60A Alternator good enough for audio amp?

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CBJoe
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60A Alternator good enough for audio amp?

Post by CBJoe »

76 Cherokee Chief w/ carb'd 360. All stock electrics except for radio, LED headlights, and 12V relay feeding DUI Distributor.

Currently has a 60A alternator.....I'll start by saying ahead of time that I will be upgrading the alternator in the future....but I've done so much work on this I'd rather not right now.

I will be bypassing the ammeter at same time as upgrading the auido. But my question is will the 60A be ok to power a 325W RMS Max Amp and Speakers? Or am I asking for trouble? Amp will have a direct relay feed.

Regards, Joe
1976 Cherokee Chief / Stock Q-Trac, Stock 360

ferrum
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Re: 60A Alternator good enough for audio amp?

Post by ferrum »

I think you should be fine. When I was young and stupid, I had once installed 1600A amp without bypassing amp meter. I had it cranked up so high that all my gauges moved when base hit but it survived. My jeep had 60A alternator.
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tgreese
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Re: 60A Alternator good enough for audio amp?

Post by tgreese »

Basic electricity. Power equals current times voltage, P=I*V.

or I=P/V. 325/12.3=26.4 amps. Should be plenty.

Realize that peak power of 325 (if it's truthfully RMS - probably not) only happens occasionally with music. The battery is a buffer and the charging current needed will be well below 26 amps. Unless you drive the amp (overload) into constant distortion, and then it will sound really bad. Really bad.

Amplifiers can draw a lot of power, but nothing like electric motors (ie your starter motor, or a winch).
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Re: 60A Alternator good enough for audio amp?

Post by CBJoe »

Excellent…thanks folks


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Pablo
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Re: 60A Alternator good enough for audio amp?

Post by Pablo »

When you get rid of the old unsafe amp meter, add a new voltmeter in its place and watch it. If the voltage doesn't drop when you use the amp, you are good. If it goes down much below 13.5 volts-- then maybe don't use the amp until you get the new alternator... or turn the volume down until the voltage recovers (gasp).

Just because the alternator was rated at 60 amps doesn't mean it still puts out 60 amps, and even if it is in great shape-- the 60 amp rating means it puts out 60 amps at higher cruising RPMs and not at engine idle. At idle, it probably only puts out 30 amps or less. When waiting for someone at night in the rain, you may not be able to listen to the tunes and run the windshield wiper with the head lights on. The voltmeter will help tell you before you end up with a dead battery.
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CBJoe
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Re: 60A Alternator good enough for audio amp?

Post by CBJoe »

Thanks Pablo...this is exactly what I did. Looks like I'll be replacing the alternator sooner than later. I did not notice a voltage drop when the amp is powered on. However as the alternator heats up after 10 mins of driving or so the voltage goes from 14ish volts down to 12.8 no matter the RPM. I also noticed a fluctuating whine from the alternator itself once it heats up (even with the amp off).
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Yeller
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Re: 60A Alternator good enough for audio amp?

Post by Yeller »

Be sure to check voltage with a quality multimeter. If using an off the shelf automotive gage, most show a voltage drop over time running. At least that’s been my experience. I have a “high quality” name brand voltage gage, it shows 14 cold at start up and an hour later 12, check with a real meter and it’s at 14. Every sweep style aftermarket volt meter I’ve checked has had a voltage drop after time.
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CBJoe
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Re: 60A Alternator good enough for audio amp?

Post by CBJoe »

I have a nice Fluke Meter...I'm getting ready to go for another test run. I'll check with the fluke at the battery before the run and after.
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