[Ovmsdev] Storing Calibration Data

Tom Parker tom at carrott.org
Mon May 2 18:51:15 HKT 2016


The Leaf's range estimate is pretty wonky as it's strongly influenced by 
your recent consumption. A much better range estimate is obtained from 
the current gids (approximately the kWh stored in the battery) and a 
Wh/km value. The Gen 2 Leaf is a little more efficient and I'm guessing 
people might want to adjust the value, so this efficiency probably 
shouldn't be hard coded into the firmware.

I'm currently using the gids value to calculate state of charge, based 
on the maximum gids that the car can hold (as the battery degrades it 
can't store so many gids, so the SOC calculation needs to know this. I'm 
currently using the largest gids value seen since startup. Every period, 
I set the maximum gids to the largest I've seen in the period (currently 
60 days) to allow the maximum gids to sink as the battery degrades.

I've since found the BMS's state of charge field and may abandon this 
complex gids based SOC and use whatever the Lithium Battery Controller 
thinks the state of charge is. The car also knows it's Wh/km (it's 
displayed on the dashboard) so if I could locate that data in the CAN 
bus, I could replace the hard coded efficiency with something based off 

In the meantime, I'd like to store both the efficiency and the maximum 
gids in parameters so they're visible to the user and they can be changed.

Is it safe to use Parameter 0x14 and 0x15 (20 and 21 in the app) to 
store calibration data? These parameters don't seem to be defined or 
used and the android app will let you modify them.


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