charging fault

[cummins19642000]

hi, just want to pick your brain's, r100 gs charge fault ,charge light stays on when running goes slightly dimmer when riding at high rev's .i've checked the brushes and have continuity thru them removed stator and windings and b4 that overode the reg and run it but still the light's on anyone had this before???

 

[DrFarkoff]

hi, just want to pick your brain's, r100 gs charge fault ,charge light stays on when running goes slightly dimmer when riding at high rev's .i've checked the brushes and have continuity thru them removed stator and windings and b4 that overode the reg and run it but still the light's on anyone had this before???

Did you check that you have Voltage increasing with rpm to indicate that it's charging?

If you have that okay then look carefully where the wires exit the starter cover you may find a wee blue one in the that is nipped and broken

Clean it up solder / rejoin / replace (your call) and that shoudl cure it!

That's the alternator charge wire to make the lamp go out

 

[cummins19642000]

hi, yes checked and when running not charging all lights on 11v when at high revs

 

[Steptoe]

Have you checked resistance across the stator slip rings

 

[cummins19642000]

yes removed stator and rotor ,rotor resistance betweenslip rings 0.3 ohms but if connected between one slip ring and rotor body gettin resistance but no reading if i put 12v thru and check with meter ??

 

[hennpinboy]

Try jumping the bottom two terminals for the voltage regulator. The running voltage at 3000 rpm should climb to the 15+ volt range. If so it's the voltage regulator. If the voltage does not climb to 15+ volt range plug the regulator back in. Check the voltage at the B+ terminal on the diode board, at the + terminal on the starter and on the positive terminal on the battery. The voltage should be the same. If not there is resistance in the circuit. Airhead charging systems are very simple, but can cause major head aches.

 

[cummins19642000]

hi, i took another look at things today and now i'm gettin a chargin rate and with the multimter across the battery so i've re-checked things and have removed the diode pack and i can see one damaged so checked the diodes and one seems to be faulty,so first thing tomorrow one new diode unit to get hopefully this will sort it!!

 

[cummins19642000]

just lettin you know replaced diode pack all sorted,just 50 notes lighter

 

[deefer666]

I have a similar fault on an R80 RTIC, no generator light though, but its putting out 12.4 volts with the lights off, and about 11 with the lights on.

I have replaced the reg/rect, alternator, & diode pack...but still the same fault

Any ideas

Also runs very rich on the left hand cyclinder regrdless of how I adjust the carb... Is it possible to put the choke discs in the wrong way ? (Bing carbs BTW)

 

[hennpinboy]

Check the running voltage at the B+ terminal ( the large 10mm one on the side of the board) the voltage should be the same as at the positive terminal on the battery. If not you could have a burned wire that runs from the B+ terminal to the positive stud on the starter. I fought with intermittent charging problem for a whole summer, until when replacing a timing chain I found the wire to be very stiff and hard feeling. Cut off the heat shrink tubing, the wire insulation under the tubing was burned and stripped the wire insulation I found the wire to be corroded and burned from excess heat (resistance). Replaced the wire I have had no more charging problems.
A quick way to check the diode board with a digital VOM is to:
1. Place the VOM on the AC voltage scale
2. With the engine running, measure the voltage between the positive and negative terminals on the battery.
3. The AC voltage should be near "0" zero. If you read any more then a couple of tenths of volt indicate that you have a defective diode on the board.
I learned this test from Matt Parkhouse's keep them flying article in the January 08 BMWMOA magazine.

Rich running on one cylinder, check that the choke is pulling completely off, try pushing it closed with your finger. The cable may be out of adjustment. Also check that the slide needle in in the same slot for both carburetors and that the diaphragm is positioned in it's proper position. You would be surprised how well these engines run with the carbs messed up, and how much better they run set up correctly.

 

[deefer666]

Finally traced the fault with my R80.... There is no continuity from the rotor... Just got to find one and change it now.

 

[bakerlonglegs]

Helpful thread, this

I'm chasing charging problems on my G/S too. Originally, the charging light stayed on until 2k-ish, then dimmed. The brushes were right at the limit of their service life, so they got changed this weekend, and now the problem's getting worse....

Now the charge light stays on permanently. I measured the voltage across the battery and this doesn't dim with a rise in revs, staying at around 12.4.

I also tried hennpinboy's ruse of measuring the voltage on AC. The reading I got was around 26!!! Now either a) my digi VOM is knackered or b) I assume the diode board has had it.

The voltage regulator is brand new, so I'm assuming this is OK (but I will check it). I measured the resistance across the slip rings and got 3.7 ohms, which is OK but at the top end of the spec range. The stator winding resistances were around 1 ohm, measured across the three terminals.

Any comments/suggestions gladly received!

 

[(RIP) pastyman]

Check the running voltage at the B+ terminal ( the large 10mm one on the side of the board) the voltage should be the same as at the positive terminal on the battery. If not you could have a burned wire that runs from the B+ terminal to the positive stud on the starter. I fought with intermittent charging problem for a whole summer, until when replacing a timing chain I found the wire to be very stiff and hard feeling. Cut off the heat shrink tubing, the wire insulation under the tubing was burned and stripped the wire insulation I found the wire to be corroded and burned from excess heat (resistance). Replaced the wire I have had no more charging problems.
A quick way to check the diode board with a digital VOM is to:
1. Place the VOM on the AC voltage scale
2. With the engine running, measure the voltage between the positive and negative terminals on the battery.
3. The AC voltage should be near "0" zero. If you read any more then a couple of tenths of volt indicate that you have a defective diode on the board.
I learned this test from Matt Parkhouse's keep them flying article in the January 08 BMWMOA magazine.

Rich running on one cylinder, check that the choke is pulling completely off, try pushing it closed with your finger. The cable may be out of adjustment. Also check that the slide needle in in the same slot for both carburetors and that the diaphragm is positioned in it's proper position. You would be surprised how well these engines run with the carbs messed up, and how much better they run set up correctly.

How about including parts of this in the new Tech section, sounds like a common problem.

 

[Tigger80]

Charging fault.

Hi All. Recently had charging fault on my R80GS (1993). Found to be rotor open circuit in alternator. resistance between slip rings should be 3.4 ohms. The resistance between each of the three stator terminals should be 1.8 ohms. Had 2nd hand rotor from Microworks, sorted. Voltage at about 400 revs now about 13.6 - 14.5 volts. Didn't need a new battery after all.
Good handbook to download in .PDF format. Tigger80 (Glyn)

 

[deefer666]

Just one more simple question..... How do you get the old rotor off?

 

[Rob Farmer]

Just one more simple question..... How do you get the old rotor off?

With a rotor removal tool of course

 

[deefer666]

right so if I put a dowel pin in and then replace the original bolt, it should do the same job then.

 

[MickDB1]

I put a piece of 1/4 steel in the hole and it must have tilted sleightly then bent had to carry on tightning it in - thrashed it with a hammer to get the rotor off
I have since bought a removing bolt = its a 8 mm setcrew with the thread turned off it for the first 1 1/2 or so ( I will measure it if you want )
If yer using a pin make sure it only just fits down the threads and is hard and stiff ( OOO errrr ) Allen key may dooo it better

The bolt is made of stainless I think ( thats not hard so maybe I had a barst rotor )

HTHY

 

[deefer666]

Well, the dowel/orginal bolt worked and the rotor popped off... I have fitted the new one, the only thing that has changed is that now my generator light is on.

Its still not charging!!! grrr fooking thing

 

[dickster]

R100 charging fault

Hi,
Can anyone point me in the right direction? my R100GS charging light comes on @ 4250 RPM,irrespictive of lights,bar grips or anything else ON or OFF.as soon as you back off to under 4250 or 4000 RPM the charging light goes out.
Any help would be greatly aprecited - trying to get the bike ready for the Stella 2010,many thanks