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No doubt that what you are seeing is real but I don't understand how you can even see individual cell voltage. Isn't the traction battery hundreds of cells wired in series?
You can use torque with OBD2 and load the PID for Kia Phev (https://github.com/JejuSoul/OBD-PIDs-for-HKMC-EVs) and setup the dash to monitor each cells from 1-96 for voltage.

I been using SoulEVSpy with OBD2 instead as it has all the 96 cells setup to be displayed, you can see each individual cell voltage and Temperature per module.

I think perhaps you are misinterpreting the numbers. It’s also an open question in my mind if it’s safe to extrapolate the numbers for the 2017 HEV to your 2020 PHEV, but let’s assume that it is (aside from the battery size, which we know is larger in the PHEV).

I assume you’re getting the 4.15 from an OBD reader? What is the resolution of the numbers it reports? Do you ever see something like 4.14, or does it go from 4.15 to 4.10? If the resolution is 0.05 V then we might contemplate that even if the actual voltage is 4.199, your reader might report 4.15. In other words, perhaps your system is charging to 4.2, and the difference between 4.15 and 4.2 is not “the buffer”.

It’s appealing to think that the cells might have been designed to have a maximum capacity of 5.0 V. If that is true, the difference between 4.2 and 5.0, expressed as a percentage of 5.0, is 16%. That lines up nicely with your observation that on the low end, the hybrid kicks in when the SOC is 16%.

On the other hand, the page you referenced points out that a 64 cell battery has 240 V at 55% SOC. That implies that each cell would have a max capacity of 6.8 V, in which case the buffer between 4.2 and 6.8 works out to about 38%.
The resolution I'm getting is down to 0.01 V, so you would see a change from 4.15 to 4.14.

I believe the maximum capacity per cell is 4.2 V, it is the same for HEV and PHEV.
Obviously to prolong battery life they never fully charge the cell to 4.2 V, so that's why i see only 4.15 V when charged to 100% shown on the dash in the car.

The HEV has 64 cells vs 96 cells for the PHEV.

The max voltage per cell 4.2 V was from the Kniro tech site which is for the HEV.
Operating Voltage (V)​
160 - 275
[2.5V ≤ Cell Voltage ≤ 4.2V]​

For the PHEV when fully charged to 100% the battery voltage was at 398.4 V / 96 cells = 4.15 V per Cell.

This was all observed using OBD2 connected to SoulEVSpy and confirmed using torque with PID for the Niro PHEV
 

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The HEV has 64 cells vs 96 cells for the PHEV.
I have a problem with that number, assuming both batteries use the same cells. That's only a 50% increase in cell count, when the actual reported capacity of the HEV is 1.56 kWh while the PHEV is 8.9 kWh. Can't get from A to B using the same cells if those are accurate cell counts.
 

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I have a problem with that number, assuming both batteries use the same cells. That's only a 50% increase in cell count, when the actual reported capacity of the HEV is 1.56 kWh while the PHEV is 8.9 kWh. Can't get from A to B using the same cells if those are accurate cell counts.
Actually, they do not use the same cell. The Cells that are used in HEV has lower amp hour rating.

The HEV has total of 6.5 AH at 55% SOC.
6.5 AH * 64 Cells * 3.75V = 1.56 kWH

The PHEV has 24.7 AH at 55% SOC.
24.7 AH * 96 Cells * 3.75V = 8.892 KWH

The battery information I'm getting for the PHEV is from "Michael Jones" from this post.

I'm not 100% sure if his information is correct, guess i won't know unless i sign up and confirm the data on the Kia technical site.
 

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Yes, thanks for the numbers Mikek7.

Going back to your post, you mentioned that you were charging to 88%. Is that an option that you can configure in software on your 2020 PHEV? In my neighborhood, my garage typically experiences several days above 100 F during the summer months and during that time, I try to avoid charging to full capacity, but my 2018 PHEV doesn't allow me to limit the charge directly. Instead, I've had to make do with charging schedules that shut down the charger before it reaches full. Always a bit of a challenge to figure out how long to configure the charging schedule for and I'm much prefer something that allowed me to shut it off at something like 88%.

I do still think that you might be looking at the wrong numbers when calculating the buffer. The battery is an expensive item and Kia warranties it for 10 years (although in the USA manuals, they don't specify what the point is where the battery degredation would be considered subject to warranty replacement). So I'm strongly tempted to think that 4.2 V is the bottom end of the buffer, not the high end.
 

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Yes, thanks for the numbers Mikek7.

Going back to your post, you mentioned that you were charging to 88%. Is that an option that you can configure in software on your 2020 PHEV?
At least on US models, the PHEV doesn't have an option to limit the % of charge. Unless that's a new feature for 2020, I've looked all over the settings in my '19 and there's none there.
 

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At least on US models, the PHEV doesn't have an option to limit the % of charge. Unless that's a new feature for 2020, I've looked all over the settings in my '19 and there's none there.
That feature is in their EVs but not their PHEVs. Again unless Kia added it for the 2020 PHEV model.
 

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Yes, thanks for the numbers Mikek7.

Going back to your post, you mentioned that you were charging to 88%. Is that an option that you can configure in software on your 2020 PHEV? In my neighborhood, my garage typically experiences several days above 100 F during the summer months and during that time, I try to avoid charging to full capacity, but my 2018 PHEV doesn't allow me to limit the charge directly. Instead, I've had to make do with charging schedules that shut down the charger before it reaches full. Always a bit of a challenge to figure out how long to configure the charging schedule for and I'm much prefer something that allowed me to shut it off at something like 88%.

I do still think that you might be looking at the wrong numbers when calculating the buffer. The battery is an expensive item and Kia warranties it for 10 years (although in the USA manuals, they don't specify what the point is where the battery degredation would be considered subject to warranty replacement). So I'm strongly tempted to think that 4.2 V is the bottom end of the buffer, not the high end.
It is the same for 2020 Phev, there is no limit option on when to stop charging. I just use the charging schedule to stop charging so it doesn't hit 100%.
 

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WOW, the apparent knowledge about batteries on this site is pretty phenomenal.
I must admit you guys lost me pretty early in this, but I'm impressed for sure!
6245
o_O
Meanwhile my PHEV seems to be doing fine at 6K. I don't expect to see much degradation for at least 5 years, God willing.
 

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Yeah, I'm not keeping my PHEV after the lease is up. So long term degradation isn't on my radar. But I do intend on moving to a BEV at that time, so the overall dynamics of battery degradation will still be something I think about. May '22 is too far away to make any firm plan on what to get. The Niro EV is a solid consideration, but Kia is also supposed to be coming out with a EV only platform by then, so they might have something different to consider. VW will have the ID.4, Ford will have the Mach-e, and who knows what else might be around. The Tesla Model Y of course, but I feel it's a bit overpriced, and really am uncomfortable with the entire car being controlled via a touchscreen.
What about an entire Dragon being controlled by a touchcreen.
 
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