Replacing the Hybrid's OEM 12v. Battery

[MakinDoForNow]

i'll be testing this theory this afternoon. 5900 miles. charged to full last friday. drove 75m each day mon and tues. had all interior lights mon morning. idr tues morning. deep sleep msg at 2am wed morn. bricked this morning. been on the noco5 for 5 hours and still on the first red led. going to do my first jump after lunch and drive it to the dealer. fingers crossed.

5 hours is not long but if you start with first red light taking longer than 30 minutes (my experience) expect 3 days to charge not counting the optimization time. The high current will cause battery cool down times. The regular 20 hour estimate assumes battery is at 70% soc (11.5+/- volts?). I am going to guess you have 1 or 2 bad cells.

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[SafetyGuy]

Question: this portion of the manual says "if equiped" with the BMS. Which Mavericks have BMS, and which don't? I have 2023 Hybrid XLT.

I don't have the reference immediately at hand, but from what I remember most or all Fords since (2011?) have had a BMS system with upgrades to it since then.

So, I believe all our Mavericks have a BMS.

I will go look for a reference and will include it here when I find it.

Andy

 

[SafetyGuy]

Question: this portion of the manual says "if equiped" with the BMS. Which Mavericks have BMS, and which don't? I have 2023 Hybrid XLT.

Okay, I only have my 2025 Maverick Manual, not your year but I would imagine they are pretty close in page references.

Take a look at the my page below, and it directly gives direction as to BMS management, this shows me mine has a BMS.

In your manual as you have a hybrid as well, it should say the same thing, though the page number may differ.

The Eco-Boost directive is just above the Hybrid information....for anyone wondering about their truck as well.

I hope this helps,

Andy

 

[DS_Ohio]

5 hours is not long but if you start with first red light taking longer than 30 minutes (my experience) expect 3 days to charge not counting the optimization time. The high current will cause battery cool down times. The regular 20 hour estimate assumes battery is at 70% soc (11.5+/- volts?). I am going to guess you have 1 or 2 bad cells.

6 hours charging now, still on the first red led. but it somehow managed to find enough juice somewhere to send me a 'entered deep sleep message' in the ford app just now

 

[HeyBales]

i'll be testing this theory this afternoon. 5900 miles. charged to full last friday. drove 75m each day mon and tues. had all interior lights mon morning. idr tues morning. deep sleep msg at 2am wed morn. bricked this morning. been on the noco5 for 5 hours and still on the first red led. going to do my first jump after lunch and drive it to the dealer. fingers crossed.

That sounds more like an intermittent parasitic drain.
You got the alert as it was draining down.
And if that comes up again a few times - it'll kill a new battery.

Spell out what happened as far as full charge, long drives - dead in 1 night.
Don't let them chalk it up to "bad battery".
(never mind it was likely made "bad" by the charging strategy - but leave that out of it. 1 point at a time or you'll confuse them)
They should at least follow the SSM for the AC module software upgrade, in case that was it and hasn't been done yet.
As we enter more of AC season.

Also - they'll do the BS reset, but you'll have to do the sit locked 9 hrs for BMS Relearn.
Suggest you top off the charge for a few hours before that.

 

[HeyBales]

Okay, I only have my 2025 Maverick Manual, not your year but I would imagine they are pretty close in page references.

Take a look at the my page below, and it directly gives direction as to BMS management, this shows me mine has a BMS.

In your manual as you have a hybrid as well, it should say the same thing, though the page number may differ.

The Eco-Boost directive is just above the Hybrid information....for anyone wondering about their truck as well.

I hope this helps,

Andy

That wording in the manual started with the 25MY hybrid, and has always been there for the EB's.
There is no such indication of battery info entered for the pre-25MY hybrid, in the manual. In fact the BCM PID's show no info entered, empty choices.

They all have the BMS, unless there were some very early builds that left it out - betting the BCM got the upgrade to include it though, and that was probably the EB's.

 

[MakinDoForNow]

6 hours charging now, still on the first red led. but it somehow managed to find enough juice somewhere to send me a 'entered deep sleep message' in the ford app just now

The noco is furnishing up to 5 amps. So the truck borrows what it needs from that. This is why a maintainer of at least 4 amps is recommended to charge the 12v. If you used a 2 amp charger it might take a week of one red light.

 

[DS_Ohio]

The noco is furnishing up to 5 amps. So the truck borrows what it needs from that. This is why a maintainer of at least 4 amps is recommended to charge the 12v. If you used a 2 amp charger it might take a week of one red light.

i top off my not-daily drivers on the 1st of the month. i topped off the mav 4/17 as i planned to drive it mon the 20th. it was solid standing green after a couple of hours. i moved it from underhood to the battery directly and it went to solid green in about 3 or 4 minutes. it should not have been flat this morning, that's why i was chuckling over the hours-long red led, that's all. i got that single red on my mower battery last month and after 3 days, the noco just turned off. that battery was 9 years old.

i got one of the plug in voltmeters from amazon last week, so i was curious to see what it showed. something like 15.05 to 14.98 mon and tues both days, both ways, night and day. i didn't try to start it on it's own this afternoon, i jumped it and went to the dealer. voltmeter read 12.82. turned on my headlights and it went to 15.00 turned off headlights, back to 12.82. interesting. service writer said something about a trailer module update, but nothing else was tardy as far as recalls. IDK. gut says battery is fragged. if i get a new battery i will pay lots more attention to mavster's observations about charging the battery.

 

[HeyBales]

The AC module update is NOT a recall.
It's an SSM - if you have what appears to be an intermittent drain (is once intermittent yet?) - the update is the given solution.
With a current warning it may not be the only possible drain to be found.

Sounds like you got the battery totally charged high enough, with those volt changes.
Hopefully they can do the load test immediately - but probably will hold it overnight to see if it drops voltage anyway - then test.

If battery is in good state (your charging may have helped), one drain may not have ruined it, and they'll say no problem.
Still request the ACCM update because of what did occur.
That way if it happens again - you got the one known causes out of the way - they can move on to next investigation.
Intermittent though - tough to find.

 

[DS_Ohio]

The AC module update is NOT a recall.
It's an SSM - if you have what appears to be an intermittent drain (is once intermittent yet?) - the update is the given solution.
With a current warning it may not be the only possible drain to be found.

Sounds like you got the battery totally charged high enough, with those volt changes.
Hopefully they can do the load test immediately - but probably will hold it overnight to see if it drops voltage anyway - then test.

If battery is in good state (your charging may have helped), one drain may not have ruined it, and they'll say no problem.
Still request the ACCM update because of what did occur.
That way if it happens again - you got the one known causes out of the way - they can move on to next investigation.
Intermittent though - tough to find.

i just texted a request for it, thanks. the service rep texted me late last afternoon that the state of health of the battery was 8% and would get back to me, with Rotunda results.

 

[HeyBales]

i just texted a request for it, thanks. the service rep texted me late last afternoon that the state of health of the battery was 8% and would get back to me, with Rotunda results.

Talk about not holding a charge!
feed me, feed me - puke

So that was likely the simple test, which it seems more report false positives on, and later the Rotunda results show it actually was bad. Look forward to your new AGM!
I think they measure resistance too, I seem to recall a post printout that had that on it.
That could have been terrible too. You should request that, even if for a replaced battery.
I know my 8 month old OEM battery (but was 1 yr since manufacture) resistance was worse than my Rav4's 6 yr old battery, using my tester.
Pretty sure the BMS system takes that into account for deciding some charge levels to use, since I've logged differences.

 

[DS_Ohio]

Talk about not holding a charge!
feed me, feed me - puke

So that was likely the simple test, which it seems more report false positives on, and later the Rotunda results show it actually was bad. Look forward to your new AGM!
I think they measure resistance too, I seem to recall a post printout that had that on it.
That could have been terrible too. You should request that, even if for a replaced battery.
I know my 8 month old OEM battery (but was 1 yr since manufacture) resistance was worse than my Rav4's 6 yr old battery, using my tester.
Pretty sure the BMS system takes that into account for deciding some charge levels to use, since I've logged differences.

I haven't heard about the rotunda testing results, but the rep said SSM 53801 'doesn't show anymore'. They're going to go after SSM 54632 now. i guess since ford couldn't correct the ACCM software, they're going after the ABS software now. '....update expected to be available in late Q2 of 2026'

it's like deja vu all over again, i tell ya'

 

[DS_Ohio]

Just got a text my battery passed the Rotunda test. i'll pick it up this evening.

 

[doug maverick]

Just got a text my battery passed the Rotunda test. i'll pick it up this evening.

I still haven't figured out what the Rotunda test is.

 

[MakinDoForNow]

I still haven't figured out what the Rotunda test is.

I am assuming that is the test they do when they keep the truck overnight. Seems like it takes several hours. @Darryl should know.

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