How to Recondition/Service Your 12V Battery

generaltso

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I was surprised to see how much interior, door, and frunk lights pulled down the voltage (with MME 'off'), and glad to see that your fresh new battery was pulled down basically the same as mine..
Just to be clear, my battery is freshly charged but not new. I had it charging at 13.7V for about 64 hours.
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dtbaker61

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Just to be clear, my battery is freshly charged but not new. I had it charging at 13.7V for about 64 hours.
got it..... and I appreciate the data point to compare with my in-car charge by leaving MME 'on' for 24 hours (with internal system charge voltage apparently around 13.5). My MME was delivered to NM late Feb, so it was in the batch that sat in a lot somewhere for a good month too.

If my 'sleeping' LVB = 12.85 , and settles down to pretty much the same as yours after 64 hrs at 13.7v charging.... then I am hoping we all can relax a little knowing that our on-board charging/maintenance of the LVB is adequate.
 

generaltso

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If my 'sleeping' LVB = 12.85 , and settles down to pretty much the same as yours after 64 hrs at 13.7v charging.... then I am hoping we all can relax a little knowing that our on-board charging/maintenance of the LVB is adequate.
Yeah, I'm pretty sure that a resting voltage of 12.85V is totally fine. Mine was more like 12.4V before, so I'm hoping that the long charging session will bring it back up to that range.
 
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Mach-Lee

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My working hypothesis is:
- if the sleeping LVB is 12.8+ , all is well
- if showing < 12.8, with no lights on or doors open,
in-car LVB charge-to-full may be accomplished by:
- plugging in
- turning MME 'on'
- disabling auto-off timer
- leaving overnight
The Mach-E charging system only charges the 12V to 90% SoC, so leaving the car on is not a suitable means of fully charging the battery (DC/DC does not continually charge at a high enough voltage). Some form of external charging is required to get it all the way to 100% and completely cure any sulfation issues. Again, external charging is only necessary if you are getting repeated low battery errors/issues, not everyone needs to do this.

Also, the point of fully charging is to restore lost capacity, not just to raise the SoC. Voltage only tells part of the story, so checking it is not the final determinant of whether or not you need external charging, or whether it was successful. A low capacity battery might show 12.8V but sill need charging if issues are ongoing. The proper way is to do a capacity test, but this requires special lab equipment. Most folks will just have to adopt a “wait and see” approach after charging to determine if their battery issues are solved, or if they need to take the next step of having the battery replaced.
 
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Mach-Lee

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11 hrs 31 mins screen prints. Now at 11hr48min, 13.565V, 33.3 ma.
(there was probably a short National Grid power dip/glitch overnight)
FLT_I.png
FLT_V.png
Did your voltage set point change there?
 


generaltso

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Most folks will just have to adopt a “wait and see” approach after charging to determine if their battery issues are solved, or if they need to take the next step of having the battery replaced.
Yep, that's where I am at this point. After 3 hours of sleeping, my battery is reading 12.8V. Hopefully, it will stay there and I won't see the battery fault message again. I'll just have to wait and see.
 

louibluey

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Did your voltage set point change there?
I think there was probably a momentary power dip, it happens a few times a week here.

PS voltage was 13.65V the entire test (read 13.649 on the display, a quirk of that old 90's hp design).

FWIW, I when I run FDRS, I am seeing a lot more cases of 15.0V and 15.1V today, perhaps more with colder weather? The converter ran at 15.0V for some tens of minutes today.

I had the PL6100 out for programming, so left it running in charge mode when I finished. After first setup this evening, before I went to PS mode I checked and I think it said something like 64%. When I finished the ForScan and FDRS work (PS set to 13.4V), went back to charge mode, and it started at 95%.
 
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louibluey

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Okay, round 2. I put the new LVB into MME and now have my original Dec, 2020 LVB on the bench. Just started the float test. The original battery was charged/conditioned in MME, then again on the bench a day or two ago. So, going into this test, It should be fully charged. I set both DMMs to digitize at 10Hz to get back into practice, and write to file, but I think the default displays were nicer.

At first glance, only a short ways in, this 1 year old battery seems to be flattening out the current curve around 100 mA, (104 mA at 6:53pm). Will be interesting to see what the float current looks like in the morning. The new LVB settled out around 33 mA after 11 hours or so. Updated picture at 7:18pm. (I am out of practice, set for 2.4 hours instead of 24 hours, will run continuous as the earlier test after this one runs to completion.)
Ford Mustang Mach-E How to Recondition/Service Your 12V Battery Unknown
 
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louibluey

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Check this out, after about 4 hours of 105 mA, then actually increasing to something like 125 mA last night before these graphs, the current started to drop. Now at about 66 mA. This is possibly an example of what @Mach-Lee was talking about where it might take some time at 13.65 V to condition the battery.

These graphs of about 13.5 hours began, after about two hours of the test described above. This is the one year old AGM 12V low voltage battery (LVB) that I recently took out of MME in my small quest to learn more about the care and feeding of AGM batteries.

As I have noted recently, the DC-DC converter routinely goes as high as 14.0 V to 15.0 V, but perhaps Ford should consider some longer time periods above 13.65 V for battery conditioning / maintenance. Maybe when MME is plugged into L2, possibly overnight for a typical MME. Also, this battery has been through two tens of hours of cycles on smaller Clore battery charger, which I think did it some good, but possibly still not as good as just sitting at 13.65 V+ for an extended period of time. Of course this test is outside of Mach e, so even asleep, add 50 mA+ to an in-car connected measurement where MME always uses some amount of LVB current, even asleep.
Ford Mustang Mach-E How to Recondition/Service Your 12V Battery Unknown
 
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generaltso

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I'd love to hear what the LVB battery rests at after you put it back in the MME and drive for a day or two, and check after the MME has been 'off' for a couple hours.
Well, after my experiment charging at 13.7V last weekend, my battery is back to measuring 12.1V at rest. I assume I'll see the fault message again at some point and a trip to the dealer will be in my future.
 

louibluey

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Well, after my experiment charging at 13.7V last weekend, my battery is back to measuring 12.1V at rest. I assume I'll see the fault message again at some point and a trip to the dealer will be in my future.
mine is 12.3 V, about 43F in the unheated garage -

The next morning after the new battery was installed, I noticed a Sync 4 display that MME was asleep. This morning, I had to use the fob to open it (so a short wake up and a moment of 14.4V), but after a minute (no start), my OBDII port 12V measured (just taking the power from there to dual banana plug) indicated on the Fluke 376 at 12.3 V, about 43F in the unheated garage. I left the Fluke meter on the seat set to min/max, it might stay on for a while that way, and I can read it with a light through the window.
Ford Mustang Mach-E How to Recondition/Service Your 12V Battery Unknown
 
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dtbaker61

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Well, after my experiment charging at 13.7V last weekend, my battery is back to measuring 12.1V at rest. I assume I'll see the fault message again at some point and a trip to the dealer will be in my future.

VERY interesting point of info, thanks for posting followup.....

I would agree that if your battery is returning to rest at <12.3 after a couple days back in the car, then either the LVB, sensors, or charge module/software needs replacement. I dunno if I would wait until it throws another error.... I'd call into the Dealership Service Dept, and give them a heads up on what you are likely to need so they can have a new battery on hand, and verify that their techs are trained and able to diagnose and execute via Warranty.

By contrast, my LVB continues to settle to 12.8 after a full night's 'sleep' (not plugged in or on), measured at the 12v connection points if you wait long enough for the Frunk light and everything else to go back to sleep.... so I'm considering that 'full' with just a little bit of background load.

Interesting note is that if you open the hood, and measure at 12v while frunk light is on and other background stuff has not gone back to sleep, the LVB measured at 12.3 .... waiting 10+ minutes for everything to go back to sleep measured at 12.8 ... so there is quite a bit of background load going on that we can't always see; and because the LVB is so small, the voltage sag is substantial.

It would be nice to KNOW what the low-voltage trigger is to wake up the dc-dc is.... I wonder if it is 12.1, or less ?! It would be interesting to apply load to a sleeping MME to increase the voltage sag, to see when the dc-dc wakes up to feed the LVB!
 
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louibluey

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VERY interesting point of info, thanks for posting followup.....

I would agree that if your battery is returning to rest at <12.6 after a couple days back in the car, then either the LVB, sensors, or charge module/software needs replacement. I dunno if I would wait until it throws another error.... I'd call into the Dealership Service Dept, and give them a heads up on what you are likely to need so they can have a new battery on hand, and verify that their techs are trained and able to diagnose and execute via Warranty.

By contrast, my LVB continues to settle to 12.8 after a full night's 'sleep' (not plugged in or on), measured at the 12v connection points.... so I'm considering that 'full' with just a little bit of background load.
I doubt a battery replacement is needed, it seems to be more of how MME is charging / maintaining the LVB. I had several FordPass LVB warnings to see the dealer, yet my old battery is looking good once charged outside MME.

Interesting question on the sensor, if the LVB ground terminal sensor alone could cause substandard charging.

It would be good to have some guidance from Ford on what they consider acceptable LVB voltage in car, when open, and later at rest. @generaltso maybe ask the service department if they have a range of normal/acceptable 12V LVB voltages from Ford?

Update (4:01 pm, average 12.5 V, MME resting)

Good point @dtbaker61 on rechecking 10 minutes later or so! Just realized I left the Fluke on "min", just reset it to avg (1:55 pm), will check it later. I could set a DMM/digitizer up out there, maybe that is next, but the fluke is so easy for a first test. I should check the manual for time-out, it might only stay on for min/max/avg.

It is possible (if there are no hardware faults) that Ford could improve the LVB charging strategy.
 
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generaltso

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It would be nice to KNOW what the low-voltage trigger is to wake up the dc-dc is.... I wonder if it is 12.1, or less ?!
Judging by what I just saw, that sounds like a good guess. I checked my battery again, and this time it read 14.7V, so it clearly hit some threshold for the DC-DC converter to kick on. I left it for 30 minutes and it now reads 13.1V. I'm not sure if that's the DC-DC converter ramping down the voltage or if it has turned off and that's just the battery. I'll check it again in another 30 minutes.
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