Lithium plating and battery heater

[pmbdk]

Living in a temperate climate (to the cold side) and never doing long road trips, I will most likely never see too high of a temperature on my batteries. However, we do often get freezing temperatures in the winter, down to -10-15 deg C. Contrary to common belief, lithium plating does not magically start below the freezing point; it simply get worse and worse with lower temperature and higher current and SoC.

I obviously want to reduce the degradation of my battery as much as possible, so I generally L1 charge (6A@230V => 0.03C) right after coming home between 45 and 60% SoC, however even though the batteries are the warmest at this point in time, they are still below the freezing point at the moment.

As far as I understand most Leafs have a battery heater, but it only turns on a very low temperatures (-25 deg C?) which - for me - may happen once every 5 years.

Is is possible to hack this heater to heat the battery in general low temperature weather?

 

[Mcflocki]

I don’t believe it is possible, there is another person on here that has been trying to get the 62 KWH leaf heating software to turn on and has never seen his battery get cold enough to activate it. He wanted to know more about how it works but he doesn’t live in a cold enough area. He even took the day off work on the coldest day and put dry ice inside the car trying to get it to activate. It was cold enough outside but the battery didn’t get cold enough within the cold weather window to actually turn on the heater. Do you have LeafSpy? Have you watched the battery temp sensors to see how cold your car is getting to see if it’s in the cold enough range to worry about it? What year and model is your car?

 

[Learjet]

I thought it was well established that the 62 kWh battery doesn't have a battery heater?

 

[Mcflocki]

It has a “heating method” but no one understands what that is. It will heat itself supposedly but how can it do that without a heater. That’s why there is a whole thread of people trying to figure out how and if it actually works. I only brought it up as a way of saying people on that threat would love to know how to activate the heater function other than actually cooling the battery to -4 degrees.

 

[SageBrush]

OP, I think you are doing about what is possible given the LEAF's engineering (or lack thereof)

One possible trick to add to add to your kit is to charge up to 100% before the pack is quite cold. That might be enough to carry you until the pack warms up, or at least limit the number of charging events with a very cold pack. You could also think about DC charging before the cold spell, to start with a higher pack temperature.

One aspect of Li plating I have read about but do not yet have a good grasp for has to do with a reversible component. I *think* it stands to reason that driving soon after charging may maximize the reversal.

 

[BillAinCT]

Isn't it possible to self heat the 62kWh battery by turning on all of the shunts (as reported by LS, which I believe are balancing resistors)? If every cell had a small discharge though its resistor could it heat the battery enough to matter? Maybe this is the software method I've seen mentioned.

 

[knightmb]

That's the theory, but no one has (to my knowledge), taken a 62 kWh battery apart to pick out the pieces to show us either through videos or pictures what is inside besides the battery cells. At least if we had some part, would could run some part number checks on the specs to how much heat said shunts could produce in theory. I just wanted to measure the power consumed by this "software" mode heating and it wouldn't take much math to figure out how much heat it would generate with no where to go instead the battery.

 

[cornbinder89]

I know Dala has had the 62 pack apart, may be he could answer that question?

 

[knightmb]

I know Dala has had the 62 pack apart, may be he could answer that question?

I looked on his channel. Didn't know he has taken apart one recently, good idea.

 

[Daklein]

Swap batterie Leaf – Véhicules électriques Simon André I don't see any heaters in the 62 pack.