Has anyone tested an alternator? - BMW Luxury Touring Community
 
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post #1 of 8 Old May 7th, 2014, 5:27 pm Thread Starter
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Has anyone tested an alternator?

My '06, with 91,000 miles, hasn't seemed to be charging as well as it used to. I've done all of the normal tests: it puts out 13.6 volts at 2500 rpm. However, since I have the bike apart for a rear main seal job, I figured I would have the alternator tested, and maybe rebuilt, by an auto electric shop. I'm having trouble finding anyone who will do it since it doesn't have a pulley like it would on a car. I guess I can find a pulley at a junk yard and mount it on the alternator, but that seems like a pain in the neck.

Has anyone here ever had an alternator professionally tested?

TIA

George Barnes
'06 K1200LT
'01 K1200LT, totaled with 180,000 miles, 10/18/07,

'97, '99, '01, '05, '07 & '09 Iron Butt Rallies, (won the '99)
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post #2 of 8 Old May 7th, 2014, 6:06 pm
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Re: Has anyone tested an alternator?

I would check/replace the bearings, throw a set of new brushes on it and call it good.


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post #3 of 8 Old May 7th, 2014, 6:15 pm Thread Starter
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Talking Re: Has anyone tested an alternator?

Quote:
Originally Posted by deanwoolsey View Post
I would check/replace the bearings, throw a set of new brushes on it and call it good.
Dean,
The video here: https://www.youtube.com/watch?v=bTcMD5_EznI

explains how to replace the brushes. It seems like a lot of work if the alternator is OK. On the other hand, after the rear main seal job, what's another hour or so, right?

George Barnes
'06 K1200LT
'01 K1200LT, totaled with 180,000 miles, 10/18/07,

'97, '99, '01, '05, '07 & '09 Iron Butt Rallies, (won the '99)
IBA#146


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post #4 of 8 Old May 7th, 2014, 6:24 pm
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Re: Has anyone tested an alternator?

When I replaced my clutch at 180,000 miles I replaced my alternator & starter with rebuilds I had done at a local re-builder. I had spares that I had rebuilt a few years ago. Phil's Alternator & Starter in Cherryville NC rebuilt mine. Phil is factory trained at Bosch in Germany for his rebuilds. My rebuilt starter cranks the engine much faster than the OEM starter did.

Dave Selvig
2004 Black LT
2000 Canon Red LT



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post #5 of 8 Old May 7th, 2014, 9:52 pm
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Re: Has anyone tested an alternator?

13.6 at 2500 RPM is more than enough to properly charge the battery since the battery open circuit voltage is 12.7 tops. Current will go into the battery. But really the job of the alternator is to provide power to the electrical loads and anything left over is for charging the battery. So unless the thing puts out less than 12.7 volts it is working correctly.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
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K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

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post #6 of 8 Old May 7th, 2014, 9:55 pm
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Re: Has anyone tested an alternator?

Quote:
Originally Posted by jzeiler View Post
13.6 at 2500 RPM is more than enough to properly charge the battery since the battery open circuit voltage is 12.7 tops. Current will go into the battery. But really the job of the alternator is to provide power to the electrical loads and anything left over is for charging the battery. So unless the thing puts out less than 12.7 volts it is working correctly.
At higher RPM the normal charge voltage is 13.4 volts +/- 0.3 volts.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
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EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
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post #7 of 8 Old May 7th, 2014, 10:05 pm
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Re: Has anyone tested an alternator?

One problem with the LT alternator is that one slip ring on the rotor wears much faster than the other one. If I remember it is the inner one that wears first.

The slip ring assembly can be replaced. Best done by an alternator shop.

http://europartshouse.com/index.php?...roducts_id=123

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EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
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post #8 of 8 Old May 8th, 2014, 11:45 am Thread Starter
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Re: Has anyone tested an alternator?

Quote:
Originally Posted by dshealey View Post
...The slip ring assembly can be replaced. Best done by an alternator shop.
My thoughts exactly. I saw your post about this a while back and it seemed like a good idea.

GB

George Barnes
'06 K1200LT
'01 K1200LT, totaled with 180,000 miles, 10/18/07,

'97, '99, '01, '05, '07 & '09 Iron Butt Rallies, (won the '99)
IBA#146


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