Alternator Discussion

[ESHALLBETTER]

Hey All,

OK, I did a search and came up empty, so here it goes.

I am getting ready to put an anternator (or alternators) in the class 3 Bronco. I am going back and forth between a high output single alternator, or running dual alternators. I am hoping to get a discussion going on which method would be best AND WHY, what others are doing that works well, and just general information on the topic.

Right now I am leaning to one high output alternator, and bringing a spare. But I like the idea of being redundant as well. I will be running 2 Optimas.

Thought on the topic?

[ChaseTruck754]

Haven't talked with anyone running dual alternators but I like redundancy as well, so I'm interested to hear what people have to say on this. I do have a bunch of buddies running high output alternators though and I have 2 here (junkyard GM ones cuz I'm cheap & so are they) - 1 for each truck project.

[Phoenix0783]

Do you have to do wiring any different for 2 alternators or can you just hook them up in parallel?

[guard]

I know these 160 amp alternators are quality products...

http://www.rjminjectiontech.com/collections/alternators

[Carlos83]

its a good question..........

))But I like the idea of being redundant as well. I will be running 2 Optimas.
))Do you have to do wiring any different for 2 alternators or can you just hook them up in parallel?


first of all lets clarify the goal.

a) increased current output
b) increased reliability by redundancy


to acomplish "a" you could wire them in parallell. theoretically you would have the combined current output of both. the biggest drawback i can think of is that if one of your alternator´s recitifier bridge goes south, it will short circuit the battery line to the ground (where your parallell alternator is connected too), dragging it to death...........some kind of protection like maxi fuses are needed.

I would favor "b" (increased reliability) because it can make the difference between being stranded with a shot alt in the middle of nowhere and being able to return safely to your camp.

I think the best approach would be to have a flexible system where the alternators could be run as separate circuits (sharing the ground). then, the different circuit loads (ignition, lights, fuel pump, etc) should be selectable, meaning being able to be loades in Alt1 or Alt2 circuit. this can be accomplished by relays and solenoids. an additional step would be to have a heavy duty solenoid bridging the two circuits together by the flip of a dedicated switch in case the owner wants it. (for example to have both batteries connected together)

I am sure there are many other ways.
One I was thinking the other day was about to have an two alternators in parallell, but have the "I" connected to a switch on each alternator. without voltage on the I terminal, the voltage regulator shoud not get energized, then output is zero. idea would be to run only one alternator at the time. of course, switch between Alt1 and Alt2 would be when engine is OFF. (similar to switching batteries in a boat) additionally I would run a continuous duty relay at each alt output to be able to isolate the rectifiers when not in use.... i will test this experiment as soon as i have time



mis dos centavos

[BajaF250]

In this case, simpler is better, get an alternator that meets your needs and carry a spare... complexity with all the wiring and dual extras just makes it a nightmare to deal with should something go south... plus, trying to troubleshoot makes it that much more difficult... use one and then if it goes bad, swap it out.

[philofab]

I don't think I would run dual alternators. Just a single high output Ford 3G and carry a spare alt and a spare brush/regulator. Don't go past 160 amps as the belt can not support it.

Make sure to mount it in such a way you can change it fast and also access the brush holder.

Stay away from single wire alts. They have there own set of problems.

[hobbyturnedobsession]

Im cheap so i run an alternator from i believe a 96 mustang. 160 amp alternator and i havent had any issues. I had a 200 amp and as Philo said my bronco would squeel like a stuck pig when it first fired up. It went away quickly though.

[Seabass]

Are the 3g's internally regulated?

[philofab]

Are the 3g's internally regulated?

Yes, but the regulator can be changed in about 60 seconds. The 3G is one of the most reliable and tough alternators ever built. It was used beginning in the 90s or so.

[ESHALLBETTER]

I don't think I would run dual alternators. Just a single high output Ford 3G and carry a spare alt and a spare brush/regulator. Don't go past 160 amps as the belt can not support it.

Make sure to mount it in such a way you can change it fast and also access the brush holder.

Stay away from single wire alts. They have there own set of problems.

I assume you are speaking from a stand point of using a v-belt? And if thats the case, do you think that a serpentine belt set up would support a larger (200a) alternator? That is not necessarily the route I would want to take, as I just put on a brand new Edelbrock Waterpump and it is set up for a V belt.

[philofab]

I assume you are speaking from a stand point of using a v-belt? And if thats the case, do you think that a serpentine belt set up would support a larger (200a) alternator? That is not necessarily the route I would want to take, as I just put on a brand new Edelbrock Waterpump and it is set up for a V belt.

No. A single V belt will not support more than about 90 amps. Dual is a little better. A six rib serpentine belt is good for about 160-180 amps. An 8 rib will do 200 or so but I have never seen that stuff for a small block.

You can of course tighten the belt to support a little more load.... at the cost of belt life.

[ESHALLBETTER]

Good info, thank you.

Does anyone know anything about these guys? I am looking at the 200 amps.

http://www.mechman.com/index.php/products/g-series.html

[Dezertbronco]

I used to be really into car audio and had a 160a Alternator out of an ambulance. Never had any draw issues.

I will be looking to do the same thing on the bronco, and buying a spare and fabbing a mount to keep it secured.

[ESHALLBETTER]

I am really leaning toward the Ford 3G. They seem to be cheap and abundant with a good output rating and durability.

[SteveG]

I am really leaning toward the Ford 3G. They seem to be cheap and abundant with a good output rating and durability.

That's what I have on mine. It was a piece of cake to install and wire.

I also don't see them fail very often.

[Froggmann]

I am really leaning toward the Ford 3G. They seem to be cheap and abundant with a good output rating and durability.

Not to mention with the 3-bolt 93-96 side mount quick to switch out if there is a failure. I've been running a junkyard 130A 3G for about 7 years now with no problems.

[MOSS2]

The late model Ford ones last about 70-80k miles in all my street vehicles like clockwork. None will last more than a few thousand race miles without some repair. The pile of dirt and rocks that comes out of a clean looking one when you dissasemble it is amazing.

[kylesgorter]

I have a 200 amp 3g and I think the pulley is smaller to make it spin faster. The belt was too loose so i got a smaller one but can't remember the size. It doesn't squeal now and the belt isnt super tight. If I turn on everything sitting at idle the gauge barely moves

[PaulW]

Dual would not be my choice, but if you did the set point for the reg S/B slightly less for one. This is so one reg does all the work and the second one kicks in when the high set one quits.
Then there is the wiring schematic. Best would be to follow the Ford wiring for the dual alt on the superduty ambulance option. Not for me so I don't know the details.
Get a G3 from Fireguy on FSB. Mine was advertised at 170a and the dyno sheet says 175. He also has a 200a unit but you have to install the diodes yourself.
It is my understanding the G3 will fit most all the Broncos we talk about.
BTW, you should know that the HP required for a 170a G3 is more than a vee belt can transmit. This means a serp setup is mandatory.
Yes, Fireguy sells a smaller pully for more amps at low revs. Creates a bigger issue transmitting the power with the smaller pully.
Small pully is good for rock crawlers creeping with all the bolwers going. Not so good for A prerunner wher revs are always at the upper end. Best to use the stock pully.
Hope this helps, PW