Defective Alternators

[GlenB]

Have to you had to go through 1 or 2 alternators before you've gotten to a good one?

That happens a lot.

Some are legitimately defective. Shopping the lowest price will find the lowest quality... you know, you get what you pay for.

However, some are actually due to the battery. One common scenario goes like this.... alternator quit and the driver drives the vehicle until they get home or it leaves them on the side of the road, whichever comes first. The battery is either stone dead at this point, or very weak.

They buy an alternator, fire it up and the alternator is now having to charge the battery... at full output. Alternators are rated at various peak amp output... it may be 100 amps, 130amps, ect. This is a peak output, not a continuous duty output. Charging at peak output creates a huge amount of heat in the alternator. Its one thing to peak every now and then for a few seconds at a time, but to run steady at peak output for several minutes, even hours (added up over the different drive cycles the car goes through over several days time), the otherwise good alternator is burned out.

After the second or 3 rd alternator, the battery may have been charged up enough (assuming they didn't drive until dead this time), that the 2nd or 3rd alternator lasts.

So charge the battery, or even replace it, when you need a new alternator. That may save you some headache.

[PNG]

I have replaced the alternator in my 240SX three times - granted, not one after the other... Seems like 30k miles or one year is about all the service I can get out of one before it goes to Alternator Heaven. Good thing I bought the "lifetime" model, so I get a new one for free each time it happens. It does suck to replace it, though, since you have to get under the car to do it. Sadly, I can complete the swap (including a trip to Kragen for the replacement) in about an hour now.

[GlenB]

Big amplifier and woofers?

When you figure the first original factory one went "XXX" number of miles, and the replacements can only go "xx" number.... something is up there.

That is one thing the discount auto parts stores are good for... lifetime warranties and no hassle parts exchange. I won't use them on a customer's car due to the often questionable quality (rare times I do, I get the higher names in the biz... like Bosch, Delco, ect). But I'll put the house-brand with the life time warranty on my personal stuff... heck yeah, perfectly understandable when you can do it yourself. It'd get real old real fast though if you had to keep paying someone else to do it over and over again.

[ryans]

i hate when you have to make two trips to the part store for alternators. happens often with this rebuilds!

[PNG]

Big amplifier and woofers?

When you figure the first original factory one went "XXX" number of miles, and the replacements can only go "xx" number.... something is up there.

That is one thing the discount auto parts stores are good for... lifetime warranties and no hassle parts exchange. I won't use them on a customer's car due to the often questionable quality (rare times I do, I get the higher names in the biz... like Bosch, Delco, ect). But I'll put the house-brand with the life time warranty on my personal stuff... heck yeah, perfectly understandable when you can do it yourself. It'd get real old real fast though if you had to keep paying someone else to do it over and over again.

Heh. That car barely even has a radio...

I don't know what the deal is. I got the car with 89k miles on it, and like clockwork, every 30k miles (or about once a year) the alternator takes a dump.

[Starke]

any parasitic draws going on?
what brand of alternator are you using?

[Starke]

you should also check to see if there are any shorts in the system

[XtremeModifier]

What type of alternator? Post up on forums for that make/model/year vehicle ... see if it's a common issue. like with mx6's, due to the limited number around, lots of replacement parts were low-quality rebuilts, and would often fail quickly. Go buy a mazda factory starter, it lasts for 100k+, autozone rebuilt, 5k and go buy another.

[ryans]

with my 944 I was always changing alternators. they'd seem to go bad every month.