How to Recondition/Service Your 12V Battery

chrisGT

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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.
My GT can sit unplugged with the LVB SoC at 60s% for hours or days and the DC/DC converter will not kick in to charge it. Then immediately when I plug in the charger it starts charging both the HVB and the LVB and I can see the LVB SoC going up.
I am almost sure that the algorithm prefers to charge the LVB when the car is plugged in to external power. I don't know if the HVB is charged for 22 hours (say it is plugged near empty to a 240v 16amp charger) if the DC/DC converter will condition the LVB for 22 hours as well but it is worth a try.
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My GT can sit unplugged with the LVB SoC at 60s% for hours or days and the DC/DC converter will not kick in to charge it. Then immediately when I plug in the charger it starts charging both the HVB and the LVB and I can see the LVB SoC going up.
I am almost sure that the algorithm prefers to charge the LVB when the car is plugged in to external power.
Maybe. But if the voltage gets low enough, the LVB will get charged even when it's not plugged in. I do think it waits too long before doing so though, which is likely the cause of the erroneous 12V fault messages.
 

louibluey

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My GT can sit unplugged with the LVB SoC at 60s% for hours or days and the DC/DC converter will not kick in to charge it. Then immediately when I plug in the charger it starts charging both the HVB and the LVB and I can see the LVB SoC going up.
I am almost sure that the algorithm prefers to charge the LVB when the car is plugged in to external power. I don't know if the HVB is charged for 22 hours (say it is plugged near empty to a 240v 16amp charger) if the DC/DC converter will condition the LVB for 22 hours as well but it is worth a try.
I am seeing different conditions for when the DC/DC converter comes on, and when it comes on to charge the LVB. We could probably build a pretty good chart at some point.

Apparently MME off, the designers generally see the LVB charge model as draw down, then recharge. This is very different from the old ICE model where when the alternator is running, charge LVB to full, then car off, well nothing there to charge LVB. (although it has been pointed out by @BMT1071 that some new alternators are run less for energy savings).

MME off, preconditioning complicates the situation. I often run a 15 minute or 30 minute session because I am thinking of driving, or just looking at something in the cabin, that's a big LVB draw for lights, fans, etc.

My indications which seem to agree with other observations is that off, MME seems to allow the LVB to discharge to 40% (possibly 34%/35% with service warning), then takes it back up to 90%. Several of us have commented that 35% to 40% might be too low for the low trigger, and @Shayne has noted might be a particularly bad LVB charge strategy for a MME out in the cold, especially below say 10F, and many of us see -25F a few mornings a winter if not more often to the north.

Here is a recent example, plugged in all night, you can see the LVB charged from a low 35%, but L2 plugged in, was not continuously charging or conditioning LVB: Anatomy of a 12V Fault-Service with OTA Ford Power-Up 2.1.0

Accessory mode, unplugged is really interesting, because no matter what the initial soc, MME seems to charge for about 24 minutes. I've never seen a second shot because of auto-shutdown, need to try again someday.

Driving (cool / cold temps), I have seen several indications where the DC/DC converter runs 100%, and brings MME LVB to full, could be partly temperature related, will need to look more next summer. DC/DC converter running 100% might also just be an artifact of running seat heat, wheel heat, fans, sometimes windshield heat, etc.

MME often turns on the DC/DC converter momentarily (plugged in) with opening the doors, or other wake events, then turns it off. So to a glance it might look like it is charging, but generally, as you noted, it is not charging the LVB, not an extended charge session anyway.
 
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louibluey

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Quick follow up for @Mach-Lee, so the new OEM Motorcraft 35 Ah battery was in my MME for a month before I swapped out for the new AC Delco 50 Ah battery (in the interest of science :) ). My original one year old LVB was fine too.

Anyway a week or two ago, I just put the new OEM Motorcraft 35 Ah battery on one of those hp supplies at 13.65V, and FWIW, the float current is now down to about 6.n mA (n varies, probably just the electrochemistry).
 

Shayne

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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?
It pops up to 15V on the 120V charger while charging? I have not tested. I know starting it does for me. Started while still plugged to a 240V charger as well.

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.
Every time I start the vehicle it is time to charge as it starts right away at around 11 amp due to the low state of charge of the 12V when it is started. Wishing it would just happen in any state but thinking not plugged behaves better for me or maybe just was warmer. Can't do that any more due to temperature. I see it sucking power from the charger for hours a few times a day now "preparing for drive" sometimes displayed in FP. What it is doing is a Ford secret.

Maybe. But if the voltage gets low enough, the LVB will get charged even when it's not plugged in. I do think it waits too long before doing so though, which is likely the cause of the erroneous 12V fault messages.
Bet they freeze faster at a lower soc. For me at around -28C I would say you should keep an eye on it.

I am seeing different conditions for when the DC/DC converter comes on, and when it comes on to charge the LVB. We could probably build a pretty good chart at some point.
Yes please would be great if you summarize what you know on the first post of your thread and a new post to flag it has been edited. The testing blows my mind a bit but the findings I look forward to.

We have remote start and we have departure start. We have no preconditioning and it is really confusing when I read this as to which one people are talking about. A tesla has preconditioning the ford does not. The closes is departure time from what I have seen. Is preconditioning a big draw when plugged in and which one? It does no 12V charging during that time even when plugged in? Departure runs for over an hour here now a days but never a problem if the cycle starts.

You can turn off auto shut down resets every cycle but just do it again.
 


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I have mentioned this before... In a MMEGT, remote start (not departure time set, just remote start) DOES seem to pre-condition (heat) the HVB battery, based on what I see in the dashboard power meter, regardless of whether or not it is plugged in. Other GT owners have reported the same. The non-GT may be different.
 

Shayne

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I have mentioned this before... In a MMEGT, remote start (not departure time set, just remote start) DOES seem to pre-condition (heat) the HVB battery, based on what I see in the dashboard power meter, regardless of whether or not it is plugged in. Other GT owners have reported the same. The non-GT may be different.
Difference may be one is for 15 minutes and one is for over an hour. Don't know if we should believe it but the range (GOM) increases with departure time but not in the 15 minutes with remote start. The cabin blowers do not come on until the last 15 minutes or so with departure. Uses all it has just on the batteries and runs longer?
 

MachEZRt1

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My LVB maintenance and emergency kit. Am I missing anything?
  • Gooloo jumper
  • 10mm battery terminal wrench
  • Cigarette outlet voltage meter with USB plug
  • Battery Tender 800 (not pictured)
Ford Mustang Mach-E How to Recondition/Service Your 12V Battery 1642266294587
 

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My GT can sit unplugged with the LVB SoC at 60s% for hours or days and the DC/DC converter will not kick in to charge it. Then immediately when I plug in the charger it starts charging both the HVB and the LVB and I can see the LVB SoC going up.
I am almost sure that the algorithm prefers to charge the LVB when the car is plugged in to external power. I don't know if the HVB is charged for 22 hours (say it is plugged near empty to a 240v 16amp charger) if the DC/DC converter will condition the LVB for 22 hours as well but it is worth a try.
I think the algorithm prefers to charge the LVB during use or while charging vs energy transfer while parked off plug. The tech sheet even mentions if the energy transfer is allowed to occur daily then the LVB will be damaged.
 

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Battery Charger Method:

The easiest method is to use a regular automatic battery charger that has a float mode. Preferably it should have an AGM mode, if not it will just take a little longer. DO NOT USE A DUMB CHARGER that must be manually turned off.

When the current drops below 1A or 6 hours have elapsed, lower the voltage to 13.6V (float mode) and let it sit for as long as you can. The battery is done desulfating when the float current stops decreasing. This could take a day or several weeks. A battery in great shape will have a float current less than 0.1% of its C rating (35 mA for the Mach-E 35 Ah battery). For comparison, I had an AGM sitting around at 75% SoC that hadn’t been charged for a year or two, it took about 5 days of floating to reach a current minimum. Last little bit is very slow.
After seeing all the new posts regarding LVB issues this winter, I returned to this thread to refresh my memory from what I read before. I have not had any issues myself, but I am thinking I might do a light reconditioning once and a while. I also have another AGM battery that appears to need reconditioning, so I may do that one as well.

Can I use a power supply and set the voltage to 13.6 V and just monitor the current until the current has dropped to around 100 mA? It can also be used for FDRS programming, so I thought I could kill two birds with one stone and get this to use for reconditioning my batteries. https://www.ebay.com/itm/165213749070

I don't care if the process takes longer because I am not starting with 14.7 V. My car sits in my garage for hours and I can wait.

@louibluey thanks for all your contributions to this topic. Your research is very impressive.
 

louibluey

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After seeing all the new posts regarding LVB issues this winter, I returned to this thread to refresh my memory from what I read before. I have not had any issues myself, but I am thinking I might do a light reconditioning once and a while. I also have another AGM battery that appears to need reconditioning, so I may do that one as well.

Can I use a power supply and set the voltage to 13.6 V and just monitor the current until the current has dropped to around 100 mA? It can also be used for FDRS programming, so I thought I could kill two birds with one stone and get this to use for reconditioning my batteries. https://www.ebay.com/itm/165213749070

I don't care if the process takes longer because I am not starting with 14.7 V. My car sits in my garage for hours and I can wait.

@louibluey thanks for all your contributions to this topic. Your research is very impressive.
I'm kind of rusty and mucking along, just fun for me. Others may have more experience with that power supply, 30A is on low side for FDRS, but should work fine. Using @Mach-Lee's 13.6V or 13.65V conditioning method, I have been seeing under 35 mA, and lately my newest OEM LVB went down to about 6 mA on the bench. Possibly just a curiosity, I have no idea what that means for real life performance if I put it back in MME and ran it for a year or more.
 

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I'm kind of rusty and mucking along, just fun for me. Others may have more experience with that power supply, 30A is on low side for FDRS, but should work fine. Using @Mach-Lee's 13.6V or 13.65V conditioning method, I have been seeing under 35 mA, and lately my newest OEM LVB went down to about 6 mA on the bench. Possibly just a curiosity, I have no idea what that means for real life performance if I put it back in MME and ran it for a year or more.
I picked that one because someone posted in a FDRS thread that they used it and it worked fine, like you said. I am not sure I will dive into the FDRS world, but if I do, at least one component will be purchased. That model probably can't measure down to 35 mA, but that is OK. I don't want to invest a lot of time or money in this if all I need to do is connect it and let it sit.

So do you think I can use that to recondition a AGM battery? Based on what I have read it seems like it would work but just take longer.
 
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Mach-Lee

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Can I use a power supply and set the voltage to 13.6 V and just monitor the current until the current has dropped to around 100 mA? It can also be used for FDRS programming, so I thought I could kill two birds with one stone and get this to use for reconditioning my batteries. https://www.ebay.com/itm/165213749070

I don't care if the process takes longer because I am not starting with 14.7 V. My car sits in my garage for hours and I can wait.
Yes, you can leave it connected to the power supply at 13.6-13.7V for a couple days to recondition. Looks like that one only shows 0.1A current resolution so you'll have to go by time then. Min 2 days to be safe.
 

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Yes, you can leave it connected to the power supply at 13.6-13.7V for a couple days to recondition. Looks like that one only shows 0.1A current resolution so you'll have to go by time then. Min 2 days to be safe.
Do you know if the MME can be 2 wired tethered for days and no problems with it system? Wonder if a 12V charger in the frunk for the 12V and the 240V plugged in outside would pose any problems after a few days/weeks? Reconditioned regularly for days. The cord slips right under the tip of the fender and hood closes no probs.
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