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Old 05-09-2011, 07:26 PM
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Default Alternator Size?

Just rapping up some of my parts list to complete project and was wondering what size alternators I should get. As of now I just have the stock ones that came on the original 454/330's. They are back from 78. Have added Some JL amps since. I am going to add a 3rd battery also. New stereo equip:

#1) JL 1000/1
#1) JL 500/1
#2) JL 300/2
#1) JL 250/2

Everything is going to be running at 4oh and will be at advertised wattage.

Thanks,
John
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Old 05-09-2011, 07:38 PM
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Upgrading to some 100AMP units wouldnt be bad. Just be sure, that if you go with bigger amp alternators, be sure to upgrade the wire lead to it. Stock gauge wire wont support the extra amps, could burn up on you.
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Old 05-09-2011, 07:49 PM
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Go check out Balmar.net.

These guys know Marine alternators.

A 100 Amp unit will also likley require a 1/2 belt vs a 3/8th unit.

Uncle Dave
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Old 05-09-2011, 08:00 PM
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Thanks guys. What do the stock ones put out on offshore boats w/o many goodies? Are they like 40 amps?
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Old 05-09-2011, 09:26 PM
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Originally Posted by getrdunn
Thanks guys. What do the stock ones put out on offshore boats w/o many goodies? Are they like 40 amps?
40 60 for stock stuff.

UD
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Old 05-09-2011, 09:42 PM
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John-
Your running all Class D amps. These are very efficient amps. Look up the owners manuals at JL and total up the max amps needed to run these. My guess is it may be around 90 amps... If you get two 60-65 amp alternators you should be fine and then you won't have to change pulleys and belts.
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Old 05-10-2011, 07:33 AM
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That 1000\1 will use up almost 90 amps on its own under load. These are Class D and are rather effcient compared to others, but that is the biggest amp JL makes and you are running it along with 3 others including a 500\1 which is also thirsty!

Those amps will probably draw the same current or near the same rather 4ohm or 2ohm they way those are setup. You have 4 power suppys all fighting to stay charged that is allot of draw!
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Old 05-10-2011, 12:18 PM
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Originally Posted by endeavour32
John-
Your running all Class D amps. These are very efficient amps. Look up the owners manuals at JL and total up the max amps needed to run these. My guess is it may be around 90 amps... If you get two 60-65 amp alternators you should be fine and then you won't have to change pulleys and belts.
I might try this route first especially cause it's not that often when I will be listening to it like years ago. However I do tend to slame some beers from time to time and will probably have it drawing a little more amperage than anticipating. Hopefully the 3rd battery which will be located right at or very near where the amps will be will also help some. Having an alternator with high amperage at lower RPM would be advantageous cause typically when I'm in the pins WFO I have the music down low enjoying the other out the transom.

The higher amperage alternators don't have a tendency to have more interference with the stereo equip do they?
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Old 05-10-2011, 08:08 PM
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http://stores.ebay.com/DB-Electrical...=p4634.c0.m322 try this i got a alt. for $88ship to me i have two batt.and a 3000watt amp works fine . the alter.is 100amp15years on the frist one i got from them . just got a new one. cant beat there price . good luck
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