12V Battery FAQ

[JimmyMachE]

I also have the Home Assistant FordPass plugin installed configured to default poll rate (5 min).

Wow, what is your parasitic standby drain measured by the vehicle (Quiescent current mA in Car Scanner)? I see values between -20mA and -50 mA.

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[hartmms]

Quiescent avg current: 77ma.

So the battery was at 88% last night and it was 76% first thing this morning. I highly doubt the car used 4.2A last night. 77ma*12hours = 0.924 amps. That's no where near 12% of the 35Ah AGM battery.

This pic shows the bulge on the battery. Note how both ends of the ruler are not flush with the battery, only the middle is flush. I'm starting to wonder if the battery has a problem.

My battery is only about 12 months old (car made in Feb 2023), so it should not be near the end of it's life. It did spend a good chunk of that time here in Phoenix. On previous cars, I never had a 12v flooded batter last more than 18-24 months. From what I've read AGM batteries are better at heat tolerance that flooded.

 

[Mach-Lee]

Quiescent avg current: 77ma.

So the battery was at 88% last night and it was 76% first thing this morning. I highly doubt the car used 4.2A last night. 77ma*12hours = 0.924 amps. That's no where near 12% of the 35Ah AGM battery.

This pic shows the bulge on the battery. Note how both ends of the ruler are not flush with the battery, only the middle is flush. I'm starting to wonder if the battery has a problem.

My battery is only about 12 months old (car made in Feb 2023), so it should not be near the end of it's life. It did spend a good chunk of that time here in Phoenix. On previous cars, I never had a 12v flooded batter last more than 18-24 months. From what I've read AGM batteries are better at heat tolerance that flooded.

Yes you should get that replaced. Drain is also too high and should be investigated. Swelling is indicative of overcharging or a frozen battery. Make sure you’re not trying to recondition the battery with a charger or resetting the BMS more than once.

 

[JSW]

My 12v battery management has me stumped. I just had a new 12v battery installed last week when I took the MMe in for warranty work.

1. The new 12v loses its charge very quickly according to the Ford Account page, dropping from 90% to 50% in 5 hours.
2. My battery tender now indicates it’s fully charged (solid green light) while the Ford Account reflects 54%.

I‘ve had quick access for my battery tender installed since 2/21, so its easy to open the frunk and connect the tender (the dealer reconnected the leads it after installing the battery last week). https://www.macheforum.com/site/posts/120154/

Why is my Ford Account indicating a 54% state of charge (it’s a fresh %, not lagged) when the tender thinks it’s fully charged (solid green).

At this point I’d like to just go with the tender and stop worrying, but parking the car with 90% and watching it drop below 50% in an afternoon is disconcerting.

 

[mdolan92869]

My 12v battery management has me stumped. I just had a new 12v battery installed last week when I took the MMe in for warranty work.

1. The new 12v loses its charge very quickly according to the Ford Account page, dropping from 90% to 50% in 5 hours.
2. My battery tender now indicates it’s fully charged (solid green light) while the Ford Account reflects 54%.

I‘ve had quick access for my battery tender installed since 2/21, so its easy to open the frunk and connect the tender (the dealer reconnected the leads it after installing the battery last week). https://www.macheforum.com/site/posts/120154/

Why is my Ford Account indicating a 54% state of charge (it’s a fresh %, not lagged) when the tender thinks it’s fully charged (solid green).

At this point I’d like to just go with the tender and stop worrying, but parking the car with 90% and watching it drop below 50% in an afternoon is disconcerting.

I’ve seen something similar. Need to cause the car to refresh with the server, I usually just hit the unlock button since it’s in the garage. Wait for it to complete then refresh the Ford page.

 

[JSW]

I’ve seen something similar. Need to cause the car to refresh with the server, I usually just hit the unlock button since it’s in the garage. Wait for it to complete then refresh the Ford page.

Agreed. That’s what I did and what I meant by a “fresh” state of charge (you can also use a hard refresh on FordPass ).

 

[Mach-Lee]

My 12v battery management has me stumped. I just had a new 12v battery installed last week when I took the MMe in for warranty work.

1. The new 12v loses its charge very quickly according to the Ford Account page, dropping from 90% to 50% in 5 hours.
2. My battery tender now indicates it’s fully charged (solid green light) while the Ford Account reflects 54%.

I‘ve had quick access for my battery tender installed since 2/21, so its easy to open the frunk and connect the tender (the dealer reconnected the leads it after installing the battery last week). https://www.macheforum.com/site/posts/120154/

Why is my Ford Account indicating a 54% state of charge (it’s a fresh %, not lagged) when the tender thinks it’s fully charged (solid green).

At this point I’d like to just go with the tender and stop worrying, but parking the car with 90% and watching it drop below 50% in an afternoon is disconcerting.

Did they reset the BMS when the battery was replaced? Very important. After doing so the vehicle has to be parked undistributed for 8 hours so the BMS can re-learn SoC. Recommend parking on the street so fobs are not a factor.

The car will lose about 10% each time the ignition is turned off over the next two hours. So 90% to 80% after parking is normal.

Are you keeping fobs or PAAK near the vehicle (within 25') possibly waking it up?

 

[JSW]

I’ve been very careful about the phone and fobs.
I don’t know if they reset the BMS after replacing the battery - How can I tell?

I still don’t get the battery tender saying it’s fully charged and my Ford Account now says 50%.

 

[Mach-Lee]

I’ve been very careful about the phone and fobs.
I don’t know if they reset the BMS after replacing the battery - How can I tell?

I still don’t get the battery tender saying it’s fully charged and my Ford Account now says 50%.

I would personally reset the BMS then. Disconnect the battery (remove negative terminal), charge to 100% overnight, reconnect and reset BMS. Then park for 8 hours for SoC learning. See instructions here (you can park it instead of doing the last steps for updating): https://www.macheforum.com/site/threads/how-to-get-failed-otas-to-install.29749/

 

[RobbertPatrison]

My 12v battery management has me stumped. I just had a new 12v battery installed last week when I took the MMe in for warranty work.

1. The new 12v loses its charge very quickly according to the Ford Account page, dropping from 90% to 50% in 5 hours.
2. My battery tender now indicates it’s fully charged (solid green light) while the Ford Account reflects 54%.

Yeah, I am stumped as well by the excessive 12V battery drain. I too see the SoC drop from 90% down to 75 in 2 hours and down to 50% overnight. I do wonder whether this is 'normal' or that my MME has an issue. I am on my 3rd 12V battery already. In other words: will many other MME owners have to replace the 12V battery as many time as I had to?

Here is what I observed doing a few experiments over the past weeks:

• Every night the 12V battery drains. On a good day it is down to 70% the next morning, on a bad day it is down to around 50%. The battery is brand new. I get no messages about battery drain. After start it charges initially at 22A, and when about 80% the charge current is down to 2A. It takes about 20 minutes to get it back over 80%.
• The car charges the 12V battery anytime it drives or while it is charging. Even when plugged in it won't trickle charge the 12V battery unless it is actively charging the HV battery.
• The only way my OTA update worked was to manually trigger it after I had driven the car enough to the SoC to be about 80%. On the regular schedule it is supposed to update at 3am, by which time the battery is always drained below the 80% threshold so the update fails.
• Calculated from the OBD2 bus data the DC/DC converter that charges the 12V battery does not seem very efficient: only 70%. So it is understandable that the MME does not trickle charge.
• Switching off all wireless connectivity had no effect. The suspicion was that some polling from Fordpass would keep the car awake. But polling seems not the problem.
• Switching off the bluetooth on my phones seemed to have perhaps a little effect, but not significant. The though was that walking through the house would wake up the car through PAAK. This happens indeed, but even with bluetooth the 12V battery drains down almost as much.
• The iPhone has a very lazy bluetooth, and therefore wakes up the car less. The Android bluetooth connects more eagerly over Bluetooth and therefore seems to trigger more wakeup events.
• Unplugging my dashcam front the USB had no measurable effect. The idea was that perhaps the dashcam drains extra. The USB plugs are powered for 30 minutes after locking the car (that is wierd...).
• I put a security camera on the car to record when it wakes up overnight. I have noticed that it switched on the lights for 15 minutes. But not all activity is observable.
• I was wondering whether the 12V battery SoC is perhaps off. But the SoC tracks well with the charge current and idle voltage.
• I measured the current draw of the 12V battery using a clamp multimeter. It seems to draw 10 amps for 3 minute after locking, and then ~3 amps (36 watts) for 15 minutes before it goes to a deeper sleep. After that it does seem to use ~100mA (1.2 watt) regularly, but unfortunately that could beyond the resolution om my multimeter.

I do not understand why the car is not programmed to go to deep sleep immediately. And I have witnessed several wakeup events either because of a PAAK event or out of nowhere in the middle of the night. Every wake up events drains the 12V by a few %. That seems unnecessary.
It should be that between drives the 12V battery a few %, not 30%. That will wear out the 12V.

 

[Mach-Lee]

Yeah, I am stumped as well by the excessive 12V battery drain. I too see the SoC drop from 90% down to 75 in 2 hours and down to 50% overnight. I do wonder whether this is 'normal' or that my MME has an issue. I am on my 3rd 12V battery already. In other words: will many other MME owners have to replace the 12V battery as many time as I had to?

Here is what I observed doing a few experiments over the past weeks:

• Every night the 12V battery drains. On a good day it is down to 70% the next morning, on a bad day it is down to around 50%. The battery is brand new. I get no messages about battery drain. After start it charges initially at 22A, and when about 80% the charge current is down to 2A. It takes about 20 minutes to get it back over 80%.
• The car charges the 12V battery anytime it drives or while it is charging. Even when plugged in it won't trickle charge the 12V battery unless it is actively charging the HV battery.
• The only way my OTA update worked was to manually trigger it after I had driven the car enough to the SoC to be about 80%. On the regular schedule it is supposed to update at 3am, by which time the battery is always drained below the 80% threshold so the update fails.
• Calculated from the OBD2 bus data the DC/DC converter that charges the 12V battery does not seem very efficient: only 70%. So it is understandable that the MME does not trickle charge.
• Switching off all wireless connectivity had no effect. The suspicion was that some polling from Fordpass would keep the car awake. But polling seems not the problem.
• Switching off the bluetooth on my phones seemed to have perhaps a little effect, but not significant. The though was that walking through the house would wake up the car through PAAK. This happens indeed, but even with bluetooth the 12V battery drains down almost as much.
• The iPhone has a very lazy bluetooth, and therefore wakes up the car less. The Android bluetooth connects more eagerly over Bluetooth and therefore seems to trigger more wakeup events.
• Unplugging my dashcam front the USB had no measurable effect. The idea was that perhaps the dashcam drains extra. The USB plugs are powered for 30 minutes after locking the car (that is wierd...).
• I put a security camera on the car to record when it wakes up overnight. I have noticed that it switched on the lights for 15 minutes. But not all activity is observable.
• I was wondering whether the 12V battery SoC is perhaps off. But the SoC tracks well with the charge current and idle voltage.
• I measured the current draw of the 12V battery using a clamp multimeter. It seems to draw 10 amps for 3 minute after locking, and then ~3 amps (36 watts) for 15 minutes before it goes to a deeper sleep. After that it does seem to use ~100mA (1.2 watt) regularly, but unfortunately that could beyond the resolution om my multimeter.

I do not understand why the car is not programmed to go to deep sleep immediately. And I have witnessed several wakeup events either because of a PAAK event or out of nowhere in the middle of the night. Every wake up events drains the 12V by a few %. That seems unnecessary.
It should be that between drives the 12V battery a few %, not 30%. That will wear out the 12V.

I can appreciate the struggle here. I can tell you from my tests it's abnormal for the car to keep waking up. When you shut down the car, something stays awake for two hours afterwards, but after that everything should shut down indefinitely and you should see less than 60 mA draw. When BLE connects for PAAK you'll see a couple extra mA of draw, not a big deal. But if you get too close with a PAAK or fob the car will wake up and go through the pattern of decreasing amp draw you saw, which repeats a second time after 10 minutes on my car. Here is a recording of voltage after shutting of my car, with a welcome lighting event. Again it takes 120 minutes to fully shutdown modules:

Please disable welcome lighting if you haven't already. I've identified that as a drain problem on some vehicles.

Connected vehicle pings will only wake the car up one time, back to normal after 10 minutes. There should not be any occurring unless you've just sent a command or initiated a refresh.

This could also be software related on your vehicle. What updates does your car have available? I recommend you get 6.1, 6.2, 6.3, and 6.8 updates installed if you don't already. Basically this TSB: https://www.macheforum.com/site/thr...-defaults-to-normal-mode-while-driving.33163/

 

[JimmyMachE]

Quiescent avg current: 77ma.

So the battery was at 88% last night and it was 76% first thing this morning. I highly doubt the car used 4.2A last night. 77ma*12hours = 0.924 amps. That's no where near 12% of the 35Ah AGM battery.

Quiescent current average (77mA) is probably measured when car is fully asleep, no modules active at all. But as we know, vehicle electronics keeps waking up periodically or randomly.

I’ve been very careful about the phone and fobs.
I don’t know if they reset the BMS after replacing the battery - How can I tell?

OBD2 dongle will show number of days since '12V battery reset'
https://www.macheforum.com/site/threads/12v-values-carscanner.33237/#post-744774

 

[MachE70]

I have a similar issue with a mismatch between my battery charger SoC and my Ford account SoC. I bought a new Pro-Logix PL2310 charger and put it on my '22 Mach e GT yesterday. It reached 100% SOC at 12.8v in about 6 hours, and is still reading those values now after 24 hours with the charger in the Resting phase. However, my Ford account is only reading 83% SoC. Why the difference in the two readings? I suspect the charger readings are more accurate - is that the case?

Based on my previous Ford account readings, the SoC will drop about 10% the first day after charging the battery up to 80% plus, then drains at a slower rate of about 3 to 5% per day. Does that sound like normal behavior? This is still my first 12v battery in the car and I have never really had any problems with it, other than one failed OTA due to low battery and maybe 3 - 4 "system off to save battery" messages.

 

[Mach-Lee]

I have a similar issue with a mismatch between my battery charger SoC and my Ford account SoC. I bought a new Pro-Logix PL2310 charger and put it on my '22 Mach e GT yesterday. It reached 100% SOC at 12.8v in about 6 hours, and is still reading those values now after 24 hours with the charger in the Resting phase. However, my Ford account is only reading 83% SoC. Why the difference in the two readings? I suspect the charger readings are more accurate - is that the case?

Based on my previous Ford account readings, the SoC will drop about 10% the first day after charging the battery up to 80% plus, then drains at a slower rate of about 3 to 5% per day. Does that sound like normal behavior? This is still my first 12v battery in the car and I have never really had any problems with it, other than one failed OTA due to low battery and maybe 3 - 4 "system off to save battery" messages.

Leave the charger on for at least 12 hours after charging done indication (solid green no flashing yellow).

Yes 10% loss in the first two hours after key-off is normal, followed by 5% per day.

 

[RickMachE]

My BMS was just replaced on my truck, they didn't reset anything. After a week sitting on the Battery Tender, I'll do a reset.

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