last year my son gave me a portable electric heater for my truck. I think he said it came out of a road tractor or maybe a farm tractor, I don t know.
anyway, it came with about 10 feet of factory wiring with a fuse and ring terminals on the end.
I hooked it up straight to my battery, and used it here and there thru the winter. in early spring my voltage reg. went bad.
I suppose this is related, but maybe not. any ideas on how to prevent it if it was the cause?
How many amps or watts does the heater draw and what type (year make model) of vehicle are you connecting it to??
not sure exactly, it came with a 20A fuse and the wire is 14ga or 12 ga. it probably says on the heater, but it out in the garage, and it s raining…
…and its my old 75 ford f100 with a 360cu in motor
Those old trucks had weak alternators compared to today due to the biggest electrical load being the headlights. Ford used the 1G alternator rated at 38A, 42A, and 55A. If it was replaced anytime after the mid 80’s, it is probably a 55A, but no guarantees. That means the heater could be pulling 1/3 to 1/2 of the capacity of the alternator alone. Couple that with an old-style regulator and a near 100% duty cycle, and that ancient charging system was asked to run a full marathon. Something was bound to break.
thank you. it has an electronic regulator on it now that I bought last year when the other (electronic also) went bad. I do have a new mechanical regulator put away as well. I have no idea which alternator I have. I have a spare one too, from a 76 ford with a 390, I ll check how many amps they are.
A heater like that will not be able to do much good to heat the interior of a vehicle. The alternator just cannot put out enough amps to give very much heat.
Was the heater intended to preheat the cab and/or defrost the glsss, or would it augment the coolant heater while driving?
is there any way it will work? if I have the 55A maybe?
it s the only heater I have in there.
(I totally removed the factory heat and ac systems. it was just too cluttered under the hood.)
this heater takes the chill off my legs, that’s about it. I have no idea of its original use, just that it was in the cab of something…
Electric heat is a real energy hog. I was researching using electric heat to replace a very difficult to get to heater core in my classic just to provide enough heat to defrost the windshield. After trying a couple of cigarette lighter heaters and doing some math, I figured a minimum 40A of juice was required just to barely get the air slightly warmer than ambient. That amp pull would trash my car’s electrical sysem unless I spent even more to upgrade the charging system. I wound up finding a much more reliable heater core and using it. Similar to this. http://www.heatercraft.com/productimage.php?product_id=70
yeah… 
You could look into getting a more powerful alternator. Some of the old motorhomes on Ford chassis’s around that time had 100 amp alternators. Or, retrofit a 90-120A one-wire the hotrodders use. Here’s one at Summit for less than a $100. http://m.summitracing.com/parts/tff-7068
cool. junkyard trip. that should give me enough juice for my hydrogen generator too…
its nice to have a little heat at least.
I ll figure something out, if I have run some hotwater baseboard sections I will…
You’re running an HHO set-up, too? If I were the original-style alternator, I’d be screaming ‘No Mas!’
Well now if you want a redneck hillbilly suggestion because your heater core is shot, just get a trans cooler, connect the heater core hoses to it, and a stupid little 12 volt fan. Won’t defrost well, but what is the problem with a new heater core?
jst a joke about the hydrogen…
and that is under consideration barky, I wish id saved the one off my parts truck
…I m gonna power the HHO up with solar…
Yeah, leave it parked outside overnight to charge up a bunch of HHO with that solar set-up. 
I ll be happy if my legs are warm…
I agree an electric heater will tax or overly burden an alternator with 45a,55a,65a of that vintage.
However, the OP said his voltage regulator burned out and was wondering if it was related.
Does anyone think the small amount of current needed to excite the field would be negatively affected from the heavy current going through the alternator’s main stator windings?
I can see how excessive current load on an alternator can cause it to fail, but I didn’t think it would show up in the voltage regulator circuit.