AndyH wrote:Cool! Inquiring geeks want to know!
Expect 3.0V for LiMn like LiCo. I understand that AESC lists LiMn2O4/spinel on their website, but Nissan's been working on/another variant with a bit higher max and nominal voltages. The BMS voltage reporting points seem to favor the slightly higher voltages. That's my guess, though...
Care to share how the car reports cell capacity? I'm surprised that it's aware of and reports total as opposed to 'consumer' capacity.
Thanks for this!
I think it reports usable capacity in Ah, not "total". This means down to whatever the Leaf considers LVCO.
I did not see any parameters to indicate any per-cell capacities are calculated or recorded. They do monitor each cell's voltage and there are 4 temperature probes. There are also quite a few parameters pertaining to capacity calculation, but they are all pertaining to the pack as a whole.
I suspect they monitor health at the per cell level simply by watching the voltage. If any one cell gets too far out of wack, you get a code, and the pack will go into reduced performance. The Battery ECU tells the rest of the car the maximum kW that can be drawn and put in at any given time, and this is what limits motoring and regen respectively. When I tested these, the car was at around 50% SOC and the pack reporting about 55 degrees F. The max out was at 110kW and the max in was at 30.34kW. I suspect 110kW is the maximum, because it was at 110kW even, whereas the max in parameter was an arbitrary value. This means at that particular time, regen or external charging would be limited to 30.34kW, but the car was not performance limited in drive.
All of this data is available over the primary CAN bus (EV), and each parameter seems to support a refresh frequency of at least 5hz. The Battery ECU alone has about 30 pages of parameters, with a lot of the pages consumed by the individual cell voltages, and there are also a lot of historical parameters. The ECU records at least a handful of different parameters for the last 8 events in a rolling buffer.
I will keep everyone posted next time I collect any juicy information of interest.