12V Battery FAQ

[RonBme]

I think it's fair to state that the onboard low voltage battery charging strategy is optimized for AGM batteries. Ford absolutely states as much.

I don't know if that would lead me to state that nothing but an AGM battery will function properly in the Mach-E, but it would be a decision to use a battery that the Mach-E charging logic might not be the best match.

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[RonBme]

Yet we use a lithium battery to power the vehicle and this subject is over a year old and today we have newer lithium batteries that can and do hold. I personally use a few lithium batteries in my truck in my motorcycle both Street as well as cruiser. I also have friends personal friends that use the lithium battery in their mme I actually read the battery specs myself yet I haven't seen any specs from Ford on what battery they want us to use so the option is there. You got to understand with the batteries are made of and AGM is nothing but a piece of glass inside of it that Shields it. You won't need to shield lithium and yet it still has battery management built into it so is to each his own. But unless you have the fax from the reputable companies, this is just opinion

 

[Sikkun]

haven't seen any specs from Ford on what battery they want us to use

Ford uses a OE BHAGM-H3 and will gladly sell you a new one.

But you are also providing nothing but opinions with way less technical information than the OP.

 

[RonBme]

And that's there battery but like I told them I want a upgraded battery for longer life even power and they said lithium but they don't sell them

 

[JimmyMachE]

Quick question. Does anyone know what the charging modes 0-4 are on CarScan? I did several Google searches and could not find an answer.

Not sure. Someone with a Forscan might have an answer:
https://www.macheforum.com/site/thr...acts-and-info-thread.18143/page-9#post-431851

BAT_CHRG_MODE in Forscan:
https://www.macheforum.com/site/threads/deafeningly-loud-vibrating-car.31862/page-2#post-718564

 

[hartmms]

And that's there battery but like I told them I want a upgraded battery for longer life even power and they said lithium but they don't sell them

If you would like to look it up, charge curves for AGM batteries are different than Li-ion. One piece of data is from the Victron Multiplus inverter/charger I have for my RV. There is an explicit setting where you indicate what type of battery is in the system (lead acid, AGM, Li-ion).

It's also worth considering that the BMS in the car is likely tuned exactly for the OEM AGM battery capacity. If you put a larger capacity Li-ion battery in, LVB BMS status will likely be wrong. I'm not sure if the BMS has a fixed AmpHour value, or it's tuned to look at the AGM battery voltage to report out a SoC. Both of those will be off with a larger Li-ion battery.

If you haven't already, you should probably let your li-ion battery vendor know that our cars have a BMS on the 12v battery unlike 99% of ICE cars on the road.

Some good resources:
https://www.victronenergy.com/blog/2015/03/30/batteries-lithium-ion-vs-agm/
https://batteryuniversity.com/article/bu-403-charging-lead-acid
https://batteryuniversity.com/article/bu-409-charging-lithium-ion

 

[Fixbear]

I call bullshit on some of the no's here's why. I personally know a few people that actually use a lithium battery and the battery performs and charges with zero issues

My, MY, He has done a lot of research on this and other topics of the Mach-E and Lightning. I spent the last 55 years in the repair field. Worked for 5 dealers before going on my own. I also did a lot of reading on the Mach and AGM batteries. If you look at the charging curve for the Lithium vs. the AGM vs the lead acid, you'll see that the optimal on a lithium is way far different than a AGM. Not saying that the lithium will not work for a bit, but it is far away from what the system is designed for. And overcharging a lithium can be dangerous beyond just premature battery failure.

 

[Mach-Lee]

Quick question. Does anyone know what the charging modes 0-4 are on CarScan? I did several Google searches and could not find an answer.

I've seen those modes, but have not spent any attention trying to figure them out. It's not really important IMO as long as the battery is charging when the car is on.



In terms of the lithium battery, some people that have put them in have had problems keeping them changed because the Mach-E's electrical system can drop to low voltages at times. 12.8V just isn't enough voltage to keep a lithium battery charged that requires a minimum of 13.5 volts. The voltage/discharge curves are also completely different between the two which throws off the battery computer.

Also, I hate to be frank but the Ohmmu batteries are overpriced garbage. If you actually take one apart, they are literally held together with packing tape and spray foam (see below). There is no internal heater, so the lithium cells will be destroyed by charging if you live in a below-freezing climate. They cause lots of problems in Teslas too, but the company sweeps that all under the rug. Don't assume something is "better" just because it's more expensive. They might work fine in older cars with "dumb" charging systems, but not in cars that have a modern BMS with managed charging.



Teardown and analysis by an electrical engineer:



Just put in a new AGM battery and save yourself the headaches.

 

[SonicBlue]

@Mach-Lee great write up. You might consider adding a few things:

1. Under the “what to do if the battery dies” section, you might add a trick that worked for me to open my car door. Even though the car was otherwise unresponsive, the door sill keypad still worked for me to open the door! The numbers on the keypad did not light up, but the door did open after tapping in my passcode. It’s at least worth a shot before going to the trouble of jumping open the hood.
2. Maybe include the video of that woman replacing her battery without removing the entire frunk tub? I found that video super helpful.
3. Just for grins, maybe include Darren Palmer’s remarks on the 12v issues being “a thing of the past” back in 2021. LOL.
   

 

[phidauex]

I just swapped my 12V battery at 40ish months (May 2021). Went smoothly!

I can recommend the minimal method of just removing the upper cover, drivers side cover, and driver side of the strut brace, but NOT removing the frunk tub. The order of operations matters, but the battery slides out very easily - no shimmying or shoving.

Here is a photo of the battery in its tray, slid all the way to the right. You can see it lifts straight out without interference. Whole thing took about 45 minutes, including digging around to find my 10mm and 8mm nut drivers, which are very helpful for the task. A long thin extension for your 8mm socket would also work.

A few tips to make this go smoothly:

1. Remove the upper plastic cover
2. Remove the driver's side plastic cover
3. Remove the driver's side strut brace nut (18mm), and gently slide the strut brace out of the way
4. Disconnect the negative battery cable from the frame (13mm)
5. Disconnect the negative battery cable from the battery (10mm) and flip it up and behind so it is out of the way
6. Disconnect the metal bracket holding the battery down in the tray (rear side of the battery) (8mm)
7. Slide the battery to the right (toward back of car), open the positive battery terminal, and remove the positive terminal from the battery (10mm)
8. The battery is now clear to lift straight up and out.
9. Drop the new battery in place, and reverse these steps. The most helpful thing is doing what you can while the battery is still in the right-most position.

New battery back in place with bluetooth battery monitor installed as well. Strut brace not yet bolted down.

Battery is charging now (car on and plugged in, lights and HVAC off), here is what the battery monitor and CarScanner say:

At this rate should be about an hour or less to get to full float voltage and 100% SOC. I'll manually reset the BMS after that.

Hope this helps!

 

[zvez]

I just swapped my 12V battery at 40ish months (May 2021). Went smoothly!

I can recommend the minimal method of just removing the upper cover, drivers side cover, and driver side of the strut brace, but NOT removing the frunk tub. The order of operations matters, but the battery slides out very easily - no shimmying or shoving.

Here is a photo of the battery in its tray, slid all the way to the right. You can see it lifts straight out without interference. Whole thing took about 45 minutes, including digging around to find my 10mm and 8mm nut drivers, which are very helpful for the task. A long thin extension for your 8mm socket would also work.

A few tips to make this go smoothly:

1. Remove the upper plastic cover
2. Remove the driver's side plastic cover
3. Remove the driver's side strut brace nut (18mm), and gently slide the strut brace out of the way
4. Disconnect the negative battery cable from the frame (13mm)
5. Disconnect the negative battery cable from the battery (10mm) and flip it up and behind so it is out of the way
6. Disconnect the metal bracket holding the battery down in the tray (rear side of the battery) (8mm)
7. Slide the battery to the right (toward back of car), open the positive battery terminal, and remove the positive terminal from the battery (10mm)
8. The battery is now clear to lift straight up and out.
9. Drop the new battery in place, and reverse these steps. The most helpful thing is doing what you can while the battery is still in the right-most position.

New battery back in place with bluetooth battery monitor installed as well. Strut brace not yet bolted down.

Battery is charging now (car on and plugged in, lights and HVAC off), here is what the battery monitor and CarScanner say:

At this rate should be about an hour or less to get to full float voltage and 100% SOC. I'll manually reset the BMS after that.

Hope this helps!

I'm curious about the charging of the new battery. Would fully charging on a standalone charger BEFORE install still work instead of having to leave the car powered up for hours? It seems like it would certainly be easier and faster.

 

[Mach-Lee]

Would fully charging on a standalone charger BEFORE install still work instead of having to leave the car powered up for hours?

Yes. Then you can reset the BMS as soon as you install it.

If the battery is above 90% charged you can reset the BMS, close enough. It doesn't need to be exactly 100%.

 

[phidauex]

I'm curious about the charging of the new battery. Would fully charging on a standalone charger BEFORE install still work instead of having to leave the car powered up for hours? It seems like it would certainly be easier and faster.

Yes, that would be a good way of doing it if you have a charger that is AGM compatible. I thought about it while dropping the new battery in, and my AGM charger was elsewhere with my truck, so I forged ahead. A full charge on the battery the day before dropping it in would make the whole process much faster.

 

[zvez]

Yes, that would be a good way of doing it if you have a charger that is AGM compatible. I thought about it while dropping the new battery in, and my AGM charger was elsewhere with my truck, so I forged ahead. A full charge on the battery the day before dropping it in would make the whole process much faster.

so reading the faq, you need car scanner and obd to get the percent SOC? Or can you just go by voltage?

 

[Snakebitten]

so reading the faq, you need car scanner and obd to get the percent SOC? Or can you just go by voltage?

The SOC value that matters, in this case, is the Ford derived SOC. So a voltage reading may or may not reflect the SOC algorithm in the car.

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