[Ovmsdev] Leaf canbus

[Nigel Jones]

I have the OVMS module running in my car so found an hour tonight to start
looking through the source - sorry it's taking a while to catch up, so
forgive the newbie questions too......

One thing I noticed is that I'm getting a 0% state of charge indication,
and regular texts saying my battery is low (for testing I setup the sim
with unlimited texts.....). I see there was a commit last year which used
some of the data from the spreadsheet at

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dGRaSWl6VTV2eXBQMy1ON2xZSzlMUXc#gid=0

which I found references from the nissan leaf forum discussion at
http://www.mynissanleaf.com/viewtopic.php?f=44&t=4131&start=340

If I'm not mistaken the OVMS currently reads the CAR CanBus ?

There's an indication in the spreadsheet that CAN message 0x5b3 contains
SOC information - but in fact the spreadsheet refers to it as SOH. I have a
leafDD and I think this is also known as the Hx figure -- ie it seems to
vary with battery age/capacity -- mine for example is down to around 82%,
but it is not current state of charge, so I don't think decoding that will
help?

GIDs are what I use in daily driving as they are absolute. The sheet
suggests that figure might be retrievable from this message, but then most
people would only see a % of 95% for example as life is lost? Is that's
what's wanted? I suspect not for the overall SOC figure.

I can't see much else decoded yet (I was looking for low hanging fruit!) on
the CAR canbus - instead most work was done on the EV canbus, including
looking at state of charge etc.

So the question comes how to bridge the data from that bus onto the CAR
can. There was reference to this previously on the list at

http://lists.teslaclub.hk/pipermail/ovmsdev/2013-October/001712.html

It would appear the way to get any of the EV can data is to actively
request the data. I can see examples of CAN data requests in the tesla
module but haven't yet figured how I might for example retrieve CAN msg
0x5bb for example (it's one of the ones to try). I can also see the
developers guide p24 which refers to writing on the bus. I'm also wary of
the need to be careful in making active requests rather than the easier
passive monitoring! Can anyone point me to an example of how I might do
this? I'd make that call from the ticker functions? and then handle it in
the poll right?

Apologies if this is all covered in the nissan leaf forum thread - I have
39 pages to read now...

Thanks
Nigel.
nigel at cherrybyte.me.uk

-- 
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Nigel Jones
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