Tonight I noticed that with my headlights, fog lights, a/c, and radio on at idle my batt voltage was bouncing between 13.2-13.5 with everything turned off it would jump between 13.6-13.9. My batteries are about 6mo old die hard gold 850 cca. This just seems a little low to me. Also I still have the stock alternator. Any thoughts?

 

Those numbers are pretty good with the stock 110 alternator.

Overall are they great? No, the 140 6G, 130 3G or an aftermarket alternator would be better. Your batteries, FICM and headlights will thank you.

Josh

 

need to replace it. ford use way too small of an alt (110amps). you buy a 140amp from advance auto parts. must be for 2005 with dual alt and top alt only. you also shop on ebay and a lot of people like DC power.

or
You need to fix this ASAP. The low output will kill the fcim and truck will not run anymore.

 

use coupon code TRT30 at Advanced on-line to save 30% or $50, get the 2005 140amp new, not a rebuild and lifetime warranty. Then select your store, stock check the part and then go pick it up.

 

Where are you measuring this voltage at? If it's via the OBDII port with an Insight or something like that, bear in mind that due to voltage drop through harnesses and connectors those readings can be anywhere between 0.2V to 0.4V less than what you'd read at the batteries with a DVM. You might want to check your voltage at the batteries, as there may not be an issue at all.

 

Pretty normal, put on wipers, or heated seat(s), or rear window/mirror electric defrosters (I have an Excursion) and the voltage would drop to 12.4

I have a digital voltage gauge tapped into a key-on fuse under the dash..

On the stock alternator:
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My voltage would be around 11.6-12.2 until the glow plugs turned off. I would routinely sit (with the A/C, lights all OFF) until the voltage got to 13+ before doing anything.

With DC Alt + Wiring upgrade from Ed @ Ficmrepair:
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Voltage takes a couple of seconds after a cold start to get into the high 12s or low 13s and then a few seconds later 14.4+. I can turn on the A/C or lights and go. My wife has even noticed - "don't you need to let it warm up before we can go?".

Nope, I wasn't waiting for it to warm up - I was waiting for the voltage....

 

Does anyone know the hot idle specs on the stock 110A and 140A alternators?

 

Mustang_309 has done testing with both versions and also with the smaller pulleys

Josh

 

About 70 amps and 95 amps at hot idle (not hi idle). I was able to use a clamp meter and measure mine hot idle 95 amps, 110 at high idle. My truck came new with a 140 upgrade and I ran it for 8 years with no trouble. I keep as a spare but am running a PRestolite 230 amp unit in my signature. Its actually for the International version of VT365 and its direct bolt in, you use your existing small pulley. They use these alteranators in international LCFs and F650 and F750s I beleive. My brother ordered it from his international dealer, hes on the parts counter. For me, ordering a DC unit is impossible. I am getting about 175 hot idle, over 200 high idle, but its brand new. We shall see how she does over the longer term....

 

I'll check mine with a clamp meter, what rpm are you supposed to use for hot and high idle?

 

hot idle is about 800 rpm, should just be hot, ie up to water and oil temps >190 f ish. Hi idle is 1240 on my hi idle set up. I didnt do a 2500 rpm like for diagnostics, dont have someone to hold the pedal while I measure anyway.

 

Thank you I will try and check it tonight, I do have the high idle seiches to the up fitter switch

 

Any suggestions for a factory dual alternator replacement? My understanding is that the truck pcm will randomly choose which alternator to use each time, never using both at the smae time. This tells me I would have to replace both as I am sure the lower, secondary, alteranator is even smaller than the upper, primary.

 

Mine idles at 600 and I believe most do, for 800 that may require you to hold the throttle as well.

 

Looks like mine idles at 690rpm and high idle is 1200rpm


Also all of my voltage readings so far have been through my SCT, I will also check it at the batteries tonight