I think my alternator just bit the dust

[mdaniels]

My '92 K75S has been running pretty well since I bought it two months ago, but this morning on my way to work the battery light started to come on faintly. No issue in how it ran and I made it to work just fine.

After work it started right up, but the battery light was still on faintly. The light did go out as I started riding, but about half way into my 19 mile commute it came back on. A few miles later it started to cut out and then died. The battery was pretty much dead and it wouldn't restart. I ended up calling a tow truck and got it home.

I've got it on the battery charger, but my guess is the alternator decided to die on me. Anything else I should check while I'm at it?

I'm just happy it happened today and not tomorrow, when I was thinking of going on a local BMW Club ride that which usually ends up being about 400+ miles.

[Grim]

Sounds like the brushes have worn out. Not a hard or expensive repair if you have a soldering iron. Pandora (Chattanooga BMW) Max or really any dealer can order them for you. If your not handy see if you can find a local automotive electrical specialist. They will likely have the parts in stock and if you bring the alternator to them they can turn it around in a few hours. 

[TimTyler]

I just replaced my alternator brushes.

If you want the old ones which probably have several thousand more miles of service left, you can have them for the cost of shipping.

[pdg]

First thing to do is drop the alternator out and have a look. That's the exact symptoms mine had when the drive ate itself quite comprehensively - faint battery light but still working, still starting, then bright battery light, sluggish for about 6miles or so then cut out. Fortunately for me, it cut out as I was parking at home.

[mdaniels]

I just replaced my alternator brushes.

If you want the old ones which probably have several thousand more miles of service left, you can have them for the cost of shipping.

Thanks for the offer, but I think I'll go buy new ones. I'll hope that's the issue, wonder if my local dealer will have them in stock?

[pdg]

Have you taken the alternator out to check anything yet?

[mdaniels]

Have you taken the alternator out to check anything yet?

Not yet, probably later today or tomorrow.

[mdaniels]

Have you taken the alternator out to check anything yet?

Ok, I have the alternator out, but don't know what to look for. Other than it looking like it's really old, everything seems normal to me.

EDIT: I did a little research and figured out what the brushes where. Here is a picture of mine - guessing these are well worn and have seen better days?

[racinrich]

I have a shop that still rebuilds alternators and starters, Its a bosch that is a common design he had ALL the parts for it ,mine was noisy and he had it done and bench load tested in 3 hours,that was 5k ago no probs

[racinrich]

forgot to say price 45.00 us. all  bearings. new brushes would have been 15.00 more but were ok

[mdaniels]

Thanks to those that offered suggestions. New brushes arrived today in the mail and I installed them this evening. It started right up and I let it idle for about 10 minutes before taking it for a short ride. Everything seemed to be OK and the battery light didn't come on while running, but I wasn't able to take a long ride due to an incoming storm.

[Thorfinn]

Hope that's cured it for you! BTW, what mileage had the bike done (as far as you know)?  :euro

[racinrich]

109000 miles when I serviced the alternator

[mdaniels]

Hope that's cured it for you! BTW, what mileage had the bike done (as far as you know)?  :euro

Sorry for the really late response, it's been a busy couple of weeks. My bike had a around 68,500 miles on it when I replaced the brushes. I've been riding every day to work since then and all has been good so far.