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when an alternator rebuild shop rebuilds your alternator for a higher amperage, like a 65 or 75 amp alternator, making it a 135 or 145 amp unit, what is involved in doing this? thanks..

I would say such modification is not possible.

To double the power, it would have to be a bigger beast. Just replacing windings/rectifiers with double the amperage capability would not fit in place. A larger capability stator, field, and diodes are, that, larger.

Stacking two stator cores and rewinding both as a single, would also make it... bigger.

And if it is an automobile alternator, such increase of amperage makes no sense for the standard consumption of on-board equipment.
Miguel

A high current alternator is in order if you say upgrade your sound system sio they can hear it in the next county. Or add any accessory to the vehicle that is high power. For example commercial vehicles, ones used in camper conversions might make sense but for the average passenger car, it will not get you anything except maybe a faster charge on a dead battery. A higher capacity battery is a better upgrade for a passenger vehicle.

I agree, in most cases any real increse in current capacity would also result in a larger package. What a rebuild shop calls higher power may not be what we are thinking of. It may be a highly qualified term. I suppose manufacturers might build lower current alternators in larger housings for the sake of standardization. In this case there would be extra room inside for more windings or larger gague windings as well as higher rated diodes. But I can't say thats the case for sure.

Advisible, maybe not. Impossible? I doubt it. Good engineering practice normally allows a fair amount of tolerance to minimize the risk of premature failure. Just a I would never design an electrical with a 5 watt resistor when the maximum expected power dissapation is 5 watts (I would design it with at least a 10 watt resisitor), there may be alterators out there which can handle double their nominal power without any internal changes at all. It could be as easy as reducing the size of the pully, resulting in increased rotationals speed thus increased power output. Another method might be to tap more power from the output coils feeding back the bias current to the exciter coils which could increase the magnetic field and thereby also increase the power output. Food for thought.

Agg

I'm putting dual batteries in my jeep, with an isolator.. have a WARN winch, off road lamps, etc.. that require a lot of power, plus when my radiator (electric) fan comes on, the voltage drops to 11vdc or lower.. with headlights and that fan, I'm going backwards.. so I wanted an alternator that would crank out enough amps to cover both batteries and all my accessories.. without cooking the battery I have.. probably go to two gell cells..

Understood.
Even with a higher amperage alternator, using the winch, fan and superlights you will get a noticeable voltage drop, as such equipment will likely operate while engine is idling.
First you need to measure the current your alternator delivers and compare how much under its capabilities is.

If the alternator is rated -say 50 Amperes- but is delivering only 10 A when the extra equipment is on; a solution could be to have a 'manual' throttle and/or trick the reference voltage sensing wire from the alternator with a resistor to force it to deliver more charge.

Anyway, the rated current capability is at certain RPM. If under that, you will get not much improvement with a beefed up alternator. It is the rpm what produces the high rates current.

I would not consider anything gel, but that's me.

Miguel

So now you might want a circuit that senses the voltage drop and somehow increses the RPM of the engine.

cool... na.. that would be asking a bit too much.. thanks.. great idea tho

A plain fast idle solenoid from air conditioned vehicle raises the rpm at a flick of a switch by engaging the throttle lever. Available in all flavors at boneyards. And they are adjustable. No building circuits to sense anything.
Miguel

Does your jeep have a Delco -Remy alternator? If so you might find one from a suv or caddy that has a higher output rating. The amp rating used to be stamped near the tab for the adjusting bolt, not sure any more. Another vehicle to look at is an old ambulance, cop car or other emergency vehicle, those will usually be a Prestolite- Leece-Neville made in several different configurations.
http://www.prestolite.com/index-na.php

More info about Delco http://www.madelectrical.com/electrical ... remy.shtml

will check it all out later today.. thanks..

Sorry I'm late to the discussion but as an electrical rebuilder your question caught my eye. Alternators can be rebuilt to deliver more amps to a certain degree BUT watch out, more amps mean more heat with the same surface area so that means a hotter running alt. which cuts the life. Also if you tweak the max amp output up you almost always decrease low end output. (lower amp output when idling ) I would advise going to http://www.electricalrebuilders.org and search for a member closest to you and ask for more information.

I'm putting dual batteries in my jeep, with an isolator.. have a WARN winch, off road lamps, etc.. that require a lot of power, plus when my radiator (electric) fan comes on, the voltage drops to 11vdc or lower.. with headlights and that fan, I'm going backwards.. so I wanted an alternator that would crank out enough amps to cover both batteries and all my accessories.. without cooking the battery I have.. probably go to two gell cells..

You want to supplement a low battery with more power when needed so use a solar charge controller for a car battery and get the power from another battery. It's probably the same thing as a regulator. That might mean switching the batteries around for normal charging but if you used a knife switch to do that it might work. It seems like a lot to put in a jeep though. Try asking some rv'ers for that problem.

I suppose you can switch to LED Off road lamps. They are a little pricy but compared to a second battery, a new alternator and all that labor, it may turn out to be cheaper in the end. in general 16W-18W LED will be about as bright as a 50W Halogen a more than 50% decrease power.

Heres an OK one for example
http://www.ebay.com/itm/2x-16W-High-Pow ... 6d&vxp=mtr