I am having what seems to be intermittant charging problems on my 1973 F250. Let me start by saying that the battery is new, and I fairly confident that it is not the problem. I the first alternator I had tested at the local auto parts store, and it got a clean bill of health. And the charge/discharge ammeter is pretty much worthless. This is what I know for sure.

With a charged battery, engine idleing, the voltage reads 12.2ish
With the battery disconnected, engine idleing, voltage reads 12.2ish
With a charged battery, engine idleing, lights on, the voltage reads 12.2ish
When I disconnect the battery with the lights on, everything goes black and the engine dies.

I really don't know where to go. I have a suspicion that I have a wire crossed or something. But I don't know where to start. Any suggestions will help!

 

Your voltage at idle should be higher. You can get your regulator tested as well, however the tests are not always conclusive. It's often hard to narrow down charging problems between the alternator and regulator because multiple problems between the two can exhibit the same symptoms. If I had to guess at this point based on the information you described, I'd suspect the regulator, the regulator ground, or the harness in between.

 

I know on newer cars YOU SHOULD NEVER DISCONNECT THE BATTERY WHILE THE ENIGINE IS RUNNING. These older alternators I am not sure on, but let me repeat YOU SHOULD NEVER DISCONNECT THE BATTERY WHILE THE ENIGINE IS RUNNING. This can cause most alternators to go full field and if your alternator was good, it may not any longer.

12.2V all the way around means the battery isn't getting charged. Even in thses old trucks with a stock factory alt you should see around 13.6V and up.

Why do you susspect that there is a crossed wire? Were you doing some wiring work? If so go back and check your work.

Again as I am not entirely sure on these generation of charging system, but look for loose or undone connections on the alternator. Field Wire, Mains, grounds. Check them all back to the battery.

 

Thank you for the info! Is there a good way to determine if the battery is charging under a load without removing the battery post while the truck is running?

I did suspect that the wires may be crossed simply because I had the entire harness removed, and added it back with a second fuse block for additional accessories. What is stumping me is the engine not running with the lights on. But by Dons reply, it would seem that it is not a valid test anyway. But as is sits all assembled, The battery doesn't charge and discharge fast enough to tell if anything I do makes a difference.

Also, the stator post on the alternator is not being used. Does this seem right? Some diagrams show it going to the regulator, and some don't.

Thanks again!

 

Update. I changed the regulator. Now, I am getting just over 14v, running, with the battery connected, lights on/off. So, I believe the problem is solved! Thanks for the help.

 

Have got same problem with my 96 F350.But I think my reg. is fine is a build in one. Seems to test ok. With the Bt wire unhooked Alt. putting out 40 volts at idle. When hooked up no charge. Now this is where it gets alittle confusing,unplug the wire from key to starter relay,at relay and idle picks up,put meter on wire and get around 5volts. HELP

 

Try crossposting your question in either the 92-97 forum, or the electrical forum. That alternator/charging system is a completely different animal.

 

Congrats Bigperm2, I just resolved an elictrical issues with the help of everyone here. I's nice to get the problem resolved, and to wipe the sweat from your brow. I agree with Masterbeavis there Countryboy, different animal.

 

bigperm2, great to hear the problem is fixed. Yeah if you test battery voltage with the truck running you should always see 13.6V or greater. If it is around battery voltage 12.6V then the alternator isn't doing anything.

When you read 40V with the battery wire unhooked was the truck running. If so that is your alternator going full field and with newer computer controlled vehicles that will fry and ECU quickly. That is why I say to NEVER UNHOOK THE BATTERY FROM THE ALTERNATOR WHEN THE VEHICLE IS RUNNING.

And if you have fried a regulator on an alternator with an internal regulator (i.e. you have to disassemble the ALT to replace it) You might as well have a alternator shop rebuild your alt. or get a new one.

 

The kind of alternator he has uses a regulator that is integral, however is serviceable from the outside.

 

{edit: The OP fiNgured out the problem using a meter! YeeeeHaaw! :) }

Just this weekend a friend said...
"I was told that's a good way to test an alternator :)"
I told him...
"that's a good way to burn up your electronics danggit! :/" **

Guess what, I did exactly that tho, right after telling him not to. LOL :)

But...

I had a booster cable hooked to that clamp -while- removing the clamp.
I had both booster cables hooked to his battery and mine.

My voltage regulator was "seeing" his dead battery instead of -my- charged
battery. That's a trick I used (in the middle of the night) to charge dead
(or weak) RR signal batteries when the power was off (because of the utility
company or something).

The whole time I was very-careful not to let the booster-cables come loose
from the removed clamp -or- from the dead battery or my battery either.

I -never- let my alternator -not- have a battery hooked-up to it to control
its voltage. :)

Told other signal-apes about this trick but they weren't interested. :/

Alvin in AZ
ps- **even a '73 might just happen to have a dumb ol' radio "on" ;)

 

i have a problem with my truck i will start it up and let it run for like 10 mins since its a 360 and its cold blooded but if i shut it off or it dies the solinoid clicks and its a newly rebuilt engine with less then 12 miles on it but i went out and tryed starting it today after it was dead a few days ago and it cranked slow at first but fired up and then it died and the solinoid clicked again im wondering if i have the wiring wrong on the alternator or if the alternator is just burnt out

 

You must of had some nice cables to not melt with 60 amps coursing thru its veins. I don't trust cheap 12GA cables to not melt carrying any kind of serious load.

I have had two batteries die deader than a doorknob on me in two days. Come to find out each time I left the key on, once in the ACC position, another time in the Run position. Surprising enough, the points did not burn.

 

Could be something as simple as a solinoid going out. Or possibly a ignition switch issue.

 

The stuff I used is called "bond strand" and is relatively fine stranded tin
coated 6ga cable with "underground" insulation. Klein line pliers have a
tough time cutting it, when it gets real old it's next to impossible to cut it,
got to where I'd use tree trimmers to cut the dangged stuff (winter of '74).
(others were using a cold chisel and hammer on the base of the rail;)

Bond strand was supplied in 150 foot rolls in a box or on cable reels.

Couldn't beat the price. ;)

Weren't closed? :)

-----------------------------

Brandon,

Do yourself a favor and get a meter (or a buddy with a meter) to figure out
what's going on while it's -still- failing. Don't mess around and clear up the
trouble or mess around and wait until the truble clears itself up. Find it with
a meter, as a favor to yourself. ;)

The voltage should be >12 volts to start with.

Put the meter leads directly on the battery's posts, not on the clamps and
have a helper try starting it.

The voltage should drop to no more than say... 10 volts.

If it don't drop at all you've got an "open circuit" somewhere.
If it drops way down, you prob'ly have a weak battery and need a jump or
even an over night re-charging.

If the voltage didn't drop, move the meter leads "on down the circuit" to the
clamps first then if you are still reading full voltage (when the key is in the
"start" position) then go farther down the circuit... like... put the negative
lead on the engine somewhere and the positive lead on the far side of the
starter relay. Etc. As soon as you find the voltage dropping way down, then
the open is in between where you checked. Narrow it down. See it? :)

When you get the sucker running, the voltage should go up around 14 volts
after the battery is charged up good and you have it revved up. The voltage
might only go up just a little bit above the original ~12 volt reading tho, if,
the battery is very weak to start with. But, after you start it and rev it up,
it's got to go-up at least a little or the charging circuit isn't working right.

It'll make more sense when you are out there with the meter? ;)

Butthead in AZ
ps- Found a few times (using a meter!:) the open was the little cable
clamp that's -on- the clamp itself. Don't know if you've got one or two
of those sorry-*** clamps or not. :/