For a green faced clock its $168.00 ouch. A white faced clock is $100.00.
To me, the clock is leaking voltage internally, however any tests I have done do not prove this.
GT DOUG

 

[20774]

A voltage leak or drop that might occur in the clock will result in heat being generated. It's possible that the device is breaking down internally and heating up. Or maybe the connections to and from the clock are corroded, creating an extra voltage drop.

Try taking out the clock and hooking it up on the bench and see if you can repeat the problem.

There are places that can repair the clock, although the cost will be as much or more than a replacement. You could check with Overseas Speedometer, for one.