Hey all I need some help on this one. I've got an ambulance that keeps eating the alternators up. The batteries are new upgraded grounds and all that goodness. Problem is that every 3 months or less the alts fry. I've tried the DC power alts as well they last about 6 months, ford gone in 3. All the wiring harnesses are good with no breaks or chafing. Even went as far as checking the fuseable links in the harness. Anyone e have a suggestion as to wear or what else to check. Outside of the alternative going out engine and all other systems are perfectly fine.

 

Are you useing the dual alt. system or ambulance package? Do you still have the air diverter for the alternator in place on the fan shroud?
Ambulances draw a lot of juice and on a E series has poor airflow so more retained heat.

 

What AMP alternator are you using? What gauge of wire are you using for the charge and ground wire? And what are the CCA ratings of the batteries you are using?

 

It's ambulance package dual alternator setup with the fan cage still installed. Twin 160 amp alternators upper and lower. Grounds are heavy gauge welding wire. Can't remember the gauges off the top of my head. Batteries are brand new 850 CCA remote mounted in the side box.

 

What loads are you running from the alternators? They are designed for around 50% of rated maximum load on a continuous basis.

Brian

 

Altogether I have 12 ambulances and 5 brush trucks that I maintain all have the dual system on them. There set up exactly the same way. This is the only rig I'm having this issue with. Any and every update and upgrade that's out has been done to them. Just haven't gotten this 1 rig to keep its charging system to stay together.

 

Last time I checked the load on it I was pulling around 90 amps or so. Then I went and switched out all the box lights and emr lights to led . After all that with everything on to run code in severe weather was only pulling 70-75 amp.

 

I would suspect a short to ground [not a dead short] but a wire with only a few bare strands touching ground causeing too much draw continueousely.

 

I would suspect a short to ground [not a dead short] but a wire with only a few bare strands touching ground causeing too much draw continueousely.

 

Aren't the dual alternator setups PCM controlled unlike the single alternator setups? Is it possibly a PCM problem?

 

A viable possibility. There is some disention on how that actually works tho.

 

If he has 12 units that are all set up the same, swap a PCM with another truck and see what happens?

 

That's a great idea -- the PCM is what controls the dual alt set-up, correct?

 

my understanding is that the PCM selects and controls which alternator is on during the glow plug on phase of engine start up, then controls which alternators are on - one or both - in response to load. I can see a scenario where only one alternator is being switched on at a 90 amp load, and that is pretty high for just one alternator continuously.

Brian

 

Yes they are pcm controlled. Just finished replacing the failed alt and charging the batteries up. It's now on the way to dealership (which sucks by the way ) for a pcm update if needed. As of now everything is working like it's supposed to be. I'm thinking with that many failures happening it has to be a pcm controller problem. I'll keep you posted as to what I find out