I don't drive my truck much so I decided to check my batteries this past weekend. They tested at 11.6V. I put them on the charger for as much time that I had available. I'd say probably got a total of 10 hours in. Anyway I checked this morning and it showed the batteries were at 12.1 volts. It started just fine (New batteries were installed about 6 months ago, along with a new alternator "DCPOWER190HD" from FICMrepair) and I plugged in a voltage meter in my cigarette lighter to see how charging was going. If the RPM was around 1250 it would show 14.1 volts. Any deviation from that rpm and the voltage would go down.

Now as I was driving the voltage staying in the 12.6 range until my coolant got to 150 and then the voltage went up to 14.1. The longer I was driving from that point the lower the voltage read. By the time I got to work the voltage was reading 11.6. I checked the FICM voltage and it was running 47.5 -48. Once I turned off the truck the battery was reading 12.1 volts.

So I don't know if that is normal behavior for an alternator or maybe the batteries are too far gone. I haven't taken the batteries anywhere to be checked by my charger checks the battery and states if a battery is not taking a charge and is bad. So I'm not sure what direction I should go to determine what is not correct.

 

Pull the batteries from the truck and let them cold soak over night. Take them to Oreilly and have them checked, batteries show their colors when they sit overnight.


If you want to try charging them again, if they're maintenance batteries, top them off with distilled water then slow charge them individually and off the truck.


You also need to pull the alternator and have it tested. If it is indeed bad, consider upgrading to the 140 amp large case.


Edit: Take Randy's advice on the Leece Neville, this is what happens when you don't get enough sleep....you don't think and suggest inferior products

 

Sounds like your alternator took a dump... call Ed @FICM repair and ask about warranty service. Then ask about upgrading to the Neece Leville 230 amp unit. DO NOT mess around or you FICM will be next!

Install a smaller pulley as well, you want the 58mm one to increase RPM at idle. With that alternator and pulley combo, that should net you 14.2 amps at idle even with glow plugs on.

Batteries should read around 12.6-12.7 fully charged and the alternator should produce around 14.2v when charging and above idle RPM. The 11.6 reading when you got to work isn't good, also means that the input to the FICM is low, which can damage it very quickly.

 

Randy has it covered.

The only thing I would reiterate is that after a few hours rest, the power port voltage readings should never be below 12.5-12.6v. I've giving a little leeway for harness drop. And when driving without a lot of accessories being powered you should not at the power port see below 13.6-13.8v, again giving leeway for harness connections. Accessories on, voltage will depend on alternator capability.

 

I would measure directly at the battery posts to ensure an accurate reading. Power port and scangauge readings can be off a bit. Tenths matter a great deal when it comes to batteries.

Modern (virtually all batteries sold today) "maintenance free" and AGM/VRLA batteries are fully charged at 12.80 volts at 80F. The 12.65 figure is for old school lead-acid batt types (with caps for the addition of water). The distinction is important because a couple tenths is the difference between full charge and say 75%, where sulfation starts.

 

What Tedster9 is saying is absolutely true!

My power port shows 14.25v at start-up, glow plugs on or off, doesn't matter... it's solid. My 12v cigarette lighter plug, on another circuit, shows 13.8 mostly and my Scan Gauge II OBD port shows 13.9-14.1v.

Measuring at the post should show a slightly higher number, but I'd suspect it to be nearer a .3-.5v increase and not nearly enough to say your system is operating correctly.

Let me clarify my statement... its true about different locations can show a different measurement for voltages. I can not validate the statement about AGM batteries being 12.8 volts fully charged. I do have AGM's installed in my truck and don't see 12.8 as fully charged. I'm seeing 12.6-12.7 on average, but not convinced to say I'm the standard as I don't have any amplifying information to compare it to.

 

Well, hold on here guys. I don't agree declaring everything AGM and the voltage expectation should be higher for ALL.

I haven't bought an AGM for any of my applications yet, and the latest ones don't have the caps, but are not AGM. The lastest ones are from Walmart, settle out at 12.6v and have the same tops as some from Sears and other stores.




Agree there is a distinction between the AGMs old "old school", but so far "old school" isn't so old. Agm's I agree are the future and Ford has started to use them production line. I'm not comfortable at this point in declaring all batteries should be at a voltage higher then 12.6v for everyone like it's being stated.

Editing in more pics in a second.

 

Jack,

That picture.. to me... appears to be a "maintenance free" battery, not an AGM battery. And with that said, I'd assume a 12.65 type.

 

Correct. So there are still a lot being sold out there and often at a price point that is acceptable to many. I may be reactive here a little (headache for 6 days now) but there are going to be a number of people viewing this post who I don't want to see going friggin nuts that they are not at 12.8v. These settle out at 12.6-12.65 off the charger. I've got three and these are the new design being sold at Walmart, Sears, etc. and yes there are others sold as AGM.

 

It has to do with the plate materials used that allow for a sealed battery. A battery will settle out at 12.80 if it is charged thoroughly. It is possible to overcharge a battery but it takes dedication.

http://jgdarden.com/batteryfaq/carfaq4.htm

 

I've had these on a regular charger, I've had these on a maintenence charger, I run with these in my truck with the L-N 230a alternator for a two hour drive. They settle out at 12.6v. I might take back the characterization of maintenance free as they do have the same venting that comes with the Ford batteries in the Lincoln LS placed in the trunk, with a nipple for exterior venting. You may not be able to get water into them per the normal vent caps, maybe they just want to run them out to failure but they are not the typical construction of maintenence free. These will not charge up and maintain at 12.8v.

 

I can't keep my AGMs at 12.8 either and they are less than a year old.

 

Have you inspected your ground cables ????

Check and clean all of the grounds. On the frame body and engine. Then check all your connections on the batteries too. Put some red grease on every connection point.

I see you have a DC Power 190 HD, that's a great alt. I'm thinking you have cable issues myself. I really do.
Alt is making power just can't keep it coming to the batteries. Ed will set you up with supplemental cables to help the truck !

 

He's seeing more than a 2 volt drop, it's not just a cable issue, although they are a large contribution to the equation.

 

Well on the way home I was worried since the was a major accident which caused me to sit in traffic for over an hour. Anyway, I was watching the voltage on the cigarette lighter and again it was fluctuating from 13.4 volts down to 12.3 for the first 30 minutes. At times I didn't even need to look down at the voltage meter because I could hear the cabin fan get louder (push more air) when the voltage went to 13V+ then a couple seconds later it would get softer and the volts would be down to 12.0-12.2. Then about 30 minutes into the drive the voltage went down to 11.8 then to 11.6. Since I was stuck in traffic I put it in Neutral and revved the engine up a bit. It would go from 11.6 to 11.8 but nothing more. After about 20 minutes of this I was getting worried that maybe the battery would die from not charging at 12.6 volts. Then about an hour into the drive the voltage went to 12.6 then it would slowly climb up. 12.7, 12.8, 12.9, 13.0 up to about 13.8. As I was driving it would fluctuate from 13.8 to 13.0 when I accelerated then go back to 13.8 when at cruising speed. By the time I got to my destination it was pretty much constant at 13.8 with a couple blips to 13.9.

After about 5 hours I got off my 2nd job and plugged in the voltage gauge to the cigarette lighter and it was reading 12.6V. The truck started up way faster than it had the previous trip. Voltage started at 12.5V and was around 13.9V after my short trip home. I haven't checked the sitting voltage of the batteries this morning since I took my main vehicle to work so I will check when I get home later today. I wonder if the low voltage I was experiencing was the alternator overheating from trying to get the batteries charged and "turning off" to cool down then once cool turn back on. Now that the batteries are theoretically charged maybe it's not working hard anymore hence the higher voltage?

I added the ground cables that "TooManyToys" recommended and I have added additional charge and ground cables for the higher amp alternator. I also cleaned all the ground cables when I was adding the cables to the truck. So that shouldn't be an issue.