HV Battery Calibration Procedure

[sglewiswl]

It would take too long, and the battery current would be too low for an accurate measurement of energy added to the pack.

Has anyone tried to do this? I currently only have access to L1 charging and am willing to try. I work from home so my car sits idle for days.

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[Mach-Lee]

Has anyone tried to do this? I currently only have access to L1 charging and am willing to try. I work from home so my car sits idle for days.

Be my guest. I think it will take like 4 days to charge from 5% to 100% on level 1, so if you can go that long without driving it…

 

[sglewiswl]

Be my guest. I think it will take like 4 days to charge from 5% to 100% on level 1, so if you can go that long without driving it…

I can, I have another vehicle. My longest round trip right now is 40 miles and most of them are under 15 miles. It took me over a week to get below 50 miles . I bought an EV to be a good steward and I would have upgraded the battery in my Leaf but I decided putting that money towards a Mach-E was better choice.
I'll experiment and let you know. I have a suspicion that the reason my SoH is at 90% is that between me and the previous owner it was never discharged enough to re-calibrate the BMS. When you only put 5000 miles year the battery doesn't get a lot of usage.

 

[sglewiswl]

Be my guest. I think it will take like 4 days to charge from 5% to 100% on level 1, so if you can go that long without driving it…

It took 55 hours. I have never seen it at 100% before. I've only had the car a month.

 

[Mach-Lee]

It took 55 hours. I have never seen it at 100% before. I've only had the car a month.

And what does the SoH say now? Did it change?

Also 55 hours seems too short to charge from 5% to 100% unless you have a standard range pack?

 

[sglewiswl]

And what does the SoH say now? Did it change?

Also 55 hours seems too short to charge from 5% to 100% unless you have a standard range pack?

It is still at 90% I do have a standard range pack.

 

[CarlSagan82]

@sglewiswl
Did this make any change to the bms? I am in a similar situation less than 10k miles a year and L1 charging only. So I never really go from 5 to 100% ever

 

[sglewiswl]

@sglewiswl
Did this make any change to the bms? I am in a similar situation less than 10k miles a year and L1 charging only. So I never really go from 5 to 100% ever

Not yet, but I haven't driven the car. I need to do the next step which is drive it to below 50% then charge it back to 90%.

 

[mkhuffman]

Rivian used to provide SoH via the API from their servers (there is no OBDII data connection available). Not now. They removed it because of concerns like this. Also, I heard Rivian plays around with the buffer to try to keep range consistent, so a SoH number would not reveal a real-world impact.

I think Ford is not dynamically changing the buffers, so it matters more here. But still I wonder if Ford will change what is reported via the OBDII to remove that data field, especially since it seems to also not be well correlated with actual range available.

 

[sglewiswl]

In LeafSpy on my Nissan Leaf the SoH was % of battery remaining measured by capacity I believe. So the correlation for range was (somewhat) accurate. The challenge was the m/kWh didn't include accessories so the range would drop really fast if is was cold or you needed the wipers. We also had a value for reactance which appeared to be valuable as if it was low or decreasing so was your SoH. My Leaf was at 61% SoH when I traded it in. All the cells were in balance, but it was the original 13 year old battery and was losing it's charge across all cells, time was catching up with it.

 

[Brad R]

I have a 2025 with a 72kwh LFP. My problem is living in a condo with no access to L1 or L2 charging; DCFC is my only option. There is no way for me to do Lee's procedure. Being retired, I do not put a lot of miles on the car, so I am only charging 2 or 3 times a month, generally staying between 30% and 80% state of charge. If I charge it to 100% once a month, as Ford recommends, it would mean every other visit to the charging station. Lee recommends every two weeks, so for me probably every time I charge. I know DCFC charging is harder on battery health, but I have no choice. I want to avoid the "sudden drop from 50% to 1%" that could occur as Lee has pointed out. The question is how often should I charge to 100% to find the balance between harm and benefit?

 

[E90alex]

I have a 2025 with a 72kwh LFP. My problem is living in a condo with no access to L1 or L2 charging; DCFC is my only option. There is no way for me to do Lee's procedure. Being retired, I do not put a lot of miles on the car, so I am only charging 2 or 3 times a month, generally staying between 30% and 80% state of charge. If I charge it to 100% once a month, as Ford recommends, it would mean every other visit to the charging station. Lee recommends every two weeks, so for me probably every time I charge. I know DCFC charging is harder on battery health, but I have no choice. I want to avoid the "sudden drop from 50% to 1%" that could occur as Lee has pointed out. The question is how often should I charge to 100% to find the balance between harm and benefit?

You have no practical way to follow the calibration procedures so don’t worry about it unless you suspect something is really off.

Otherwise you need to find a public L2 charger you can leave it overnight at if you want to do the calibration. Or ask a friend or family member with a home charger. Just hitting 100% is not enough for the calibration. PLEASE do not do it at a DCFC and leave your car sitting plugged in at 100% for 3 hours.

For your daily usage I would just charge to 100% every time (and then unplug and leave) and run it to 20% or less. If you’re charging in the middle of trip then goto 80-90%.

 

[Brad R]

You have no practical way to follow the calibration procedures so don’t worry about it unless you suspect something is really off.

Otherwise you need to find a public L2 charger you can leave it overnight at if you want to do the calibration. Or ask a friend or family member with a home charger. Just hitting 100% is not enough for the calibration. PLEASE do not do it at a DCFC and leave your car sitting plugged in at 100% for 3 hours.

For your daily usage I would just charge to 100% every time (and then unplug and leave) and run it to 20% or less. If you’re charging in the middle of trip then goto 80-90%.

Thanks! Don't worry, I wouldn't sit at a DCFC once it reached 100%.

 

[Mach-Lee]

I have a 2025 with a 72kwh LFP. My problem is living in a condo with no access to L1 or L2 charging; DCFC is my only option. There is no way for me to do Lee's procedure. Being retired, I do not put a lot of miles on the car, so I am only charging 2 or 3 times a month, generally staying between 30% and 80% state of charge. If I charge it to 100% once a month, as Ford recommends, it would mean every other visit to the charging station. Lee recommends every two weeks, so for me probably every time I charge. I know DCFC charging is harder on battery health, but I have no choice. I want to avoid the "sudden drop from 50% to 1%" that could occur as Lee has pointed out. The question is how often should I charge to 100% to find the balance between harm and benefit?

You are correct that you will not be able to do the full calibration procedure. Based on your situation, I would recommend you try to find a public Level 2 charging station in your town and do a monthly charge to 100% on it (perhaps after you hit 80-90% on the DC charger).

The periodic charge to 100% is important for LFP batteries to reset the coulomb counter of the battery's capacity to full. The periodic charge to 100% will prevent the sudden early drop to 1%.

If you cannot do regular charges to 100%, then I would avoid going below about 40% due to fear of running out of charge unexpectedly due to an uncalibrated BMS.

This is one of the pitfalls of owning an EV with no at-home charging. Given that situation, I would recommend getting the extended range NCM pack instead of LFP.

 

[sukhoi_584th]

Depending what DCFC are around you, you could also charge to 100% at one of the slow 50-62 kW chargers that tend to be in much lower demand.

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