Charging issue

[geepeetee]

Hi

My 1977 R60/7 has stopped charging. Ive had it about 20 years and the gen light has always been quite dim but usually shows 13v (ish) on the fitted voltmeter.

For.the.past few rides upon starting, the voltmeter has shown under12v for a couple of minutes then returned to 13v (ish). This weekend it stopped charging, the gen light doesnt appear to be working.

I've csrried out simple continuity and resistance checks suggested online, which appear to suggest the stator and rotor are ok. Connecting the slip rings to each other didnt make the gen light work, apparently suggesting a bulb issue.

Tonight i have checked the bulb and holder which are ok but the voltage at the gen light connector pins is 4.7v, the oil and neutral votages are 12.

Advice appreciated.

Thanks

Gary

[gspd]

Connecting the slip rings to each other didnt make the gen light work, apparently suggesting a bulb issue.

Connecting the slip rings together to make the gen light go ‘on’ only works if the brushes and their wiring are OK.

It's really weird that your gen light, oil light and neutral light don't all have the same steady power (12V) when the key is ‘ON’.
That sort of points to a fault in the printed circuit in the dash. Check for cracks, discolouration or corrosion around those 3 circuits. The voltage at these 3 lights should be the same as the voltage of the green/black wire at the dash multi-plug.

Just in case, if you want to check the ground side of those 3 lights…
The gen light goes on when grounded through the voltage regulator (blue wire) when system is not charging.
The oil light goes on when grounded through the oil switch when no pressure.
The neutral light goes on when grounded through the neutral switch (oops. edit)when in neutral.

[geepeetee]

Hi

Thanks for your reply, as is probably clear electrics arent my strong point lol.

The dash was replaced a few years ago and looks as new with no visible marks or corrosion on the circuits. With a common feed and different ground points it seems logical that would be a good place to start.

I had an earth issue a few years ago causing problems with the indicators, it was a number of poor earth connections in the headlight.

I'll investigate further.

Thanks again for.the reply.

Gary

[Brickboy]

If your generator light has always been dim it sounds like you've always had a problem that has deteriorated a little more. 13v seems low for charging - 14v would be much more cheering.

A bad earth or poor connection somewhere would be a likely culprit given the age of the bike but brushes that are worn might be a good place to start. Before you remove the engine front cover for a look do disconnect the battery to avoid any unfortunate shorts of the diode board.

If you think BMWs are bad with their simple electrics try a 50s Brit - with hardly any wiring at all electrical problems on them can drive you properly bonkers!

[Jeff in W.C.]

I would check all of your wiring. My 88 R100 RT sat for about 5-6 years. Prior to sitting, the voltage was indicated a bit above 14 volts. When I got it back on the road, the voltage was around 13.75. A year and a half ago, as part of replacing the timing chain, I replaced the alternator brushes, all of the wiring that connected to the engine regarding the alternator and cleaned up the slip rings. All of the wiring that connected to the engine was hard and brittle. I can only guess that the wiring itself was also a bit oxidized. I also replaced the positive and negatives to the battery. Now the charging is much higher than it ever was. So I would go through and check the wiring.

[geepeetee]

Thanks, i'm sure you're correct re the dim charge light.

Tonights mission was to investigate the now not working charge light further. My haynes manual shows blue going to the voltage regulator and green to the starter relay.

I've cleaned and tightened the VR connections. Also done the same with the starter relay, and confirmed 12v out of the relay. There's a spade connection in each just before the wires disappear in the loom, split, cleaned and reconnected and confirmed 12v here too. But still only 4.5v between the charge light terminals in the connector block.

The manual doesnt show anything between the relay and charge light so tried a continuity test between the spade connector i split and the dash connector block but wasn't continuity according to my meter. That said, i have read elsewhere that the kill switch is in the equation too but not sure where (kill switch seems to function ok).

Thanks for the help

Gary

[Rob Frankham]

Power (Battery voltage) connects from the battery to the starter relay, goes straight thropugh the relay to the ignition switch (red wires). It than goes from the ignion switch to the kill switch (via one end of the fuse but the curcuit is not actually fused... the two wires share the sa,e connection) (green wires). From the kill switch it is distributed to various points from a solder connection in the loom. One of the wires goes back to the starter relay where it shares a connection with a wire taking battery voltage to the binnacle. (green/blue wires)

Points to note...

The charge light shares it's 12 v connection with the oil light, the neutral light and the brake failure warning light. If these lights are working normally, then you can be pretty sure the problem is not in the wiring leading to the binnacle, it is either in the binnacle itself or in the wiring after the binnacle.

Check the voltage between the positive connection for the bulb (with the bulb in place, everything connected and the igntiton on. If you get battery voltage, the wiring to that point is sound.

Short the negative bulb connection to ground. If the buld lights it proves that the bulb and the bulb holder are good.

Go to the voltage regulator. Remove the connector and use a pirece of wire to short the blue wire to ground. If the bulb lights, it proves that the wiring from the bulb to the voltage regulator is sound.

Short between the blue wire and the brown wire on the regulator connector. If the bulb lights it proves that the earth connection to the voltage regulator is good.

Short between the blue wire and the black wire on the voltage regulator connector. If the bulb lights, it proves the wiring from the voltage regulator to the brushes is good, that the brushes are making connection. It also om-ples that the rotor and that the alternator rotor is good but that might change when the engine starts.. It also suggests that the voltage regulator itself is bad.

If the bulb doean't light in the test above, look at the alternator brushes to make sure they are making contact with the slip rings and check the continuity of the alternator rotor.

If you do those checks in sequence, you should ding the area of the problem.

Rob

[geepeetee]

Hi

None of the tests made the gen light work, and still have 4.5v between the terminals in the dash connector. I've read elsewhere this would suggest the VR, dash wiring, plug or wiring between the dash and VR at fault.

I did a continuity test on the VR connector block. The Df and D- connectors were ok to their respective connections at the alternator brushes.

The wiring diagram in my haynes manual shows D+ goes from the VR connector to the gen light, there isn't continuity between these, could this be my.problem?

Cheers

Gary

[gspd]

If you followed RobF's instructions to the letter and didn't find the problem, this isn't making a lot of sense.

Pics of your voltmeter probes on the exact points where you are reading 12v and 4.5v might help clarify things.

[geepeetee]

Hi

I've followed the circuits in the dash from the warning light bulbs and taking the readings in the appropriate holes on the large.connecting plug.

Readings are taken with ignition on, engine not running. The previous owner disabled the light switch (on all the time) which may be relevant to the readings i'm getting.

I've attached a few images showing:

Dash with ignition on (no charge light)
Test showing 11.96v (oil light terminals)
Test showing 4.12v (charge oight terminals)

Thanks

Gary