ive been struggling with sluggish starts as in previous post.took to a mechanic that my brother uses planning to buy new batteries.they tested fine but amps a little low.so he checked alternator while I started it.i loaded it with everything on in truck and it would only put out 50 amps max.then he loaded it more with his machine and it stayed at 50 amps.checking at batteries they were only getting 13 amps total for both for charging?he said cables looked good no corrosion.said alternator was weak and with my short trips to work (10miles one way)it wasn't enough to recharge them.he said if he was fixing it he would do new alternator.98%sure he said?does this sound right.
thanks in advance for any input

 

The alternator on a 7.3 is supposed to put out 110amps.....The short trips to work wouldn't kill it, a 10 mile drive is plenty of time for the batteries to recharge unless they themselves are already weak.

You can have the batteries and alternator tested at Autozone for free, both are easy to remove and re-install. You can actually replace both right there in the parking lot at Autozone.

Here's how I would and have done things:

-Pull the batteries and Alternator
-Have Autozone test both
-If the batteries are weak have them charge them (2 hours) and see if it holds a charge.
-If the batteries hold a charge and the alternator fails, obviously replace the alternator.

You'll walk out spending close to $400 or $500, but your charging system will be fixed.

 

both were checked today.batteries tested fine by the garage and advanced auto.although not fully charged.alternator tesed fine at advanced on bench but failed at garage for low amps(50).he said adavanced bench test isn't thourough enough to check full amps at load?i am going to charge batteries here then take them back and test them again. my alternator now is only putting out 50 amps at max load.i will be heading to autozone in the next couple days to get a alternator for sure.they have the best price/lifetime warranty

 

JMHO here but I'd check around your town & see if there is a good alt. repair/rebuild shop.I'm pretty sure you'll come out way ahead $$$ wise & will know you have a good alt., box store on the other hand is a crap shoot

 

^^^^HEED THIS WARNING^^^^

Do not buy an alternator from Autozoo or any other box store unless you have NO OTHER choice!!

 

Make sure you keep the tools in the truck to change the AZ alternator with u after you install it. Some folks have had them go out every year after installing one. If you do not mind spending the time changing it, having the tools in the truck will help keep you from getting stranded far from home if thats the only one you can swing.

I have had really bad luck with aftermarket alternators from anywhere. I had one truck with a lot of electronics w/ a 6.0 ( a pain to change b/c of the belt) that would eat one every 6 months. I finally got a ford one and it lasted until i got rid of that truck 90k miles later. It was a service truck and lost time was lost money.

I understand what your brother is saying perfectly. I can see a possible hard to recharge situation @ 50 amps in your short drive just by the number of amps a hard start with glow plug activation would eat up. I bet with the blower motor and a/c and other necessary truck electronics, you are using most of that to run the truck and very little is making it back to recharge the batteries. If you want a cheap easy way to keep batteries fully charged, get a battery tender from somewhere. The jr models are about $40. It comes with a quick disconnect pigtail that you mount to the battery and the other end in a convenient place. Plug the fully automatic charger in and it costs very little to operate and will charge the batteries to optimum charge and the maintain it there. All you have to remember is to unplug it before driving off.

 

yes with just my blower and lights on 13 amps was making it back to charge batteries when he tested it.he said in 10 miles that will never charge them back up fully.i called the rebuild shop I used before.hes just about as much with 90 day guarantee.i know its a game of chance with auto parts anymore I went through two starters in my old chevy a couple of years ago till I got one that even worked!never gave ford a thought guess ill call them tomorrow.thanks!

 

If you are going to replace the alternator, read through this thread started by F350-6 about his up-grade.

https://www.ford-trucks.com/forums/1...lternator.html

 

I hear lots about the bridges in the alternator burning out and causing low amps. They are the bridges that convert the AC power to DC and there are a number of them. As some burn out the AMP output drops off. Still a good alternator but not putting out what it should. Now the bridges are something that need to be soldered out and in and stuff I hear unless you can get a rebuild deal with a new rectifier.

I believe my X as well has some bridges burnt out and when doing many short trips like you mention it gets harder and harder starting (slow starter) but if I charge the batteries it cranks good for awhile again. This is all started after I jumped started another diesel a couple years ago.

I have been tempted to just get some rectifier bridges and some day tear into it and see what I can do.

 

What the geniuses at autozone/o'reilly's, etc will check for is voltage output. Your alternator can crank out plenty of voltage and be low on amperage. The guy at the shop probably used a VAT 45 to test your alternator which is a much more reliable machine than any bench tester a part store will have. Go with the tech. It's his job.

 

as stated above, i agree with the mechanic that said your alternator is going out the door.
i also agree with staying away form parts store alternators if possible.
look for a starter/alternator rebuilder in your area and get one from him.
i had a custom alternator built for my truck for $215. puts out 255 amps.
parts store crap shoot 110 amp alternator was $198.
it was a no brainer to go with the custom built twice the output for almost the same price.

 

Wanted to add another post warning against alternators from the box stores. On my brother's 2007 6.0 he got a battery warning light, replaced both batts but the light immediately returned. He replaced the alternator which tested bad, but the new alternator (from AutoZ...) didn't fix the prob with the battery warning light, in fact the truck was stranding him because it would kill the batts and not start up. He had the boys at AutoZ test the batts and the new alternator...all showed good.
Thanks to this and some other posts I suspected a bad new alternator, which is exactly what it turned out to be. Turns out AutoZ's alternator tester does not load test it, it only measures the voltage output and can show that the alt is good even if it is not putting out adequate current (amps)
Stick with a motorcraft alternator.

If you suspect the alternator, find a shop that can load test the alt and tell you what current it is making.