Can the balancing shunts be on when not charging

I did a search on balancing and most of the threads were from long ago and were 10 posts and out but I noticed something in a posted leafspy screen shot that has been asked about many times and decided to make a new thread. This screenshot shows the 2016 Leaf that came from day 1 with a bad cell and Nissan won't do anything about it because somehow this still does not set the Malfunction light on. Red indicates active shunts even though the pack is near the bottom and not on charge. see the -0.14A in the upper right hand corner. So apparently if the imbalance gets bad enough, the BMS can engage the balancing shunts at anytime. Even when not on charge and at the bottom of the pack.
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Shunts can be activated on will. Even if contactor is off battery BMS can be active.
Same with battery warmer. No need to be on charge.
Does it change anything?
Battery tries to discharge all other cells that are at too high voltage.
It clearly won't work :lol:
You should try to kill that cell faster. Run in down and keep it there for longer periods.
Pack should die when weakest cell is at 2.6V I believe.

You clearly have massive drop in range due to that cell.

If ever there was a photo that illustrated the correct shunt order...

edit: personally I think if the BMS has the same 95 of 96 shunts on 24/7 for some period of time, that should be a fault and warranty issue right there.

GregH said:

If ever there was a photo that illustrated the correct shunt order...

edit: personally I think if the BMS has the same 95 of 96 shunts on 24/7 for some period of time, that should be a fault and warranty issue right there.

Click to expand...

With court it is possible to win. Thing is that even if we exclude range loss there is also loss of efficiency.
Shunting means that energy is just wasted on nothing. If you prove that (easy to do) then Leaf, as an EV
doesn't pass emission test. (promised MPGe rating).

Is is possible to observe battery self-discharge over period of few days?
Like battery dropping from 40% down to 35% in a day or two?

I don't believe the shunts are active when the car is off.
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But it is interesting to see that contrary to what most people had previously thought, if the imbalance get bad enough the BMS will engage shunts to balance the pack even at a low state of charge and even when not charging.

Sorry, my bad.. yeah the shunts are off when the car is off. I recall posting a video of the shunts turning on after power up using LeafDD.

Still. If the same 95 shunts are on any time the car is powered up that would imply chasing a self discharging cell. And yeah, that's wasteful but probably well under 1%/day.. the shunts are pretty weak.

If it really was a self discharging cell, the car would eventually become undrivable.

BMS almost constantly engages shunts. Sometimes only few at whatever SOC.
Very often at full and at low state of charge but also at 50% SOC.
Sometimes it engages shunts only if D is selected and stops if P is selected.

LeafSpy is not actually able to read shunt stats while vehicle is asleep.
But vehicle can wake up on demand without user noticing.

I would torture the battery. Would not charge above 95% and would discharge to turtle on regular basis.
Turtle in this situation will only torture that weak cell. All others are most likely at much higher voltage.

GregH said:

If it really was a self discharging cell, the car would eventually become undrivable.

Click to expand...

This not really a self discharging cell. just a very weak cell in a 1 year old 30kWh pack that has been taken to turtle to accentuate the problem of the mismatch to try to get Nissan to acknowledge a fault. Which they never did. Until he filed buy back papers.
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http://www.mynissanleaf.com/viewtopic.php?f=27&t=22667
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