2024 having 12v low voltage battery issues with my Hybrid...

[Bruce W]

As best I can explain the BMS issue is this. First off the BMS if it is the same as the ecoboost engines should be the black box on the negative cable right before the battery terminal connector. It will also have sensor connector and wire which among other things allows it to talk to the BCM module. With the information it monitors i.e. current, voltage and voltage temp it passes that along to the BCM which uses that to determine the battery's charge state whether it is 100%, 90% etc. Now if the current from a charge goes around it on the terminal the BCM can't update that correctly. If that state got too low and it started soft offing circuits like the dome lights even if you do charge the battery it will still keep doing it. The BCM has no way of knowing otherwise. If it keeps doing that eventually even though the battery maybe charged it will think it is at a low enough level that hard off's start like permanent shut off of the auto start/stop system which can only be reneabled by reseting the BMS.

That is why the negative has to be connected somewhere before the BMS sensor not behind it when charging. The surefire way to fix that is to get the BCM to relearn the battery's charge status and in turn recalculate the battery's life. The only 2 ways I know that it does is when you change the battery or you reset the BMS.

Won’t the BMS reset by itself after a few days of driving?

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[Bruce W]

Thanks for all the great info…
If I understand this correctly the AGM can better handle being in a low state of charge and recover slightly faster than a Flooded battery.
This to me just means that it might last a little longer before it take a shit as well..
Without a way of other than an outside charging device (IE a battery charger) as others have done to there trucks there is no way we’re going to keep the battery at a good SOC…
Its apparent that Ford is not doing anything to correct this issue as it’s been going on for 3 years now… I know some have changed the charge parameters with Forscan but that is just another band-aide just like adding a remote changing system…
It appears to me we have a fake plug in hybrid… Not one that plugs in to recharge the hybrid battery but one that needs to recharge the 12v battery…

Just have to live with frequent charger episodes. A parts store employee said many newer vehicles of all makes and models have the same problem. The industry needs to move to a higher voltage, more robust electric systems on all vehicles.

 

[HSBII]

Just have to live with frequent charger episodes. A parts store employee said many newer vehicles of all makes and models have the same problem. The industry needs to move to a higher voltage, more robust electric systems on all vehicles.

Or simply add a tried and true conventional charging system for the 12v side….

 

[Darnon]

The clicking is totally normal (if slightly disconcerting at first).
If you're driving only 5 miles a day, you're probably on electric for much of the drive. Depending on a few other factors, the truck probably won't charge the 12v much if at all while in electric mode.
You might try driving it in Sport mode once every couple days to force the ICE to run more. Or try taking an occasional longer drive, with some higher speeds, again so the ICE gets the HVB to a higher state of charge. That should make the truck more willing to charge the 12v since it's not worrying about the HVB.
The whole charging thing is complex and computer driven and is trying to solve a bunch of things simultaneously. Like most software, it sometimes makes mistakes (or more charitably has sub-optimal results for one of the goals).

What driving state the vehicle in has no effect on the DC/DC converter output.

 

[Bill K]

Seek the simple solution. You may not be driving enough highway miles w ice to keep the battery charged. (Assuming the battery is good.)
That was my issue.

 

[Timothyd]

Have you tested it against a multi-meter from the plug?
Mine reads 0.2 higher than MM or PID for it. Just started using it.

That 0.2 makes a difference. This morning was 11.8.
Initially thought in good range though bottom.
Then started truck and saw 15.0 and realized no it was 11.6, under good range, no wonder it's maxing out the charging at 14.8.

Haven't tested it with my Fluke but I'm after the consistency. So, if it's off from 14.8 running and 12.5 not running I know somethings off and I can start troubleshooting. Catch something early.

 

[Hdscreens]

If battery is pulled out to fully test can a ford dealer do the same and replace on the spot if battery is bad without even taking vehicle to dealer?

First off just get it tested at an auto parts store, they usually will do it for free. That will rule out the battery being bad.

As far as your electrical mods goes did you wire in the negative connections directly to the battery terminal or somewhere further up?

As far as you charging the battery that is user error and causing some of the issues after the first problem popped up. I'll explain in separate post why but the short answer is you need to charge the battery so current goes through the BMS sensor not behind it. The negative needs to be connected to a chassis ground or engine block. To correct what you do is reset the BMS and let the BCM then relearn the battery's charge status which requires the truck be key off, doors locked for about 8 hours, page 311 in the owners manual explains how to do it manually.

 

[HeyBales]

Seek the simple solution. You may not be driving enough highway miles w ice to keep the battery charged. (Assuming the battery is good.)
That was my issue.

Oh hybrid - battery doesn't charge from the ICE directly - so running or not doesn't matter.
It charges from the HVB.

Which if you stop and park with it running HVB SOC around 60% - I've sat for good 20 min while it dropped to 30% and finally ran the engine - the whole time charging up the car battery to 65% SOC. And my phone. Tad difference there of course.

 

[HeyBales]

If battery is pulled out to fully test can a ford dealer do the same and replace on the spot if battery is bad without even taking vehicle to dealer?

"ford dealer do the same" - yes
"replace on the spot if battery is bad" - could
"without even taking vehicle to dealer" - I'm betting that depends on dealer - they probably don't want to throw a "good" new battery (in relative terms) as a solution to a truck that could have an issue killing batteries. Well, sooner than they seem to be at least. And then just have it come back again.

 

[Matso]

RevHart mentioned a "battery stratification", does anyone have an idea of what that is?

 

[Matso]

So regarding battery stratification, It sounded like a process to correct a problem. It's actually a condition where heavier acid settles to the bottom of a battery in the electrolyte solution. So maybe take it out once in a while and shake it up like a can of paint? Let's give it a shot.

 

[MakinDoForNow]

Have you tested it against a multi-meter from the plug?
Mine reads 0.2 higher than MM or PID for it. Just started using it.

That 0.2 makes a difference. This morning was 11.8.
Initially thought in good range though bottom.
Then started truck and saw 15.0 and realized no it was 11.6, under good range, no wonder it's maxing out the charging at 14.8.

When ambient temps get below 30°F when you start truck you will see increases in the voltage, most I've seen around 20°F is 15.6. the dcdc converter needs more volts to deliver the amperage.

 

[MakinDoForNow]

So regarding battery stratification, It sounded like a process to correct a problem. It's actually a condition where heavier acid settles to the bottom of a battery in the electrolyte solution. So maybe take it out once in a while and shake it up like a can of paint? Let's give it a shot.

Stratification is one of the reasons I put my Noco g5 maintainer for several days every 2-3 months. After charging it will go into maintenance mode and slowly blink. Maintenance mode will check periodically and top off battery then desulfate/destratify. Due to the drain on battery it can do this for several days. Not sure how stratification is handled physically. I have seen no dome lights three times in 30 months and immediately left my hybrid in ready to drive for an hour or so or put my noco on it.

 

[HoustonAreaHybrid]

My battery failed the load test two months after I picked up my truck. I drive 60 mi/day, but dealer said they're just seeing more bad batteries right out of the factory and not just for the Maverick. I've had the new one they put in for 6 weeks. We'll see how long it lasts.

 

[Matso]

I sure hope that works out for you. What I didn't disclose in the latest thread was I did have my factory battery replaced under warranty about 3 months ago. It took some convincing. Unfortunately that has not remedied the problem.

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