hawgrider1200

Where did u get this information from? I believe we started using alternators instead of generators because they generate the same amounts of amperage at all rpm's as opposed to what a generator will do. However, I am not infallable and not opposed to learning something new. So, if u tell me where u got this information I will look at this so that I may improve my mind today. I found 200 amp alternators for less than $200 at db-starter-alternator.com/ they obviously do not stock for our JK yet. Maybe the TJ alternator will work though. Haven't reseached that yet.

08{GA}RUBICON

I was also thinking the same thing about overloading my stock battery! Thanks to all for the input!

RedneckJeep

Cool! Do yall ever visit him? If so, holler at me, we need to get together. All of us.

Frog Rubicon

Sorry, I meant to buy an bigger aftermarket alternator

JoeBlob

Thanks calibutcher! What do you think about using an isolator like lorrel suggested?

Also, does anyone have pix of where to put the 2nd battery?

JKjunkie2009

would it be to much on the batter if i was running 4 lights, and a winch?

joejeeper

Not much room under the hood- any pics of (2) batteries hooked-up in a JK ?

Lorrel

You are somewhat correct here, and I may have confused you a bit in my post.
When I stated that the aftermarket alternator would produce less power at a lower rpm, what I ment was since the alternator was either rewound or a low price custom high output, the specifications of output/rpm had been changed, therefore to produce the higher power output, a higher rpm will be needed. This is inherent in the windings and number of poles used in its construction.
By the same token, your statement that alternators will generate the same amount of amperage at all rpms is incorrect. The main reason of the move to the alternator is because they are lighter in weight, more rugged in construction, have less moving parts, control the output better, and are cheaper to build.
A generator produces power that is directly proportional to the speed of the armature and strength of the magnetic field. So a generator produces more power at a higher rpm, up to it's maximum output, whereas the alternator does allow for producing power output at a lower engine rpm, as seen below.
The basic different between an alternator and a generator is what spins and what is fixed. On a generator, windings of wire (the armature) spins inside a fixed magnetic field. On an alternator, a magnetic field is spun inside of windings of wire called a stator to generate the electricity. This allows the wires to be directly and easily connected to their outputs without the need for sliding contacts to carry the relatively high output current. The magnetic field is still generated via electro magnets mounted on a rotor, and the relatively small field current that powers them is supplied to the rotor by two small brushes that ride on separate and continuous slip rings. These smooth slip rings, unlike the comparatively rough contacts on a commutator in a generator, and the fact that the relatively heavy windings are fixed instead of rotating allows the alternator to be spun to much higher speeds. This allows it to reach it's maximum output sooner and in most cases to be spun fast enough at engine idle speeds to produce enough electricity to power most of the needs of the vehicle without relying on the battery.
Since the alternator is specified to the vehicles needs and at a given rpm in stock or factory form however, once adding auxillary equipment such as watts and watts of lighting, a high end sound system, a compressor, winch and so forth, the alternator can no longer supply the power needed.
Don't get me wrong there are other differences between the generator of yesterday and the alternator of today due to the fact that todays vehicles require much cleaner power, however the basic concept, producing electricity is the same.
Since both devices are used to produce electricity, both are subject to the basic principles of ohms law, and both outputs are determined by the number of poles and the rotational speed.
As noted in at least one post, the idea of replacing the stock pully with a smaller one would in fact allow the alternator to be spun up quicker and maintain a higher rpm as compaired to the larger pully. This would become even more important when heat, and the lower rpm's used during offroading come into play, and outwardly appears to be a very good idea, providing the bearings can tolerate the higher speed.
As with all information, the information I posted has been obtained through many years of research, experience and practical use, during my 20+ years of military service and the last 19+ years working as an electrician at a large industrial facility.

Choppus

Yeah I just checked my ENCS quote sheet and it has it labeled to come with 140 amp alt. They know how us Jeep people use them. I think they should come stock with 200 amp alternators.

cufojeep

When, oh when, will we see an aftermarket dual battery tray?