# Nissan Leaf: SOC curve?



## miscrms (Sep 25, 2013)

Seemed like some good info here:
http://elmoto.net/showthread.php?t=4086

Link to a curve from that thread:


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## miscrms (Sep 25, 2013)

Also some good info here regarding where a 2011 Leaf hit low battery warning, very low battery warning, and protect/turtle mode vs. pack voltage as reported by the internal battery controller. The x-axis are "GIDS", basically the capacity unit used by the battery controller. As I recall the full pack is 96s cells. The L2 charge terminated at 244 GIDs, indicating this particular battery has experienced about 13% capacity degredation (1 - 244/281).

http://www.mynissanleaf.com/viewtopic.php?f=31&t=6116&hilit=turtle+dead&start=79










Picking points off the curve for this particular case would give roughly:
Discharge Low Battery Warning: 3.77V
Discharge Very Low Battery Warning: 3.625V
Discharge Turtle Mode (Protect): 3.22V
Discharge Dead (Shutdown): 3.20V
Charge Termination: 4.10V

Of course these warnings / states are being generated relative to GIDs (capacity), but interesting to see where they fall for voltage for this case. I'm sure they vary a bit with temperature etc.


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## WolfTronix (Feb 8, 2016)

Excellent!!!

Thanks, for the graphs.

I hope this is similar for the 2012-2015 Leaf cells.

As for temperature compensation do you have to charge to a higher voltage when the cells are cold (lower voltage when the cells are hot), like you do for lead acid?

There does not seem to be much temperature compensation info out there for Lithium.

Thanks,
Wolf


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## miscrms (Sep 25, 2013)

Good question. I've seen mention that the Leaf charge often terminates at ~394V even at a fairly wide range of temperatures, but don't know for sure if the internally reported voltage is absolute or temperature compensated. Or if this is an actual metric for charge termination or a byproduct of SOC calculation and termination on a certain amount of energy replaced. There is discussion that the Leaf's use of a hall effect type current sensor is not hugely accurate, and Nissan engineers had to use a number of other inputs (voltages, temperatures, etc) to revise SOC regularly. This was given by Nissan engineers as a reason why the Leaf doesn't have a numerical SOC meter available.

Here are two more charge cycle captures from the same owner (from Phoenix, AZ area) showing the further degradation of their battery. Although capacity has continued to decline, the charge termination voltage has remained quite similar in these two examples made in winter and summer.

http://www.mynissanleaf.com/viewtopic.php?t=9981#p227142


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## jimmyaz (Oct 9, 2017)

Hey guys,

Sorry to bring back a old topic... But got to ask... What would be the cut off voltage per cell... if I only want to bring it down to 20% SOC?


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## kennybobby (Aug 10, 2012)

from the chart above, 20% looks like 3.8 V


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