12V Battery Recharge Threshold Improved in Latest BCM Software!

[MoonRiver]

Finally Ford did something.
Now the question is when it drops down to the threshold would it get charged in any condition regardless whether it's in drive or not power all on or not, plug in or not? as long as HVB has enough juice?

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[grein002]

It'll probably ship by default on 2025 models. And they've sent BCM updates OTA several times before, so I bet they'll do so eventually, but right now there's a bit of a backlog of updates as you're probably aware, so who knows when.

Right after your LVB dies...

 

[MBCook]

What makes 55% the ideal point to recharge?

 

[HuntingPudel]

I don't have that either....

This is the first module update I have seen that I'm interested in getting...

Find someone near you who has an FDRS rig? ?‍?

 

[Billyk24]

No idea if or when it's coming OTA....understatement for those of us with a Job 1 2021.

 

[mkhuffman]

What makes 55% the ideal point to recharge?

Because it is better than 40%.

 

[mkhuffman]

I wonder if the higher charge level will increase vampire drain to a level that is actually noticiable. Right now, the car can sit a week or more and not lose a single percentage of its charge.

(Actually, I should do a test on that to confirm. The SOCD does not change, but does the EtE decrease over a week of time? I bet it does, but not enough to drop the SOCD. For science, someone should test two MMEs: one with the set point at 40%, and the other at 55%. Measure the EtE in both before and after a week has passed. Yeah, science!)

 

[Mach-Lee]

This is great news. I haven't seen a BCM update since July, 2024. Do you know the software version for this latest BCM update?

The strategy is MU5T-14C184-ACT. I think it's from sometime last summer or fall but I didn't update for a while.

Finally Ford did something.
Now the question is when it drops down to the threshold would it get charged in any condition regardless whether it's in drive or not power all on or not, plug in or not? as long as HVB has enough juice?

Yes, the car was off and unplugged when it recharged there. It should auto-recharge as long as the HVB is above 15%.

What makes 55% the ideal point to recharge?

The cardinal rule with lead acid batteries is to keep them above 50% SoC as much as possible. Cycling them below 50% causes problems with sulfation and decreased lifespan due to deep cycles. It can also cause the battery to freeze in the winter (bad). On the flip side, you don't want to set the threshold too high because then that causes unnecessary recharge cycles that occur too often. 50-60% for an automatic recharge threshold is really the ideal zone. There is still enough of a reserve left in case the battery is marginal or the software doesn't wake up the car immediately.

I wonder if the higher charge level will increase vampire drain to a level that is actually noticiable. Right now, the car can sit a week or more and not lose a single percentage of its charge.

(Actually, I should do a test on that to confirm. The SOCD does not change, but does the EtE decrease over a week of time? I bet it does, but not enough to drop the SOCD. For science, someone should test two MMEs: one with the set point at 40%, and the other at 55%. Measure the EtE in both before and after a week has passed. Yeah, science!)

It only takes about 0.5% of the HVB to recharge the 12V battery. Most people will never notice. In normal circumstances, the 12V will only need to recharge after the car has been sitting for 5+ days. Most people will drive the car before that occurs. If you park the car for a month, it will go into deep sleep mode after a couple of weeks, which will significantly reduce the 12V drain and the LVB might go a whole month before needing to be recharged.

In your test scenario, it won’t make a significant difference because both cars are likely to recharge only once a week. Consequently, the overall energy consumption will remain relatively consistent, as the 12V drain rate will remain unchanged. However, the recharge events will occur slightly more frequently and be slightly shorter in duration. And of course if there is some kind of rapid 12V drain, the car will let you know about it via "Electrical System Drain Service Required" message.

In instances where the vehicle is only driven for short trips (which has historically been a difficult situation for 12V charge level), the higher 55% threshold will ensure the 12V battery retains enough charge without owner intervention. You won't have to worry about leaving the car on or charging extra slowly to keep the 12V topped off. Those were workarounds until the software was updated. Now, it will take care of itself.

 

[astrocket]

Great information! So in the needing to park for a month scenario, would keeping the car plugged in charged to ~50% limit help to maintain the LVB SOC before this software update?

 

[Shayne]

so, what voltage is this ?

....and for those of us that are avoiding, or have not gotten an update in a long time... is it possible to update JUST the BCM ?

I hear you trouble is if you want hope of a BCM or a SOB you need to leave auto updates on. I got power up 6.8 a couple of days ago; just rolling in now. I spent the day listening to the louder tailgate chime in delight.

6.8 failed to install twice with Update Interrupted! It had a tap with Call Help! Too funny what will I do no louder chime. I then threw a 12V charger on it and the update installed at the scheduled time no problems.

An update that the car is smart enough to charge the 12V for installs would be good. As well as keeping the 12V over 80% all the time. 35 40 55 seems like someone is just too stubborn to admit the logic is lead acid not lithium. Running them too low is what kills them.

Mr. G 12V charged and came back green 3+ years and counting A story of abuse.

The cardinal rule with lead acid batteries is to keep them above 50% SoC as much as possible. Cycling them below 50% causes problems with sulfation and decreased lifespan due to deep cycles. It can also cause the battery to freeze in the winter (bad). On the flip side, you don't want to set the threshold too high because then that causes unnecessary recharge cycles that occur too often. 50-60% for an automatic recharge threshold is really the ideal zone. There is still enough of a reserve left in case the battery is marginal or the software doesn't wake up the car immediately.

So 35% was no good? So we are now up to the bare minimum and if a sudden drain happens there is a real good buffer of 5%. Not sure of 50 to 60% being ideal. I will go with more charge cycles if the car drains the battery and keep the 12V over 80% at all times. Unless the car really drains 12V's the cycles should be minimal just a different limit.

 

[chesteroberto]

The strategy is MU5T-14C184-ACT. I think it's from sometime last summer or fall but I didn't update for a while.


Thanks--- that's the strategy I got using FDRS in July of last year.

 

[Shayne]

Thanks--- that's the strategy I got using FDRS in July of last year.

I got 24-PU0121-FTDI-FX in December 2024 (March 2024 release). Anyone know if this is the same thing? GFM, BCM update. Think it helped L2 charging speed but needs it to warm up to be sure.

Edit: Answered thanks to Mr. Lee.

 

[Mach-Lee]

I got 24-PU0121-FTDI-FX in December 2024 (March 2024 release). Anyone know if this is the same thing? GFM, BCM update. Think it helped L2 charging speed but needs it to warm up to be sure.

Mr. G (@Mike G) 3FMTK3SU6MMA01581 can you tell which version 24-PU0121-FTDI-FX installed?

No, this newest software has not been released via OTA yet. FDRS only.

The OTA you referenced is the prior version, MU5T-14C184-ACS. The recharge threshold was 45% on that software IIRC (still an improvement over the original 35%).

 

[Mike G]

I got 24-PU0121-FTDI-FX in December 2024 (March 2024 release). Anyone know if this is the same thing? GFM, BCM update. Think it helped L2 charging speed but needs it to warm up to be sure.

Edit: Answered thanks to Mr. Lee.

You have the "-ACS" rev.

 

[Mike G]

No, this newest software has not been released via OTA yet. FDRS only.

The OTA you referenced is the prior version, MU5T-14C184-ACS. The recharge threshold was 45% on that software IIRC (still an improvement over the original 35%).

Thanks, Lee, for filling in the missing knowledge gap about what the latest BCM was intended to fix. I've been seeing this update in a lot of folks available software lists but had not, until now, seen anything mentioned about what the benefits of updating the BCM would bring.

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