How to Recondition/Service Your 12V Battery

[Shayne]

I wonder why would we need to go thru this whole charging procedure just because the MME toke a bit of time to deliver. So it sat for awhile and if the BMS was working as it should why exactly should that be a problem? The 12V should be fine and no need to bring it back to life as the BMS should have looked after that? The fact that it may have not is the reason to try to bring it back to life correct?

Okay first result is in, did not take long at all! The LVB voltage started at 12.322V at 12:43 pm (about 12.13V at the bottom of that first curve). By 2:05:36 pm, 11.885V, the DC/DC converter came on to charge LVB and save the day! So for this first test, MME resting, no charge plug, MME off, frunk light off, about 45 degrees F, about 11.9V is the magic number for the converter to come on. The frunk light did come on, when the DC/DC converter started. See graphs below.

This is the most interesting real life of all your tests. What about different states? What happens when plugged in to 240V, 120V EVSE. I would say the LVB is not fine if it needs to be brought back to life on a bench after only one year. Maybe just have caught it in time?

Alright, so 1.37 hrs x 4A = only 5.5 Ah? Your discharge rate is approximately 0.1C, so I would estimate the battery was drained down to about 30% SoC before it turned on (assuming voltage reading was accurate). That would mean the total battery capacity is only about 8 Ah? Seems way too low.

I agree 30% soc sounds low.

Sponsored

 

[Mach-Lee]

I wonder why would we need to go thru this whole charging procedure just because the MME toke a bit of time to deliver. So it sat for awhile and if the BMS was working as it should why exactly should that be a problem? The 12V should be fine and no need to bring it back to life as the BMS should have looked after that? The fact that it may have not is the reason to try to bring it back to life correct?

We don't know that the BMS functions properly while in transport mode, off-state charging may be disabled. It also stops maintaining the 12V battery below 15% SoC. Some vehicles have been delivered with extremely low SoC which may explain why the 12V may have gone dead during shipping.

 

[mkhuffman]

We don't know that the BMS functions properly while in transport mode, off-state charging may be disabled. It also stops maintaining the 12V battery below 15% SoC. Some vehicles have been delivered with extremely low SoC which may explain why the 12V may have gone dead during shipping.

I suspect some cars that sat for a month or more on "chip hold" experienced extremely low SoC and drained LVBs. Mine sat for a long time also, but I have not received any LVB errors. I worry that the LVB may be damaged but I have not done the work describes in prior posts to determine if it needs reconditioning. Should I make that a priority or should I stop worrying?

 

[generaltso]

I have not received any LVB errors. I worry that the LVB may be damaged but I have not done the work describes in prior posts to determine if it needs reconditioning. Should I make that a priority or should I stop worrying?

If you haven’t gotten any warning messages, why worry?

 

[mkhuffman]

If you haven’t gotten any warning messages, why worry?

Only because I know it sat around for over a month before it was shipped, but you are right, I need to let it go. If I get a LVB message, then I can worry.

 

[Kamuelaflyer]

If you haven’t gotten any warning messages, why worry?

It’s our hobby for some of us.

 

[Shayne]

We don't know that the BMS functions properly while in transport mode, off-state charging may be disabled. It also stops maintaining the 12V battery below 15% SoC. Some vehicles have been delivered with extremely low SoC which may explain why the 12V may have gone dead during shipping.

So the 12V BMS is just not functioning adequately when in transport mode is your take away. We have someone here that is all set up and could test that with a couple of settings on the main screen. May not come on until 11.9V would be my guess. Maybe gets missed a few times?

Saw two graphs one unplugged and one plugged (240V?) and both came on at 11.9 to 12V neither in tow mode. Guess I wonder why it is not sitting at 13V or at least trying to keep it at or above 12.5 V not 11.9. How long would it take hovering around those lower voltages until the first post would be required or do you think the battery would remain healthy?

Twice here now once plugged to 240V and one 10 months later plugged to 120V both times with the Ford mobile charger. I never had a battery that works for a year and then becomes defective. Just wondering if it was a discharge problem and not defective to start. Time will tell.

I do see it coming on now it is colder here and on a 240V grizzle. States "Preparing to Drive" in the FP app. It draws wall current and have seen it go on for an hour. Just a wee bit less technical than @louibluey . MME widget 12V flags reported at two significate digits.

 

[Mach-Lee]

Only because I know it sat around for over a month before it was shipped, but you are right, I need to let it go. If I get a LVB message, then I can worry.

This is the correct attitude, if you aren't having problems then don't worry.

So the 12V BMS is just not functioning adequately when in transport mode is your take away. We have someone here that is all set up and could test that with a couple of settings on the main screen. May not come on until 11.9V would be my guess. Maybe gets missed a few times?

Saw two graphs one unplugged and one plugged (240V?) and both came on at 11.9 to 12V neither in tow mode. Guess I wonder why it is not sitting at 13V or at least trying to keep it at or above 12.5 V not 11.9. How long would it take hovering around those lower voltages until the first post would be required or do you think the battery would remain healthy?

Twice here now once plugged to 240V and one 10 months later plugged to 120V both times with the Ford mobile charger. I never had a battery that works for a year and then becomes defective. Just wondering if it was a discharge problem and not defective to start. Time will tell.

I do see it coming on now it is colder here and on a 240V grizzle. States "Preparing to Drive" in the FP app. It draws wall current and have seen it go on for an hour. Just a wee bit less technical than @louibluey . MME widget 12V flags reported at two significate digits.

FYI transport mode is a special factory mode the car is shipped in for battery conservation, your dealer takes it out of transport mode before delivery. It's not tow mode or anything you can do.

Personally I wouldn't want to leave a lead acid below 12.0V for more than a couple days, but practically I would say a week before you start getting difficult sulfation buildup. People driving multiple times per week shouldn't have too horrible of issues, but if the car is sitting a week at a time or for winter then I'd probably want to intervene more so. The recharge threshold is too low IMO, it should happen at 12.3V or around 40-50% SoC.

The batteries are more stressed in the cold, so it's more likely you will see a recharge warning in the cold. Big cold spell this week, so a lot more people may be finding this out now.

 

[phil]

I suspect some cars that sat for a month or more on "chip hold" experienced extremely low SoC and drained LVBs.

Mine was among the quickest electric Mustang deliveries ever: four months and change from the date I ordered to the date I purchased. Yet when it arrived at the final rail destination, the 12v battery was dead and they could not get the car on the truck to deliver to my dealer.

I don't think an extra month of sitting or a missing chip is the issue.

 

[louibluey]

I am currently focused on getting the LIN bus monitor working, because that unit directly records BMS data 24/7 to a SD card, so it would be very convenient to watch MME go through various cycles of LVB care and feeding under different conditions. This is a painfully slow process, but I am learning a lot.

Just a caution, I reconditioned my one year old LVB only because I wanted to try and better understand the process @Mach-Lee was describing. Other than various 12V warnings (which in my case, I think were all bogus), I believe my 12V LVB is and has always been fine. I did not have all the tools and test methods yet, so it is possible I rejuvenated it, but more likely, it was always fine, and now it is near perfect+ condition.

There are so many of us looking at data from all sorts of directions, it is likely someone will see a problem soon (if there is one), or Ford will beat us all to it, and just improve LVB maintenance.

In addition to the apps, some are looking at CAN data, some FDRS (FDRS has a data logger function, no additional hardware needed) / ForScan data, some measuring the LVB by chargers with soc displays, and all kinds of voltmeters, usually 12V lighter/accessory plug in units. My focus is on direct measurements at the LVB with lab quality equipment, and now reading BMS data directly from LIN bus #4 (LIN sniffing).

For anyone just passing through this thread, generally any measured voltages between about 13.4V and 15.5V means the DC/DC converter is running, so you are seeing the DC/DC converter forced voltage at the LVB terminals, just for info.

 

[rzanzerkia]

Some of you are really expert in battery measurement
I didn't understand half the stuff.
I do have a question related to LVB.
Is it possible to upgrade the battery with aftermarket version (same form factor and specs with higher capacity)?

I ask this because I had a tractor brand new and it came with low end battery that would not hold the charge.
Once I replaced it with higher capacity all problems disappeared.

If possible I would just change the battery and not worry about border line performance in the cold weather.

I don't have the MachE yet but we live in north east and usage will only be 4-5 miles a day so this is a concern for me.

Thanks

 

[generaltso]

Some of you are really expert in battery measurement
I didn't understand half the stuff.
I do have a question related to LVB.
Is it possible to upgrade the battery with aftermarket version (same form factor and specs with higher capacity)?

I ask this because I had a tractor brand new and it came with low end battery that would not hold the charge.
Once I replaced it with higher capacity all problems disappeared.

If possible I would just change the battery and not worry about border line performance in the cold weather.

I don't have the MachE yet but we live in north east and usage will only be 4-5 miles a day so this is a concern for me.

Thanks

This is the only bigger replacement I've seen that's been reported to fit. But I believe @louibluey still got the 12V fault message with it, so I'm not sure it makes much difference.

https://www.macheforum.com/site/threads/ac-delco-12v-mme-50-ah-chevy-spark-cadillac-battery.12747/

 

[mkhuffman]

Some of you are really expert in battery measurement
I didn't understand half the stuff.
I do have a question related to LVB.
Is it possible to upgrade the battery with aftermarket version (same form factor and specs with higher capacity)?

I ask this because I had a tractor brand new and it came with low end battery that would not hold the charge.
Once I replaced it with higher capacity all problems disappeared.

If possible I would just change the battery and not worry about border line performance in the cold weather.

I don't have the MachE yet but we live in north east and usage will only be 4-5 miles a day so this is a concern for me.

Thanks

One of the good things about an EV is how it uses the high voltage battery (HVB) to keep the LVB charged. It is not like an ICE, which requires you to run the engine to keep it charged. The MME is supposed to maintain the battery even if the car is off, so your 4 mile drive in the cold should not put any extra stress on the LVB.

Some early production cars had issues with maintaining the LVB, but it appears that is no longer an issue. Yours should be fine.

 

[chrisGT]

I have seen that every time the HVB is charged the LVB is charged as well by the DC/DC converter. So here is a thought how to give a long charge to the LVB.
Wait until HVB SOC is low, then plug in a slow charger (either 240v 16amp or even the factory 120v charger) to prolong the charging duration. Shouldn't that provide a fairly long charge to the LVB, without the need of an LVB charger and without the need to remove the panels to access the LVB?

 

[generaltso]

I have seen that every time the HVB is charged the LVB is charged as well by the DC/DC converter. So here is a thought how to give a long charge to the LVB.
Wait until HVB SOC is low, then plug in a slow charger (either 240v 16amp or even the factory 120v charger) to prolong the charging duration. Shouldn't that provide a fairly long charge to the LVB, without the need of an LVB charger and without the need to remove the panels to access the LVB?

The LVB doesn't necessarily get charged every time the car is plugged in. The car monitors the voltage of the LVB, and the DC/DC converter kicks on to bring the voltage back up when it gets low. This can happen whether the car is plugged in or not.

Sponsored