'86 cutlass charging system

I have a '86 2-door cutlass supreme,307 V8 rear wheel drive. I'm on my 3rd altenator in 2 months.After the original altenator went out after 140,000 miles I put a new altenator on and it lasted about 5 weeks. I found out later that it would not handle the load of the lights and the heater on at one time, it would load down too much.I did not know that for a couple of weeks because I did not drive it at night. I put a warranty exchange unit on and checked it for the load. I turned on all the lights plus the bright lights and the heater on high and let it run for @ 20 minutes. It drew 51 amps and the altenator put out 54 amps charging at 13 volts-ok. Turned off the electrical componets and the vostage jumped up to 14.5 v. ok Let it charge for an additional 10min. The car sat for 3 days and then I took it to work in the early AM. It started right up but by the time I got 2 miles away, the battery was going dead. lights were dim and the radio cut out. Got it back home and altenator had no output. I checked all the wiring for bad connections, shorts and checked the field wire. I do not have a external regulator. The batt wire to the altenator is a 12 inch long and in good shape. The field wire is good because when the key is on and the engine is not running, I have a charge light showing. With the engine running, the charge light is out and batt voltage is dropping to 9v. I took it to the parts house and they said it was only putting out 8 v. so they gave me another exchange unit. With everything checked out, I put this one on and from the get-go, it would not come on line. I put a 10 ohm resistor from the battery to the B lead in place of the charge light wire and still no output. I can't beleive I got another bad altenator right out of the box. I can pull my ElCamino up along side the Cutlass and jumper cable it to the Cutlass and let both cars run for along time with lights and blower running on both cars and it carries the loads of both with no problem. I have done this several times. WHAT GIVES ?

Also the sheet with the new altenators say not disconnect the battery with the engine running because it will damage the altenator. We used to do this all the time to prove weather you had a bad battery or a bad altenator.Are these new regular stabdard altenators that susceptable to damage? PLEASE HKELP.

Sounds like a bad alt, rebuilt units can vary greatly in quality. Make sure all the engine grounds are good also. No do not disconnect the battery engine running this will ruin an alternator.

I went through 3 alternators on a maxima, all rebuilt from Pep Boys. They would put out 14.5 until you restarted the car then put out 11.5.
I ended up buying a Nissan reman from a dealer for $275.00 its been good for 3 years.
I installed a Auto Zone alternator in my Altima thats been good 2 years.

Almost sounds like a bad battery.....

Doesn't the ignition switch also effect this charging system(on this make model) Max ?

Pretty basic system, there is a shunt circuit for the gen lite in case the bulb burns out.

Yeah this is a very basic ciruit.

I had an 86 442 and it was overcharging, replaced everything , it ended up being a bad ignition switch. :2cents:

Correct, any high resistance in the affected circuits can these anomolies.

Thanks guys for the info. I've taken this last altenator and had it checked by 5 different autoparts houses and they all came up with the same conclusion - is't a good altenator. I don't think the ignition switch is bad because the charge light comes on when in the run position and the engine is not running. also I put a 10 ohm resistor from the battery lead to the B terminal and I still have no output. All grounds are good and wiring is good. If my theory is correct, once the engine is started and the altenator is pulsed by the field wire from the charge light to start current flow, the internal regulator takes over for the charge line in adding current draw. Is the ignition switch not out of play at this point concerning the charge line? The parts house is not buying that it is another bad altenator - don't blame them. According to the Oldsmobile book there is a blocking diode in the field line down stream from the charge light. What is it's purpose?

Problem solved!
Found that the power steering belt was slipping on the harmonic ballancer/crank shaft pully not turning the water pump fast enough. The altenator is driven by the water pump pulley only and thus not comming up to the speed needed enough to get the altenator to kick in. It was only producing about 7 volts at that speed. You really could not see that the altenator was turning slower than it should. Put a new power steering belt on and everything works great. So in sumery, the crank turns the power steering which in turns the water pump which then turns the altenator. Pretty much a weak link in the system if the crank only turns only one belt and the rest of them follow in series. Anyway, problem solved.
Thanks for the input. MALIM

Wow that was basic, we all assumed an issue like that would not be the problem, thanks for the feedback.