1994 F250 Battery Isolator and Hardwire Inverter Question
 

I am currently upfitting a 94 F250 to be a service truck and as part of that I needed to install an inverter to run the plasma/welder. When it comes to installing the isolator Ford is different because there is a 3 pin wire connector on the side of the alternator rather than your standard charge wire. This leads to a solenoid right behind the battery on the right side. Does anyone have a diagram of the correct wiring to the alternator pin of the isolator or know which wires to cut and how to properly route them?

It does not sound like you are working on a 1994 F250.
On a 1994 F250 the alternator has a one bolt hooked to the charging wire going to the battery by way of a post on the battery side of the starter relay.

The three pin plug only controls the the alternator.
The three pins are:
1. The "A" wire to for field current and to tell the voltage regulator the state of the charge of the battery.
2. The "I" wire from the ignition switch vi way of the cluster to turn the alternator on and off.
3. The "S" wire for, once the generator begins generating current, a voltage signal is taken from the stator and fed back to the voltage regulator S circuit, turning off the charge indicator/lamp.

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http://i54.photobucket.com/albums/g9...ps3194f3dc.jpg

This diagram should be close to what you have.
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Thank you -

In this case, should I then cut the heavy gauge wire leading to the relay and attach that to the ALT terminal on the alternator side and the BAT 1 pin on the battery side in order for the isolator to function properly?

I have a NOCO inverter, which I do not recommend. The unit is massive and the instructions are weak to say the least, particularly when it comes to Ford.

What brand and model number is the isolator?
And what is model number of the NOCO inverter?

A Battery Isolator is used to charge two batteries and let you drain one while the other remains charged with the engine off.
Is this what you want to do and the hook the Inverter to the extra battery?

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For what he's doing (rather sketchy on details yet) I'd think he wanna use multiple battery’s and all of them for AC power with an isolator to handle charge rates.

Most (all?) modern inverters auto shut off at around 10v anyway to retain vehicle start juice, and probably needs the motor running regardless. I haven't ran plasma/welder off a truck yet so couldn't say one way or the other for sure at this point.

I do know I can power couple of laptops off my little inverter all day long on a single battery just fine engine off, need to cut a sheet of plywood with a circular saw? the engine has to be running or its not enough juice (using a good fresh battery of course).

I would think he would need a gas powered AC generator for what he wants to do.

Yes I'd agree cheaper/easier to implement cheaper to run and almost sure to include higher degree of dependability too.

Most plasma cutters won't run off of a generator unless it is a good and expensive one. They need stable voltage and cheap or even mid-level generators aren't that stable. An inverter delivers an extremely stable voltage and the hertz it right-on.

This is exactly it. I had to get one of the Tripp-Lite pure sine wave inverters in order to provide the stable voltage required for a plasma, even a modified sine wave inverter won't do it. With the heavy trucks I normally deal with there are two pins only on the alternator, a positive and ground. This one has multiple smaller gauge wires so I needed a diagram to be certain of which wire to cut and splice for the alternator pin on the isolator. After that it is basically alternator charges both batteries, optima yellow top provides power to the inverter and the rest of the upfits - air compressor, fuel transfer pump, jump starter and work lights - and inverter powers the plasma/welder. We are using a plasma/stick/tig combo because carrying gas for the mig is a pain. Basically this lets us service the other trucks wherever they break down.

I am a she btw, not a guy with a girl's name, but I get that a lot being a female mechanic, really a diesel mechanic these days, but I started on cars and light trucks in the mid-90's so I still work on the little trucks on the fleet. Mostly I work on tractors and dumps these days though.

If I did not say it before, yes you would cut the large wire and you do not touch the smaller wires in the plugin as they control the alternator.
There is no ground wire as the frame of the alternator is ground and it is grounded through the engine block to the large ground battery cable that is bolted to the block.

I do have a plasma cutter but have never tried it with a generator.

Yea no doubt would take a quality generator not a home center special, not sure which inverter is being used here but still sounds like it a cheaper and easier option.

Plasma/welder are now built better too, powered by a generator taken into consideration in design.

Stable power bolted to the bed and without need to have a large displacement truck engine running burning fuel to do it.

I suppose amount of "tool time" comes into play here as well, short couple little cuts/beads a small inverter/welder might be just the ticket while taking up less space.