12V Battery FAQ

[Jerrytball]

It appears that this was finally "fixed." I'm seeing my HVB charge level now:

Wait a second this screenshot. Is it from the webpage on Ford or from FordPass because I thought if it was in the webpage this is your low-voltage battery not the big battery. I’m confused sorry.?

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[garyd9]

Wait a second this screenshot. Is it from the webpage on Ford or from FordPass because I thought if it was in the webpage this is your low-voltage battery not the big battery. I’m confused sorry.?

That's a snippet from the ford.com webpage. It's showing my HVB state of charge. That was the point of my post: Ford fixed/changed the website to show HVB SOC.

 

[zvez]

Wait a second this screenshot. Is it from the webpage on Ford or from FordPass because I thought if it was in the webpage this is your low-voltage battery not the big battery. I’m confused sorry.?

this is from the ford.com site, it just changed today, I checked mine as well and now it's the HVB percentage. FYI, an owner in Canada said ford canada still reads the 12v

 

[Jerrytball]

That's a snippet from the ford.com webpage. It's showing my HVB state of charge. That was the point of my post: Ford fixed/changed the website to show HVB SOC.

OK, I was just gonna say I just looked and my car is at the same 49% as it shows on the webpage, but I thought the whole idea was the low-voltage battery level was what was showing on the webpage before which was good that we know what the level was , Because last week my High voltage battery was 60% and my low-voltage battery according to the website was at 96% so I thought they wanted to show the low-voltage battery somewhere. I guess it changed now.
So I guess we have to use our scanner now to check the low-voltage battery?

 

[garyd9]

So I guess we have to use our scanner now to check the low-voltage battery?

yes. Unless you have some mechanism to access the API (such as a home assistant plugin, etc.)

 

[Homestead]

It would be so easy for Ford to put both 12V and HVB on that page. Come on Ford!

 

[SebastienMachE]

this is from the ford.com site, it just changed today, I checked mine as well and now it's the HVB percentage. FYI, an owner in Canada said ford canada still reads the 12v

I can confirm that in Canada, Ford.ca is now showing the HVB %SOC...

 

[Rudi Krupsdahl]

Please see this topic for ideas on what causes 12V drains: Thread 'Troubleshooting "Electrical System Drain Service Required" Message' Complete the checklist.

A 10% drain in the 2 hours after ignition off is normal. <4% per day drain after that if the car isn't disturbed. Note: waking the car up to check 12V status takes 2% each time.

Recommend you update the PCM and BCM software which should increase the 12V recharge threshold from 35% to 45%.

FYI NOCO chargers suffer from early charge termination, I do not recommend them. If you want to reach 100% SoC you will need a 13.6V power supply that outputs constant voltage.

Do you have a link for a charger that never stops?
I a se is charger thats stop og maintain.

 

[Mach-Lee]

Do you have a link for a charger that never stops?
I a se is charger thats stop og maintain.

The CTEK MXS 5.0 seems promising, although I haven't test it to be 100% sure. The voltage stays on for several days IIRC, so that might be enough to get it above 95% at least.

I don't know if you have 120V charging there, but that's another option because it's very slow (charge from like 10-100% over 3 days) which gives the 12V plenty of time to charge up.

 

[Kachook]

@Mach-Lee thank you for this most excellent write-up. I cannot believe I am only seeing it now, but I appreciate the time and effort you took to put write down all of this information. If I may pick everyone's collective brain... is there any issue leaving the OBDII reader plugged in or should I remove it? Second, using a Carista OBDII and a Car Scanner app, my SOC for the LVB is 71% when I turned it on today and the wifey had not driven it since Sunday or Monday. I bought the MME in July of 2021 and it has about 22k miles on it. It has been garage-kept for all of its life although it had been in the sun periodically whether at work or driving around. When do I know it is time to change the battery? A most recent update did not complete although I don't know the reason. With my other vehicles, it wasn't as big a deal if the battery were to fail because it was easy enough to open the doors and hood to jump the battery. Lastly, when is the best time to check the battery's state of health? I also have a little voltmeter in the cigarette lighter power outlet in the armrest and it shuts off automatically, but it has been reading between 12 - 14 every time I check. TIA.

 

[JM22681]

I saw the answer on jump starting but I'm not familiar with the different technologies. Are these Lithium-Ion devices adequate?

https://a.co/d/4sFuF3a

If so, what's the minimum amperage/Wh?

 

[Jerrytball]

I saw the answer on jump starting but I'm not familiar with the different technologies. Are these Lithium-Ion devices adequate?

https://a.co/d/4sFuF3a

If so, what's the minimum amperage/Wh?

Similar to the one I have I can’t answer the question to amperage, but it did jumpstart a dually Dodge with a huge diesel engine engine in it, and I only had a half charge on it!

 

[JM22681]

Similar to the one I have I can’t answer the question to amperage, but it did jumpstart a dually Dodge with a huge diesel engine engine in it, and I only had a half charge on it!

What about your MME??

I also have an older 300A (that one I linked was 3,000) for up to 2.1L gas engines. So curious where the sweet spot is. Assume the 300A is too small.

 

[Jerrytball]

What about your MME??

I also have an older 300A (that one I linked was 3,000) for up to 2.1L gas engines. So curious where the sweet spot is. Assume the 300A is too small.

Well, here’s the problem you can’t test it on the front hood opening unless your batteries dead and my battery stays anywhere between 85 and 97%. The car has only 6000 miles

 

[Mach-Lee]

@Mach-Lee thank you for this most excellent write-up. I cannot believe I am only seeing it now, but I appreciate the time and effort you took to put write down all of this information. If I may pick everyone's collective brain... is there any issue leaving the OBDII reader plugged in or should I remove it? Second, using a Carista OBDII and a Car Scanner app, my SOC for the LVB is 71% when I turned it on today and the wifey had not driven it since Sunday or Monday. I bought the MME in July of 2021 and it has about 22k miles on it. It has been garage-kept for all of its life although it had been in the sun periodically whether at work or driving around. When do I know it is time to change the battery? A most recent update did not complete although I don't know the reason. With my other vehicles, it wasn't as big a deal if the battery were to fail because it was easy enough to open the doors and hood to jump the battery. Lastly, when is the best time to check the battery's state of health? I also have a little voltmeter in the cigarette lighter power outlet in the armrest and it shuts off automatically, but it has been reading between 12 - 14 every time I check. TIA.

OBDLink MX+ and Vgate iCar Pro 4.0 BLE are the two adapters I've tested and verified to have a low enough standby draw (<5mA) not to drain the 12V battery. Other adapters can have higher standby drains and drain the 12V battery, so it's best to leave them unplugged (it's also a security risk with most adapters since anyone can connect to your car). Leaving the Car Scanner app active in the background (forgetting to disconnect and quit the app) can also cause a major drain since the car won't go to sleep while data collection is active.

A 12V SoC of 71% is perfectly normal after the car has been sitting. I would not worry about this. If you have trouble with an update installing, see my other topic about getting failed OTAs to install.

You cannot check the 12V battery's state of health. You can check the state of charge, best time is to use Car Scanner is right after you start the car. The battery will drain 10-15% after you shut off the car, this is normal. Again, I would not worry unless you consistently saw SoC values below 60%.

I saw the answer on jump starting but I'm not familiar with the different technologies. Are these Lithium-Ion devices adequate?

https://a.co/d/4sFuF3a

If so, what's the minimum amperage/Wh?

Yes the lithium jump start packs are acceptable to use. Keep in mind the amperage ratings they put on them mean almost nothing because there is no standardization and the manufacturers can claim whatever they want. The medium size ones or larger should work okay. Looking at Amazon, it appears that would mean something like >2000A peak amps and capable of starting a 6.0L diesel.

However the most important thing the lithium jump pack needs to have is a manual override or boost button, otherwise it will be useless for opening the frunk. I see not all brands have this anymore. The override allows the jump pack to supply power even when no voltage is detected on the terminals (which is the case with the frunk leads). The override is usually a small button somewhere on the safety device at the base of the jumper cables. FYI it appears the one you linked does NOT have an override, so I would not buy that one. My preferred brands are NOCO or GOOLOO which do have the boost/override capability.

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