Significant drop in SoH

[GreaseMonkey]

I’m not one who gets too concerned about SoH and battery deterioration as a general matter. However, I measured it a couple of times in the past and it hovered in the 94.5-95%. Last time to measure was around beginning of the year.

However, today it dropped to 85.5%! My vehicle has 9,670 miles and is 21 months old. What gives? Any thoughts? I DCFC weekly due to lack of Level 2.

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[RickMachE]

To be accurate, needs to be 77 degrees, and 100% SOC.

 

[Mach-Lee]

I’m not one who gets too concerned about SoH and battery deterioration as a general matter. However, I measured it a couple of times in the past and it hovered in the 94.5-95%. Last time to measure was around beginning of the year.

However, today it dropped to 85.5%! My vehicle has 9,670 miles and is 21 months old. What gives? Any thoughts? I DCFC weekly due to lack of Level 2.

This drop is associated with the 24-PU0102-CHG-SUFX powertrain/BECM update. Basically it forces a BMS health update, for better or worse. Shallow charge/discharge cycles may be affecting accuracy. You can try performing a battery calibration to see if it improves. Try to do the calibration with the battery warm (25ºC) for best results (warmer weather).

 

[GreaseMonkey]

This drop is associated with the 24-PU0102-CHG-SUFX powertrain/BECM update. Basically it forces a BMS health update, for better or worse. Shallow charge/discharge cycles may be affecting accuracy. You can try performing a battery calibration to see if it improves. Try to do the calibration with the battery warm (25ºC) for best results (warmer weather).

Ok, so do it in June then. The drop in this figure is so drastic for a car as new as mine, although I charge DCFC all the time. My car almost never gets charged to 100%, mostly 50%-80% cycles.

I assume that’s what you mean by shallow cycles.

 

[SpaceEVDriver]

Ok, so do it in June then. The drop in this figure is so drastic for a car as new as mine, although I charge DCFC all the time. My car almost never gets charged to 100%, mostly 50%-80% cycles.

I assume that’s what you mean by shallow cycles.

I saw a similar overnight drop in the middle of a road trip. It did not impact my actual range.

 

[GreaseMonkey]

I saw a similar overnight drop in the middle of a road trip. It did not impact my actual range.

Yes, my range is 280 miles, if extrapolated from the current estimate.

 

[dtbaker61]

I’m not one who gets too concerned about SoH and battery deterioration as a general matter. However, I measured it a couple of times in the past and it hovered in the 94.5-95%. Last time to measure was around beginning of the year.

However, today it dropped to 85.5%! My vehicle has 9,670 miles and is 21 months old. What gives? Any thoughts? I DCFC weekly due to lack of Level 2.

I would suggest driving around down to something around 10-20% remaining, then do a nice long L2 charge to 100%, THEN take another look at your SOH

 

[Scooby24]

If you're DCFC I'm guessing you don't hit 100% very often, which is when I've seen the load balancing occur. If I recall correctly, we should be charging to 100% every month or couple of months. I don't know if it's explicitly called out in our manuals but Kia does in theirs so I assume the same logic applies

 

[GreaseMonkey]

If you're DCFC I'm guessing you don't hit 100% very often, which is when I've seen the load balancing occur. If I recall correctly, we should be charging to 100% every month or couple of months. I don't know if it's explicitly called out in our manuals but Kia does in theirs so I assume the same logic applies

So many rules, man. And you’re right. I charge 50-80 most weeks. We don’t drive much here in the city and we both work from home.

 

[Shayne]

If you're DCFC I'm guessing you don't hit 100% very often, which is when I've seen the load balancing occur. If I recall correctly, we should be charging to 100% every month or couple of months. I don't know if it's explicitly called out in our manuals but Kia does in theirs so I assume the same logic applies

You are most likely right batteries are batteries. Is this to help the batteries or to just get a better reading on the app?

I only use the app when I have problems and do understand why this one stood out to the OPer.

I gauge by % and know what % at different temp it takes for a few of my regular trips (right at the begining). If I start seeing those trips use a lot more I will know something is up and plug in the OBD. It was +7C here yesterday and one on my normal trips did it in 19%; if cold I have seen high 30%. 15 - 20% range is about my best ever for that trip so appears after 3 winters not much has changed this winter. Range appears to be still there.

 

[dtbaker61]

You are most likely right batteries are batteries. Is this to help the batteries or to just get a better reading on the app?

I only use the app when I have problems and do understand why this one stood out to the OPer.

I gauge by % and know what % at different temp it takes for a few of my regular trips (right at the begining). If I start seeing those trips use a lot more I will know something is up and plug in the OBD. It was +7C here yesterday and one on my normal trips did it in 19%; if cold I have seen high 30%. 15 - 20% range is about my best ever for that trip so appears after 3 winters not much has changed this winter. Range appears to be still there.

discharge and charge to 100% help to 'reset' the monitoring and internal 'top balancing' of all the individual cells. repeat cycling in the middle is good for battery life, but the cells never balance, and the amp-hr counter gradually 'drifts' since all cells are not exactly the same.

periodic discharge to 10-20% and slow (level 2) charge to 100% is a good thing to enable top balance and reset 'counters'.

 

[Guss-E 2021]

Ok, so do it in June then. The drop in this figure is so drastic for a car as new as mine, although I charge DCFC all the time. My car almost never gets charged to 100%, mostly 50%-80% cycles.

I assume that’s what you mean by shallow cycles.

From what I've learned there is less expansion and contraction in the barrery when charging between 50% and 80%. If you are doing that, I'm not sure DCFC would be an issue. Also, that worry about what SoC is best to store the battery does not apply in the cold. I think it was Tom's State of Charge YouTube channel that interviewed a battery specialist about it.

 

[Scooby24]

You are most likely right batteries are batteries. Is this to help the batteries or to just get a better reading on the app?

I only use the app when I have problems and do understand why this one stood out to the OPer.

I gauge by % and know what % at different temp it takes for a few of my regular trips (right at the begining). If I start seeing those trips use a lot more I will know something is up and plug in the OBD. It was +7C here yesterday and one on my normal trips did it in 19%; if cold I have seen high 30%. 15 - 20% range is about my best ever for that trip so appears after 3 winters not much has changed this winter. Range appears to be still there.

I have zero knowledge on how SoH is calculated, but there are measurements of module variation from pack to pack that you can see in the app. Without load balancing the modules, I would assume those variations drift and could be perceived as poor health of the battery.

 

[Robob]

I wouldn’t worry with what obd tools spit out. Unless you run a battery health check with FDRS which takes a few minutes and generates a report like this. Then you can see cell voltage issues etc.
As you can see in image here I’m at 97% at about 10.5k miles

 

[Shayne]

I have zero knowledge on how SoH is calculated, but there are measurements of module variation from pack to pack that you can see in the app. Without load balancing the modules, I would assume those variations drift and could be perceived as poor health of the battery.

Is it just to get a better app reading or is the unbalance a physical performance thing? Something that should be reset once in awhile? If they drift too much does the monitor put out a code or no longer will full charge the pack?

I wouldn’t worry with what obd tools spit out. Unless you run a battery health check with FDRS which takes a few minutes and generates a report like this. Then you can see cell voltage issues etc.
As you can see in image here I’m at 97% at about 10.5k miles

I guess we need to get Mr. G on this. I do not think he is worked hard enough around here yet

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