[B0B]

2005 F350 with dual alternators. New Motorcraft batteries

I'm seeing 13.5-14v on my Livewire while driving, and measure 14.0v at the batteries while the engine is running. My concern is that I never really see the batteries get charged above 12.3v. I can drive it for a short or long period of time, but after sitting overnight the batteries will typically be in the 12.2-12.3v range, sometimes getting down to 12.1v when it is cold. I can let it sit for a week and they hold steady between 12.1-12.3v, depending on the temperature. I replaced my batteries a couple of months ago thinking they were getting old (they were a little over 5 years old), and the new batteries act exactly the same. The truck cranks a little bit slow on a cold morning, but it hasn't ever had an issue starting.

I'm not sure if this is something normal for these trucks or if I have an issue somewhere. Do you guys have similar experiences with yours? It seems the batteries aren't really ever getting fully charged.

 

[007matman]

I would check what your alternator output is. It's my understanding that in the dual alternator setup, it only pulls from the second alternator when needed.

I have a single and when running I'm seeing over 14v. A fully charged (resting) battery should be around 12.6. If you have new batteries, there is very little reason to be less than that.

 

[Heavy_GD]

I would check what your alternator output is. It's my understanding that in the dual alternator setup, it only pulls from the second alternator when needed.

I have a single and when running I'm seeing over 14v. A fully charged (resting) battery should be around 12.6. If you have new batteries, there is very little reason to be less than that.

Correct

It seems the batteries aren't really ever getting fully charged.

Are they 12v batteries or 14v?
Also, FWIW, CCA's are what start the truck not V's.

 

[TooManyToys]

I'd also check the voltmeter, only because on another forum, we chased our tail for several pages only to find the voltmeter read low.

It's not unusual to have the OBD2 port show a voltage 0.5v lower than at the batteries.

And how about taking a few pictures around the engine compartment, including the tops of the batteries, so we can see what the terminals and cables look like?

Not having a problem starting with batteries under 50% charge is unusual.

Temperature vs. State of Charge (SoC) chart.

 

[B0B]

Here are some photos. It seems to be charging at the normal voltage. The batteries will be at 12.6v after shutting off the truck, but after a just a few minutes will be down closer to 12.4. If it sits overnight they will be even lower.

Just today I let the truck run for about 15 minutes and shut it off, then disconnected the batteries. After letting it sit for about an hour the batteries were at 12.4v.


Running

Right after shutting off truck. If I let it sit for an hour or two, the batteries will be in the 12.4v range whether or not they are connected. Overnight they dip down to 12.3 or less depending on temperature.

Engine running, measured at battery terminal. If I disconnect the alt wires they are showing 14.6V at the alternator.

 

[Heavy_GD]

Great looking truck

Regarding the V's I do not see any real cause for concern.
I have seen 14 on the meter/monitor while running but that is usually with a cable/connector upgrade and additional grounds.
As for the 12vs at rest, the truck wont "sleep" until doors are closed and everything powers down. I can see it pulling .5v overnight.
You could pop the caps on the battery and make sure they are topped off and I would consider upgrading those terminals down the road.



Also, unrelated, I'm not sure this pipe is seated all the way

 

[B0B]

Great looking truck

Regarding the V's I do not see any real cause for concern.
I have seen 14 on the meter/monitor while running but that is usually with a cable/connector upgrade and additional grounds.
As for the 12vs at rest, the truck wont "sleep" until doors are closed and everything powers down. I can see it pulling .5v overnight.
You could pop the caps on the battery and make sure they are topped off and I would consider upgrading those terminals down the road.



Also, unrelated, I'm not sure this pipe is seated all the way
View attachment 792224

Thanks, I'll double check that CAC boot. I just powder coated my tubes a couple weeks ago, it might not be seated.
I checked the fluid level in the batteries, they are good. I just drove to town and back, shut it down, and disconnected the batteries. I'm going to let it sit for a couple of hours and check the voltages.

Love the truck, its my baby.

 

[Hydro]

When you check that hose, it would be a good idea to flip that clamp around
Keeps from getting a hickey in the hood, if the hose ever blows off

 

[TooManyToys]

Nice truck. Well cared for under the hood.

I wouldn't be disconnecting the alternator connections while it running, though.

Checking the batteries right at engine off should have them at ~13.6v with a slow drift down.

 

[mlgjellybean123]

Shouldn't there be an extra ground coming off the passenger battery onto the body? Mine does at least

 

[TooManyToys]

It's there; it's just hard to see.

 

[SuperDave23]

What kind of batteries? Flooded or AGM? AGM's need a higher voltage to charge fully. I believe the number is 14.8V to get them fully charged which a normal alternator will not do. Also an AGM can be drawn down further in voltage than a normal flooded battery. From what I've found they are considered discharged at 11.7V and charged at 13.0V.

My wife's new Pilot has AGMs (for the silly autostart feature) and runs 14.0-14.4V while driving but the batteries are only 12.2-12.3 after sitting all night, even after a 6-hour road trip. Never seen them bump up above 14.5V. From what I've researched this is normal and Honda does this for fuel efficiency. At times it will even "turn off" the alternator at low loads to where its not charging at all and you're getting <13-volts driving down the road.

 

[Heavy_GD]

What kind of batteries?

He literally posted a picture of them.

The picture is right above your post.

 

[TooManyToys]

Not AGM. Nope, nope, nope. Old tech with cell caps.

 

[SuperDave23]

Wow I'm blind! Rough crowd!

 

[B0B]

Here is a video I took today. The truck hadn't been touched since the night before, including leaving the hood open. The truck is asleep here. As you can see, it is a pretty warm day, and it is showing just over 12.4v. According to the chart @TooManyToys posted, my batteries are only about 75% charged. Everything indicates it is charging properly, and the battery fluid level is good.

 

[Hydro]

I just drove to town and back, shut it down, and disconnected the batteries. I'm going to let it sit for a couple of hours and check the voltages.

What were the findings from this test ?
Did both batteries settle to the same voltage
Leave them disconnected for at least a day and check

Go you have a different meter to verify the reading ?

Making me want to test my truck to see if it acts like yours

 

[TooManyToys]

I will do my occasional truck exercise run tomorrow, so I'll video the voltage before shutdown at engine running, shutdown, and then Monday morning for the overnight sitting. At engine start won't be valid; I got it on a maintenance charger. I will leave everything connected but will pull the one negative terminal so I can record the voltages of each battery when the engine is off.

B0B is down to 10.19v at starter engagement, which is not exceptionally bad considering the resting voltage, which isn't right. Those injectors don't sound like a healthy FICM is driving them.

Only one alternator (generator) will be on during the glow plug operation, and then it goes to both. At that point, the voltage at the battery should be in the 14.2 to 14.4v range.

I believe those batteries are supposed to be new, but I've bought batteries at the Ford dealer that were on their bench for a year. I would get those tested individually at a parts store.

And as both Hydro and I have noted, I like to see another voltmeter in place. BluePoint is not bad, but crap happens.

But do your thing too, Hydro.

>Everything indicates it is charging properly, and the battery fluid level is good.

No, no it doesn't.

 

[TooManyToys]

So far ......

 

[B0B]

What were the findings from this test ?
Did both batteries settle to the same voltage
Leave them disconnected for at least a day and check

Go you have a different meter to verify the reading ?

Making me want to test my truck to see if it acts like yours

I haven't had a chance to leave them disconnected for a full day yet. Just 2 minutes after shutting down and disconnecting batteries they were at 12.74v. After an hour they were in the low 12.6v range. Both batteries are showing the same (within .02v).

I have not had a chance to use an additional meter, and I don't own a clamp or have the ability to measure amperage. I can try to borrow one from a friend, or just bite the bullet and buy one.

I will do my occasional truck exercise run tomorrow, so I'll video the voltage before shutdown at engine running, shutdown, and then Monday morning for the overnight sitting. At engine start won't be valid; I got it on a maintenance charger. I will leave everything connected but will pull the one negative terminal so I can record the voltages of each battery when the engine is off.

B0B is down to 10.19v at starter engagement, which is not exceptionally bad considering the resting voltage, which isn't right. Those injectors don't sound like a healthy FICM is driving them.

Only one alternator (generator) will be on during the glow plug operation, and then it goes to both. At that point, the voltage at the battery should be in the 14.2 to 14.4v range.

I believe those batteries are supposed to be new, but I've bought batteries at the Ford dealer that were on their bench for a year. I would get those tested individually at a parts store.

And as both Hydro and I have noted, I like to see another voltmeter in place. BluePoint is not bad, but crap happens.

But do your thing too, Hydro.



No, no it doesn't.

Thank you for the input and the link to the charging system diagrams. Also, after watching your video below, it is obvious there is something going on with the charging system, as yours holds much higher after shutting off and after sitting.

I have not had a chance to have the batteries tested. The stickers said they were 3 months old when I installed them. I'm having identical symptoms with these new batteries that I had with my previous set. I'm not going to rule out batteries, but I'm doubting this as of now.

The results of my test today are:

Truck running, after glow plug cycle is complete

Lower alternator disconnected at the terminal: Upper alternator output: 14.2 at terminal, 14.0 at battery connection.

Upper alternator disconnected at the terminal: Lower alternator output: 13.67 at terminal, 13.63 at battery connection.