re: 40kWh 2018 low mileage Leaf

Can anyone shed light on significance of the LeafSpy battery condition bar graph that usually shows a lot of red (shunted) pairs, but after full charge from near empty (6% dash display, 15% LeafSpy display), the bargraph now shows all blue (no shunted pairs).

Also, any links to better explain the 'shunting' algorithm/ mechanism appreciated 😎

I guess you mean LeafSpy screens like these. I too have a 2018 40kWh Leaf and these are screenshots at 100% SOC (displayed on dashboard) and 0% SOC (displayed on dashboard). At 0% the cell pairs show alternate red and blue, which I infer means that those pairs are balancing.

As for the interpretation of the red and the blue, I can only point to other threads on this forum, mainly the Mark 1 Leaf forum (which uses the same LeafSpy plots). Such as this thread. But I have always interpreted all blue bars to mean - all balanced and ready to go.

 

Thanks for the pointer to thread on 'battery graph' -- my take away was that there is a lot of confusion surrounding interpretation 😎.

I went back to LeafSpy Help manual and found this helpful note:

"Shunt Order This option controls the highlighting in Red of the cell voltage bars on screen 1. A Red battery voltage bar indicates that the Shunt is active for that cell. Shunts are small resistors that can be switched in to drain a small amount of energy from one or more of the 96 cells that make up the high voltage battery pack. This is the method used by Nissan to balance the pack by draining energy from the high energy cells. This works because charging stops to prevent overcharging the highest energy cell. So by reducing the energy in the highest energy cell all the other cells are able to be charged to a higher level."

LeafSpy Help Version 1.5.0 (Android) For LeafSpy Pro version 0.45.163 or higher. (p. 65).

The 'Help' author continues with "(Warning this gets complicated . . ."

So, I'll take a small gain of understanding how and why balancing is accomplished, and reserve a deep trek into the weeds for later. (e.g. Does draining to <15% and charging to 100% (as I did) actually result in good enough balance so that no shunts are required? Or is the all blue histogram merely an artifact of the algorithms . . .?)