Stereo killing alternators?

[Bronco Paul]

Hi guys...
Just was wondering if anyone has had a problem with killing alternators after installing an aftermarket stereo? I'm running a stock unit but after I installed the stereo with just the one 5 1/4 speaker I've killed three alternators. The first time it fried the ground wire. I have a lifetime warranty on the alternator...but the guy at the parts store is not going to like me killing all of his stock! So I'm assuming that the stock unit is about a 35W one? and my stereo is 55W...is this a simple math problem...I need to upgrade to an alternator rated high enough to power that plus lights, windshield wiper, heater, turn signal, and occasional horn toot all at the same time? or do I just have a wiring issue? ...or just bad luck with alternators?

Thanks,
Paul.

 

[Broncobowsher]

You are confusing watts and amps. Stock alternator should be a 60 amp unit (usually in a case originally designed and marked 35 amp). So how many watts is a 60 amp alternator? Watts = Amps x Volts. Using the generic 12V auto electrical system (actually a bit more) you have 12V x 60A = 720 watts. Now that is peak, when cool, turning at faster then idle, in a lab... I have used stock 60A alternators with headlights, twin motor electric wipers, Heater fan on high, heated mirrors running, radio going, and EFI (2 fuel pumps, injectors, etc.) and it can keep up.

So before you go looking to upgrade, you need to find your problems and fix those.
What are you failing on the alternators?
Have you done anything with the voltage regulator?

 

[BRONCROB]

You are confusing watts and amps. Stock alternator should be a 60 amp unit (usually in a case originally designed and marked 35 amp). So how many watts is a 60 amp alternator? Watts = Amps x Volts. Using the generic 12V auto electrical system (actually a bit more) you have 12V x 60A = 720 watts. Now that is peak, when cool, turning at faster then idle, in a lab... I have used stock 60A alternators with headlights, twin motor electric wipers, Heater fan on high, heated mirrors running, radio going, and EFI (2 fuel pumps, injectors, etc.) and it can keep up.

So before you go looking to upgrade, you need to find your problems and fix those.
What are you failing on the alternators?
Have you done anything with the voltage regulator?

I think he meant stock radio output watts vs new radio watts.I would have to agree on checking the reg and wiring.

 

[DirtDonk]

Which ground wire did you fry Paul? The little tiny one between the alternator and regulator? Or a larger one somewhere? Or the negative battery cable?

Paul

 

[broncnaz]

Your stereo is no wheres near big enough to kill a alternator. I highly doubt it even puts out 55w most of the claims they make about power output are not entirely correct.
Most likely your issue is badly rebuilt alternators. Sometimes theres a reason for those lifetime warrentees. on the other hand if your fring ground wires then you have a issue somewheres.

 

[Ranchtruck]

The voltage regulator is seperate from the alternator, unlike newer alternators that were combined into one unit. So charging problems may not be the fault of the alternator itself, but the voltage regulator that controls it. The voltage regulator is a 2"x3"x1.5" or so box mounted to the inner fender.

 

[KyleQ]

Just 3G it and ditch the lousy external regulator...

 

[01Dudley]

Yeah I gotta agree. No way did a simple radio install "kill" a alternator. You have something else going on. You may have just uncovered the issue by installing the new radio.

 

[Kyle.malone]

Just a littel info on stereo equipment. You have to go by the RMS rating of the stereo for its true output in power. A radio that says it puts out 65W really only puts out like 19W RMS. Speakers say they can handle up to 200W really only habdle about 75W-100W RMS.

I would say that you have just uncovered a problem that you have had for some time now and it just now is coming to light. I would check all the grounds and see if you can find any thing drawing power with the vehicle off. Good luck.

 

[broncobilly72]

I vote for a bad regulator. Had one go bad once and it made my alternator run at full power and cooked my battery.