[jstpsgthruyrwrld]

Has anyone else had an alternator go bad, early? Truck is '05 Frontier v6 w/26000 mi. A battery check 3 mos ago, turned up a reading of 260 cranking amps and a new battery was suggested. I continued to drive without change, because there were no warning signs of doom. Instruments showed about 13 volts while driving and no codes were being thrown. Suddenly, the truck wouldn't start. Autozone test w/old battery killed the engine. Testing after new battery showed the alternator failed and was "low." What do I need to make sure is checked before agreeing to a new alernator? I have appt. Wed @ dealership, but was wondering if an alternator should fail so quickly, even with a low battery? Could it be loose or too tight belts or ground or other wire, fuse? Is it common knowledge that alternators fail like this? Thanks for letting me vent and thanks for any knowledge you may share.

 

[Whiffle]

If the battery is not holding a charge like yours was, then the alternator will constantly be charging it. Constant charging is bad for the electronics in an alternator as they generally aren't designed to have a constant load like that on them. It doesn't surprise me that your battery killed the alternator. There isn't much else to check if you've got a fresh battery. It wouldn't hurt to check grounds and battery cables though, thats an awfully short life for a battery. Do you live somewhere hot? The original batteries in these aren't "maintenance free" and it may have dried up.

EDIT: I thought about it some more. The most common way for batteries to fail is for the cells to short out internally. When this happens, it presents a larger load to the alternator, causing it to work harder. If enough of the cells are shorted, then you're essentially shorting out the alternator which will kill it in short order. Its basically what i said before, with different words.

 

[jstpsgthruyrwrld]

Thanks for the reply, Whiffle. I was really hoping that the alternator might not have to be replaced. Sorry, if I misstated, but the battery was the original that had been in the truck for five years. It kind of galls me that there is no warning or instrument in the vehicle to tell you that something, as important as the alternator, is working too hard (it just shows 13 volts.) The original battery was a 5 year battery and it has been checked periodically, so this deterioration has happened over six months and 3000 mi.

 

[Whiffle]

I think I caught your disease... my battery is dead It was fine the other night, and then suddenly..gone. If I put my meter on it with no load, its 11.75 volts. If I hook it up to the truck with about .5A load...goes down to 8. Either its really discharged (which it shouldn't be, I didn't leave any lights on or anything), or its toast. We shall see...luckily I just fixed the girlfriends car so I can drive that

 

[Tarmac Wizard]

Thanks for the reply, Whiffle. I was really hoping that the alternator might not have to be replaced. Sorry, if I misstated, but the battery was the original that had been in the truck for five years. It kind of galls me that there is no warning or instrument in the vehicle to tell you that something, as important as the alternator, is working too hard (it just shows 13 volts.) The original battery was a 5 year battery and it has been checked periodically, so this deterioration has happened over six months and 3000 mi.

unfortunately there's no sensor to detect that the alternator is constantly in use. technically it's not working too hard, it's just working too much.

TW,
Alternator | Car Alternator

 

[Whiffle]

unfortunately there's no sensor to detect that the alternator is constantly in use. technically it's not working too hard, it's just working too much.

TW,
Alternator | Car Alternator

Well, they could probably put an ammmeter on it and then you could see what its up to, but you'd have to have to program the computer to decide how much is too much and put up a warning.


Just put a new interstate battery in mine, and got rid of those crappy little battery terminals these come with from the factory. It should be good for a while.

 

[jstpsgthruyrwrld]

Update: I'm not quite sure what was going on, but I guess my alternator is ok. Took truck to Nissan for one of those free multi point inspections (never know how much they actually ck.) They said there was no problem w/the alternator. So, I went back to Autozone, where they checked again, and now say the alternator checks good. I'm wondering, now, if AZ was trying to "sell" an alternator? Regardless, I guess this should serve as a cautionary tale ... to always get things double checked before spending more money. Thanks, again, for the help and knowledge.