The 40KWH Battery Topic

[jmurtagh13]

I just follow the Ahr readings

You started at 115 Ahr
By 11/2019 you had dropped to 106.04
By 11/2020 you had dropped to 101.43

So the battery has lost
1 - 101.43/115 of its capacity since you brought it home
and
1 - 101.43/106.04 of its capacity in the past year.

I know the type is small and hard to read, but it's down to 103.43, not 101.43. Still not great. 99% of the time i only change to 70% but it is Atlanta and it is hot here.

[SageBrush]

So the battery has lost
1 - 101.43/115 of its capacity since you brought it home
and
1 - 101.43/106.04 of its capacity in the past year.

I know the type is small and hard to read, but it's down to 103.43, not 101.43. Still not great. 99% of the time i only change to 70% but it is Atlanta and it is hot here.

Ah, thanks. Time for new eyes

[Jollermd]

Our LEAF is almost never used for more than 30 miles between charges at home and our model has a choice of charging to 80% SoC so my wife who is the main driver and user of the car has an ingrained habit of plugging in the car after every drive, and the car is set to charge to 80% SoC. I program the timer to finish charging at 6am in the summer, and to not delay charging in the winter.

I may be playing devils advocate here:

However this statement above concerns me. I have always run my battery as low as possible (not enough charge for the next day) and then charged, with the assumption it was good for the battery to have less but deeper charges. fallacy?

And I want to thank you for all your comments.

Nick

[LeftieBiker]

Sagebrush lives in the mountains of Colorado, IIRC, and his climate is generally favorable for keeping the car at 80% charge. I wouldn't suggest doing it under all circumstances, though.

[goldbrick]

I have always run my battery as low as possible (not enough charge for the ext day) and then charged, with the assumption it was good for the battery to have less but deeper charges. fallacy?

I don't know of any professional Li battery engineers here on the forum but from what I've read, the things that age a battery are (in no particular order) time, heat, very low and very high % SOC. I don't think there would be much difference between charging from 20% to 80% half as often as charging from 35% to 65% but that is just my guess. I've heard that keeping the battery close to 50% SOC is ideal but I think the real damage occurs at the extremes and there probably isn't much difference in aging when the car sits at 40% vs 60%.

One thing to keep in mind is that charging generates heat. It may be the case that several small charges will heat the battery less than one longer charge. Otherwise, I'd just try to avoid high SOC in combination with high temperature. Also, high charge currents (eg CHAdeMO) at low temperatures are supposed to be damaging so it's probably best to avoid those as well. All just IMHO.

[SageBrush]

Our LEAF is almost never used for more than 30 miles between charges at home and our model has a choice of charging to 80% SoC so my wife who is the main driver and user of the car has an ingrained habit of plugging in the car after every drive, and the car is set to charge to 80% SoC. I program the timer to finish charging at 6am in the summer, and to not delay charging in the winter.

I may be playing devils advocate here:

However this statement above concerns me. I have always run my battery as low as possible (not enough charge for the next day) and then charged, with the assumption it was good for the battery to have less but deeper charges. fallacy?

And I want to thank you for all your comments.

Nick

Your charging behavior from a low-ish SoC is fine. Our LEAF does not live at 80% or anywhere near because it is a 24 kWh model with limited range. SoC mostly ranges from 80 <-> 40 with a focus on minimizing the time at 80% in hot weather. I don't care if the SoC is 80% if it is 30- F ambient, and I like the idea of not charging the car when the battery is cold to minimize battery plating.

By the way, my *Tesla* charging routine is similar to yours. It is done that way for calibration reasons, not degradation reasons.

[SageBrush]

I don't know of any professional Li battery engineers here on the forum but from what I've read, the things that age a battery are (in no particular order) time, heat, very low and very high % SOC. I don't think there would be much difference between charging from 20% to 80% half as often as charging from 35% to 65% but that is just my guess. I've heard that keeping the battery close to 50% SOC is ideal but I think the real damage occurs at the extremes and there probably isn't much difference in aging when the car sits at 40% vs 60%.

All just IMHO.

My opinion as well

[DaveinOlyWA]

Our LEAF is almost never used for more than 30 miles between charges at home and our model has a choice of charging to 80% SoC so my wife who is the main driver and user of the car has an ingrained habit of plugging in the car after every drive, and the car is set to charge to 80% SoC. I program the timer to finish charging at 6am in the summer, and to not delay charging in the winter.

I may be playing devils advocate here:

However this statement above concerns me. I have always run my battery as low as possible (not enough charge for the next day) and then charged, with the assumption it was good for the battery to have less but deeper charges. fallacy?

And I want to thank you for all your comments.

Nick

As EVs grow in popularity, more and more versions of batteries with somewhat different properties, emerge with Lithium being one of the few common characteristics but thru it all it has been proven over and over that more frequent, shallower cycling, is the best for longevity.

Now we have to take that tidbit and make it work in a car. Its easy to do it on a cellphone, not so much on a car. So you want enough to cover your needs which may include any or all of the following;

Basic commute
weather adjustment
common detours
anti stress range

Either way; if you drive every day whether it be a little or a lot but don't charge every day then you are overcharging. Living in the middle implies being super low is just as bad as being super high on the SOC scale but not sure I am accepting that.

So yeah, charging to 60% SOC and running it down to 40% and recharging WILL make your pack last the longest but can your sanity last that long? But if you are like most of us; your car has more range than you normally use.

[goldbrick]

There is also the issue of 'bang for the buck' to consider. If I can get 95% of the life out of the battery for 25% of the stress level on how/when to charge that seems like a good bargain.

Everyone's situation is different but I like my Leaf a lot more now that I just accept that battery degradation (aging) is a fact of life and not stress out on it too much. I'm still careful to avoid the really dumb things (eg, 100% SOC all day in the hot summer sun) but otherwise I'm just driving it and charging it when needed. From 20ish % to 80ish% most of the time but sometimes less, sometimes more since it's too hard to get it exact all the time.

[GaleHawkins]

Our 2016 Leaf SL got a new 40 kWh February 2020. SOH was 99.87 at install. Rate degradation was .01+% daily for first 6 months and had slowed to about .01% every 3 days and was down to 96.07% when it was totaled 15 days ago due to a teenager running a red light.

2 hours ago ran SLP again SOC and SOH readings were unchanged to my surprise. About a week ago I drove it about one 1/10th of a mile and backed it onto our tilt trailer and brought it home.

This Wednesday we plan to clean out a bay to get it into the shop so we can strip the front cap and all parts forward of the motor.

I ran SLP a second time to double check the readings but I could tell by the low battery temperature it was today's reading.

We have not yet bought the parts car.