15.2v charging seems a bit high while driving

[Builder]

I've been keeping up with the extensive discussions regarding the Hybrid Mav 12v battery issues. My Hybrid Lariat Mav was built 10/5/23 and I took delivery in mid November. Love this truck!!! No deep sleep issues/notifications so far but I decided to plug a well rated system voltage monitor into the lower center dash 12v socket. The voltage reads a consistent 15.2v while driving and 12.3v at rest. When I put my Noco Genius5 on the battery, it shows a full charge. The 15.2v seems rather high and does not change whether I have the heated seats and heated steering wheel turned on or off. I drive the Mav about 5 times a week but, typically at distances <20 miles. This seems like a rather high charge rate for a 12v system and a recipe for a short battery life or other unknown issues ..... thoughts??

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[fossil]

I've been keeping up with the extensive discussions regarding the Hybrid Mav 12v battery issues. My Hybrid Lariat Mav was built 10/5/23 and I took delivery in mid November. Love this truck!!! No deep sleep issues/notifications so far but I decided to plug a well rated system voltage monitor into the lower center dash 12v socket. The voltage reads a consistent 15.2v while driving and 12.3v at rest. When I put my Noco Genius5 on the battery, it shows a full charge. The 15.2v seems rather high and does not change whether I have the heated seats and heated steering wheel turned on or off. I drive the Mav about 5 times a week but, typically at distances <20 miles. This seems like a rather high charge rate for a 12v system and a recipe for a short battery life or other unknown issues ..... thoughts??

I see the same voltage on mine. 2.0L AGM batteries do take a higher charge voltage to operate.
My plug in charger runs .6-.7V higher than my old Battery Tender when in AGM mode.

 

[papak]

I have noted pretty much the same thing. I have 8k on mine now with no issues. Guess I'll just roll with it.

 

[huunvubu]

I've been keeping up with the extensive discussions regarding the Hybrid Mav 12v battery issues. My Hybrid Lariat Mav was built 10/5/23 and I took delivery in mid November. Love this truck!!! No deep sleep issues/notifications so far but I decided to plug a well rated system voltage monitor into the lower center dash 12v socket. The voltage reads a consistent 15.2v while driving and 12.3v at rest. When I put my Noco Genius5 on the battery, it shows a full charge. The 15.2v seems rather high and does not change whether I have the heated seats and heated steering wheel turned on or off. I drive the Mav about 5 times a week but, typically at distances <20 miles. This seems like a rather high charge rate for a 12v system and a recipe for a short battery life or other unknown issues ..... thoughts??

You are not seeing 15.2V charging. The 12V Battery is not constantly being charged.

What you are seeing is the HV battery "DC-to-DC converter voltage" that powers the low voltage stuff.

The BMS that charges the 12V battery will charge from the "DC-to-DC converter voltage" if and when needed.

 

[Darnon]

You are not seeing 15.2V charging. The 12V Battery is not constantly being charged.

What you are seeing is the HV battery "DC-to-DC converter voltage" that powers the low voltage stuff.

The BMS that charges the 12V battery will charge from the "DC-to-DC converter voltage" if and when needed.

That's the actual power the battery is seeing. There's no other voltage control element between the DC-DC converter output and the battery positive.

 

[mav47]

The stock battery in the Hybrid is a flooded cell battery, NOT an AGM, even though the settings in the vehicle are supposedly for an AGM battery. Note that comparable Toyota planetary gear hybrids all come standard with AGM batteries.

Word is that Ford has been unable to source enough AGM batteries, so they ended up putting flooded batteries in the Maverick Hybrids. Or it was simply a matter of cost as I understand they're still putting flooded batteries in these trucks.

Lots of Hybrid owners have reported deep sleep trouble caused by under voltage, which supposedly goes away after replacing the stock battery with an AGM. This to me indicates that this vehicle should have had an AGM battery in the first place.

After getting some deep sleep messages I played a bit with ForScan and changed the settings for the BMS (battery management system) from 80% state of charge to 95% state of charge (SOC). The system voltages never changed. It didn't seem to make a difference: I still got the occasional deep sleep. Sometimes right after parking it after my 40 mile commute to work!

Similar to the OP, a few weeks ago I put a voltage meter display in that same 12V plug and I noticed the same: system voltages between 14.8 (rare) and 15.1 (most of the time). I've seen 15.2V too! That seemed wild to me.

So yesterday I bit the bullet and installed a new Group 140R AGM battery. I also reset the BMS. Note: the Group 140R is a straight drop in replacement battery for the Maverick Hybrid. Same size and shape as the stock Group 99R flooded battery.

As others reported when replacing their flooded battery with an AGM: the system voltage instantly dropped to more "normal" values well below 15V!

Edit 4: with a few hundred miles on this new battery I have been seeing voltages between 14.6-14.8, right after startup and then after a while it drops down to 13.0V. Occasionally it will charge for a longer time steadily at at 14.6V. Seems to me that all is well.

Edit 7, nine months, and about 18,000 miles later: Indeed, the random deep sleep issues are completely gone, and the system voltages stay between 14.6 and 14.8V, dropping to 13.0V once the battery reaches its target SOC.


Here's what I think happens on these Hybrids:

1) My abused (chronically undercharged) OEM flooded battery likely has too high an internal resistance, which means that it will accept fewer charging amps at any given voltage. This battery was probably always below its target SOC and the BMS tries to bring the SOC up by feeding it charging current, and it raises the voltage to get there (north of 15.0V). Essentially the BMS was ALWAYS charging the battery but never quite get there, and that's exactly what I observed: voltages always showing between 14.9 and 15.2V, while still too low for a solid charging current to get the battery up to the required SOC.

2) The new AGM battery has a much lower internal resistance (lower even than a brand new flooded battery), and will take a significant charging current already at much more "normal" voltages: I'm typically seeing 14.6-14.8 when it is charging. Once the BMS determines the battery has reached the required SOC level, it drops the system voltage to 13.0V which means the battery does not charge anymore.

Again: this vehicle should have had an AGM battery in the first place.

I've had ONE occasion where the truck reported going to deep-sleep, and that was after being parked for 16 days while we were on a family vacation. I consider that fine as that's what this deep sleep feature is for. Interestingly: when I first turned on the truck after 19 days it started charging at 15.2V for the first 10 min or so, then dropped to its normal 14.6-14.8V. That was the only time I've ever seen over 15V on the system with this AGM battery , and must have been due to a lower than normal SOC.

To anyone with similar problems (deep sleep and/or occasionally even not starting): put in a Group 140R AGM battery. Simply replacing the FLA battery with an AGM pretty much solves the issues.

 

[Storm Ranger]

Mav47, keep us posted on how the AMG battery does. I plan to replace my hybrid battery with a AMG when needed. Can you share the AMG battery model you purchased?

 

[Montana]

That's what I see with my EB and it does not have the AGM battery (yet).

 

[Chris_G]

Amazon will deliver my AGM battery tomorrow

 

[huunvubu]

That's the actual power the battery is seeing. There's no other voltage control element between the DC-DC converter output and the battery positive.

The BMS determines when the 12V Battery is charging. It is not a constantly charging.

When you see the 15.2V you cannot make the assumption that the BMS is charging the battery with that voltage.

 

[uga]

This AGM looks good according to others here on the forum :

https://www.rockauto.com/en/moreinfo.php?pk=8878472&cc=0&pt=2476&jsn=4

Curious, what AGM did you get mav47 ?

 

[MakinDoForNow]

I've been keeping up with the extensive discussions regarding the Hybrid Mav 12v battery issues. My Hybrid Lariat Mav was built 10/5/23 and I took delivery in mid November. Love this truck!!! No deep sleep issues/notifications so far but I decided to plug a well rated system voltage monitor into the lower center dash 12v socket. The voltage reads a consistent 15.2v while driving and 12.3v at rest. When I put my Noco Genius5 on the battery, it shows a full charge. The 15.2v seems rather high and does not change whether I have the heated seats and heated steering wheel turned on or off. I drive the Mav about 5 times a week but, typically at distances <20 miles. This seems like a rather high charge rate for a 12v system and a recipe for a short battery life or other unknown issues ..... thoughts??

My dash power point voltage shows 14.4 to as high as 15.6 when running. It appears that ambient temp plays a role as 14.8 generally above mid 80's, 15.1 at around 60 with 15.5 around 30. Rarely it will show 15.6 for very short period. Never showed over 15.2 until reprogram 23E09 and 23E07 were performed at the same time. Ambient temps dropped about same time those were done so it may have been that instead of a program change which caused the higher voltages. I believe that the bms program will adjust it's routine to allow for the higher voltage. Ford does claim it is an Enhanced flooded battery so I expect the plates and specific gravity of the acid are also designed to fit the usage. I am currently at 26k miles and 24 months with my lariat first edition hybrid. Never a deep sleep (don't have Ford pass on my phone but wife has it on hers and claims she has never seen it) but have had no dome light several times. After 18 months I finally put my noco genius 5 on Underwood posts

 

[BlueRaven]

my 22 xl eco awd charged between 15.2 to 13.5v. same so far with my 24 xlt eco awd. doesnt stay at over 14.9 much. im used to 14.6 being high, these new vehicles just like higher voltage. it is, what it is.

 

[CurtisB]

I have a flooded Diehard Gold T4 470 CCA 585CA that I put in 2 months ago. I have had 2 "sleep" notifications but after driving it, it goes away. I will most likely go the AGM route sometime this summer and be totally done with this. If the on-board computer system is configured for an AGM battery my flooded battery is doomed to fail.

 

[Bob The Builder]

It is too high. Conventional wisdom states that AGM batteries should be charged at 14.2 volts.

Last time I checked my Maverick was charging at 15.4V. My battery is still starting my truck with no issues at sub zero temps even though I believe the BMS is cooking my battery and the SOC never permits the A.S.S to work.

Almost same exact situation with my friends 2022 GMC Denali. We took it to the dealer to get his 2 year old battery replaced under warranty.

It is almost like these BMS do not have all the quirks worked out and we are the guinea pigs.

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