Highest Safe Storage Charge

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bongo2

Active member
Joined
Jan 23, 2017
Messages
34
What's the highest charge you're comfortable leaving your Leaf for a long time? Or, if you think about it the other way, what's the lowest charge that would worry you? Imagine you've just boarded the plane for a one-month trip. Then you remember you left your Leaf charged up to X and you wish you'd drawn the charge down a little bit. How small could X be and you still wouldn't like it?
 
bongo2 said:
What's the highest charge you're comfortable leaving your Leaf for a long time? Or, if you think about it the other way, what's the lowest charge that would worry you? Imagine you've just boarded the plane for a one-month trip. Then you remember you left your Leaf charged up to X and you wish you'd drawn the charge down a little bit. How small could X be and you still wouldn't like it?

There are many threads covering this. Lithium batteries do best when stored with a charge level between 20 and 80 percent. I would recommend keeping it between 25 and 75 percent, especially for extended periods. Leaving it stored at 100 percent charge is not recommended, especially in hot climates, as it speeds up degradation. The amount of degradation will vary with the battery chemistry, and the climate. Leaving it at 100 percent in Seattle is not near as damaging as leaving it at 100 percent in Phoenix.
 
According to this paper: http://jes.ecsdl.org/content/163/9/A1872 you want to store your Leaf at 0% SOC for least amount of capacity fade over time. But storing at around 20% SOC or right after low battery warning would be most reasonable and give enough buffer for self-discharge and system vampire loss. 0% SOC does not mean 0V per cell. Notice how much storage temperature plays a role.
fToxYpZ.png
 
LeftieBiker said:
there are several topics on this already.

Indeed! And you may have noticed opinions range from 100% to 0%, so I thought something like a poll might be useful. If no one wants to play, though, that's cool.
 
AntronX said:
According to this paper: http://jes.ecsdl.org/content/163/9/A1872 you want to store your Leaf at 0% SOC for least amount of capacity fade over time. But storing at around 20% SOC or right after low battery warning would be most reasonable and give enough buffer for self-discharge and system vampire loss.

That's interesting! I'm surprised by that big dip from 60-80%. Do you know how that reconciles that with the manual recommendation: "Avoid leaving your vehicle for over 14 days where the Li-ion battery available charge gauge reaches a zero or near zero (state of charge)."
 
AntronX said:
According to this paper: http://jes.ecsdl.org/content/163/9/A1872 you want to store your Leaf at 0% SOC for least amount of capacity fade over time. But storing at around 20% SOC or right after low battery warning would be most reasonable and give enough buffer for self-discharge and system vampire loss. 0% SOC does not mean 0V per cell. Notice how much storage temperature plays a role.
fToxYpZ.png

0% SOC as the leaf sees it requires a dealer visit to reset the BMS. The Leaf will protect itself if the SOC goes below the cutoff just after Turtle. I wouldn't call it bricking as it is easily reset by a dealer and you can drive away after charging.

Also the Leaf has a counter that counts how many times you allow the battery go near that. I don't remember the actual trigger percentage it might be near VLBW (around 7%). Nissan considers this counter when deciding on warranty pack replacement though they don't publicly state what count would be enough to void a warranty.

To top that off if you are anywhere somewhere that it might get below 0F the battery heater will come on and drain it lower. If that is a concern I'd want an additional buffer for that drain.

From my own use I see minimal to no degradation below 80F (which meshes with the graph for 25c which is about 77F) so I'd have no qualms about charging to 50% and leaving it there if I know it isn't going to be hot.

The colder it is the more likely I'm going to charge to 80% or 100%. Just no reason not to charge it up when it's below freezing out.
 
bongo2 said:
AntronX said:
According to this paper: http://jes.ecsdl.org/content/163/9/A1872 you want to store your Leaf at 0% SOC for least amount of capacity fade over time. But storing at around 20% SOC or right after low battery warning would be most reasonable and give enough buffer for self-discharge and system vampire loss.

That's interesting! I'm surprised by that big dip from 60-80%. Do you know how that reconciles that with the manual recommendation: "Avoid leaving your vehicle for over 14 days where the Li-ion battery available charge gauge reaches a zero or near zero (state of charge)."

That big drop is at 40c and 50c constant temps. 40c is 104f 24 hours a day for 10 months on that graph. 50c is 122f 24 hours a day for 10 months on that graph.

If you are keeping your leafs pack at 104+ 24 hours a day for 10 months in MN you are doing something wrong, and highly unusual. I'd suspect you were keeping it in a paint booth / oven


but as to the 0% thing see my post above, Nissans 0% and the test graph above's 0% are two different things. Putting a leaf at 0% for even one second will have you towing it to a dealer.
 
That's interesting! I'm surprised by that big dip from 60-80%
Me too.
so, does that means keeping daily soc below 60% is best for long life?
also, the paper is testing LiNiCoMnO2. i wonder how much different from the battery used by leaf.
 
soldcake said:
so, does that means keeping daily soc below 60% is best for long life?
Yes. As low as possible while still being usable. I try to keep mine at 20 - 30% SOC on days when I am at home, while having just enough charge to run to a store or something.
soldcake said:
also, the paper is testing LiNiCoMnO2. i wonder how much different from the battery used by leaf.
I would make a guess that all current lithium batteries share similar degradation pattern. Lets look at behavior of other chemistries:

oCtUXNR.png
 
80% on the dash is around 73% absolute (graphs shown).
1 month is not a long time. Also 12V system will discharge main pack slowly.
So 80% is reasonable enough.

If any vehicle is stored for longer than 3 months it is reasonable to remove 12V negative terminal.
Close all doors. Wait for 5 minutes to let modules fall asleep.
Remove negative terminal. Verify that you can open-close drivers door with mechanical key. Close the hood.
For EVs discharge main pack to 30-50% as pack will not be drained by 12V this way.
 
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