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jersey girl 09-07-2012 12:24 PM

What can kill an alternator?
Everyone in my family seems to destroy the alternators in their cars. I have no idea what they are doing or if all the mechanics in Jersey are shady. I just bought a 2007 Ford Focus & I actually noticed on the Carfax that the original owner replaced the alternator at 50K miles. I've personally never had this part go on me on any car I've owned. What do you think is happening?

elsolo 09-07-2012 12:35 PM

Alternator is an easy sell for a shady mechanic, if the car needed one or not.
Car comes in with any charging problem, even just a loose battery cable:
"your car needed a new alternator, and this battery cable needed to be replaced also."

Running in full charge mode continuously can kill an alternator, so trying to have your new alternator try and charge your dead battery can result in immediate alternator failure.

cbdallas 09-07-2012 12:51 PM

Anything that causes them to work hard, especially in hot weather, can kill them. This is why I don't really like DRLs. It's also a good idea to do a voltage test on your battery occasionally, because if it's not taking a full charge, the regulator never shuts off and the alternator charges the entire time the engine is running.

Some people drive around all day with their headlights on, not giving a thought to where that energy is coming from. I only use my headlights at night, I don't do major stereo upgrades, and I don't do anything that causes any significant battery drain when the car isn't running. I've also never had to replace an alternator.

VEGAS 09-07-2012 12:59 PM

Car Stereo Amps with small battery and no Cap can kill it...
Heat kills it, constant charging, surges and bad wires.

swansong 09-07-2012 01:06 PM

Forgetting to cover it when washing the engine bay... [paranoid] ...not that I'd know.

mikeeshaq 09-07-2012 04:04 PM

See the link:

SilverST05 09-07-2012 10:31 PM

Bad batteries. Bad connections, corroded cables. And everything else everyone has said.

Now534 09-08-2012 06:04 AM

I've had my stereo in my car for 2 years now. (Rockford T1500.1bd wired to 1 ohm which is about 1500-1800rms depending on the song) I never run a cap and never will and my alternator is just fine and i drive with my lights on during the day sometimes (mostly when cloudy should be a law in every state especially when raining). My alternator is constantly running and it has never failed. Hell the Alt in my truck lasted damn near 20 years before it finally gave way last year and it had pretty good sized stereo in it and multiple battery draining instances.

If anything Caps are worse for your alternator than adding another battery. Constantly charging and discharging is not good for your alternator at all. Plus a battery is cheaper than a cap and can have more reserve.

05focusST91 09-08-2012 06:57 AM

Running the car at high rpm constantly can do it too, but usually its a cause from what they^ said, weak batteries, bad cables, even the fuse on the alternator could go bad

whynotthinkwhynot 09-08-2012 05:47 PM

How about "Lifetime Warranty" alternators. I always advise people to go with a local rebuilder. It's more of a PITA because for people with one car you have to bum a ride, and you might need a ride to work, but the alternator rebuild you get will last longer and be cheaper. A more expensive, but work approved method might be to purchase a new alternator, then have your old one rebuilt and put it in a box somewhere for next time. Hopefully your car won't be crashed before you need an alternator. It's not as cost effective either.

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