I have replaced the alternator 4 times in the last year. Replaced the wiring harness to the alternator. Getting a batt light again and the voltage from the alternator is 11.8 and batteries were both at 11.7 In the morning the light will be out and it will run fine for a couple days to a week then go it again. Autozone alternator which is lifetime Warren but I am getting sick of replacing it.

Amy thoughts appreciated

04 F250 6.0. Stock

 

How old are the batteries and what CCA rating are they?

 

850cca sear gold bought about a year ago. Had them tested a mon5h ago and they were good

 

Anything on the truck that would cause high amperage loads? Plow, a lot of lights, inverter, etc?

 

Short trips? Constant re-starting?

Josh

 

Is it dead when you go to start it, or are you just getting the light?

Could that lighting circuit be bad? Are they testing the alternator, or just giving you a new one?

Test the batteries individually. Dad had a collapsed cell on his '06 and I watched the shop test them in parallel and argue with me that it wasn't the batteries. Did their load test, and then says "I'm not sure what else it could be."

Finally disconnected them and one had a collapsed cell, and the other one went out about three weeks later. Musta been a bad batch.

 

Still having intermittent Alternator issues. Just replaced it again this morning...
What controls the alternator? I know its internally regulated. I replaced the harness on top of the alt. I am going to throw another ground on it from the alt to frame, or should I go to the battery? Have not killed the FICM yet, but really dont want to either.

 

Good news is it's easy to replace. Bad news it's a reman from Autozone. I know I've replaced a forever warranty alternator 3 times.

Find a good body ground, not off the battery. The regulator will adjust based on need. From 14.4 volts approx max to 13.4 when near fully charged.
Once hooked up, check your static battery voltage and then check with the engine running. You will see a little loss of voltage due to resistance between the alternator and the battery. If significant, replace the charging line with a larger sized wire.

 

Add a second wire from the + post of the Alternator to the + passenger battery. Then a ground wire from the alternator mounting bolt - the body. Clean the other grounds as well on the frame and cab, drivers side.

 

Consider upgrading the measly OEM alternator.
I think it's only 110 amps, the same one they use in the Fusion...
With a dual battery set up a larger alternator will definitely help.
I upgraded to a larger one and also upgraded the associated wiring and bought the stuff from Ed at FICMRepair.com - FORD Powerstroke 6.0 FICM Repair, PHP Tuning and Truck Parts
Lots of good reading on his site.

 

Check all the grounds including the ground straps from the frame to the block. I had a starting issue and of purse I found on of the ground straps loose.

 

Buy a Ford 140 amp alternator from the dealer.

 

Went through the same thing a couple years ago. Went through 4 Ford alternators in a 3 week period. Even they were all under Ford's 12k mile warranty, finally got fed up and went with a DC Power 190 amp alternator. Not a problem since.

 

I think most of us have went through that experience with alternators and starters. I dont remember going past 3 until I got a good one though. A relatively inexpensive wat to deal with the underpowered factory unit is to use an older style 3G case alternator from a earlier model 7.3 power stroke. Some of those make 180amps, a good update from the factory 110amp 6G. It's a little larger but bolts right up with no clearance issues and is often cheaper than the 6g. It does require an short, inexpensive adapter harness available online at eBay or wherever. While you're ordering the harness you can also get a smaller (58mm) pulley for it to help it spin a little faster at idle. The tesioner will make up for the difference in size so you don't need a shorter belt.

Another option is to get a NEW higher amp alternator from Advanced Auto Parts. If you look through their website you'll find a higher output (150amp I believe), new, alternator listed for the 2005 trucks it's a few bucks more but check out using coupon cod TRT30 and pick it up at the store for $50 off. We did this on my sons truck last week on the advice from a member here at FTE and it worked great. It came with the smaller pulley installed and no adapter harness necessary. It is a visibly beefier unit and as I said is new, not a quick rebuild and has worked well for him so-far.

As someone said above the factory 110amp unit simply isn't up to the task of keeping two larger sized batteries topped up on a diesel truck, especially if it sees any grocery getter duty or around town driving. Either of these two options are an inexpensive way to upgrade the system.

 

And that coupon code works for almost everything they sell, buy on-line, do in store pick-up. It's the 2005 140amp and been running on my truck for a while without issues!

I carry the adapter harness in the truck if I find myself somewhere they don't have a 6G in stock the 3G will work and not leave me stranded.... just in case.