Alternator output

Charging, starting, lighting, gauges, HVAC

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RandyP63
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Alternator output

Postby RandyP63 » Sun Jul 09, 2017 5:12 pm

I installed a new battery on my F-100, the truck would not start after a couple of trips, when I tried the volt meter on the new DieHard battery, it read 12.6 volts. I looked at the alternator and the previous owner put a Transpo 7078 one wire setup on it. There was a lot of heat damage to the BAT terminal on the Alternator. I had the alternator rebuilt, and returned the system to stock with a new voltage regulator from NPD.

On initial startup I had 14.2 volts, yesterday I drove the truck for about 100 miles, today though the output voltage from the alternator reads 12.9 , and when I turned the lights on it dropped to 12.6.

I have done a parasitic load test and it was normal, no draw. Any ideas? The truck runs great, but the battery dies after 3-4 starts. My next test is to load test the battery. Thanks.

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Re: Alternator output

Postby Busboy » Sun Jul 09, 2017 5:58 pm

The latest episode of " I tried to reinvent the wheel". Leave your trucks stock people! :cuss:
1969 F-250 Camper Special, custom cab.
1967 F-100 4x4 custom cab.
2016 F-150 Eco-Boost 3.7 liter. (It will smoke the tires!)

RandyP63
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Re: Alternator output

Postby RandyP63 » Sun Jul 09, 2017 8:31 pm

Uh, I returned it to stock, but thanks for the insight, that is something I will use.

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MadMike
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Re: Alternator output

Postby MadMike » Sun Jul 16, 2017 5:39 pm

FWIW, having a similar issue with neighbors '70 F250.

Ditched all the homemade 'house' wiring and extra battery/diode from P.O. Wiring is back to stock-ish. Has a 460 swapped in(from P.O.) place of the original 360.
Truck is an F250 w/ammeter which makes the F-350 diagrams more accurate for this truck.
'I' terminal is not used, it would be if there was a dash 'ALT' light.
Connector to Volt regulator is greem. IIRC this indicates the ALT is a 63 Amp unit.

Battery is at 12.6 Volts resting, less than a year old. Can spin the 460 no problem. Even when it has been drained it can still crank. Running, voltage is only 12.8, doesn't matter if there is a load or no load.

'I' terminal not used.
'A' terminal is constant Batt voltage. Yellow wire. Has a factory shared splice that goes to a capacitor mounted on the bolt for the regulator mount, firewall side.
'S' terminal is switched Hot. Turn ignition switch to 'ON' 11 Volts, jiggle key it can jump up to 11.8Volts, worn ign switch contacts. Green w/red wire. Has been spliced into for electric choke for Holley(Why they just didn't ring terminal it to the ALT *shrug*). I believe this should be with-in .5V of battery voltage.
'F' terminal goes to ALT. Orange.
A ground wire from the engine harness is attached to the opposite volt reg mounting bolt.

I haven't pulled the alternator but the wiring on the back looks pretty thrashed, it's intact, but ugly. Not sure if there was a proper Alt to ground cable installed.

Only Negative battery connection is main terminal to engine block. Pretty sure a ground to the body and to the Alt ground terminal is probably needed.

I would check to see what your switched hot is doing, and if the voltage is low, jiggle the key while watching the voltmeter. ~50year old truck that switch is probably in need of some TLC.

Also not sure if there Alt is the factory unit from the 360 or for the 460(which I think is from a 76/77 vehicle). 460 cruises about 2500rpm on the freeway and has been revved north of 4K quite a bit. Found literature that the 360 ALT has a max(engine) rpm of 2200, not sure how accurate that is as the door label max rpm for the 360 was 3000rpm.

I'm still in the process of diagnostics as time is limited to work on, and the truck is a cluster of splices and wire hackage.
-Michael

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Re: Alternator output

Postby MadJoe » Mon Jul 17, 2017 7:35 am

MadMike wrote:
Also not sure if there Alt is the factory unit from the 360 or for the 460(which I think is from a 76/77 vehicle). 460 cruises about 2500rpm on the freeway and has been revved north of 4K quite a bit. Found literature that the 360 ALT has a max(engine) rpm of 2200, not sure how accurate that is as the door label max rpm for the 360 was 3000rpm.


That can't be true (not about the alt, I'm sure it quits being effective past 2200), but a 360 generates max HP at 4000 and can rev to 4500 - it isn't pretty, and it isn't getting you anything but more wear and less fuel, but it will do it - so that plate must have been for something else.

Or am I misunderstanding? Are you saying the Alt is maxed out at 3000? That could absolutely be true.

-Joe
1971 F-350 DRW SWB Stake Body
360 FE
C6 transmission
OEM disc brakes
OEM power steering
Dana 70 4.10 rear end

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MadMike
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Re: Alternator output

Postby MadMike » Sun Jul 23, 2017 2:04 am

MadJoe wrote:
That can't be true (not about the alt, I'm sure it quits being effective past 2200), but a 360 generates max HP at 4000 and can rev to 4500 - it isn't pretty, and it isn't getting you anything but more wear and less fuel, but it will do it - so that plate must have been for something else.

Or am I misunderstanding? Are you saying the Alt is maxed out at 3000? That could absolutely be true.

-Joe


Looking over the book I had, I think it was an error for the alternator. Most likely they meant max 'AMP' rather than 'RPM' at 2200. If I'm correct the alternator is a 63A unit.
As for the door tag, I'm fairly sure it says 3000 rpm, I'm too lazy to look again and have misplaced my notebook on the truck. It may have not been max rpm but possible in relation to the HP rating that was on the door tag.


Regarding the wiring issues. Ground terminal on the back of the Alt is heavily corroded and looks like it will snap off if touched and the other end that is grounded to the regulator corner is clean but the bolt is partially stripping the sheetmetal and there is not a good bite, its loose. So that will have to be redone.

Orange Field wire at the ALT is corroded as well, pretty much all the terminals look fairly corroded at the Alt.
The main battery terminal wire is bolted right above the alternator case, which is in very close proximity to two of the terminals. I guess the PO felt the closer the battery terminal was to the alternator the better the charging would be. IMO I think it has boogered up a few things. Cable is homemade.
-Michael

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MadMike
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Re: Alternator output

Postby MadMike » Wed Jul 26, 2017 1:59 am

Tried to pull the harness off the back of the Alt tonight, the nuts were seized and the eyelets could be rotated. Ground eyelet was the worst, it was very loose and the wire snapped off. This would explain the erratic charging. Had to pull the alternator off with the regulator harness still attached.
-Michael

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Re: Alternator output

Postby MadMike » Thu Aug 03, 2017 4:00 pm

Looked at the door tag, 4100rpm.

As for the alternator/wiring;

'S' terminal wire(green w/red) was where the choke had been spliced into. This splice was not bad but it was ugly, removed the female spade connector from the plastic terminal and there was only one strand of wire holding on. Replaced the terminal.

'A' terminal(yellow wire) was covered in rust, cleaned it up and reinstalled.

'F' terminal(orange) was slightly corroded, cleaned up and reinstalled.

Voltage regulator male terminals were all corroded, cleaned up and coated in OX-Gard. Lag screws into the inner fender for the V.R. had stripped holes, replaced them with 1/4-28 bolts with nylock nuts and hardened washers. Cleaned the V.R. mounting and inner fender mount along with the choke mount and alt grnd cable. Coated in Ox-Gard and snugged down the nuts.

Cleaned the terminals and replaced the corroded grnd terminal on the alternator. Reinstalled components.

Checking voltage at the 'S' terminal, it is now 11.6 Volts, jiggling the key brings it up to 12.2 Volts. If the ignition switch is serviceable I'll try and clean the contacts first before replacing. Still need to do a full field test.

Does anyone know if the harness originally used the plastic holders/clips that secure the harness to the inner fender? There are a few holes punched in line with where the harness naturally falls, but there were no clips preset upon removal. Thanks.
-Michael

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sargentrs
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Re: Alternator output

Postby sargentrs » Thu Aug 03, 2017 6:13 pm

From the low mileage '71 Custom in the photo gallery. http://www.fordification.com/fairburyF100.htm

http://www.fordification.com/images/fai ... 9518hi.jpg. Photo shows plastic clips in fender and IIRC the main harness had a plastic bar with a tip in the middle that stuck in the inner fender. That clip was taped into the harness wrap. If you zoom in you can see it near the right edge of the photo.
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1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: viewtopic.php?f=22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1964 Ford Fairlane 500. 289/Cruise-O-Matic, A/C, P/S.

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MadMike
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Re: Alternator output

Postby MadMike » Sun Aug 06, 2017 1:50 pm

Thanks.
-Michael

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Quick update

Postby MadMike » Wed Sep 27, 2017 2:33 am

Finally got around to finishing up the alternator wiring and re-installation.

Being the truck has gauges the S terminal on the V.R. does not go to the stator terminal on the alt but becomes CT904 and goes to the ignition switch, which leaves the stator terminal on the Alt unused. Since the truck is now sporting a 600cfm Holley with an electric choke I needed to reattach the choke wire, made a wire from the choke to the stator terminal on the Alt. When running the voltage is only 9volts*, this has been enough to fully open the choke. Engine runs much better when cold with the choke operating more in sequence with temperature changes rather than just snapping open after a set time with the ignition in the ON position.

Measured voltage at the battery when running.
Rock steady 14V. Tried the various load tests that I've found in various manuals and online. No change, never a dip in voltage.
I'm very pleased with this, I was not expecting as such a solid voltage output. Engine runs much better, quieter in fact.

Ignition switch was still heavily suspect as being faulty. Owner did take it for a spin and it stalled. Coil was only getting 3.6-4.1V jiggled the key and eventually the voltage at the coil bumped up to 12.1V(ignition ON, engine Off) with a battery voltage of 12.6V. New Ford ignition switch has been ordered. More fussing with the ignition switch causes random/erratic voltage changes to the coil. *I did not check the choke voltage or how much it changed, if at all, when jiggling the key.
-Michael


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