Jump to content
Ultimate Subaru Message Board

HELP!!! Car suddenly didn't start this morning. Didnt' charge coming to work either


Recommended Posts

Ordered an alt. from Schucks today, it'll be in by the time I get off work. $155.00 with the core deposit.No one ever responded to the "Why did it fail after on 84,000 miles..." question. I'm sure it was a chicken/egg thing. If the battery failed I suppose it could over drive the alternator and burn it up...

We did. A bad old battery can kill a alt.

 

It was old, 7 years old, which is a long time. Sort of like asking why 1 95yo died.

 

For more detail explination.

 

A battery (std lead acid) is a bunch of plates. Over time the plates shed material from normal cycling (this can be accelerated if the battery is not porperly bolted down). Eventually that material shorts out one or more sets of plates (each battery cell has plates in it). When the cells short out, the battery beomes a giant reisitor. this can overwork the altenator and burn it up. There are other ways the plates can be damaged too.

 

At this point a cell will no longer hold a charge.

 

http://www.mpoweruk.com/leadacid.htm

 

nipper

Link to comment
Share on other sites

You stated that the alternator had excessive ripple. This is different than a regulator problem and is what Skip and I mentioned may be the problem in earlier posts. The excessive ripple is due to bad output diodes. The old battery may have caused the alternator to work too hard and it killed some of the diodes and that causes ripple. There are a lot cases like this and with less mileage than you got. You should be good to go for a long time again with the new replacements. Be sure the new battery is fully charged before it is installed in the car.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...