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Discussion Starter · #1 ·
alternators.... high output at low RPM\'s??????

Is there an alternator that puts out high amps at low rpm's?

I have a 105 amp alternator from an 80's camero that is good if I'm going down the road, but while rock crawling it dosen't keep up with all my electric B.S. By the end of the day my volt meter is holding 10 volts on two red top Optimas /ubbthreads/images/graemlins/crybaby.gif

I would like to buy something from the parts store if possible. -or- Is there a way to make (or trick) the 105 amp alternator into putting out more amps at 1200 rpm's?

/ubbthreads/images/graemlins/givemebeer.gif /ubbthreads/images/graemlins/givemebeer.gif /ubbthreads/images/graemlins/givemebeer.gif
 

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Re: alternators.... high output at low RPM\'s??????

I think you have something wrong there. WHat do you have on that is pulling all that power?
 

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Discussion Starter · #3 ·
Re: alternators.... high output at low RPM\'s??????

Tauras fan + rear steer pump + headlights + rocklights

The fan and the pump are the killers...

edit- and if I ever have to use that winch I'll have some major catching up to do in the volt's dept. /ubbthreads/images/graemlins/ooo.gif
 

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Re: alternators.... high output at low RPM\'s??????

im not 100% sure but i think big trucks have alts set up like i know diesels do you might hafto mess with them
 
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Re: alternators.... high output at low RPM\'s??????

The 100A unit out of my CJ kept up just fine....The old unit it replaced had the same symptons you noted...as long as the RPM's were above 1000, it was fine.

Too bad it will not fit my SBC....

Aaron...do NOT buy from Kragens, Pep Boys, etc. It's worth the money to buy from NAPA or a good altinator shop. A few bucks saved is quickly lost on that long walk home.

If you want to try a new used Delco...I still have the 100A...It just needs a good home....
 

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Re: alternators.... high output at low RPM\'s??????

Change the pulley ratio so that the alternator is turning faster at any given RPM. Just don't Tim Taylor it to the point that the alternator is over revved when you wrap up that big block.

/ubbthreads/images/graemlins/40BEER.gif
Dale
 

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Discussion Starter · #7 ·
Re: alternators.... high output at low RPM\'s??????

[ QUOTE ]
Change the pulley ratio so that the alternator is turning faster at any given RPM. Just don't Tim Taylor it to the point that the alternator is over revved when you wrap up that big block.

/ubbthreads/images/graemlins/40BEER.gif
Dale

[/ QUOTE ]

ok, that is a good simple and cheap way to go about it.
/ubbthreads/images/graemlins/goodpost.gif
Where could I get a smaller pully?

and how small is too small?
 

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Re: alternators.... high output at low RPM\'s??????

What are the rpms going down the road when it is "working fine"?
What are the rpms when rock crawling?
Take the percentage difference and go for that much smaller of a pulley. Or you could just go down about .5" and call it good.
I ran a one inch smaller set of pulleys on the altenators on my old show car. That, along with srockets and motorcycle chain allowed me to put out 390 amps at 1000 rpms... /ubbthreads/images/graemlins/grin.gif
 

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Discussion Starter · #9 ·
Re: alternators.... high output at low RPM\'s??????

[ QUOTE ]
What are the rpms going down the road when it is "working fine"?
What are the rpms when rock crawling?
Take the percentage difference and go for that much smaller of a pulley. Or you could just go down about .5" and call it good.
I ran a one inch smaller set of pulleys on the altenators on my old show car. That, along with srockets and motorcycle chain allowed me to put out 390 amps at 1000 rpms... /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

Road RPM is 2500 to 3000 (guessing). But you see I don't use the rear steer at 45 mph and I can turn the electric fan off cause I'm getting plenty of air.

On the trail I'm usually at 1000 to 1200 but it could see as much as 5000 or 6000 at times and I don't want to damage the alternator by over spinning it. I'm guessing that could be a factor?

Where can I find smaller pullys (V-belt) and do I need a special tool to get the pully on and off?

Are they all the same arbor size?
 

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Re: alternators.... high output at low RPM\'s??????

I got one from www.4alterstart.com a few months ago. It runs the lights and taurus fan well enough too. I got the 135 amp but there is a 180 amp too.
 

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Re: alternators.... high output at low RPM\'s??????

Hi all. I hang on the Jeepster board and lurk here quite a bit, since my CJ is next after my Jeepster.
Aaron- You probably have a Delco 10si alternator, and they have the same problem on diesel equipment engines (not kicking in at low speed). There is more than one size arbor, but the most common one is what you have. No special tools needed to get it off, you just have to get the pulley to stay still while you break the nut loose. The easiest way is an impact. You can put a fair amount of torque on it going back together, but don't go crazy. I always impact 'em on, but stop after it hammers a couple times. Pay attention to all the little spacers and make sure you put them back in the same order. If all you take off is the pulley, none need to come off.

Steve.
 

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Re: alternators.... high output at low RPM\'s??????

[ QUOTE ]
Where could I get a smaller pully?

[/ QUOTE ]

Not sure it they would fit your app, but I picked mine up from Kilby.

On board air
 

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Re: alternators.... high output at low RPM\'s??????

It could also be the way you have it wired in the circuit too.
The so-called "one wire" or "cheat method" will cause it to not know the battery is running low and won't let it charge it right.

Make sure the small side connector's red wire goes DIRECTLY TO THE (+) BATTERY POST, not to the alternator's output post like is so popular a method. That way, the "sense" line can see the drain, instead of being "tricked" by looking at itself.
IT HAS TO BE A SEPARATE WIRE TO THE BATTERY!

The smaller pulley on the alternator, or a larger one on the drive pulley will enable it to spin faster, but if it's wired wrong that won't help much.
 

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Re: alternators.... high output at low RPM\'s??????

Because of the design of the armature, alternators can spin really fast without damage.

DC generators are a different story. In the early 60s they put a really big pulley on Corvette generators because they would spin up until the windings started to stretch out of the slots in the armature.
 

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Re: alternators.... high output at low RPM\'s??????

I don't have any nifty ideas to make the alternator put out more power at low rpms but one thing to mull over... you might want to rig up a hand throttle set-up so you bump up the rpms while you're winching (like the 7-ton trucks do) just to try and prevent your batteries from getting smoked...
 

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Discussion Starter · #16 ·
Re: alternators.... high output at low RPM\'s??????

[ QUOTE ]
It could also be the way you have it wired in the circuit too.
The so-called "one wire" or "cheat method" will cause it to not know the battery is running low and won't let it charge it right.

Make sure the small side connector's red wire goes DIRECTLY TO THE (+) BATTERY POST, not to the alternator's output post like is so popular a method. That way, the "sense" line can see the drain, instead of being "tricked" by looking at itself.
IT HAS TO BE A SEPARATE WIRE TO THE BATTERY!

The smaller pulley on the alternator, or a larger one on the drive pulley will enable it to spin faster, but if it's wired wrong that won't help much.

[/ QUOTE ]

I've got it wired the way you said. /ubbthreads/images/graemlins/thumbsup.gif
 

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Re: alternators.... high output at low RPM\'s??????

Then your next step is make it turn faster.
Sometimes easier said than done.
Going to a smaller pulley on the alternator - if possible - but most are small already. Much smaller the belt won't have enough grip on it, it'll slip, same problem.

You'll have to get creative. I did this for a tow truck once - I found a larger pulley that I could weld onto a different driven pulley - the power steering pully. By attaching the big one to the power steering pully, making it a dual pulley, it gave me a faster running surface to hook the alternator to. A separate belt ran between them.

I had to move the alternator forward a tad, no biggie.

That way the alternator spun considerably faster than it did stock. The only negative was at higher RPM, it started sounding like a siren!

Kilby has several pulley combinations, and if you give them a call they will costom make you whatever you need. Good people to deal with too.
 

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Re: alternators.... high output at low RPM\'s??????

You won't spin it too fast with a big block.
Acura integra type R engines use the same type of alternator and redline at 9k RPMs. I don't think you will have a problem.
You could always go to a super high output alternator. At any given RPM, you will get more power froma higher output alternator.
Ex.
1000 RPMs on a 140 amp alt. = maybe 60 amps
1000 RPMs on a 210 amp alt. = maybe 105 amps

Or you could stop playing with the rear steer at URE when you KNOW you don't need it... /ubbthreads/images/graemlins/grin.gif
 

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Re: alternators.... high output at low RPM\'s??????

Or you could power the alternator with an electric motor - then it would always run at the same speed. /ubbthreads/images/graemlins/grin.gif

A solution for every problem.
 
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Re: alternators.... high output at low RPM\'s??????

Better yet, go down and buy one of those Honda Generators and put it in the back. Not only can you use it to run the electric motor Jim suggested above, you can run your blender and make frozen daiquiris....and you'll be the most popular guy on the trail
 
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