[Ovmsdev] User guide update for Nissan Leaf

Robin O'Leary ovmsdev at caederus.org
Mon Feb 4 23:44:19 HKT 2019

On Mon, Feb 04, 2019 at 01:55:59PM +0000, Robert Sharpe (Electric Vehicle Consultant) wrote:
> On a slightly different, if OVMS was more plug-and-play it would be easier for users to setup and be more attractive to less technical users.
> Do you think it is technically possible to use the VIN number to set the year and capacity related parameters automatically?

Although only 24kWh was available before some point in time (2015?), both
24 and 30kWh size options were later available in the same model year.
It seems likely that we will also need to deal with that situation again
in future, when the 60kWh pack is available becomes an available option
(alongside the 40kWh).

> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/180
> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/181
> I have VIN numbers for an early 2011 Leaf and a 2014 Leaf if that helps.

At least some LEAF VINs, like my own, don't use the 10th character
for a year (or if they do, they use a different decoding table).
For example, decoding my UK-built 24kWh 2015 VIN yields:

	Characters 1-3 "World manufacturer identifier":
		SJ	= UK
		N	= Nissan
	Characters 4-9  "Vehicle descriptor section":
		E	= Electric?
		0	= check digit?
	Characters 10-17  "Vehicle identifier section":
		U	= year? 
		6	= plant code?
		nnnnnn	= serial

The year-letter code table for North America does not give a value
for 'U' (it jumps from 'T'=2026 to 'V'=2027).

However, there may be easier (and perhaps more reliable) ways to determine
what we need to know from other CAN signals.  For example, issue 170
(cited earlier in this thread) is relevant:

	Turns out the PollReply for the battery info is 41 bytes long
	on these models instead of the 39 bytes we have previously seen
	on the 24KWh models.

So that gives us an automatic way to tell the difference between 24kWh
and 30kWh pack sizes.

For me, a major difficulty in knowing that such differences exist, and
confidently writing code to deal with them, is that I generally only
have access to logs from my own car to experiment with.  Having access
to an annotated collection of logs from other model years with different
battery pack sizes, regional differences and other options would be
very helpful in checking ideas and code.  I would certainly be willing
to contribute my own logs to such an effort.
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