55 Amp Alternator Enough?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=16590
Printed Date: June 19, 2025 at 6:37 AM
Topic: 55 Amp Alternator Enough?
Posted By: scroley
Subject: 55 Amp Alternator Enough?
Date Posted: July 22, 2003 at 8:07 PM
Me again, with the 80 Scout and weak alternator at 40 amp (originally thought 35). I can upgrade to a 55 amp but thats as high as I can go. I'll call an alternator shop and see what they think but I was told it ain't gonna happen on anything higher. Anyways, my question is this: whats the maximum safest load I can run on this alternator? My desire is two 10" subs at 100 watts each, two 6 x 9"s and two tweeters at about 50 watts each. Safe? Crazy? or Stupid? Full explanation and recommendation would be great! refer to my earlier post on two batteries just a few posts from this one... -------------
Thank you,
Aaron
jackjeckyl@hotmail.com
Replies:
Posted By: Big Purds
Date Posted: July 22, 2003 at 10:09 PM
post what amps and subs and speakers you want...100W means so many different things to different manufacturers...so does 50...
Posted By: speedwayaudio1
Date Posted: July 22, 2003 at 10:26 PM
sure it can happen. all you need is a 1 wire alt. get at least a 100amp. even if you don't have a big power audio system. man you got a SUV. you need power for Head lights,a/c, spot lights, wench, CB or any thing else you can think of. all you need is a 1 wire alt and connect it to the positive term on the batt. no problem. the alt shop will do it for you. it will be worth it.
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Big Dave
Posted By: scroley
Date Posted: July 23, 2003 at 7:21 AM
I was looking to use a Rockford Fosgate 4080. 80 watts bridged to two subs, and 40 to the four speakers. The Scout doesn't have much in the terms of electrical stuff, although your right on the winch, CB, and aux lights although they're very sparingly used.
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Thank you,
Aaron
jackjeckyl@hotmail.com
Posted By: pureRF
Date Posted: July 23, 2003 at 10:20 AM
you will be fine with the alternator u have right now and if you did somehow blow it you could then just replace it
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dream it, build it, fiberglass it
Posted By: bberman1
Date Posted: July 23, 2003 at 10:32 AM
From the specs you give above, 80 watts bridged (40 watts per sub) and then 40X4 your total wattage is 80+160 =240 (I don’t know if this is the RMS or MAX wattage) now the current draw on 240 watts RMS is 18.9 amps. So with a 55 amp alternator you should have sufficient power for both your audio system and your cars electrical system.
Posted By: scroley
Date Posted: July 23, 2003 at 11:50 AM
Its RMS (what I'm planning). So to sum up: I'm going to use a 4 channel Fosgate 4080 amp. I'm going to bridge two channels for the subs (80 watts RMS) and split the four remaining speakers in series over the other two channels. I will likely use Infinity Kappa subs, 6x9s, and tweeters along with a JVC head unit and CD changer. All this over a 55 amp alternator. All fine and good? Replacing is not a viable option. The alterantor with 55 amps is $500. I'll take the 40 amp one off and save it for later. -------------
Thank you,
Aaron
jackjeckyl@hotmail.com
Posted By: wvsquirrel
Date Posted: July 23, 2003 at 9:45 PM
You would probably want to wire the other 4 speakers in Parallel, not Series. Parallel will produce a 2ohm load per channel with 2 speakers on each channel. Series will produce an 8ohm load per channel with 2 speakers on each channel (not even worth doing IMO because you wont get much from the amp at all). ------------- Squirrel
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Posted By: stegen
Date Posted: July 30, 2003 at 12:28 AM
I would just stick with the stock alt and run your system and aux lights seperate or for short periods of time together. $500 for a alt upgrade is sad. the stock should be fine. it is small but you arent running anything big anyway.
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