Charging to 100% -- voltages, SOC, and capacity

Firn · Nov 10, 2024

Recently charged from 50%to 100% and threw car scanner on it while I did so. Here are the results.

SOC, SOC displayed, and capacity.

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241110-215948

Module voltage

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241110-220014

Average module voltage at 100% soc displayed was 4.09v. Considering a 3.0v to 4.2v range for NMC that translates to 90% peak for the chemistry.

Previous charges indicate a module voltage of 4.04v at 90% displayed soc.

So there is some top buffer, but not a huge amount.

Maquis · Nov 11, 2024

I don’t understand how the kWh can drop while charging? Red curve.

Firn · Nov 11, 2024

Maquis said:
I don’t understand how the kWh can drop while charging? Red curve.

I'm not sure either. It happens at the same time that the truck reached "100%" so I'm assuming it is related to the charger turning off. I'll pull the voltages here when I can.

Firn · Nov 11, 2024

There was around a 1v drop in pack voltage at the time the charger stopped, this is also the exact time the capacity dropped.

Looking quickly at the data and it appears 1v change in pack voltage while charging does corelate to that amount of energy.

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241111-123442

Effonefiddy Lightning · Nov 11, 2024

Me, clueless as to what these graphs even mean. :surprised:

Jim Lewis · Nov 12, 2024

IIRC, the total real capacity of an ER battery is 143 kWh, with some buffer at the top and bottom of the real range. Your avatar shows a snowy environment. There are not too many trees on the North Slope, but maybe the temperature of your charging experiments is an important parameter to keep track of, especially in comparing similar experiments done at different times of year, different truck mileages, etc.

Firn · Nov 12, 2024

Jim Lewis said:
IIRC, the total real capacity of an ER battery is 143 kWh, with some buffer at the top and bottom of the real range. Your avatar shows a snowy environment. There are not too many trees on the North Slope, but maybe the temperature of your charging experiments is an important parameter to keep track of, especially in comparing similar experiments done at different times of year, different truck mileages, etc.

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241112-070734

The "top buffer" was ultimately my reason for doing this. That top buffer is nothing more than limiting the maximum voltage.

Pack voltage was 392v with a cell voltage of 4.09v at 100% displayed SOC. Assuming a 3.0v minimum voltage, and running the cells out to 4.2v per cell, would give you and overall capacity of ~139kwh, or very close to the label capacity.

Maquis · Nov 12, 2024

Firn said:
There was around a 1v drop in pack voltage at the time the charger stopped, this is also the exact time the capacity dropped.

Looking quickly at the data and it appears 1v change in pack voltage while charging does corelate to that amount of energy.

The drop in voltage is likely causing the energy graph to drop, but only because the algorithm to determine SoC uses pack voltage. In reality, the stored energy did not go down.

chl · Nov 12, 2024

Why does battery voltage drop after charging?

This is often the normal behavior of the cell. A cell's voltage will rise when it is being charged and will begin to drop somewhat after the charge current has been removed. This is a result of many factors, but primarily due to internal resistance of the cell and the charge characteristics of the chemistry.

https://www.orionbms.com/troubleshooting/cell-voltages-drop-charge-completes/

So the drop does appear to be when the charger turned off.

Hammick · Monday at 11:42 AM

chl said:
Why does battery voltage drop after charging?

This is often the normal behavior of the cell. A cell's voltage will rise when it is being charged and will begin to drop somewhat after the charge current has been removed. This is a result of many factors, but primarily due to internal resistance of the cell and the charge characteristics of the chemistry.

https://www.orionbms.com/troubleshooting/cell-voltages-drop-charge-completes/

So the drop does appear to be when the charger turned off.

Yep. I have the Orion Jr.2 BMS controlling our off grid battery bank and the voltages drop exactly as stated in that article. Our cells are 272ah Lishen LifeP04s.

chl · Monday at 2:12 PM

Hammick said:
Yep. I have the Orion Jr.2 BMS controlling our off grid battery bank and the voltages drop exactly as stated in that article. Our cells are 272ah Lishen LifeP04s.

I learned a lot about batteries when studying for my EE in the 1980's.

But I have to say I also learned a lot of more practical stuff since then, from my own experience with owning an EV (2012 Nissan Leaf) since December 2011, and from the many experienced people on these forums.

A great resource.

Firn · Monday at 3:28 PM

A few more images showing the relation between module voltage and soc displayed, and "energy to empty"

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241118-180754

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241118-182130

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241118-180959

Ford F-150 Lightning Charging to 100% -- voltages, SOC, and capacity Screenshot_20241118-182004

Shawnson · 2024-11-20T17:08:14-0800

Maquis said:
I don’t understand how the kWh can drop while charging? Red curve.

It’s just graph plotting. (No data)

Charging to 100% -- voltages, SOC, and capacity

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