[Ovmsdev] LEAF SOH (was: OvmsDev Digest, Vol 85, Issue 5)

[Robin O'Leary]

On Tue, Feb 05, 2019 at 02:46:40AM +0000, Dean MacGregor wrote:
> With the new firmware version the SOH reading doesn't work but it used
> to.  That's in both the 'Vehicle Info' and 'metrics list' command.
> I have a 2015 Nissan Leaf. 

Is this with the car switched off?  Can you check with the the car ready
to drive?

Most other values we display are passively read whenever the can bus
is active, but to get more detailed values from the battery (v.b.soh,
xnl.v.b.hx, v.b.cac), we need to send an active poll request.  We don't
want to do this when the car is asleep, since it causes modules to wake
up and consume power.

We did previously get v.b.soh from a passive message 0x5b3, which is a
7-bit value (0--100%) available whenever the car is awake.  The active
poll to 0x7bb.6101 gives better resolution (~11 bits).

We had a similar situation with the SOC, where I think we have a better
solution.  We now report both low- and high-resolution values as separate
LEAF-specific metrics: the simple percentage in xnl.v.b.soc.instrument
and the high-resolution value scaled as a proportion of the "new car"
value as xnl.v.b.soc.newcar.  By default, the standard metric v.b.soc
reports the value from xnl.v.b.soc.instrument; there is a config option
if you want it to report xnl.v.b.soc.newcar instead.

I think it would be better if we followed the same pattern with SOH.