Originally Posted by cangim

well I am a little late on the game with this one, but most all the questions have been answered. The only one that I didn't see was can you go to high of amperage, the answer is yes. You start pushing too much current though the stock wiring and it is going to melt. At what point is too much I don't know. I replaced mine with a 140A unit and have been really impressed so far. I bought mine from High Output Large Case Alternator Upgrade for Ford 7.3l, 6.0 & 6.5 Power Stroke Diesel

Originally Posted by UP_There

I have a 130amp alternator, and I"m going with a bigger one next time. My headlights dim at night when I've really got the stereo rockin, and the KC's on........that tells me it's working pretty hard even with the 130 amp.

Originally Posted by farmdad

Would dual alternator setups have heavier wiring factory installed? Or a different way of distributing it to the electrical system so all the power doesn't go through one wire? Just wondering.

Originally Posted by jhand124

So with that in mind we may be able to run a dual 135 amp setup 270 amps, about where Parkland is with his mono alt.

Originally Posted by twags6

Not exactly..... I remember reading somewhere on here about doing a conversion to dual alts and if you put larger then stock units(110 IIRC, I'll have to check) in, they'd kill each other for some reason. Now this was with them both hooked up like a factory setup with the PCM controlling the charging.


EDIT: Here's the other thread. https://www.ford-trucks.com/forums/5...ternaters.html The PCM's for the dual setups have different programming.

Originally Posted by cangim

If you are using the factory setup for dual alternators, then yes the pcm controls the second one but only when needed. I agree you'd have to be up in the amperage to melt the wire, but with these huge stereos and lights anymore, it doesn't take long to be putting a constant 100A load, some are even 200-300 amp loads with spikes higher than that. Car stereos have just gotten plum crazy with the amount of wattage they are converting. Up to 150A alt, I wouldn't worry about wiring, if you go to a 200A or so, then I'd upgrade the 6 gauge stock to 4 gauge at least. I have modified mine quite a but, but a 4 gauge splitting from alt going to the driver side battery, along with better grounding would be more than adequate. I have been meaning to get to putting a larger ground wire for a while on as well but havene't gotten to it. Less resistance=better charging. May seem overkill but it does work, especially for those that turn everything on, drive five minutes then shut it off.

Originally Posted by KelVarnson

I suspect there's something else going on, like your headlights are sharing some wiring with your stereo. Are the power leads for your stereo connected directly to your battery terminals? If not, if they are connected downstream somewhere, then the current impulses from your stereo could be causing voltage drops in the headlight wiring, and modulating the voltage to the lights.

A 130 amp alternator should be adequate to support just about any car stereo. 130 amps at 14.5 volts is close to two killowatts. How much do your KC's draw?

Also, if you are running heavy loads from dual batteries, you should connect the load between the positive terminal of one battery and the negative terminal on the other. This will result in better load sharing between the batteries, and ultimately better capacity.

Originally Posted by F350-6

...So the question is: How important are those extra 20 amps?...do the lower amps lead to a shorter life of the alternator or batteries?..The only additional electrical load would be a CB with small foot warmer, cell phone charger, & occasionally an inverter plugged in to run my laptop.

Originally Posted by F350-6

...Thanks Gene....If it's the heat that's killing the alternators, then I've got plenty of that around here. Maybe I should start taking measurements with an IR thermometer and noting the ambient air temp and trying to compare it with those that either have the stock alternator or one of the nice aftermarket ones...

Originally Posted by ernesteugene

Here's an exact temp that I measured last Thurs while towing to my current location of Bozeman, MT. I stopped at a rest stop, grabbed my IR thermometer, popped the hood, but first measured all tire, brake, and wheel bearing temps before starting my routine under the hood measurements, so these #'s are after about 5 min at idle with the hood open. Alternator was 205 F, whereas the upper radiator hose (hot one) was 195 F. Ambient air temp was in the 90's, and I got 90 F looking into the front of my Zoodad hole by reaching through the grill. The AIS air box was 100 F, the big hose from the air box to the CCV coupler was 110 F, and the hose from the CCV coupler to the turbo inlet (close to the turbo) was 120 F. The CAC tube from the IC outlet to the intake manifold was 120 F at the connection to the IM, but the IM itself, which is bolted to the turbo was 230 F!!! It would sure be a nice mod to fashion an insulated piece to connect the turbo outlet to the IM instead of a direct metal-to-metal connection!

Prior to making the above measurements, my fan clutch had been locking up during some of the steeper grades, so I know that the under the hood air temps were in excess of 200 F due to the several hours of towing before making these measurements. The above types of measurements are why I claim that an under the hood filter is not the best choice for towing, as it would be drawing air into the turbo that's more than 100 F hotter than with a Zoodad + air box type filter.