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The description is very terse. Instructions direct technicians to trigger a 48 h cycle at the end of which balancing is either done or interrupted, then scan the average voltage variation PID and repeat with extra cycles if needed. There is also another procedure applied at the large serviceable...

Another factor affecting SoC (and I assume SoH as well since it reduces the overall SoC) is cell/module balancing. If a module SoC is out of whack with respect to other modules it will drag down the whole battery SoC. According to the shop manual, module rebalancing is performed whenever trigger...

I agree. There would always be a SW component anyway since manufacturers would not want to lose the ability of patching, reconfiguring. HW changes are far more involved.

Thanks for sharing. I suppose that if a non-proprietary solution is used, one (teardown guys?) could visually inspect the BECM PCB and identify the chipset used. But then there would be no fun in reverse engineering 😄!

You can count me in. I haven’t been able to play a lot with the truck but I have been able to collect several hours of data. This includes going down to 0% SoC, going from 0% to 100% in a controlled environment with battery temperature close to nominal values, and a voltage relaxation...

Cool, thanks. You would typically see the power bar greyed out like in the attached picture. But at regular speeds and mild acceleration you may not notice anything…

Congrats on the 100k!! Out of curiosity, how many times more or less did you go lower than 20%? And did you notice there was any power limit on the dashboard? The two times I tried to go down to 0% power was limited to 70% at 10% SoC and 35% at 0%..

Very Impressive, @Helium. Thanks for sharing your experience! It’ll definitely take me a lot longer to drive that many miles 😃.

Congrats! I had the truck for 5 months now and loving it! (Apart from some initial frustration in getting service for required CSPs …)

Haha, I started doing it and already have a few. But it'll take me sometime to get to 0 since I don't drive many commute miles. So, you're saying to keep recording after stopping for say, an hour? Just saw the updated post. I suppose I could record next day before leaving but by that time some...

Definitely the BMS is the culprit. The out of spec guy was able to drive well below 0% (displayed) consuming the buffer. A BMS would typically use a resistive conductor with very low resistance and very low voltage drop that is then amplified by a differential op amp and sampled at dt intervals...

By the way, from what I can observe from the video I linked, it seems (but I still need to get my data points to be sure) more like there is a 6% buffer on top, and 4% at bottom (relative to nominal 131, but of all 144 battery) of which 1.5% is not consumed, and 2.5% is used as reserve. I...

Could you post a link? I only found this one which is crazy. As part of the test, the guy not only reaches 0% but also eats up the “reserve” buffer down to 2kWh and the truck dies a few yards from the charging station 😆. Then truck is pushed to the station and he charges at 50kW … insane 😂

I see, thanks. Something like keeping them in check. By the way, from what I read in the DOE document they don’t drive the cell below Vmin0, they just reach Vmin0 at the end of the test. Out of curiosity, and if you are at liberty to say, how many cells are you testing?

I googled the subject a few days ago and read this department of energy report of 2015: Battery Test Manual For Electric Vehicles, Revision 3 (Technical Report) | OSTI.GOV, explaining the procedures of several EV battery tests, including HPPC. In page 8, it says HPPC tests, after 10%...

Most probably, since they call it NCM 90 the CM portion might not have been disclosed at that time.

Well, they go as high as 4.5V which is even worse. When I purchase a cell I get the specs from the manufacturer and set the charger/ BMS accordingly. I assume 4.5V is within the safe range for testing the cell. Yeah, people are lazy, but it is probably ok in the context. Also the article does...

This is a 5 year old article announcing the SK NMC9: NCM 90: successor of NCM 811 battery cells - Posts - 🔋PushEVs, including some comparative data pasted below: An excerpt regarding the NMC9: The NCM 90 cathode when cycled between 2,7 and 4,3 V at 0,5 C retains 90 % of its initial battery...

Interesting, although older is quite older ... (2003) :), thanks for sharing! So, at 0.5C, room temperature, 1000 cycles, they report 14% capacity loss for 70% DOD, and 70% capacity loss for 100% DOD, under the HPPC test. They do say at the end that: "The large capacity and power losses in this...

Oh, that's much better :) It was weird that the voltage variation was low, although it would have been somewhat plausible since the voltage curve is so flat and delta V really shows up at the low/high ends.