Frequent charging when battery SOC is already high.

I had my 1 yr. battery check up today at my Nissan dealer. I scored 5 stars in the categories they checked for, except one category "Frequent charging when battery SOC is already high" I only recieved 4 stars. So my question is is it better to keep topping off the battery than to wait and charge it when close to depletion to prolong the battery life?

That just means you somewhat regularly plugged in ("topped off") your car when it was still above 80%. Nissan would like you to minimize this behavior, as it's not considered a best practice for battery longevity.

mpm3710 said:

So my question is is it better to keep topping off the battery than to wait and charge it when close to depletion to prolong the battery life?

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Answer: Neither. To prolong the life of the battery it is best to keep it in the 20-80% range (2 bars - 10 bars). The higher the state of charge and the longer it is at that higher state of charge, the worse it is for the battery. That is especially true if battery temperature is elevated (middle of 6 bar temperature range to 7 bar temperature). If you don't need to do it for adequate range, NEVER charge to 100%. If you need to charge to 100%, it is best to have the charging finish shortly before you plan to drive the Leaf (e.g., charge to 100% by 7:00 AM if you plan to leave at 7:30 AM).

neither. you should not start a charge if you are already over 80% (i only scored 4 stars on this as well...) and you should not purposefully run your battery low either.

just drive it. the other thing you should look at is why you start charging when SOC is already high. do you drive very few miles a day? if so, you should only charge to 80% and do it every other day

That's the only category I only had 4 stars in too.
In one year of operation, I think I charged when the battery was >80% (10 of 12 bars), on about 3 or 4 occasions.
And it was only when I needed to for reaching my destination and it was right before I headed out and very quickly brought the battery charge back substantially below 80%.
I think their evaluation protocol on this category is a bit picky.
Kind of like it is OK to charge to 100%, but decide that when you first set up the charge.
If you find out later that you need 100% when you previously thought 80% was going to meet your needs, you get dinged for the latter. I really don't technically see how one versus the other has any different impact on the battery life.
Total # of times that charging to >80% has been selected would be more relevant indicator of impact to battery. And then its a matter of how long you leave the batter at >80%.
Key to extending battery life is avoiding leaving battery <20% or >80% for any significant length of time, especially in hot weather.

TimLee said:

That's the only category I only had 4 stars in too.
In one year of operation, I think I charged when the battery was >80% (10 of 12 bars), on about 3 or 4 occasions.
And it was only when I needed to for reaching my destination and it was right before I headed out and very quickly brought the battery charge back substantially below 80%.
I think their evaluation protocol on this category is a bit picky.
Kind of like it is OK to charge to 100%, but decide that when you first set up the charge.
If you find out later that you need 100% when you previously thought 80% was going to meet your needs, you get dinged for the latter. I really don't technically see how one versus the other has any different impact on the battery life.
Total # of times that charging to >80% has been selected would be more relevant indicator of impact to battery. And then its a matter of how long you leave the batter at >80%.
Key to extending battery life is avoiding leaving battery <20% or >80% for any significant length of time, especially in hot weather.

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I totally agree with your points here. Unless you know at the time you start recharging that you're going to need 100%, you'd only want to charge to 80%. But if your plans change and you end up needing 100% later, you should be able to charge to 100% from 80% without penalty. The logic for the penalty is flawed, because it's actually better to keep the battery on standby at 80% then charged to 100% just before you leave, than to keep the battery on standby at 100% the whole time.

SO ... am I interpreting this correctly ? It means you are also being dinged when you try to do the right thing: charge on End-Only-Timer to 80%, and 90 minutes before you leave hit the timer override to get to 100%.

Exactly, this seems like charging directly to 100% is good, but charging to 100% after stopping at 80% is bad. This make no sense, what about if I need to charge to 100% and there is power failure. Do I need to drive car around in order to go below 80% and than charge to 100%? What about people that charge to 80 all the time and need more range?

LEAFer said:

SO ... am I interpreting this correctly ? It means you are also being dinged when you try to do the right thing: charge on End-Only-Timer to 80%, and 90 minutes before you leave hit the timer override to get to 100%.

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dinged is not a word i would use. like any "rule" there are usually circumstances that applies to the rule that do not apply to you and this is one of them.

once again, i also got 4 stars on this and i can tell you why. in winter, i made it a habit of starting my climate control to heat up the car so i plugged in to heat on someone else's range so to speak. it did not hurt me and i feel confident in saying that what you are doing does not hurt you.

after all its just a "guideline" kinda like the speed limit. so just treat it as that

I don't believe charging to 100% when you are sitting at LEAF 80% is reported as less than optimal behavior. I've done this dozens of times (when I need the range, via timer override)... and I still received 5 stars for that category.

The other behaviors Nissan cares about:
Time car is sitting idle over 80% after charging. (Try to use the energy over 80% within a day.)
Time car is sitting idle over 80% after driving. (If you log a lot of time here, you really shouldn't be charging to 100%.)

--Ron

grommet said:

I don't believe charging to 100% when you are sitting at LEAF 80% is reported as less than optimal behavior. I've done this dozens of times (when I need the range, via timer override)... and I still received 5 stars for that category.

The other behaviors Nissan cares about:
Time car is sitting idle over 80% after charging. (Try to use the energy over 80% within a day.)
Time car is sitting idle over 80% after driving. (If you log a lot of time here, you really shouldn't be charging to 100%.)

--Ron

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umm, guilty of that as well. i find that many times i fully charge in anticipation of the daily driving need. leave early in the day, spend several hours somewhere then drive on some more. there is a lot of discussion about not leaving your car sitting at 100% where your pack voltage is at 393... but i can leave my car at 90% and pack voltage is 388...

should i lower the voltage more? or is the 100% issue only because there is a much greater potential to see a high voltage situation if say you charge to 100% when its cooler (not a stretch since everyone here seems to think that is the way to go, right?) where the BMS (yes it does do "something") stops the charge at the appropriate voltage to prevent long term damage but then the heat of the day warms up the pack causing the resistance to go down and the voltage to rise?

but if we were to cruise around...even just a little, the voltage drops to a "safer" level and all is "better" (good might be a stretch)

grommet said:

I don't believe charging to 100% when you are sitting at LEAF 80% is reported as less than optimal behavior. I've done this dozens of times (when I need the range, via timer override)... and I still received 5 stars for that category.

The other behaviors Nissan cares about:
Time car is sitting idle over 80% after charging. (Try to use the energy over 80% within a day.)
Time car is sitting idle over 80% after driving. (If you log a lot of time here, you really shouldn't be charging to 100%.)

--Ron

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But the OT is about the category that says "Frequent charging when the battery SOC is already high". I would interpret this as the ACT of charging, nothing to do with the TIME the car is sitting idle. I'm not saying that Nissan doesn't care about the 2 conditions you described. I'm just saying that Nissan didn't give the OP bad point for the TIME idle. They gave the OP 4 stars for the ACT of charging after 80% SOC.

Like you, I've done this (charge to 100% after 80%) several times, too, and I still got 5 stars in all categories. But it doesn't mean that we're interpreting Nissan's category incorrectly. It can simply mean that maybe we didn't do it often enough to drop below the 5 star threshold yet (whatever that number is), while the others did.

But there is one other scenario we haven't considered in our interpretation. MAYBE you don't get dinged for doing a one-time charging from 80% to 100%, but you get dinged for charging from anywhere >80% to 100% after that. For example, you charge from 80% to 100%, and Nissan is OK with that. But you start running the battery down to >80%, then you plug in again. Now I can see that it implies that you like to keep topping off anywhere between 81-100% a lot, that I can see that it would imply bad behavior.

Whether Nissan has put the smart in there to detect and differentiate between a one-time topping off to 80%, then 100%, versus continuous topping off in the 81-100% range , we don't know.

It'd be a good question to ask the Nissan EV support hotline for clarification on. Any volunteer to call and ask and report back here?

I was also surprised to only to get 4 out of 5 stars for this. I almost always charge to 80% then top off to 100% when necessary. As stated before, this seems better than charging directly to 100% yet it appears they are viewing this as two separate sessions and dinging you for it.
Something else I thought of is that after charging to 80%, my Blink used to periodically cycle on for a few seconds and then back off. One of the software updates fixed the problem but I wonder if that skewed Nissan's data.
I typically plug in when I am down to 3 or 4 bars, I can't imagine this is considered topping-off?

DaveinOlyWA said:

once again, i also got 4 stars on this and i can tell you why. in winter, i made it a habit of starting my climate control to heat up the car so i plugged in to heat on someone else's range so to speak. it did not hurt me and i feel confident in saying that what you are doing does not hurt you.

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Excellent point Dave. I also used the Climate Control Timer most of the time in the winter, and quite a bit during the hottest part of the summer. Several times cooling it down prior to departure when it was still plugged into L2.
Even though the climate control charge duration is relatively short with the battery already at 80%, it is still counted by Nissan as charging the car when the battery is >80%, therefore I got the 4 stars instead of 5.
My guess is that most of the people who got 5 stars on this evaluation point were likely not using the Climate Control Timer. Or had it set to where the climate control was occurring during the charging to 80%.
I wonder if any of the Phoenix vehicles with battery degradation problems may have been doing this too?
Probably a real bad idea if the outside ambient is near 110F, and vehicle has been parked all day and vehicle interior temperature and battery temperature may be near 130F