Hello.... I have an Excursion with a 6.0 liter diesel. It has the stock 110 amp alternator. I replaced the batties recently and upgraded to two 850 CCA. Even with the better batteries I still seem to run them down while plowing with my aux lighting on. Has anyone upgraded from the single alternator to the dual alternator setup after they bought the truck? If not, is anyone running a higher output single alternator? Thanks!

Oh... my digital voltmeter that i plug into the cig. lighter only reads about 13.8 at idle with no load... then with a stock load... meaning headlights, radio and both heaters, it drops down to like 13.2 or lower. With any of my aux lighting it drops to 12.5 or so. Not sure if that helps. Maybe my alternator isn't performing properly? My Gas motor F250 runs 14.1 at idle and that's what i'm using as a reference... not sure whether or not you can compare a gas motor and a diesel?

Chris
2003 Excursion 4x4 6.0 diesel with single alternator and two 850 CCA batteries....

Two stock headlights, stock foglights, two hella 55watt driving lamps, two 130watt off road lamps, two rear backup work lights and a plow are what seems to drain it. I can live without running the stock fog lights or 130watt off road lamps while plowing. What I want to run are the front and rear heaters, hella 55 watt driving lamps, plow lights, two strobes and the two rear backup lamps.... I know it's a lot of draw but if an ambulance can do it then so can I!!!! Thanks for the help ahead of time!

 

What symptoms does it have to lead you to this conclusion?

 

After about six hours of plowing you go to hit the up button on the plow and everything browns out. Not just a normal amp draw... it basically dies until i turn off the lighting and heater. Then the plow will work again with no lights and no heat.

 

How have you wired all this stuff up? I would assume you have an aux fuse box or distribution terminals somewhere under the hood? The sizing and routing of your wiring may make a difference. I think I would give the batteries priority, meaning running a nice large wire from the alternator to the battery +, or the starter solenoid where the battery + connects. I am not too familiar with your vehicle, but however they have it wired, I would make sure you have a good sized wire running from the alt.

Other than the wire routing and size, the only other conclusion is you have too much load on the system for it to keep up. Your batteries are your storage tanks, and they are running dry. You may need a bigger pump(alternator) to try to keep up, or make do without all that lighting.

 

I run each accessory back to the Driver's side Battery with an inline Fuse and relay for each accessory. The only thing I run to the Passenger Side battery is the plow which has it's own 150 amp circuit breaker.

What I'd like to do is upgrade the Alternator to a 200 Amp and call it a day. The shop manager at my local dealership is looking into the PCM for me to see if it will accept a larger alternator. He says you might have to change something in the PCM. If not, he suggested buying an isolator and using that to run the Aux lighting and strobes.

Thanks again!

Chris

 

Which would require mounting another battery.

 

> but if an ambulance can do it then so can I

Since about 1990 many Ford ambulance prep packages include dual 140+ amp alternators, fwiw. The batteries I have seen are usually big Delcos with a 1050 CCA rating and 85 minute reserve.

A quick fix might be running 12 guage marine wire to every accessory, especially the 55 watt lights. The thing to do is figure out the additional load by adding all the watts or taking it to an alternator place and pay them to put a meter on it and see how much you are drawing with a full load with the plow engaged.

The problem is at low speed plowing unless you are in 4Lo, your alternator is not putting out the max watts, maybe 70-80%, if that, and your truck probably draws 35 amps just running the EFI vehicle at idle.

The problem with higher amp alternators is you do not get the full power unless you are cruising down the highway at 3000+ rpms. Sometimes buying a lower amp alternator that outputs the max near the bottom of the RPM chart is best. Western Electrical has an excellent selection of alternators.

I am including a data chart from a Ford spec book from 1990 (?) showing the amp curve of their 165 amp alternator for the Econoline. Remember to factor in the alternator pulley ratio (2x) compared to engine speed (1x).

 

First get the alt. output checked
if its not at 90% then you may just need a new one
also check out a 3G alt. upgrade
if you are lasting 5 to 6 hours as is then you
should be within 15 to 20 amps of what you are
using now