My neighbor just told me that his mechanic informed him that leaving a car parked long term not only effects the battery, but can also deteriorate the alternator.

The battery having issues makes sense to me, especially in cold weather as they were presumably discussing. But I can't understand the alternator going bad from lack of use.

Is that in fact possible?

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    I don't have a definitive answer here, but I've never heard no seen an alternator have issues from non use. – Pᴀᴜʟsᴛᴇʀ2 Feb 3 '16 at 3:18
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    I have no facts to back my claim but I don't see how that could be true. – DucatiKiller Feb 3 '16 at 4:49
  • Never heard of it either. Unless you leave it parked for 10 years. – I have no idea what I'm doing Feb 3 '16 at 7:28
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    An internal combustion engine will have more problems from long term storage than an alternator will. – HandyHowie Feb 3 '16 at 8:11
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    A bigger problem than stale fuel would be possible corrosion of the cylinder walls caused by moisture left from the previous combustion cycles. – HandyHowie Feb 3 '16 at 16:48

The only thing I can think of as a response is Copper. Copper is used in alternators to house a spinning magnet. This creates electricity to power your car. The only problem I can foresee is how easily copper is affected by weather. Copper will oxidize and create a green coat. This oxidation can impede its ability to harness/(assist in creation) electricity.

This takes years thou in normal circumstances; not just a year

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    That doesn't work. It's insulated. Alternators aren't snowflakes. They're pretty tough. – DucatiKiller Feb 3 '16 at 6:08
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    The copper wounds in pretty much any electric motor or generator are clear coated to prevent shorting to each other, weather should not affect them in any way. – I have no idea what I'm doing Feb 3 '16 at 7:25
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    If there is any slow oxidation of the copper wire going on, I think it will be completely independent of whether or not the vehicle in use. – Digital Trauma Feb 3 '16 at 23:45
  • I've seen many from humidity accumulation.... Different exposures in various climates....also cold mornings where fog or dew appears.... Alternators tend to have vents for heat where water can enter... Also oxidation – Dee Feb 4 '16 at 1:01
  • If you've ever wen through a junkyard you can see the exposure to elements has an affect on the interiors of these types of parts... – Dee Feb 4 '16 at 1:02

I do know somebody who left an older car parked for a month outside and the alternator seized, but that could happen to any number of accessories and wouldn't be specific to the alternator.

Also, if the battery has discharged from lack of use, it will cause a higher load on the alternator while it's charging it back up. This is probably more of an issue with an old battery and an aging alternator that's looking for an excuse to fail.

So yes, it is possible, but there's so many other things that can go wrong while a car is parked (including rodents moving in) that it's really pointless to worry about any single thing in particular.

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Hiya I no nothing at all too but is it possible the one off the brushes could seize a bit away from the metal where a bit off rust build up on the end if stored for a couple years and just doesn't get a connection so doesn't charge is that possible if so I can smack it with my hammer yer

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Google found this thread for me - despite last post about a year ago. An alternator has brushes because it has a slip ring (like a commutator) The slip ring can corrode and the brushes can stick - both are possible causes of failure after a year standing. Both are pretty rare, and I've only had a failed alternator once after rescuing a lot of "long standing" cars.

Lots of people mention the battery - the battery will self discharge gradually. If it is left for weeks whilst discharged, it will chemically destroy itself. Just a month without charging (by running the car or with an external charger), this will reduce the life, a few months can ruin it, and a year.. game over.

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