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Thanks for this correction Frud. It is because this line is missing from the code above: } else if (volts < 3.7488) { SoCv = 261.403598620641* volts -955.315988937822; return; Using this line the SoC only changes by 1,5% points. I have also checked the number of significant...

The interesting thing about the SoC based on low amp voltage or open circuit voltage is it's stability. The current doesn't effect the SoC and because there are, in principle, no reactions going on in the cell the temperature has little to no effect. I've also looked at the curves from the time...

Here it is Frud. And I have attached the article I found it in. You bring up a good point here. This curve isn't smooth as one would expect. I have read that this is due to the lithium ions rearranging themselves in the anode or cathode as the ions move from one to the other. At steps along the...

This has got me to thinking about how to convert as much as possible in the code to integer arithmetic. It's a good idea but right now it is best to limit the changes until we have something running dependably. However there is one thing I'm wondering about. In PID 0x373 byte 0 is the the...

Thanks for your input Frud. I'm sure there are improvements that will increase performance. However please do not change the original code for the SoCv. The original code is a series of straight lines that match the low amp voltage v SoC curve in a scientific article on the NMC cell. It gives...

Hopefully the capacity doesn't change much. The temperature effect is not large. According to the Yuasa tech report on the LEV50 at -25oC the Ah capacity is 90% of the +25oC Ah capacity. I think that piev is right when he wrote that monitoring the voltage is sufficient to avoid problems. It...

Correction: capacityAh should be 90 not the value from the BMU.

Very interesting! I may have to agree with Mickey that it's SoC and not voltage but lets see. I think that a coulomb count should be added to your program. This requires a storage variable remAh containing the remaining Ah in the battery and a calculation of the Ah added or used each time the...

Computing the SoC from the voltage is quick and easy solution and it is a step in the right direction. But it doesn't work well unless the amps are between -1 and 1 for at least some minutes. When the battery is under load the SoC computed from the voltage can be as much as 20 % points below the...

No byte 6 isn't constant. It is one of two numbers on the network that give the present battery capacity. The other is PID 762 byte 0 = 36 bytes 3 and 4. 374 Byte 6 has a resolution of 0.5 Ah while PID 762 has a resolution of 0.1 Ah. piev changed the RR when he changed the value of 374 Byte 6 so...

Hi Phximiev The cell voltage reaches 4.1 volts toward the end of the charging process but decreases quickly to 4.09 volts after charging stops. An hour after charging stops 4.08 volts is normal. If the BMU reported capacity is in error and the true capacity is much more than 19.9 say 30 Ah...

Hi Mickey The BMU doesn't have to use the 96Ah in its calculations. The formula I showed above is a way to compute what the BMU will measure as the capacity. It isn't what the BMU sees. When BMU measures the 94 Ah MNC cell at 3.85 volts, it believes that the true SoC is 30% so it computes 30%...

Hi Mickey Yes and no. A 60 Ah will probably need a hack. Nuggetgalore saw a fast drop in capacity of the NMC pack which he attributed to cell deterioration. I believe the BMU was just doing it's job reporting the capacity of 37 Ah based on its programming. So for a useful measurement from the...

Hi Mickey I downloaded nuggetgalore's post from the Australia site and I have redone the graph in the post showing discharge curves for the LEV50 and his replacement 60 Ah NMC cell. The discharging rate of the NMC cell is C 0.45. C 0.45 for the LEV50 would be 22.5 amps. For the two cell...

Hi miggols Yes I would wait 20 minutes if I had started charging at less than SoC 24%. That way I would be sure that a measurement was in progress. On the other hand the BMU sometimes pauses charging at SoC 70% but I don't know if it does a complete measurement in that the case. Maybe I will add...

Slow Charging the i-MiEV, CZero and iOn Every time our cars are slow charged from SoC less than SoC 24% to 100% the battery capacity is measure by the BMU. Here is a detailed description of the process based on a slow charge I recorded a month ago. Slow Charge May 2023 To start with here are...

This is great information. Thanks for finding it. I've noticed that new NMC cells have a max voltage of 4.3 volts. If the nominal capacity is at 4.3 volts then our capacity will be lower when the BMU in our car only charges the battery to 4.1 volts. But then charging to 4.3 volts will obviously...

You have a point Mickey. I'm sure that this will not work with LiFePO cells. It should be manganese oxide type cells similar to LEV50s. Nickel Manganese Cobalt or NMC cells are more common but the Yuasa reports on the LEV50 and LEV50N mention only MO chemistry. They may have some nickel and...

Hi Mickey Our CZero was built in February 2011. It's driven 36.6k km and the battery capacity jumped from 38.3 to 39.3 Ah 3 days ago. The temperature here in Denmark is similar but I suspect you get more rain. Yes please send your data. David

Thanks Boffingham. Have you noticed that the newer versions of OBDZero has an initial value that limits the frequency that data is recorded in the txt files on the phone. This reduces the size of the file. Cheers David