The 40KWH Battery Topic

^^^
Indeed. "kw/h" makes no sense. Watts (a unit of power) are already joules per second, so 1000 joules per second per hour doesn't make sense in this context.

As a co-worker and I discussed, a context where "kW/h" might make sense is with power plants. Let's say you had a 1 megawatt plant and you were talking about the ramp up rate in hours to reach a megawatt of output.

LeftieBiker said:

The car tries to balance the pack as it nears full. This is called "top balancing." From that very small voltage difference I deduce two things: that the pack is very well balanced, likely with no bad cells, and that it is being charged to full too often for the pack's health. This still leaves the mystery of the rapidly dropping SOH...

Click to expand...

How do folks charge to less than 100%? That feature was removed in the 2014 or 15 model.

You manually unplug the car. Once you determine how much charge your charging station or cable adds per hour, it's simple arithmetic to figure out when to unplug to get X amount of charge.

Jollermd said:

I charge after midnight, when rates are super low. I don't have ability to control charge as my Clippercreek is not programmable and as far as I know nor is the car, so charge to 100%. It seems the battery can spend a lot of time at 95%+. I assume its doing something to renew the battery. Anyone else notice that?

I drive mostly hwy, with COVID traffic around 60-75 mph. Flat the pedal plenty. Occasional 90 mile trip on hwy to beach cabin, 60 to 80mph with COVID traffic. (speed limit 70)

date..... charges qc
4/1/2018 031 04
9/29/2018 226 12
8/24/2019 539 18
1/15/2020 684 19
11/6/2020 958 22

Click to expand...

You most certainly do. Use your charge timer. I am guessing, most days a wide range of starting SOC is sufficient for your needs. How much you need to charge for the given next day's use will be something you can easily figure out in a few days.

DaveinOlyWA said:

You most certainly do. Use your charge timer. I am guessing, most days a wide range of starting SOC is sufficient for your needs. How much you need to charge for the given next day's use will be something you can easily figure out in a few days.

Click to expand...

To clarify, use the car's scheduling options

I'm not positive about the software in the newer models but if possible software wise, and OP has a predictable time the car has its first use in the AM then the best way to go about this is to program the END time about 1 hour after the car is expecting first use. This varies by the speed of the EVSE but shooting for a SoC of 80 - 95% by the time the car is first used is good battery management.

It is also possible to get fancy with the scheduling if two schedules are allowed. That lets people do the bulk of the charging when e.g. charging is cheap, and then 'top off' the battery to the desired end SoC soon before car use.

SageBrush said:

DaveinOlyWA said:

You most certainly do. Use your charge timer. I am guessing, most days a wide range of starting SOC is sufficient for your needs. How much you need to charge for the given next day's use will be something you can easily figure out in a few days.

Click to expand...

To clarify, use the car's scheduling options

I'm not positive about the software in the newer models but if possible software wise, and OP has a predictable time the car has its first use in the AM then the best way to go about this is to program the END time about 1 hour after the car is expecting first use. This varies by the speed of the EVSE but shooting for a SoC of 80 - 95% by the time the car is first used is good battery management.

It is also possible to get fancy with the scheduling if two schedules are allowed. That lets people do the bulk of the charging when e.g. charging is cheap, and then 'top off' the battery to the desired end SoC soon before car use.

Click to expand...

Thanks for all the suggestions, good to know this forum is still alive despite flagging sales:

1) yes, I could start charging at say 5:30am or so for a 12-15 Kw charge for a 40 mile commute.
What if plans change? Go get takeout in the city? meet a friend (post COVID)?
2) Do I want the extra costs of charging when rates are high from 6-8:00am rather than 1am to 5am when rates are rock bottom?. (i have highly variable electricity rates, sometimes, not often, you actually have a negative rate at 2-4am)
3) No I'm not getting up at 4am to unplug.

Jollermd said:

I posted correction , had the GIDS wrong and changed kw to kw/h.

Click to expand...

"kw/h" makes no sense. Watts are joules per second, so 1000 joules per second per hour? Huh?

https://mynissanleaf.com/viewtopic.php?f=27&t=25381&p=520169&hilit=different+metrics+hour+hours#p520169

Jollermd said:

2) Do I want the extra costs of charging when rates are high from 6-8:00am rather than 1am to 5am when rates are rock bottom?. (i have highly variable electricity rates, sometimes, not often, you actually have a negative rate at 2-4am)

Click to expand...

You may wish to read my post again.
-------

Beware of the notion that saving on charging is a good idea, if it leads to faster degradation. That is a false economy with a capital F.
My personal opinion is that letting the battery sit at 95+ SoC for e.g 6 hours daily in the winter is not a a huge deal (though still best avoided if possible) but I would not treat the battery that way in hot weather.

cwerdna said:

Jollermd said:

I posted correction , had the GIDS wrong and changed kw to kw/h.

Click to expand...

"kw/h" makes no sense. Watts are joules per second, so 1000 joules per second per hour? Huh?

https://mynissanleaf.com/viewtopic.php?f=27&t=25381&p=520169&hilit=different+metrics+hour+hours#p520169

Click to expand...

yes typo. correct in chart. I will take 6 lashes please

SageBrush said:

Jollermd said:

2) Do I want the extra costs of charging when rates are high from 6-8:00am rather than 1am to 5am when rates are rock bottom?. (i have highly variable electricity rates, sometimes, not often, you actually have a negative rate at 2-4am)

Click to expand...

You may wish to read my post again.
-------

Beware of the notion that saving on charging is a good idea, if it leads to faster degradation. That is a false economy with a capital F.
My personal opinion is that letting the battery sit at 95+ SoC for e.g 6 hours daily in the winter is not a a huge deal (though still best avoided if possible) but I would not treat the battery that way in hot weather.

Click to expand...

I looked at post again. Got it. It would work, setting timer by ending time to say 9am. may cost a little more.
Now that its possible, why did Nissan not do what Tesla did? That tweaking that occurs in the last 30 minutes "balancing" will be lost. Is there data that a Nissan battery degrades faster if you charge to 100%? or is this intuition based on what chemists and tesla says?

One reason I ask is because my 2015 had minimal degradation at 3 years with 100% charge almost every night.

Jollermd said:

That tweaking that occurs in the last 30 minutes "balancing" will be lost. Is there data that a Nissan battery degrades faster if you charge to 100%? or is this intuition based on what chemists and tesla says?

Click to expand...

The chemistry effect is *very* well described in general; the specific degradation rates are a complex interaction that also is affected by temperature and duration at the high SoC. It is also true that "100%" is set by the manufacturer.

The 'balancing' is true in theory but it is more a folk tale in practice if you routinely charge to ~ 85% and have a good pack. You can always charge to 100% SoC a couple times a year if it lets you sleep better. I can tell you that my 7 year old LEAF has charged past 80% perhaps a dozen times in the past 4 years and the cells are superbly balanced according to LeafSpy at 7 - 10 mV max delta at low SoC. Do yourself a favor and get ahold of LeafSpy and an OBDII dongle. That way you will not have to guess if the cells are unbalanced.

Sorry for not mentioning the charge timer option - it was late for me and I was tired. Still, getting the car to stop charging by itself before 100% can be a little challenging, so setting the timer for a time well after departure is easier. If you do want the car to stop on its own, be sure to disable the 'Full Charge Priority' in the charge timer menu, and don't be too surprised if the car still balks at ending the charge early. This is especially true of the Leaf S.

SageBrush said:

Jollermd said:

That tweaking that occurs in the last 30 minutes "balancing" will be lost. Is there data that a Nissan battery degrades faster if you charge to 100%? or is this intuition based on what chemists and tesla says?

Click to expand...

The chemistry effect is *very* well described in general; the specific degradation rates are a complex interaction that also is affected by temperature and duration at the high SoC. It is also true that "100%" is set by the manufacturer.

Click to expand...

I love that this forum is so alive.

your answer is fair...… but as you said there are probably a few Kwh hidden that may not be held back to not actually reach 100%;


And the only way we would really know the effects of 100% charge is to look at the degradation of a car like mine and a similar car in Illinois used in a similar fashion but charged only to 80%, and better yet a few cars and then compare averages. it would be a nice experiment.

The "Lizard" chemistry used in the 2015 Leaf was a bit more tolerant of being charged to 100% frequently, but we have still seen some from warmer climates that clearly suffered from sitting around at 100% (indicated) charge. The few percent reserved by Nissan doesn't seem to be enough to prevent degradation in hotter weather.

The 3 Leafs we have (or have had) here in Skokie (not so far away) have held up pretty well.

Our climate here is pretty good for the Leaf. My 2013 Lost a bar early in its 6th year, but that was well within my expectations. My 2 2019 Plus models are both doing very well so far. It looks like the 40s are holding up pretty well across geographies, though we are only 3 years from the earliest ones hitting the road.

Jollermd said:

And the only way

Click to expand...

I approach this question differently.
I *know* the variables that degrade batteries at a faster clip, albeit not the EXACT degradation rates.

So I minimize those things if I can, while operating the car in a manner that meets my use case and does not turn the car into a chore. As one example from my household:

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.

You will have to find what works for you. Just be aware than high_SoC * duration * high_battery_temp is a recipe for an unhappy LEAF battery. If you own the LEAF and would like to optimize its value then see what you can do about mitigating those negative variables. Some people like the idea of gaming (or trying to game) the battery by asking questions like 'what is the most important variable' ? The most honest answer (perhaps outside of Nissan, and they are not talking) is that no one is sure but the combination of all three is bad. I think most owners who are willing to put some effort and thought into mitigation find it more practical to mitigate each variable somewhat rather than ignore one variable completely and go whole hog on another. I also suspect that approach is less effective.

This does not have to be rocket science or a lifetime hobby. Being reasonable and moderate goes a long way:
Avoid 100% SoC unless there is a good reason
Avoid letting the battery SoC sit at high SoC (over 90%) unless there is a good reason
Avoid letting the battery cook at high temps. This is the problem child with the TMS-less LEAF and the least amenable to owner intervention. If you live in a cool climate -- great. In the winter -- great. For summers I do four things:

1. I let the battery cool off for as long as practical before I charge.
2. I avoid DC fast charging if at all possible
3. I do not park in closed spaces like unventilated garages
4. I avoid parking on hot asphalt. At home the car is in the shade, and away from home we seek out shaded asphalt.

Good luck !

2 years 8 months, 23,543 miles. .05% drop for this last month, 2.27% for the last 12 months.

Jollermd said:

I love that this forum is so alive.

Click to expand...

Heh. It has been many seasons since novel information was discussed, let alone presented here.
Nowadays the few people who remain with a technical bent answer the same questions over and over again for people unable or unwilling to search.

Don't feel that you have to put yourself out, Sagebrush.

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.