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Thanks piev. Here is the corrected program.

There are always corrections.

I have a confession. piev sent measurements of a NMC 93 cell that he did on the bench in his workshop two years ago. For some reason I chose to use the data from the scientific article in stead of piev's measurements. Now that we have data from the car I can see that this was a mistake. piev...

I have analyzed piev's data. piev's Arduino bridge changes only 3 values sent by the BMU. They are SoC1, SoC2 and the 100% battery capacity in Ah (PID 374 byte 6). All other values are past though unchanged. OBDZero receives and records these values independently of the bridge. This graph shows...

Thanks for the data piev. I'll try to find out what happened.

Mitsubishi defined 100% = 4.1 volts and 0% = 2.75 volts for the original LEV50 cell. In the article on the NMC cell it looks like the authors defined 0% = 3.05 volts. In the specifications for a NMC 93 cells similar to the ones piev is using, the operating range is 2.75 to 4.2 volts. In...

Hi Frud You are certainly putting a lot of effort into this. The difference between the two graphs has to do with different 100% voltages. In the graph from the article 100% SoC is reached at a voltage above 4.2. In the iMiev the cells are only charged to 4.1 volts. This is exactly what your red...

Correction volts < 3.77367 and not volts < 3.7488

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...