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Alternator upgrade?

Bobby Light

By Bobby Light,
in Modifications & Accessories

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Bobby Light Waaaaay Too Many

Bobby Light

Posted
Posted (edited)

Has anyone upgraded their alternator to a higher output say 140amps or so? Looking to do this on my boat to try and keep up with the draining of 5 optimas during those all day lake trips. Talked to a guy today at an alternator repair shop and he told me anything over 100 amps will just slip the belt. What is the belt size on the my alternator 3/8" or 1/2", I'm not near the boat right now? Any thoughts or experience on this?

I will fully charge all batteries before each outing.

I do have one battery isolated with a perko and a Blue Sea Isolator http://www.skipper-dan.com/products/30594.htm

That is a great price on these by the way, and this guy ships lightening fast.

Edited by 06vlx
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Bobby Light Waaaaay Too Many

Bobby Light

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GM offers an optional 160amp alternator on the trucks, isn't it basically the same serpentine belt set up?

It's basically the same yes. I'm not sure why this guy was saying that the belt would slip, I know the upgraded alternator would have a little more resistance but it would take quite a bit to make these belts slip. I'm pretty sure I'm just going to do the 140 direct replacent alternator.

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Gordo 'Bu Savant

Gordo

Posted
Posted

I would defer to an alternator expert, but I am pretty confident that a higher output alternator is no more a "drain" on the engine than a lower amperage model. I had my alternator rewound on an old boat I used to own (you might look into that, as I recall, it was a lot cheaper than buying one), to up the amperage output and I saw no difference in the engine output - same top end (rpm, speed).

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Bobby Light Waaaaay Too Many

Bobby Light

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YOU MIGHT HAVE SOMETHING WIRED WRONG. HOW MANY, AND WHAT SIZE AMPS ARE YOU RUNNING THAT 100 AMP ALT CANT KEEP UP?

Are you yelling at me? LOL....

There isn't a problem when the boat is running while we're boarding. The problem is when we are at the beach, middle of the lake, tied of to other boats, whatever and the stereo is on for an extended period of time. Batteries drain down, start the boat up and the batteries won't recieve enough juice to play the stereo again for hours. Does that make any sense, it did in my head anyways...

Oh I'm running a JL 1000/1, JL 450/4, and Kicker 700.5.

Edited by 06vlx
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SCOTTDOMINE 'Bu Savant

SCOTTDOMINE

Posted
Posted
YOU MIGHT HAVE SOMETHING WIRED WRONG. HOW MANY, AND WHAT SIZE AMPS ARE YOU RUNNING THAT 100 AMP ALT CANT KEEP UP?

Are you yelling at me? LOL....

There isn't a problem when the boat is running while we're boarding. The problem is when we are at the beach, middle of the lake, tied of to other boats, whatever and the stereo is on for an extended period of time. Batteries drain down, start the boat up and the batteries won't recieve enough juice to play the stereo again for hours. Does that make any sense, it did in my head anyways...

Oh I'm running a JL 1000/1, JL 450/4, and Kicker 700.5.

No yelling Fingerwag.gif That makes perfect sense. Once the batteries drop so low on charge, the average alternator does not put out enough amps to get the batts back up to where they can even take a charge. Does that make any sense :unsure: It did to me, I think Dontknow.gif

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johnsvt Never Logs Off

johnsvt

Posted
Posted (edited)

Serpentine belt shouldn't slip with a 200 amp alt. I know it isn't the same, but I have seen guys make 19lbs of boost with a serpentine belt.

Also ever consider changing from Optima to Kinetic batteries 1 HC 2400=2 Optimas plus lower internal resistance = quicker recharge

Edited by johnsvt
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Bobby Light Waaaaay Too Many

Bobby Light

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Serpentine belt shouldn't slip with a 200 amp alt. I know it isn't the same, but I have seen guys make 19lbs of boost with a serpentine belt.

Also ever consider changing from Optima to Kinetic batteries 1 HC 2400=2 Optimas plus lower internal resistance = quicker recharge

I've already got the 5 optima's not gonna switch now..

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winddawg A Decent Third

winddawg

Posted
Posted

I have the Serpintine belt on my engine and when I had the alternator rebuit and upgraded from 90 to 140 amps. At the time of the change the shop recommended that I put a smaller pulley on the alternator so that it would spin faster and develop more amperage at lower rpms. I have no pulley slippage issues.

You may want to go to one of the car stereo competion sites as those guys are regularly pushing 5kw in their cars. In the past on the Zapco site I have seen discussion on 200 amp alternators.

-Dave

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VLXRonnie Crew Regular

VLXRonnie

Posted
Posted

If you do get a new alternator just make sure it is intrinsically safe (i.e. Marine battery). Would not want any explosions while starting your boat. That would suck! :( This is the reason that I believe that most on this sight have went with the rewind option. Hope this helps some...

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Bobby Light Waaaaay Too Many

Bobby Light

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Posted
If you do get a new alternator just make sure it is intrinsically safe (i.e. Marine battery). Would not want any explosions while starting your boat. That would suck! :( This is the reason that I believe that most on this sight have went with the rewind option. Hope this helps some...

Thanks ronnie,

I think that goes without say.... And by "Marine battery" I'm sure you meant "marine alternator"..

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Pistol Pete Waaaaay Too Many

Pistol Pete

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Posted (edited)

Lets not forget that alternators just don't just put out juice. They only put out what's demanded of them.

When you're measuring the output of an alternator, you have to supply a load to make the alt. put out amps.

Edited by Pistol Pete
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Pistol Pete Waaaaay Too Many

Pistol Pete

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Posted

What I'm saying is that if you have 5 really low batteries, I don't think the alt. is going to put out 85 amps at idle just because the batteries are really low. The charging system has to be under a load to get the alt. to pop out all those amps. The batteries being low on charge is not a load. The alternator is only going to slowly charge them back up. I don't think you'd put your batteries on a 85 amp charge, would you?

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Bobby Light Waaaaay Too Many

Bobby Light

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Posted (edited)
What I'm saying is that if you have 5 really low batteries, I don't think the alt. is going to put out 85 amps at idle just because the batteries are really low. The charging system has to be under a load to get the alt. to pop out all those amps. The batteries being low on charge is not a load. The alternator is only going to slowly charge them back up. I don't think you'd put your batteries on a 85 amp charge, would you?

I see what you're saying, my answer would be that my stereo (as it will be on) would provide the load for the alternator.

Edited by 06vlx
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Pistol Pete Waaaaay Too Many

Pistol Pete

Posted
Posted

You're absolutely right.

Maybe I misunderstood...I thought you thought that having an alt. that can put out 85 amps at idle would quickly recharge your batteries after you had been playing the system for a long time w/the engine off. The bottom line is...you need that alt. and it's a great price.

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