Electrical Issue

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Seapbmw
Posts: 2
Joined: Mon Nov 11, 2013 6:13 am

Electrical Issue

Post by Seapbmw »

I need help troubleshooting what is causing my dash panel battery light to intermittently go on and off. It goes from bright red at higher rpms, fades at lower rpms and sometimes fades at higher rpms. Some background on the bike and recent charging issues:

Bike - 1992 R100R
Mileage - 29k
Battery type, age - wesco sealed, age unknow as I've owned the bike since october 2012

Recent performance - kept battery on BMW trickle charger last winter, rode occasionally last winter, rode 5k miles over last 12 months without issue.

Recent issue - battery was dead after sitting for 2 weeks, recharged then rode last week when light started coming on. Went for 2 hour highway/backroad ride last Saturday and light never came on. Went for hour long ride yesterday and light started coming on after 45 min of riding 3500-4500 rpms.

Troubleshooting so far - connections checked visually, need to remove pos/neg cables and reinstall. Also will check alternator output voltage under load. Need to check alternator but don't believe this is not the issue as I'm thinking recent charging cycle did something to damage battery.

Any other ideas are much appreciated, thanks for the help!
Charlie
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SteveD
Posts: 4909
Joined: Tue Aug 03, 2010 3:29 am
Location: Melbourne, Oz.

Re: Electrical Issue

Post by SteveD »

Welcome aboard.

This wee forum down there is something of an anomaly and seldom gets used.

Thanks for sorting it Rob. edited.....
Last edited by SteveD on Mon Nov 11, 2013 8:10 am, edited 1 time in total.
Cheers, Steve
Victoria, S.E.Oz.


1982 R100RSR100RS supergallery. https://boxerboy81.smugmug.com/R100RS
2006 K1200R.
1994 R1100GS.
Deleted User 287

Re: Electrical Issue

Post by Deleted User 287 »

I moved his OT, and deleted yours, so that link will probably dead-end...
I also deleted the ghost. I never did like those things.

edit: welcome aboard! I haven't read your issue yet. That is next. :)
Deleted User 287

Re: Electrical Issue

Post by Deleted User 287 »

Well, I am sure it is something specific, and I will let smarter folk fill in there.

I will say with certainty that you should inspect and clean all of the major connectors on the bike, making sure they are as bright & shiny as possible, and reassemble with some sort of grease to act as a dielectric.

Have you had the front cover off of your bike yet? Do you know to disconnect the ground at the battery (check for any accessory grounds at the battery) before you remove the front cover, to prevent shorting of the diode board?

Are you familiar with a VOM?
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SteveD
Posts: 4909
Joined: Tue Aug 03, 2010 3:29 am
Location: Melbourne, Oz.

Re: Electrical Issue

Post by SteveD »

The the 3 wires coming off the alternator to the diode board can lose insulation coming out from behind the ignition timing cover and may go to ground. Rare though.
Cheers, Steve
Victoria, S.E.Oz.


1982 R100RSR100RS supergallery. https://boxerboy81.smugmug.com/R100RS
2006 K1200R.
1994 R1100GS.
Seth
Posts: 275
Joined: Thu Aug 12, 2010 4:45 pm

Re: Electrical Issue

Post by Seth »

I had a similar thing with my 94 R100 Mystic.
Turned out to be the alternator rotor. The varying RPM would make the broken contact touch, which would dim the light. Also, with the key on, motor not running, the light didn't come on at all.
Deleted User 287

Re: Electrical Issue

Post by Deleted User 287 »

Seapbmw, if you don't already know about Rick at Motorrad Elektrik http://www.motoelekt.com/ you might want to bookmark that link.

Like Seth said, a alternator rotor can have a break that only opens up at speed. Bench testing (or with the engine shut off and the brushes pulled back) can often show continuity, that goes away at speed when the break opens up.

If that did indeed turn out to be the case, I would shop with Rick, unless you can buy a good used one from a trusted source.

But if you like a lot of electrics on your bike, like heated clothing/grips and/or high wattage lights (conspicuity), you might want to invest in one of the higher-output options that are available.
Jean
Posts: 1100
Joined: Wed Aug 18, 2010 7:43 am

Re: Electrical Issue

Post by Jean »

I'll toss my vote for rotor intermittent connection, too. It's spinning fast and that's why the connection can change...
Clemson, SC
R100s, R75/5
Duane Ausherman
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Joined: Thu Aug 12, 2010 12:39 pm
Location: Galt California
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Re: Electrical Issue

Post by Duane Ausherman »

Don't go using the shot gun approach, as that will waste time and money. Start with logic and do the testing.

It costs nothing to measure the charge voltage, this tests the alternator. It costs nothing to do a load test of the battery to get a rough idea.

The only way to test a rotor for sure is to swap it out.

There are plenty of websites with this info.
Ask the Indians what happens when you don't control immigration.
sterob
Posts: 148
Joined: Tue Aug 03, 2010 6:16 pm

Re: Electrical Issue

Post by sterob »

I'm sure a 'Megger' ( Insulation tester ) would expose a dodgy rotor.The high voltage should do the trick.
Find a mate who has one or get local auto lecky to do it, and test across the slip rings. A good rotor will show as a short.
Can also test each slip ring to the shaft ( should be infinite resistance ) Make sure you test BOTH slip rings....
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