My electrical problems are back...

Look over the battery cables and terminals very carefully. A bad connection will give you weird symptoms like this.

 

With this extremely cold weather lately- an old/bad battery would manifest itself.

 

Maybe the fan switch took a dump and is killing the battery with a short...just an idea.

 

It may be as simple as a defective gen or even the "new" regulator.

In spite of the previous problem with the regulator (or maybe BECAUSE of it), I am prone to think a bad gen or regulator is probably is the issue. The Ford charging circuit on my Lincoln is simple enough that if the right parts are present, not charging is usually going to be an issue with one of the components.

When my Lincoln stopped charging, a replacement generator made things start working again. (after I changed the regulator without results)

If nothing else, the ability to swap in replacement parts will allow troubleshooting.

 

When you say dead, do you mean the battery is dead or the truck just won't start? What's the battery voltage read when it won't start?

 

Is the battery really dead, or is it giving dead symptoms?

Going along the same lines as Squirrel, If the main power wire for the interior (key, heater, etc) has a sketchy spot, you'll have unexplained bouts of deadness. Another battery with an additional volt might overcome the sketchy spot, or you might jiggle a wire enough swapping batteries. Been there, fought that, have the hand held battery load tester to prove it Good luck

 

Dead as in cranks real slow then dies or dead "Click" or dead nothing happens when you turn the key?
Have you load tested the batteries? Check all connections, battery to engine & battery to frame connections must both be there and clean & tight. Smack the starter with a hammer with the key turned to start or button engaged?

 

So the battery is just run down, it's not totally dead.

Put a volt meter in the car so you can see what's happening when you're driving.

 

I would double check the output of the voltage regulator. If the fans increases speed with the engine RPM, I would think the Regulator is not holding steady. The Alt/Gen puts out voltage according to RPM. The Regulator should accecpt this voltage and regulate it so as not to exceed about 13.5 volts. At low RPM's you get the 12 volts from the battery at higher RPM's the regulator provides 13.5 volts ± a small amount. 15 volts would seem a little high to me. Batteries need 13.2 Volts to recharge, the extra 1.2 volts is to overcome the internal resistance of the battery cells.

 

Where does your charge wire go versus where the dash's voltmeter reads?

When it lit off with the late model's battery was it like you flipped a switch and it cranked perfectly?

 

Checking the voltage when it won't start may help you tell whether it's a charging system problem or a starting system problem. Then you'll know which circuit to troubleshoot. Going on a wild guess, I'm going to say it sounds like you may still have a charging system problem. If your heater stopped working on all speeds but the highest, sounds like you have toasted the resistor block and it's only working when it's getting full power bypassing the block. A condition that can be caused by overcharging. Overcharging will also kill batteries and cause starting issues. Just a guess...

 

sounds like maybe a couple of problems. Was it fine until the heater switch started acting up? if so start with that circuit...maybe take the regulator out and to the parts store and have them check it out also...hencho in mexico I'm sure (or Pakistan or Taiwan or whatever)

 

Two questions/suggetions...

Charge the battery for a few hours (cables disconnected), let it sit over night (still disconnected) and check battery voltage in the morning and post results.

When checking voltage at neg terminal, you did disconnect the neg cable from the battery, correct? If so, did you check to engine ground, or from battery to the disconnected cable?

 

On the bright side constant problems are easier to troubleshoot than intermittent ones Just remember that as you're working the jumpers at 5:00

 

If something is drawing juice from your battery with the key off, here's a way to check. Take the ground cable off the battery and clamp a trouble light to the ground post, take the other end and attatch it to the cable itself. If it lights up you have a back draw, leave it in that position with the light on and start pulling fuses till the light goes out, that will tell you where your current is going. Some newer radios have a clock that will light your trouble light in this situation, just be aware of that, but I have found many a problem, that others gave up on using this method. Good luck.

 

I would put a Disconnect switch in it. Its good thing to do because of a fire safty ( parking overnight or storage) and you can disconnect once the motor is started. You'll find the gremlin real quick.

 

You swapped batteries and the meter showed 15V with no change up or down when you changed RPM? That should have been a warning that something was wrong. I've never personally seen a full 15V, even with a stuck regulator. If it's a mechanical regulator, pull the cover and see if the points are welded shut. You probably overcharged the old battery and killed it.

 

I am thinking stuck cut out in regulator...look at the points in there. Cutout is the one at "B" terminal.

 

I would check regulator mounting. If I remenber correctly it is grounded thru the mounting screws. Might be some paint or dirt/grease under it. If that looks ok it might be time to pop for a new battery. Good luck. Old fart 1941

 

Stuck cutout=direct bat gen link. Full blast charging, then battery spends the night draining...

 

First just see if those points are open with car off, also check to see if fried if they are open.
I believe NAPA now sells 2 quality levels of reg...
They really should be pretty reliable, but crap seems to be taking over everything in parts.
Consider looking throug your old one if old and of good make and polishing up the points with a burnisher.

 

Voltage regulators are the weak link in older charging systems. If you've ever owned an old Harley, regulators are a sick joke. There really is nothing to replace an OEM regulator. If you can put your hands on an original one, the difference in manufacturing quality is amazing when you compare them side by side.

You can unstick the welded points and dress them if they're stuck closed.

 

OK...I think that stud is soldered to the winding in there and comes out through a special plastic bushing through the case. Likely the bushing is what is needed.

 

15 volts in a battery is way to much.Overcharging ,