HYBRID 12V Battery Mystery SOLVED

[Mavster Mechanic]

Are there any opinions or tests that gives an idea on how often you need to run your headlights on? Everytime you turn the truck on ? Couple times a week? i drive 4 days a week, twice a day 12miles each way to babysit my grandson. On my days "off" i like to give the truck at least one day idle and maybe a weekend run for errands, all local runs but i always drive 20min minimum even if i have to loop around the neighborhood a few times till i hit the 20min mark each and everytime i start the truck. I have a year old AGM that was the replacement after 4 batteries in a year and a half. 22 Hybrid 63k miles

Gusstimate is 1:2 ratio.

Run headlamps (or parking lamps) 1 hour for every 2 hours you run without.

In other words, run them at least 50% of the time.

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[Mareys]

Gusstimate is 1:2 ratio.

Run headlamps (or parking lamps) 1 hour for every 2 hours you run without.

In other words, run them at least 50% of the time.

Thanks so much!!!! thats about what i have been doing. One small note on my truck. like i have mentioned i went through 4 batteries (flooded) in a year and eventually they gave up and gave me an AGM but just to add to the mystery i NEVER didnt have dome lights as a warning that things were going bad. I would just come out and she would be dead, after running fine the day before. Just something no one has mentioned, there are lots of deep sleep/no dome lights warnings mentioned. Thanks again i appreciate all your hard work.

 

[Tall Hobbit]

Thanks so much!!!! thats about what i have been doing. One small note on my truck. like i have mentioned i went through 4 batteries (flooded) in a year and eventually they gave up and gave me an AGM but just to add to the mystery i NEVER didnt have dome lights as a warning that things were going bad. I would just come out and she would be dead, after running fine the day before. Just something no one has mentioned, there are lots of deep sleep/no dome lights warnings mentioned. Thanks again i appreciate all your hard work.

Dome lights have never hinted any problems in my case. Extreme difficulty starting was the first noticeable symptom. Perhaps if I was always remote starting with the app I would've noticed earlier.

 

[Waterick]

I have an 8 month old BXT 470 (490?) FLA in my '24 that was warranty installed and swore to never charge it hoping it will be replaced one more time under warranty with an AGM. Still shows a resting voltage of 12-12.1 . When driving, my voltage shows usually 14.3 on my ScanGuage II whether I have the parking lights on or not. Warranty is up come December. Anyone know if I should start charging this battery with my Noco 5, run with my parking lights on, or just hope it will fail before my 36 month warranty is up? TAIA for any input or opinions.

 

[Finnster]

@Waterick,
Being in SC, I don't think your battery will die before December. I wouldn't charge the battery, I'd just use parking lights or headlights and watch to see if that helps in the long run.
If you were in Alaska/Canada I'd say wait for it to die!
I'll add that when you need to finally get a replacement battery, I'd recommend investigating different battery types lithium, sodium, etc.
Good Luck!

 

[HeyBales]

Thanks so much!!!! thats about what i have been doing. One small note on my truck. like i have mentioned i went through 4 batteries (flooded) in a year and eventually they gave up and gave me an AGM but just to add to the mystery i NEVER didnt have dome lights as a warning that things were going bad. I would just come out and she would be dead, after running fine the day before. Just something no one has mentioned, there are lots of deep sleep/no dome lights warnings mentioned. Thanks again i appreciate all your hard work.

This is what I meant by you had something else going on with that many batteries.

You had a parasitic draw that drained the battery.

Oh - PLENTY of people have mentioned DSM & battery saver functions - that's actually the main posts about. Parasitic draws with drained battery are the infrequent posts.

Yes - all the battery saver mode and deep sleep mode are a result of 2 things.
1: your battery is undercharged and has lost it bad enough the voltage level is low enough to enable those things.
2: you have a parasitic draw and as the battery drains and the voltage drops those BSM and DSM functions happen - usually in a night. Unless the drain got cut short, and it happened the next night again.

The AGM won't stop #2 from happening, but it can take the abuse a bit better.
You may have an intermittent issue that halfway drains the battery - and due to AGM it's not as badly drained and you recover, and it stops.

 

[HeyBales]

I have an 8 month old BXT 470 (490?) FLA in my '24 that was warranty installed and swore to never charge it hoping it will be replaced one more time under warranty with an AGM. Still shows a resting voltage of 12-12.1 . When driving, my voltage shows usually 14.3 on my ScanGuage II whether I have the parking lights on or not. Warranty is up come December. Anyone know if I should start charging this battery with my Noco 5, run with my parking lights on, or just hope it will fail before my 36 month warranty is up? TAIA for any input or opinions.

Help it fail!!!

To at least get new warranty AGM replacement.
That's my plan - you are about 5 months before me.

My warranty battery from last Aug is normal morning resting at 11.8.
And that was after a week vacation with full charge ups during extended driving in Oct.

Ya - these tricks ain't helping us - you gotta get to 85% SOC before they'll matter.
Haven't seen that since last Oct.
With SG2 - you have SOC% and amp readings?
That'll tell the story.

Lot's of Accessory mode usage in cold months leading up to December.
That's my plan - radio on, dancing in the street!
Not my street of course, don't want the neighbors to video me.

 

[Mavster Mechanic]

I'm no rocket scientist but I need help.
My 2022 XL hybrid occasionally I will get in and some of the dash lights come on but the truck won't start. I've had to have it jumped on these occasions and it will be fine for a couple of months, then boom, no start.

If you know, will replacing the 12 volt battery fix my problem?

Thanks in advance.

Probably, almost certainly, yes.

Hybrids are known to start perfectly; then not at all. There's usually no "hard to start" or "slow to start" conditions.

The High Voltage 220 volt battery actually starts the engine. The lower voltage 12v battery only runs the computer and the relays to start, so it's a yes or no thing.

Yes it's good. No it's not. There is no middle ground.

 

[Waterick]

Help it fail!!!

To at least get new warranty AGM replacement.
That's my plan - you are about 5 months before me.

My warranty battery from last Aug is normal morning resting at 11.8.
And that was after a week vacation with full charge ups during extended driving in Oct.

Ya - these tricks ain't helping us - you gotta get to 85% SOC before they'll matter.
Haven't seen that since last Oct.
With SG2 - you have SOC% and amp readings?
That'll tell the story.

Lot's of Accessory mode usage in cold months leading up to December.
That's my plan - radio on, dancing in the street!
Not my street of course, don't want the neighbors to video me.

Unfortunately my SG II is older and not yet updated, so I don't have ready access to the SOC and amps. Maybe a few times "accidently" leaving my parking lights on will do it. The lights now don't stay on long after closing the doors as it is.

 

[Finnster]

I don't have the tools to see 12V SOC on my 25XL 4Ktow hybrid.
"But I can tell you that my 2025 Maverick also doesn't respond to ANY of the hacks that are working on 22-24 hybrids!"

Yeah. That was a lie!
This am. I ran a Highway run test @ 70mph, @ 63F.
I hit the highway five minutes after disconnecting my Noco 1 - battery fully charged.

At start of the run (DRL's on) my power point Voltage "supplied" meter was holding the same 14.3V that it has been showing in Run Mode recently.
At the 5 mile mark, the PP Voltage suddenly dropped to 12.9V, and then slowly dropped to 12.7V.

I turned on the headlights - Immediate 14.3 V!
Parking lights - same thing!
The hacks definitely induce increased battery charge rate. I didn't need to test further.

I also measured my gas mileage on this run,
34.7mpg average on the 36 mile 2-way run.
This is the recorded gas mileage from the "Economy" screen on drivers display. All data was captured with Vehicle @70mph. CC on, Normal mode, no hypermileing.

I apologize for any disruption caused by my earlier posts!

 

[Mavster Mechanic]

Update:

100% battery charge for more than 60 consecutive days. No help from external charger. Only lamps on each drive.

 

[Master Blaster]

Update:

100% battery charge for more than 60 consecutive days. No help from external charger. Only lamps on each drive.

So, what are you doing that the rest of us are not? I have all updates and TSBs done, have a Motorcraft AGM battery about 6 months old in my 23 Hybrid, and always read 14.3V when charging and 12.1V a half hour after shutting it off. That's only a 70% charge on an AGM battery.

 

[SafetyGuy]

So, what are you doing that the rest of us are not? I have all updates and TSBs done, have a Motorcraft AGM battery about 6 months old in my 23 Hybrid, and always read 14.3V when charging and 12.1V a half hour after shutting it off. That's only a 70% charge on an AGM battery.

Good day

(I get the same 14.3 volts indicated on my voltmeter while driving...what changes here is the amperage level, which we can not see as easily).

But, I do see my charge level the next day when I check my battery with my voltage tester...I pop my hood when I get home so I can check the charge level at the boost points with out waking the truck up again.

I have a tail led light in my Hitch receiver and it is plugged into my 4 pin trailer socket. My battery is always above 12.8 volts every morning after I have driven the day before....no more over and under charging my battery!

@Mavster Mechanic has been monitoring his 12 volt electrical charge state and has concluded that whenever you drive, either:

1-Turn on your headlights,

2-Turn on your park lights, or

3-plug in a tail ight into your trailer power receptacle (either one if you have a tow pkg).

These three things seem to turn a swith on in the truck so that it charges your 12 volt battery properly!


It is my thought that everyone should also try to get their truck to do a battery relearn to know what a fully charged battery is by carrying out a full battery recharge with a smart charge (at least 4-5 amps).

Not a quick surface charge, but a proper full charge and then disconnect the charger, lock the truck up and leave it for 9 hours...may take several tries to get the truck to do a relearn, but is worth it.

Combine that with one of the three items mentioned above, it may help you with your seriously undercharged battery!

I hope this helps, it works for me.

Andy

Edit to add agm charge chart

 

[HeyBales]

So, what are you doing that the rest of us are not? I have all updates and TSBs done, have a Motorcraft AGM battery about 6 months old in my 23 Hybrid, and always read 14.3V when charging and 12.1V a half hour after shutting it off. That's only a 70% charge on an AGM battery.

He started this testing/solution with a new battery.

As Finnster tested with a just charged battery.

Battery has to be in good enough shape the BMS is even willing to attempt 92% SOC and reach it.

I wouldn't be shocked if Finnster's battery can't hold that charge level.
Sounds like it was NOT above 92% SOC despite just having been on charger - or he would not have had to wait 5 min for the effect of the BMS dropping voltage thinking it reached 92% SOC.
So that calculated SOC% not being based on voltage during charging - I'm betting his resting is 12.4/.5.

Yours is probably below 12.1 V - do you have no battery saver things being seen?
But I think the BMS system looks at voltage some hours after turnoff to get decently accurate figure.
So even off a charger, yours may not get up to the level of 92% SOC for the effect to be possible.

 

[HeyBales]

Good day

(I get the same 14.3 volts indicated on my voltmeter while driving...what changes here is the amperage level, which we can not see as easily).

But, I do see my charge level the next day when I check my battery with my voltage tester...I pop my hood when I get home so I can check the charge level at the boost points with out waking the truck up again.

I have a tail led light in my Hitch receiver and it is plugged into my 4 pin trailer socket. My battery is always above 12.8 volts every morning after I have driven the day before....no more over and under charging my battery!

@Mavster Mechanic has been monitoring his 12 volt electrical charge state and has concluded that whenever you drive, either:

1-Turn on your headlights,

2-Turn on your park lights, or

3-plug in a tail ight into your trailer power receptacle (either one if you have a tow pkg).

These three things seem to turn a swith on in the truck so that it charges your 12 volt battery properly!


It is my thought that everyone should also try to get their truck to do a battery relearn to know what a fully charged battery is by carrying out a full battery recharge with a smart charge (at least 4-5 amps).

Not a quick surface charge, but a proper full charge and then disconnect the charger, lock the truck up and leave it for 9 hours...may take several tries to get the truck to do a relearn, but is worth it.

Combine that with one of the three items mentioned above, it may help you with your seriously undercharged battery!

I hope this helps, it works for me.

Andy

Edit to add agm charge chart

Since 25/26 have battery spec's that are entered - that relearn is probably a resistance test to decide how much it can charge safely as battery ages. Maybe an amp test to see how close it is to the logged values of new battery.
Or maybe Ford realized that for a user-replaceable item - very few are going to correctly take truck into dealer just to have battery specs entered, and it relearns the same as pre-25's.

It would be interesting if possible to compare the battery PID's for Ah and CCA and CA on new battery, to a year down the road, to see if the BMS adjusts them there, or another location.
I'm betting another location, due to the fact it already has that on pre-25's.

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