No alternator output at idle?

[FireDemonSiC]

Hey guys. First post.

I picked up this 2020 ST last Saturday and am loving it so far. 31k miles on the odometer and all stock currently besides a K&N panel filter and Livernois tune.



Speaking of the tuner however, this brings me to my reason for the post. After the vehicle has been warmed up and driven for a bit, when coming to a stop and idling, I've noticed the display on the tuner (Which is suction cupped to the windshield) will power off as if you turned off the vehicle, then turn back on when you begin accelerating again. If I manually re-activate the display and check the battery voltage reading, I'm seeing that it's fallen completely back to battery voltage (12.3-12.4) and then resumes proper charging voltage once the vehicle is in motion again.

Before I begin any further diagnostics on the vehicle and potentially open a trouble ticket with Livernois, I wanted to check if this is some sort of feature these vehicles come equipped with (The only thing I can reasonably think of is that the alternator possibly has some sort of electronic clutch that disengages for short periods at idle? I know manufacturers are getting very creative nowadays in regards to fuel consumption)? Perhaps this could also be something related to the OBD port voltage? I contacted Livernois to see what they thought and they stated I was the first person to report this behavior.

I have never had trouble starting the vehicle, no stumbling or hesitation at idle and I have never received any error messages for the charging system. The dealership I bought it from did install a brand new AGM battery just before I bought it.

Also worth noting that I had the auto start/stop tuned out.

 

[FORZDA3]

Are you SURE the engine isn’t shutting off because that’s exactly what will happen. Also note that late model Fords with battery management system (BMS) don’t charge all the time. Sounds like your device on/off settings need adjusted.

 

[FireDemonSiC]

Are you SURE the engine isn’t shutting off because that’s exactly what will happen. Also note that late model Fords with battery management system (BMS) don’t charge all the time. Sounds like your device on/off settings need adjusted.

1000% positive the engine is staying running. The charging shuts off as if the auto start/stop were still enabled but the engine remains running. This doesn't seem to happen until the vehicle is driven for a bit and fully comes up to operating temperature.

 

[GearHead_1]

How many RPMs is it idling at?

 

[Blue Beast]

Hey guys. First post.

I picked up this 2020 ST last Saturday and am loving it so far. 31k miles on the odometer and all stock currently besides a K&N panel filter and Livernois tune.

View attachment 19881

Speaking of the tuner however, this brings me to my reason for the post. After the vehicle has been warmed up and driven for a bit, when coming to a stop and idling, I've noticed the display on the tuner (Which is suction cupped to the windshield) will power off as if you turned off the vehicle, then turn back on when you begin accelerating again. If I manually re-activate the display and check the battery voltage reading, I'm seeing that it's fallen completely back to battery voltage (12.3-12.4) and then resumes proper charging voltage once the vehicle is in motion again.

Before I begin any further diagnostics on the vehicle and potentially open a trouble ticket with Livernois, I wanted to check if this is some sort of feature these vehicles come equipped with (The only thing I can reasonably think of is that the alternator possibly has some sort of electronic clutch that disengages for short periods at idle? I know manufacturers are getting very creative nowadays in regards to fuel consumption)? Perhaps this could also be something related to the OBD port voltage? I contacted Livernois to see what they thought and they stated I was the first person to report this behavior.

I have never had trouble starting the vehicle, no stumbling or hesitation at idle and I have never received any error messages for the charging system. The dealership I bought it from did install a brand new AGM battery just before I bought it.

Also worth noting that I had the auto start/stop tuned out.

Welcome to the forum

 

[FireDemonSiC]

How many RPMs is it idling at?

700~

 

[FORZDA3]

1000% positive the engine is staying running. The charging shuts off as if the auto start/stop were still enabled but the engine remains running. This doesn't seem to happen until the vehicle is driven for a bit and fully comes up to operating temperature.

It’s NORMAL for the BMS to interrupt charging. If there was a vehicle problem it will let you know. Check your device settings. You may need to turn it on/off manually.

 

[FireDemonSiC]

It’s NORMAL for the BMS to interrupt charging. If there was a vehicle problem it will let you know. Check your device settings. You may need to turn it on/off manually.

Good to know. I'll be calling Livernois Monday to discuss further in that case.

Do you happen to have any good links to documentation for how the BMS operates? Would be good to have something to Livernois. The guy I spoke to earlier seemed kind of stumped on the issue.

 

[Cdubya]

Do you have another source of voltage reading like your radar detector? Also, you running the original battery? For a MY2020, I would think you'd need a new one. I think the Livernois is meant to display all the time so what you are experiencing is a little odd. I also think it's odd that it would be battery voltage at a stop and then full charging when moving. Usually if the battery is not target (80%) it will be full charging, even when idling--that is something like 13.9-14.3V for me, and will reduce as it gets closer to being charged. Some accessories will power off if voltage is too low. To me, sounds like something is going on with your car that is unrelated to the Livernois.

 

[SimonsGTS]

Sometimes the voltage at the DLC can read lower than the actual battery voltage, and the charging is computer controlled. I wouldn't worry about it too much unless you start having other issues. Hopefully Livernois will have a similar answer.

 

[FireDemonSiC]

Do you have another source of voltage reading like your radar detector? Also, you running the original battery? For a MY2020, I would think you'd need a new one. I think the Livernois is meant to display all the time so what you are experiencing is a little odd. I also think it's odd that it would be battery voltage at a stop and then full charging when moving. Usually if the battery is not target (80%) it will be full charging, even when idling--that is something like 13.9-14.3V for me, and will reduce as it gets closer to being charged. Some accessories will power off if voltage is too low. To me, sounds like something is going on with your car that is unrelated to the Livernois.

The battery is a brand new Motorcraft AGM that was replaced just before I bought the vehicle.

And no, the Livernois MyCalibrator is not supposed to display 24/7. It watches for the battery voltage to drop when the car is shut off and the alternator output ceases (This is what's causing the display to randomly turn off while stopped and idling. Usually in traffic or at stop lights).

30 minutes after shutting the car off this evening, I verified with a multimeter directly at the battery that the voltage was 12.7. The calibrator was seeing 12.6, so within 1/10th a bolt of battery voltage. I feel as if the tuner shutdown voltage is more calibrated for a lead acid battery, which typically rest around 12.4~.

When the output drops low enough at idle to turn off the display, that's about where the battery is sitting at (12.3-12.4), but I never get any messages for an error with the charging system.

 

[F=MA]

I do not have a tuner suctioned cup to my windshield with the ZFG E50 tune. Why is it even necessary?

 

[FireDemonSiC]

I do not have a tuner suctioned cup to my windshield with the ZFG E50 tune. Why is it even necessary?

Good for you.

 

[FireDemonSiC]

FYI, I believe I may have discovered at least part of the issue with the voltage dropping out.

Last night I decided to place the battery on the battery tender and allow the PCM/BMS to get a fresh start with a completely topped off battery. I disconnected the terminals from the battery so I could hook the charger directly to the posts while at the same time allowing all the modules to reset.

Upon hooking them back up, the vehicle started behaving oddly with all power going in/out as if there was a major short or break in a cable somewhere. No power to the entire vehicle. No lights, doorlocks or etc. Was able to manipulate this behavior by jiggling the distribution block on the positive terminal.

Upon further inspection, it seems that whatever grease jockey lube tech they had change the battery, loosened this nut. It was completely backed off by a good 2-3 turns and was the source of the car losing power. Snugged it up real good and the problem immediately went away.

View attachment IMG_20231008_171958_529.jpg
Before anyone tries to call it, it is not possible that I accidentally loosened it myself while removing the battery terminal because I had not yet removed the plastic cover over the distribution block until the issue became apparent.

And people wonder why alot of us don't trust something as simple as letting someone else change our oil.

 

[Cdubya]

FireDemon, was your fix still holding. I have been noticing lately my voltages fluctuating wildly... going as low as 11.9V. I suspect my BMS is failing. When I unplug it voltages are in 13.8-14.4V range. At least I know my alternator is good. Will probably replace the BMS next...

 

[FireDemonSiC]

FireDemon, was your fix still holding. I have been noticing lately my voltages fluctuating wildly... going as low as 11.9V. I suspect my BMS is failing. When I unplug it voltages are in 13.8-14.4V range. At least I know my alternator is good. Will probably replace the BMS next...

Nope. Still the same thing. And in fact, just the other night I came out of the hardware store and started the vehicle up to a nice "SERVICE CHARGING SYSTEM SOON" message.

I've owned it going on 2.5 months now and it's been the only indication that something may be wrong.

 

[Cdubya]

Nope. Still the same thing. And in fact, just the other night I came out of the hardware store and started the vehicle up to a nice "SERVICE CHARGING SYSTEM SOON" message.

I've owned it going on 2.5 months now and it's been the only indication that something may be wrong.

Well, you might want to unplug your BMS also just to make sure your alternator is not the problem. After unplugging BMS, "charging system service soon" will appear at startup. Voltage should always be 13.5V or higher.

Im having am having a hard time researching the BMS module. I think it goes by "battery current sensor" also but it's attached to the negative terminal which may give it a different part number than what's listed on it (L1MT-10C652-AA). If you are under warranty, you may want to have them look at it. Ive owned my ST since new and for the first 4 years, it never dipped below 12.6V with the car running.




Update: Benny @ Levittown Ford found the part for me!
https://parts.levittownfordparts.com/oem-parts/ford-battery-management-system-l1mz10c679b