[Vwdiesel] Finally need a new alternator? Burning through brushes.

[mark shepherd]

Here's a guess at what is happening:
If  a car is regularly hard to start, and so battery often starts the day 
needing to be recharged from a low level, then maximum amps come from the 
alternator for  relatively long time severely loading the brushes. They get 
incredibly hot, and also the more the rings wear, the more the  carbon 
brushes erode. Jump start a car then put the 'dead' battery on, and the 
alternator to battery wire can get quite warm and  even at idle the alt 
becomes untouchable.

Mark










----- Original Message ----- 
From: "Will Taygan" <william at taygan.com>
To: <vwdiesel at vwfans.com>
Sent: Wednesday, January 14, 2009 10:22 PM
Subject: Re: [Vwdiesel] Finally need a new alternator? Burning through 
brushes.


>
> 90 amp alternator.  I'm sure I'm putting stress on it, especially in the
> winter.  I figured that was partially why I burned through brushes every
> 6 months.
>
> Does the amp rating decrease as they age?
>
> The 94 Frankenjetta has a 1.6l with a serpentine belt setup and a 120
> amp alternator.  PO set it up that way, maybe I'll reverse-engineer what
> he did someday.  Great for running, PITA when I need to work on
> anything, as it takes up almost all the space between the engine and the
> body.
>
> Yellow top is to run the Espar diesel-fired heater an hour or so and
> still have reserve for glow plugs and starting at -20F.  30 minute drive
> home hopefully is returning a full charge.
>
> Will.
>
> On Tue, 2009-01-13 at 21:17 -0600, brian gochnauer wrote:
>> >"Oh yeah, I've got a new optima yellow-top and pull quite a bit of
>> >Amperage running the heater/radio/lights/vegtherm/etc. especially in
>> the winter."
>>
>> How many amps are you pulling, how many amps is the alternator?
>>
>> Many people always forget;
>> The size of the battery does NOT help when you have a large load over
>> an extended time.
>>
>> The battery is like a cup of water, the alternator is like the faucet.
>> If your load continually nears alternator capacity, it forces the
>> alternator to run FULL capacity (AMPS) all the time.
>>
>> Battery size is for starting, not continual heavy loads.
>
> -snip-
>>
>
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