Bad 12V battery after 3 years

[Jmitchelltfo]

I imagine that the BMS is using the voltage reading of both batteries combined to evaluate SOC. (rather than one battery or the other)

It's just that with the LFP Auxiliary battery having the influence it appears to have on raising the resting voltage of the 2 batteries combined, the BMS sees 13.25V. Since it's programmed with AGM voltage expectations, that's enough voltage to rank as 100%. ??

I'd like to hear @HammaMan give his explanation, since I am just shooting from the hip in my basic understanding of such things.

So........
You and I need to put a couple of fire extinguishers under the passenger rear storage compartment? ???

I always have a fire extinguisher in my vehicles......good to go there

I agree that that the parallel setup does raise the voltage (just a bit), which is what was intended. I didn't actually think I had bad auxiliary battery. I knew I had spent too much time with the doors open listening to the stereo and it got extremely cold that same night. I wanted to add a battery for some extra head room, and having some store credit at batteries plus made the decision easy on a battery with a 10-year warranty.

It amazed me how many people wanted to jump on me for charging the LFP and the AGM with "an alternator that isn't designed for that".

I don't think any of them even had a clue that the Powerboost has a DC/DC charger instead of a traditional alternator. Thats ok, I'll just read about the issues of the masses that can't use the search function to figure out why their dash it lit up like Rockefeller Center during Christmas!

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[CoolDuDe919]

I imagine that the BMS is using the voltage reading of both batteries combined to evaluate SOC. (rather than one battery or the other)

It's just that with the LFP Auxiliary battery having the influence it appears to have on raising the resting voltage of the 2 batteries combined, the BMS sees 13.25V. Since it's programmed with AGM voltage expectations, that's enough voltage to rank as 100%. ??

I'd like to hear @HammaMan give his explanation, since I am just shooting from the hip in my basic understanding of such things.

So........
You and I need to put a couple of fire extinguishers under the passenger rear storage compartment? ???

So i went for around a 25min drive (city, so plenty of hybrid time) and got back, and after 5 min started checking the battery voltage a few times with my multimeter.

Over a period of 20 minutes, it started around 12.7x and ended up at 12.95v. This was hood up, unlocked, and i was sure to keep my keys away since i have approach detection on.

Just some quick data until i get the bluetooth monitor. Not sure if i had waited longer to check if i would have ended up at the 13.1-13.2v range you guys see?

Not sure the full sleep time for all modules and if being unlocked vs locked makes a difference.

 

[Borchelt]

A lot has to do with how much your truck runs on eco, / battery. When they run on battery they are not charging. My truck just did this last week, I noticed that my interior lights were not coming on, researched it and a few posts said just put a charger on it over night. I did that and so far, so good. I may just do that once a month because I do a lot of city driving, not many times does truck run with motor for more than 10 minutes at at a time. Time will tell.

You can also bump the fan speed to 5. Sounds weird I know but it works. Put a volt meter on the battery and watch it go from 12.3 to 14.5 charging. Don't know why the electronics are set up this way.

 

[Jmitchelltfo]

You can also bump the fan speed to 5. Sounds weird I know but it works. Put a volt meter on the battery and watch it go from 12.3 to 14.5 charging. Don't know why the electronics are set up this way.

My pickup received an OTA update a couple weeks ago, I don’t see any change in charge voltage due to fan speed anymore.

Mine sits at 14.4-15.0 volts on the low voltage set point, no matter what.

I think Ford might be on the right path to figuring out a permanent fix……..I’d like to think so anyway.

 

[Snakebitten]

My pickup received an OTA update a couple weeks ago, I don’t see any change in charge voltage due to fan speed anymore.

Mine sits at 14.4-15.0 volts on the low voltage set point, no matter what.

I think Ford might be on the right path to figuring out a permanent fix……..I’d like to think so anyway.

If the charging voltage is 14.4 or higher, then there's no need for the fanspeed hack. It's that darn 12.7v charging voltage, when the SOC is already down in the low 80's, that calls for the trick.

Good to hear Ford is raising the bar some.

 

[Gros Ventre]

I always have a fire extinguisher in my vehicles......good to go there

I agree that that the parallel setup does raise the voltage (just a bit), which is what was intended. I didn't actually think I had bad auxiliary battery. I knew I had spent too much time with the doors open listening to the stereo and it got extremely cold that same night. I wanted to add a battery for some extra head room, and having some store credit at batteries plus made the decision easy on a battery with a 10-year warranty.

It amazed me how many people wanted to jump on me for charging the LFP and the AGM with "an alternator that isn't designed for that".

I don't think any of them even had a clue that the Powerboost has a DC/DC charger instead of a traditional alternator. Thats ok, I'll just read about the issues of the masses that can't use the search function to figure out why their dash it lit up like Rockefeller Center during Christmas!

The rise in voltage, "a bit" as you note, is only there because with two batteries in parallel, the current draw is now half to one and half to the other. Thus the voltage drop from internal resistance in each battery is lower (a bit!).

 

[SnareDrum]

I got a little over 1 year out of mine.

 

[HammaMan]

No fire risk with LFP/AGM on the same voltage bus. Even w/ the fan 5 trick when the truck doesn't see any amperage going into the batteries it throttles down to 14.2v. If the LFP's BMS senses a cell at its peak voltage it will turn off charging. Over charging an unprotected LFP will just end up damaging it. They don't go into thermal runaway like other chemistries do. They just loose capacity when charged frozen or over volted.

Pretty sad, you don't even have to google things today, just go ask ai. They'll even direct you to the studies to read the data yourself.

 

[JohnMcClane]

Mine is 2.5 years old, we will be returning from a 2 week trip abroad Thursday morning and it was subjected to subzero temperatures during that period, I suspect it will be deader than Hans when we get back at 6 in the morning.

 

[Kodiak]

My 2022 just had an OTA update last week too. It would be good to see if the charge rate was addressed so I do not have to use the "Fan On 5" method. It is easy enough to do but I also have to fiddle with the temp when I do this.

It would be nice to get back to "set it and forget it" for us short distance, infrequent drivers.

 

[MJG44]

My '22 battery just bit the dust.
Has given me the save battery mode for some time.
I haven't driven it for a couple weeks and tried yesterday and now totally pooched. I'm sure I could boost the truck and see if I can try to salvage it but nah, I'll grab an H8 this week.

 

[hatallica]

Throw in the fuel economy-software controlled strategy to NOT just dumb-charge the battery everytime you start the vehicle?

Pretty sure that this is what is killing me right now. Short commute, electric-only miles, and engine off at red lights. Sustained sub-freezing temperatures finally exposed electrical snafus. Unable to connect via the app. The audible tones changed. Measured 11.9V at the terminals before trickle charging.

It is sad that so much work went into making this system perform so poorly.

 

[HammaMan]

Pretty sure that this is what is killing me right now. Short commute, electric-only miles, and engine off at red lights. Sustained sub-freezing temperatures finally exposed electrical snafus. Unable to connect via the app. The audible tones changed. Measured 11.9V at the terminals before trickle charging.

It is sad that so much work went into making this system perform so poorly.

Engine state irrelevant. These could be remedied by making the charging profile more spicy. Furthermore I believe the BMS is taking into account an inferred batt temp which won't feed it the spicy electrons as much. Colder batteries have lower max voltage charging points.

Furthermore the PB could also change its HVB strategy to use a few percentage points of the HVB to leave the DC/DC on and put a little more juice into the AGM.

 

[hatallica]

Engine state irrelevant.

I am still readjusting my thinking, as old models just don't work. Looking at the shop manual and seeing phrases about driving for hours to recharge a cold battery just deepens my sadness.

If I have to routinely connect a charger, then do I have a plug-in hybrid?

 

[Jmitchelltfo]

If I have to routinely connect a charger, then do I have a plug-in hybrid?

I'm not sure if this was tongue in cheek or not.......but either way, well played sir!

There are ways to fix it if you want to go that route. You just need to step over to the dark side of LFP for your auxiliary battery.

We don't have snacks or Kool-Aid to offer, but the voltage is high enough to keep the welcome lights on.

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