HYBRID 12V Battery Mystery SOLVED

[doug maverick]

Not a recall, as it doesn't effect everyone nor a safety issue. (dead battery that prevents driving is kinda the ultimate safety)
SSM 53801.
Hmmmm, past the 3/36k warranty.
Had a battery drain a couple times, dead one morning?

I just bought the truck. My Ford OEM battery seemed to drop voltage to the point of Battery save mode within a few hours of parking the truck every day. There is some evidence that someone had at one point jump started using the 12v battery's connection ( orange plastic positive cover was broken, as if someone had forced it open). So, my knowledge of the history is quite limited. I can ask the previous owner what he knows.

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[samspritzer]

Not a recall, as it doesn't effect everyone nor a safety issue. (dead battery that prevents driving is kinda the ultimate safety)
SSM 53801.
Hmmmm, past the 3/36k warranty.
Had a battery drain a couple times, dead one morning?

SSM53801 isn't new. It came out in May 2025. I had it applied. As I previously mentioned, I am still getting the deep sleep messages.

 

[MakinDoForNow]

Can you scan 12v SOC and 12v amps?

The 14.9 tells you nothing. That is what the DC/DC converter is putting out.
Your 12v battery could be in poor shape and you wouldn't be able to tell from that.

12.3 is a little low for a battery at "rest".

If op is opening door and taking his voltage reading from a cig style monitor, the 12.3 will be low by loads activated by door opening. I will leave my hood up over night and take the reading (without opening the door or touching the FOB) across the jump pins after the 12v has settled. Will give 0.1-0.3v higher reading.

 

[MakinDoForNow]

Point taken I exaggerated.

However, really, truly each notch of fan speed is about 10 watts. Speed 6 (60 watts / 5 amps) changed the charge pattern.

Slower /lower did not. But...

Putting 20 amps on my trailer plug with an actual camper attached changed the charge pattern. But so did attaching that simple red light above with no trailer that uses 0.1 amps.

That's why I said amps you are pulling does not determine what happens. But what you turn on does.

It's obvious that plugging anything into the oem trailer plug activates a different program routine which prepares for more 12v capacity used or not for unknown additional trailer current needs. Possibly just selecting tow/haul drive mode without attaching something to trailer plug would result in same program routine usage. Just have to try it and see???

 

[doug maverick]

Hmm.... maybe the title of this thread should be "Hybrid 12v Battery Mystery Solved Still Under Investigation" ?

Just kidding, this has been a great thread with good discussion.

 

[samspritzer]

Just to add to the conspiracy since folks keep mentioning the trailer plug…
Could the fact the trailer control sway is checked even if there is no trailer attached have anything to do with it? I keep unchecking it yet it keeps coming back.

 

[okgaz]

Nope. Just a plain old mirror. In fact, it's manual - have to stick my hand out the window to adjust!

Ok.
Do you have this light?
If you do, you have BLIS Blind Lane information system. That will be disabled if you plug in the trailer hitch brake light and you will get the dashboard warnings as shown in the above photos.

For anyone coming here / redirected here from a search - there's good news and bad news on the trailer hitch light "solution" for an XL Hybrid.

Bad news - confirmed that a 2024 XL Hybrid does not have any of those safety features.

Good news - there's no safety features to stop working and you'll get no warning messages!

I still have my doubt that this will force the truck to charge up to 100% SOC. In fact, my battery monitor does not seem to support this.

That said, a $10 additional brake / turn light installed somewhere where 99% of the time I don't have anything hooked up is also not the worst idea in the world.

 

[DS_Ohio]

For anyone coming here / redirected here from a search - there's good news and bad news on the trailer hitch light "solution" for an XL Hybrid.

Bad news - confirmed that a 2024 XL Hybrid does not have any of those safety features.

2024 XL here. Co-Pilot360 would like to have a word.

 

[okgaz]

2024 XL here. Co-Pilot360 would like to have a word.

Yeah - why I didn’t mention it. But fair point.

Just there for those of us that have the base 2024 XL Hybrid without any fancy additions.

 

[Mavster Mechanic]

But this thread is the first time something has been found to force higher charging to keep a battery from getting undercharged and slowly go bad.
It's not doing that because there was a parasitic drain, just the normal micro-drain.

I had this thought in the shower this morning.

20 Wh loss parked overnight is typical in mine, and probably everyone's.

20 Wh loss overnight could be:
20 watts of power used during the first hour

10 watts of power used for the first 2 hours.

2 watts of power used for 10 hours.

1 watt of power used for 20 hours.

I do not consider this a parasitic drain.

I believe the "problem" is; left to its own devices, the truck does not put back in 100% of what it used next time you drive it, unless you use headlamps, trailer wires, or high fan speed.

I also don't think it tries to recharge at all until you are in the 60% to 80% SOC range.

My battery was MAINTAINED at about 60% for 3.5 years. Got it past the warranty period. And driving it 5 days a week kept it out of "deep sleep" this whole time.

 

[HeyBales]

SSM53801 isn't new. It came out in May 2025. I had it applied. As I previously mentioned, I am still getting the deep sleep messages.

There isn't anything new.
The same SSM actually came out fall 2024 - no solution then. Pat on the back, told you to just wait.
Sorry yours wasn't the intermittent drain.

 

[HeyBales]

I had this thought in the shower this morning.

20 Wh loss parked overnight is typical in mine, and probably everyone's.

20 Wh loss overnight could be:
20 watts of power used during the first hour

10 watts of power used for the first 2 hours.

2 watts of power used for 10 hours.

1 watt of power used for 20 hours.

I do not consider this a parasitic drain.

I believe the "problem" is; left to its own devices, the truck does not put back in 100% of what it used next time you drive it, unless you use headlamps, trailer wires, or high fan speed.

I also don't think it tries to recharge at all until you are in the 60% to 80% SOC range.

My battery was MAINTAINED at about 60% for 3.5 years. Got it past the warranty period. And driving it 5 days a week kept it out of "deep sleep" this whole time.

My PID for mA draw during the prior sleep period usually shows around the expected 25-50 mA. Sometimes 60-70, that's when I figure a relearn happened. (this is assuming the battery sensor shunt is accurate at low draw, which they can be)
That's for easily 12 hrs or more.
I'm sure the majority of draw is from the going to sleep time - the 60-75 min while things shut down, tests are run, relays click, ect. Have no PID reading for that, nothing in service manual as to what's expected for that.

Could a higher than desired draw hit during that time (I saw avg 0.3 Amp (3.6 W) during an hour measuring) - sure. Like AC module calling for fans to run for some reason.
And a bunch of short drives with that happening each 60-75 min - ya going to be bad effect.
But that parasitic draw is still going to result in a dead battery rather quickly.

The micro-drain expected just doesn't do it.

I can get back up to 65% Ford SOC with about 3 hr drive. Usually doesn't hold overnight, I think battery can't hold it due to damage.
My normal state is 55 attempting to get to 60%.
11.8 V resting in morning.
Almost max battery saving mode on (I just noticed when the starting voltage is 11.9, the powerport is willing to stay enabled after I close door and lock, for maybe 45-60 sec, at 11.8 off on door open to get out)
Never a deep sleep mode alert - except on accidental battery drain I did. Don't ask.
And BMS system was very motivated with high charging after that - got back up to 55% post-haste from 39%! It has the ability to charge high for awhile.

 

[Hcopter]

I decided to get in on the fun, so I connected my charger overnight (under hood jump terminals) to get the battery (6mo old AGM) SOC high enough for the DC-DC voltage to drop from 14.4v to 12.9v.

Car Scanner showed 99% SOC straight off the charger. DC-DC voltage acted as described by Mavster Mechanic, 12.9v and negative amp flow until headlights turned on or fan set above 6, then voltage jumped to 14.4v and positive amp flow.

One thing I discovered by accident that I don't remember reading in this thread already; When I opened my door with the truck in park but still on, and headlights on, the voltage dropped to 12.9v, closed the door and the voltage went back to 14.4v. More confirmation that switch positions are the determining factor rather than load.

 

[El Kabong]

Can you scan 12v SOC and 12v amps?

can you find the reading for 12VB Amps?

I cannot, I think I need to import some custom PID infos into Torque for that, but I don't know where to get them for the Maverick. Plus the phone I'm using for it is extremely laggy, I do have another unused phone that is newer that would probably work better.

Would be willing to try more data gathering if someone can provide the PIDs.

 

[First Sergeant]

Point taken I exaggerated.

However, really, truly each notch of fan speed is about 10 watts. Speed 6 (60 watts / 5 amps) changed the charge pattern.

Slower /lower did not. But...

Putting 20 amps on my trailer plug with an actual camper attached changed the charge pattern. But so did attaching that simple red light above with no trailer that uses 0.1 amps.

That's why I said amps you are pulling does not determine what happens. But what you turn on does.

Cool, that makes sense to me. I think I'll start tinkering around with different things mentioned earlier, plugging in the trailer. My dash cam is hard wired, I may check that also.

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