[Ovmsdev] Leaf 2016 30Kwh flapping SOC

[Robin O'Leary]

On Wed, May 02, 2018 at 11:55:19PM +1200, Tom Parker wrote:
> On 02/05/18 01:08, ovms wrote:
> >*case 0x50d**:*   //Changed this from 5bc. 50d is the instrument SOC
...
> >SOC now shows exactly the same in the app as the instrument-panel does,
> >and is not flapping. (I know the instrument-panel is different from the
> >true SOC)
... 
> I wasn't able to reproduce this. On my car and in the CAN bus captures I've
> got, there is no 0x50d frame on the EV bus. Now that I'm back in the house,
> I see that 0x50d is present on the Car CAN bus, but I don't have any data on
> what's there.

The top 8 bits of the first byte are the instrument SOC% (on MY2015),
but it only updates when the car is on, not when charging.

Incidentally, the only other thing I have noted for 0x50d is that there
are two bits in d[6] which seem to be related to the charge port latch.

> Should I be looking at 0x50d on the car bus to faithfully display what the
> instrument cluster displays? I'll check tomorrow.

I think it's just a direct repeat of the value in 0x1db, which is more
useful because it also updates when charging:

    case 0x1db:
    {
      // sent by the LBC, measured inside the battery box
...
      StandardMetrics.ms_v_bat_current->SetValue(nl_battery_current / 2.0f);

      // state of charge percentage, as shown on dash info panel
      uint8_t soc = d[4] & 0x7f;
      if(soc != 0x7f)
        {
        StandardMetrics.ms_v_bat_soc->SetValue(soc);
        }

> My notes indicate that 0x55b on the EV bus contains the state of charge, and
> I've implemented this at https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/compare/master...carrott:nissan-leaf-soc-instrument?expand=1
> along with a configuration option to choose how to show the SOC.

> However 0x55b doesn't work how I expected on my 2016 24kWh car, I see
> 
> xnl.v.bat.gids                           140
> xnl.v.bat.soc.instrument                 56.3%
> xnl.v.bat.soc.newcar                     49.8221%
> 
> but the instrument cluster displays 52%. Could it be displaying 56.3 - 5 =
> 51.3 rounded up to 52?

Yes, the value in the top 10 bits of 0x55b is interesting since it has
a few more bits of resolution and updates when charging or driving, but
is actually measuring something slightly different from the instrument
SOC%---usually not by much, but sometimes a couple of points.

> Assuming we get this working, should we default to using the instrument
> cluster state of charge, or the "new car" state of charge? I'm guessing we
> should go with the instrument cluster value, which is a change from previous
> behavior on the leaf but is in keeping with Mark's "re-implement the broken
> calculations by the car".

That would have my vote too.
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