Pro Power reserve limit fails

[TaxmanHog]

Yes, but...if when the truck is ON the DC-DC converter is adequately maintaining the 12v battery from being deeply discharged, why would it need a shut down timer to avoid over-discharging the 12v battery?

To stop unintended discharge of the HVB, granted this would take multiple days depending on load, I don't think the purpose was about the LVB state of charge or health.

Two different programming issues, ie. properly maintaining the LVB and the situational logic behind allowing the PPOB to run for a limited amount of time or HVB reserve capacity.

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[dmd3home]

Wow...interesting stuff indeed.

But, I have more to add. First, I'm a bit confused about this 30 min shutdown timer. Is that something that is only present if you've made the ForScan conversion to run PPOB if the truck is shutdown? Because I've never seen it....I haven't made that conversion and still have to turn the truck on for PPOB.

I was planning on doing more testing soon, but it came faster than I wanted as today we had a power outage and I used the truck to power the house. It was a bit of an emergency as my wife was in the middle of cooking so I didn't take the time to carefully document the event. But, I did note some interesting data.

The power went out approx 12:50p and I was able to get PPOB backfeeding the house right at 1:00p. I still had my maintainer and voltmeter on the 12v battery and I remembered that the voltmeter was reading 13.06v earlier this morning. When I backfeed the house, it also feeds my shop where the truck is parked....and, I realized that then powers the maintainer. As I wanted this to be a test (as well as power the house to cook my dinner), I decided to unplug the maintainer and monitor the 12v battery voltage.
The house loads were not great....only about 1500W and all seemed great.

But after 53 mins I discovered that the truck had shutdown without warning....hmmmm. Is there a 53 min shutdown timer? I checked the 12v battery voltage...it was 11.94v. I don't know at what point the DC-DC inverter should kick in, nor do I know at what voltage the truck actually SHOULD shut down to protect the 12v battery, but yes, it would seem that the truck would take care of itself better than this. But, we still don't really know what caused the truck to shut down....was it 11.94v?

So, I restarted the process...and it started fine in spite of the 12v battery at a slightly low voltage and I again started PPOB and picked up the house loads. I watched it for a bit and all was fine.

That is, until 54 mins later when it shut down again! Again, is there a 54 min shutdown timer? This time I was near the truck and did see something on the screen saying that it was shutting down to protect the battery....and then it did. Again, there was no notice on the app and, of course, the dash screen went away when the truck shut down. When I checked the 12v battery voltage immediately after the shutdown it was reading 11.54v. At this point our utility power was back up so I just switched back to that (this makes my wife happier).

More testing would have been good though. If I had left the battery maintainer plugged in would the truck not have tripped off to "protect the battery"? What is the algorithm looking at to shut down the truck? This was the same question I had when traveling and after about 2 weeks the app stops showing anything and says to manually start the truck because it's off to protect the battery......uhhhh? Which battery? The HV battery was at 60% and the 12v is on a maintainer. What battery is being protected here?

 

[chl]

To stop unintended discharge of the HVB, granted this would take multiple days depending on load, I don't think the purpose was about the LVB state of charge or health.

Two different programming issues, ie. properly maintaining the LVB and the situational logic behind allowing the PPOB to run for a limited amount of time or HVB reserve capacity.

Well, Ford said it was for the 12v battery in their ICE versions before the Lightning, and they carried it into their EVs.

And there is a whole separate mechanism for shutting down when the HVB gets too low - low range warnings, Powertrain Malfunction / Reduced Power, and Turtle mode, culminating in stop vehicle now message, Also when the HVB gets dangerously low, the contactors will open and disconnect the battery as a protection mechanism to prevent irreversible permanent HVB damage.

The problem is the 12v battery is undersized for the load it needs to handle and the BMS does not act as a battery maintainer effectively to extend battery lifespan.

They seem to treat the 12v battery like one would an oil filter - as an expendable item.

 

[dmd3home]

Indeed the LVB seems to be a very weak point. But is that the whole problem? If so, it would seem an OTA to have the DC-DC inverter charge it more often would be the fix.
When I charged our BMW from PPOB yesterday, it ran for over 2 hours at 3.8 kW with no problem. But, I had it on the 12v maintainer the whole time.
But why did this only start being a problem after that update? It all worked fine for the first 2 years+. As I have said, that update ran a small pump on the rear differential for 40 mins during that update, off I, suspect, the 12v battery. Why was that running? What is it? Did that damage my 12v battery? Why '23 Pros?

 

[EVpower]

I have a theory the DC to DC convertor is not charging the low voltage battery in the affected Lightnings when PPOB is on. It's easy to confirm with a voltmeter from the DC power outlet by the passenger seat. If the DC voltage at the power outlet doesn't increase from the reading in accessory mode with PPOB on, then the DCDC isn't working, and the low voltage battery can't support the truck system power overhead for very long.

Steve

 

[dmd3home]

You are correct. I, in fact, demonstrated that when I was trying to power my house yesterday. I had a voltmeter on the battery and monitored the voltage. It slowly dropped through the process and when it got down to 11.54v the truck shut down ("to protect the battery"). It would be nice to know at what point the DC-DC inverter SHOULD kick in ....it does seem like prior to 11.54v it would. Also it would be nice to have some indicator showing when that inverter is doing its thing.

 

[chl]

Thanks for confirming the suspicion that either the DC-DC converter is either 1) not providing any energy to the 12v battery when using the PPOB or 2) is providing an inadequate level to prevent a low battery shut down under some circumstances.

When the 12v battery is weak and cannot store enough energy to compensate for the load the truck requires when ON and running the PPOB it could exacerbate the issue.

And it might only be a problem when the PPOB load is using more than a certain amount of power.

When the truck is ON, unless it has a defect, it is always providing DC to the 12v system including the 12v battery via the DC-DC converter. But sometimes the 12v system load needs the 12v battery's reserve of energy and what the DC-DC converter is providing when the truck is ON.

If the load is too high, and/or the DC-DC converter cannot supply it and maintain the 12v battery at the same time, the 12v battery energy level will fall.

The DC-DC converter gets its energy from the HVB, but when the HVB is powering the PPOB, less is available for the DC-DC converter. How much less depends on the load on the PPOB.

Yes, there is a lot of energy stored in the HVB, but the wiring of the system has a limit on how much current it can carry and therefore how much power it can provide at any given time.

In my tests, as long as I remembered to turn off the 30 minute shut down, I have run the PPOB with the truck ON for extended periods of time, beyond 10 hours.

I have also been able to run the PPOB with the truck OFF for long periods of time.

But the load I have on the PPOB for my emergency circuits is using maybe 2000W and only when I have the coffee pot and the microwave running, no where near the 7200W max.
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In short, I think the limiting factors that could result in premature shut down due to 12v battery depletion are:
1) the SOC and SOH of the 12v battery, and
2) the load on the PPOB.

Keeping the 12v battery on a maintainer while running the PPOB seems like it could be a good solution, provided it can compensate for the reduction in DC charging current from the DC-DC converter during use of the PPOB.

 

[chl]

It seems this could just be an inherent limitation of the truck's PPOB system, rather than any 'defect' caused by a software update.

 

[TaxmanHog]

I think it is logical that the DC/DC conversion process should be active during a PPOB session limited or unlimited.

 

[chl]

I think it is logical that the DC/DC conversion process should be active during a PPOB session limited or unlimited.

Yes, I think so too, and I think the question is, "is it adequate" to avoid a low battery shut down?

With a healthy battery it may be, with a weak battery, maybe not.
With a light load on the PPOB, may not be a problem, with a heavy load, maybe not.

I sent the Ford guys our latest theory and evidence about what is happening and they asked me to run another test with the truck ON without using a battery maintainer presumably to see what the effects to the 12v battery are.

I keep my 12v on a maintainer consistently (if I remember to plug it in) and have since mid-2024, and I have a relatively light load on the PPOB (usually well under 1kW), so I am not sure how useful my systems info will be.

I did mention that weak 12v battery issues are a pretty frequent issue on the forums.

If Ford could do something to fix that issue of 12v battery maintenance/health it would solve a lot of problems.

 

[chl]

The other 'weird' thing is I can shut down a PPOB session by simply touching the "Climate" button in the Ford app - the truck stays on but the PPOB shuts down.

I told the Ford guys about that as well.

 

[K6CCC]

The other 'weird' thing is I can shut down a PPOB session by simply touching the "Climate" button in the Ford app - the truck stays on but the PPOB shuts down.

I can confirm that either manually starting climate or a scheduled departure will kill PPOB.
This is on my 24 Flash.

 

[chl]

I can confirm that either manually starting climate or a scheduled departure will kill PPOB.
This is on my 24 Flash.

Glad it's not just me in my 2023 Pro, thanks for confirming!

 

[chl]

UPDATE - I sent this info to the Ford team working on this issue:

I ran the PPOB for approximately 24 hours yesterday 6/8/2026 to today 6/9/2026 and had no problems.
Truck ON, power down timer OFF, no battery maintainer connected.

I maintain my 12v battery health by using a maintainer every day when the truck is not in use, so my 12v battery should have a good SOH (Health/energy capacity).

Also I mentioned that the load I was using for the PPOB was normally below 1kW, except when running the microwave which can use 1800W for a few seconds or minutes.

I reiterated the test done by @dmd3home that avoided premature shutdowns when his 12v battery was connected to a maintainer, and that without the maintainer the 12v battery terminal voltage gradually declined during the PPOB use until it reached a level where the truck and the PPOB shut down.

I also told them about the post today on the forum thread, another member @K6CCC tested turning on the 'Climate' with the app and also setting a departure time with climate, and found that both would shut down the PPOB in his 2024 Flash trim Lightning. So the Climate-PPOB shutdown bug is not just my vehicle trim PRO or year 2023.

In my case, 'Climate' turned the heated seat on to HIGH - I had not used the heated seat recently and I never set it to HIGH.
In my experience, the Climate button usually turns on the last setting used.
I have been using cooling AC recently but always turn it off before turning off the truck.
It did not turn the cooling AC on which was what I expected.
The heated seat on high was NOT expected.

I also mentioned that I recalled another forum post where someone reported the heated seat coming on to HIGH when using 'Climate' in the app as well, but it was not in connection with any PPOB issues.

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I conclude that I can use the PPOB with the truck ON and with a fulled charged and 'healthy' 12v battery for at least 24 hours with the relatively light load (1kW) of my 10 home backup emergency circuits.

I also conclude that for a heavier load and/or a 12v battery that may have reduced capacity, using a battery maintainer while running the PPOB would be a good idea (as the referenced above test showed).

I also conclude there is something funky with the 'Climate' and scheduled departure preconditioning with Climate and not to use those when running PPOB. Because it puts the heated seat on HIGH, I think I will only attempt to use it in the dead of Winter [insert smiley face]

 

[TaxmanHog]

With regards to departure events, check the control pane in Ford App after the climate starts, view the seat conditioning mode, often it will be as last used, but occasionally it will not, so I always look and manually select warm mode/levels or cool mode/levels according to the season or temperatures of the moment.

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