HYBRID 12V Battery Mystery SOLVED

[MakinDoForNow]

Just for clarity that's a battery sensor attached to the negative post, with wires going to the BdyCM which handles the BMS function.

While it obviously senses amps going both directions charging and discharging - it only logs in the BMS charging while key on.
I do have proof.

External charging as you would do with key off (I know videos show it being done with key on with FDRS connected reading it) - does not log or report any charge going into battery.
It only reads the discharge that happens with engine off, and during the sleep time.

That battery sensor is the same as any you buy off Amazon that has a shunt and is installed on the negative line, and reports the stats to a monitor. That monitor can be live only, or feed into an app, or have some memory ability to report later - depends on your price point.

Or you can get that other battery monitor that hooks to Pos & Neg and provides Volt readings. It can be decent, especially if it has settings for battery spec's.
It'll give that ability if you think something bad has been happening - to keep phone on outside of locked truck - and watch where the volts go for the 60-75 min.
Actually - you'll want a baseline as a good graph, compared to other times.
With memory option - it should show the hourly blips thru night as modem keeps connection up.

Do you have a tow package to have trailer wiring and Tow Module?
Or the 120V option to have inverter and whatever module supports that?

Price point less than $400 not a problem over could be considered. I have 2 hybrids both 2022's. Lariat has 4 pin trailer as well as 120v inverter. The second is xlt with lux pkg which includes 4 pin trailer and also 120v inverter. Do you know if the inverter 12v input is switched off at truck off time or 120v output is switched off separately;with 12v being on time delay?

Sponsored

 

[Nuclear One]

So you did both at the same time?

No, battery 1st but still had issues a few months later.....Upon deep investigation, I learned factory SOC is 80%. I bought an OBD Forscan interface on Amazon for $20, bought a 1yr license from Forscan for $10.....changed SOC to 95%.....zero issues for last 2 years......Dealer just want to replace batteries and/or charge them......Also alot of nice features you can turn on/off with Forscan and GUI on nav center ...(I am greeted with the ST logo when I get in my truck)

 

[Nuclear One]

No, battery 1st but still had issues a few months later.....Upon deep investigation, I learned factory SOC is 80%. I bought an OBD Forscan interface on Amazon for $20, bought a 1yr license from Forscan for $10.....changed SOC to 95%.....zero issues for last 2 years......Dealer just want to replace batteries and/or charge them......Also alot of nice features you can turn on/off with Forscan and GUI on nav center ...(I am greeted with the ST logo when I get in my truck)

 

[Glen Baker LLC]

There are times I wish I could understand how to use FORScan without screwing something up.
But then I'd have to go out and buy a laptop.

 

[Dad]

It depended on whether one had one built in. I believe it was towards the 70s and 80s when manufacturers started phasing them out from the mechanical ones to solid state to built in.

The point I was trying to make is electrical current is relative; like a light switch, it's on or off. The same with computers; their instructions are in the form of bits, 0 or 1. While there are so many things along its path from point A to point B, it still behaves the same in its raw form. No one has ever figured out how to harness it completely.

That's true. I used to repair computers and people were 'shocked' (see what i did there?) when I would tell them their computer relied on magnetism and having those 1's and 0's lined up properly.

 

[Dad]

There are times I wish I could understand how to use FORScan without screwing something up.
But then I'd have to go out and buy a laptop.

I'm in your boat. FORScan only runs on Windows (there's an iOS version, but it's only diagnostic). I don't have a Windows computer. I borrowed my brother-in-law's, but it would shut down intermittently . . . worse than useless. Still looking to borrow one. Someone needs to tell the FORScan people there's another computer platform in the marketplace. Sheesh.

 

[bglinks]

Watch this video.

12.x volts and discharging to 14.x volts and charging. All I did was manually turn on my headlamps.

Watch this video.

12.x volts and discharging to 14.x volts and charging. All I did was manually turn on my headlamps.

 

[bglinks]

I'm new here, and I would like to know how to get to the screen that shows the battery charging information. Thanks.

 

[Master Blaster]

I'm new here, and I would like to know how to get to the screen that shows the battery charging information. Thanks.

There isn't one. That's a third-party app and hardware that plugs into the OBD2 port.

 

[scotty]

Some of you will laugh.
Some of you will cry.
Some of you will say "Holy Crap that's amazing!"
Some of you will say "Holy Crap that's dumb."

Here goes.

Fact: 2022 Hybrid (and others) actively drain a 12 volt battery to the computed 80% charge level.
Then do not try to add charge to the 12 volt battery until a computed 60% or lower charge is reached. God only knows why.
For 3.5 years my 12v battery has been "maintained" at about 60% charged. Always a resting voltage of 12.1 or 12.2.

Fact: running your headlamps will force the 12v battery to be 100% charged given enough time. (DRL will not do it. Parking Lamps only will do it.)

Fact: running your vents blower at speed 6 or 7 will force the 12v battery to be charged to 100% given enough time.

Fact: attaching a trailer, 4-pin or 7-pin will force charge the 12v battery to 100%.

Theory A: the truck needed to detect 12 volt demand, and above a certain wattage to trigger 12 volt charging.

Why would fan level 6 trigger battery recharging and fan level 5 would not? Why would full headlamps trigger battery recharging, but DRL would not?
Did the truck detect demand to run my camper fridge and coach battery?

I tested this last part. From Amazon I ordered a $10 LED brake light for the 2" hitch receiver with 4-pin connector.
Wow! The LED brake light pulling no power when not braking, and only 4 or 5 watts when braking DOES TRIGGER 12 volt battery recharging to 100%.
It's not the electrical demand that triggers recharging. It is simply thinking a trailer is there that triggers recharging.

Theory A shot down.

But this explains a lot.
This explains why some people have more 12v battery issues than others.

Those that drive at night a lot have more battery charging by happenstance.

Those that use fan speed 6 or 7 have more battery charging by happenstance.

Those who connect trailer wiring (and you don't even need a trailer!) have more battery charging.

Not a permanent fix. But a work around. Some of you may prefer running your headlamps more often over plugging into a home charger.

My 12v battery has been 100% for ten days in a row now. And is maintained at 12.7 or 12.8 volts. But I need to do one of the three "triggers" above or it rapidly starts to decline.

More to come...

This is great data and great critical thinking. Awesome desire for you to figure it out. Hope you slept well while researching, and trying different variables that were apart of your quest.

 

[MakinDoForNow]

@Mavster Mechanic
If you have oem 120v inverter could you check to see if a zero draw or low draw or intermittent draw would force 12v charging? Thanks in advance.
I may plug a USB charger with lit display light for a few days and then check my 12v.

 

[Mavster Mechanic]

@Mavster Mechanic
If you have oem 120v inverter could you check to see if a zero draw or low draw or intermittent draw would force 12v charging? Thanks in advance.
I may plug a USB charger with lit display light for a few days and then check my 12v.

Already did. See post #100.

 

[SafetyGuy]

Good day @Mavster Mechanic

Well, it is time for me to come back and let you know what I have been experiencing since you put forward that "an increased load on the 12 volt system seems to help the 12 volt battery charge level improve ".

I don't use or have the monitoring equipment you use of course, just my new 12 volt cigarette lighter/12 volt port voltage indicator.

This is the battery charge level upon arrival home today, truck turned off and door opened and closed to dump as much load as possible.

This is what my 12 volt battery charge level is now, when I turn on my headlights (during the day!), while we are out running errands!

Back at the end of December I spent a couple of weeks metering our battery...my charge levels upon returning home were much lower then they are now. I pulled out my notes today, just to confirm my thoughts.

In December in the same conditions, truck turned off, door opened and closed to dump any extra 12 volt loads as possible, and my battery would sit at 12.43 to 12.68...usually.

Now on the several drives we have taken, the battery voltage of our original AGM battery is consistently higher, so I am very happy!

Between everything I do, charging regularly (I may not need to do my monthly charging any more) and locking the truck up after charging in order to do a battery relearn, it is all working out quite nicely.

I again commend you for your work on this whole battery-not-charging-properly issue!

Andy

Edit

I should also add that since I have been charging my battery every month or so, before disconnecting and doing a battery relearn, that my voltage indicator shows my charge level while driving is usually between 15.1-15.35 volts.

That hasn't changed at all when I started to test the whole turning lights on when driving to increase the energy draw...it is my conclusion that the voltage stays where I already see it at but I believe the amperage has increased....resulting in the better 12 volt charge value I am seeing at shut down.

 

[bglinks]

There isn't one. That's a third-party app and hardware that plugs into the OBD2 port.

Ok, thanks for your help.

 

[Tall Hobbit]

Your cycle down to 12.x (12.8? if reading is correct) was probably when it was thinking a fully charged battery was obtained. So little to no charging amps.
That's when the test with fan @ 6 or headlights on would show the jump back to 14.x and more amps given.

But sounds like your battery has dropped below a SOC% limit now, and it's got no desire to do what Mavster has found.
Same as mine.

You have tow package & wires? (which means a tow module)
You have inverter and 120V option?

Cranking voltage - you mean it doesn't drop as much, it's staying higher during the relay engagement?
Of course that power point Voltage reading is inaccurate for compares after a charging session, like driving. Next start after that should be much higher probably.
Morning reading before going to On, that's a good point to keep noting, as that's a much more valid reading, even with slight draw with doors open and lights on.
I've noticed if I sit there until lights go off, then turn key to Accessory position - my reading is slightly higher. To your point of a bit of recovery.

Thanks for the lengthy reply. Well, now things are different -or perhaps they aren't...

But sounds like your battery has dropped below a SOC% limit now, and it's got no desire to do what Mavster has found.
Same as mine.

...just yesterday I was coming back from a 140mi highway drive, pulled off to run a quick errand, and upon restarting my cig monitor showed the obvious behavior where headlights, parking lights, and hi fan all made a noticeable boost in the voltage readout. Without these tricks, 12.x, but with them 14.x for the rest of the ride, pretty consistently. Then after 12+ hours parked and locked, on my commute today it was 14.x without the tricks. Yesterday is the only time I've proven the lights/fan settings influence the cig monitor readout at all. For me in all types of driving its 14.x all the way -except yesterday. Even the day before with the 140mi trip over, the tricks showed no effect in cig monitor. Therefore, I suppose when it reads 14.x without trying anything, there is not much to be gained in terms of voltage, only some esoteric amperage benefit, and (illusory?) startup voltages checking in acc before rolling.

No tow package, no hitch receiver even; haven't checked for tow wiring. No 120V AC inverter, strictly poverty edition + SIBL + Copilot 360. Never used a trickle charger/tender; never performed any BMS relearn/resets aside from always keeping it locked plenty of hours overnight. Never leaving it parked more than 2 days at a time either.

Morning acc voltages seem to be a bit higher after driving around with parking lights the day before, but we're talking points and not full numbers, so nothing dramatic.

edit: [the day before]

Sponsored