antony1103

Do you have any electrical mods that bypass the battery monitoring sensor? This will cause the computer to underestimate your electrical usage and undercharge the battery. If you do, make sure you wire it so the current is accounted for with the sensor. I have nothing but good things to say about Ford's battery life monitor system. I'm at 100k miles and still on the stock battery and alternator. I've never had ones last this long, especially with the wild temperature swings here in the northeast. When used correctly, it does a great job at managing the state of charge in the electrical system. You just need to make sure any electrical mods account for it.

I would try a battery reset. Simply just let the truck sit for 8 hours without opening or starting it. This will allow the system to relearn the battery state of charge.

Jim_Rockford

Yup , I just had a field day with my charging system , found the alt was not charging even though the PCM was telling it too, got one from a local salvage yard , mine was an -AA and I replaced it with the higher output -CA one and re flashed the BCM with the factory program and it showed the larger available amps on forscan so I guess it knows what it has . 35 bucks for the larger output alt was a real bargain. and it was already removed from the truck..lol . the BCM and BCM control everything with it. gotta say without Forscan I would have never figured out what was going on

TxOutlaw

N3UP

You might want to check for loose or corroded connections at the alternator.
I'm sure an intermittent fault in the voltage regulator is possible, but in my experience over the years, they either work, or they don't.

If you're seeing 17-18 volts, that sounds like something is full fielding the alternator. That is too high for the regulator to be operating properly.

The battery monitor system is used to accomplish several things on our trucks.
It reduces alternator output to match electrical demand when the battery is fully charged, which prolongs battery life by avoiding overcharging.
This also improves fuel economy by reducing parasitic load on the engine.

The Hall Effect sensor reads battery current, and is directional. It can read charge and discharge current. From that data, battery state of charge can be calculated.
This is why it is important that connections for any added accessories do not bypass the sensor.
Positive connections can be made directly to the battery terminal, but ground connections should be made to a body ground point.
There is at least one located near the battery that is convenient to use.

There is a service procedure in Forscan to reset the battery age in the body control module tab.
If you replace the battery, you should reset this as well.
While I have no direct knowledge, I think it is possible that the battery management system could take battery age into account when monitoring the charging system.

My Ham radio is connected directly to the battery and has an internal volt meter that I can display.
When the battery is charging, the voltage runs around 14.1-14.5.
Once the battery reaches full charge, the voltage on the radio drops down to around 12.9.

In the data monitoring section for Forscan, you can display battery current and it will show charge and discharge current. I have seen battery current be zero when the battery is charged while the truck is running even with lights, A/C, and even the rear defrost on.

You can also read state of charge with the data streaming.

Some of the load shed actions are time based.
I have seen the battery shut down message while sitting listening to the radio after about 45 minutes.
I have started the truck, and run it for less than a minute, then shut it off and gone back accessory on and have not seen the message again for another 45 minutes.
I didn't run the engine anywhere near long enough to charge anything.

I don't doubt that there may be truck out there with genuine issues with the battery monitor system, but I suspect that some of the trouble people have reported with that system may be a result of added accessories
that are not connected properly so the system can account for the draw.

RLXXI

Replace the alternator, the voltage regulator is built into it.
.

TxOutlaw