Update on Nissan LEAF Battery Replacement

[JPWhite]

well ASSUMING my understanding is sound and assuming we are understanding him correctly and assuming any of this matches reality here is the implication I got.

a QC user goes x miles has x degredation.

a non qc user (him) goes x miles has similar x degredation.

qc does not adversely effect the battery.

the logic is sound. if it matches results. I tend to agree with him from personal non electric car battery experience. (my 12 leaf has no qc port)

fast charging does not necessarily damage a battery. HEAT damages a battery.

if you QC a lot but don't overheat the battery your probably not going to see dramatic losses from the QC process

BUT if you QC and this results in a frequent hot battery you will see losses but its not the qc doing this its the HOT battery doing this.

of course if your qc causes the hot battery.....

at least THAT is how I understand it.

You mean like this?

I've found the temperature increase from DCFC to be about the same as L2 charging for the same amount of energy input.

The issue with DCFC is that it enables more miles to be driven and for multiple DCFC charges in one day. Serial use of DCFC in one day will elevate temperatures well above what you could accomplish with L2 only. So DCFC *could* impact the battery more but typically it doesn't.

I don't believe DCFC has a significant impact on battery degradation if performed just once in a day per Nissan guidance.

 

[nerys]

Yes. Exactly. Its not the qc but the temps. Use qc such that you dont get excessive temps and you should be fine. Qc is not really that fast a charge in reality its just fast compared to what we are used to. Now once we get into 10 to 15 minute 60kwr type fast charging. Now that would actually be fast and might strain batteries. Ours of course could not handle that.

 

[dhanson865]

Does the Nissan Leaf not have battery cooling? I'm only asking because I am also looking at a Volt and they have a cooling system for the batteries.

I think they could have put in active cooling, but they underestimated the market. Most of us do not drive more than 50-60 miles a day (Nissan figured that right), so that system may have appeared to be an unnecessary expense. Nevertheless, they did not do enough testing in the heat and cold to see what the effects would be. We have all see videos of car makers baking freezing their cars, so why Nissan did not do that to the Leaf is beyond me. Maybe it was a calculated gamble by Ghosn to bring the car to market and dominate the EV market share. The jury is still out in some of our minds if that was a good thing.

They baked it in the Arizona desert testing. That is why the warranty is void if you go over 120 degrees. There is a temp they found that causes immediate damage.

They drove it around Arizona for months and put it in a heat chamber at night to keep the accelerated testing going 24 hours a day but it wasn't the same as real world use and even with all the testing they got surprised.

----------

edit: I'm assuming that current testing would be at

http://nissannews.com/en-US/nissan/usa/channels/facilities-arizona-testing-center-atc
Nissan Technical Center North America - Arizona Testing Center (ATC)
Nissan's Arizona Testing Center is a 3,050-acre facility in Stanfield, Arizona.


but back in the day they mention Casa Grande

http://www.mynissanleaf.com/viewtopic.php?f=30&t=8802

After a news story run on CBS5 Phoenix, Nissan decided to take 6 of the most affected cars out to Casa Grande for testing

If you read the first few hundred pages of that thread you'll see talk and disbelief about how Nissan could have missed it with all the cars being tested in Arizona before and after sales started.

after further googling it appears both are the same place just the news mentioned Casa Grande but the postal address is: 7815 N White and Parker Rd, Stanfield, AZ 85172

 

[dhanson865]

FWIW, if given the option to pay an extra $2k for a Volt-style TMS on my 2012 Leaf, I would not have ponied up the money. Upstate NY may be on average colder than Seattle, but I'm pretty sure our summers get hotter. I've seen the loss of 1 capacity bar in 4 years (happened at about 3.5 years). That has not yet interfered with the car's utility to me. Meanwhile, running a TMS would have cost me more upfront, and more over time since it actively uses energy. But it may have preserved a little of my capacity.

So yeah, I'm happy without it too. It's OK for the battery in my climate, and better overall for the car, because it keeps costs down.

+1 on that and that is only part of the problem I have with TMS. Even if it was offered free, I would decline simply because there is no free lunch. The system will take range from me and for what return? I am at 38,000 miles and maybe halfway to losing bar #1...maybe. So would it be worth the extra longevity in sacrifice of a few miles?

to me the answer is no but that is me. Keep in mind, I pulled into my garage over the past 2½ years with MUCH less than a few miles to spare dozens of times...

If the TMS is configured correctly it wouldn't cost *you* any noticeable range, but it would save us southerners from degradation.

Cool the battery pack any time it is above 80F and that power draw won't come on up north. You'll haul around a couple of pounds of tubing and a pump or fan that would be a non issue for range (imagine 20 pounds out of 3600 something on the order of a half of 1 percent of the weight of the car).

Heck cooling the pack at >80F would only happen for me 4 months out of the year but it would allow me to charge the car in the heat of the day without worrying about it.

 

[JPWhite]

Cool the battery pack any time it is above 80F and that power draw won't come on up north. You'll haul around a couple of pounds of tubing and a pump or fan that would be a non issue for range (imagine 20 pounds out of 3600 something on the order of a half of 1 percent of the weight of the car).

Heck cooling the pack at >80F would only happen for me 4 months out of the year but it would allow me to charge the car in the heat of the day without worrying about it.

Range could be preserved by having a higher threshold while running on battery power only. So for the sake of argument let's say 86F would kick the TMS in when unplugged.
When plugged in it could kick in at 72F.

A 72F pack would stay that way for quite sometime before getting up into the 80's

As I left the garage this morning my pack was 83F and that was after it cooled overnight with garage doors opened to ensure the air temp gets as low as possible. With a TMS the pack could have been be 72F instead.

Other than additional cost, the only downside from a TMS is it's something else to go wrong and require periodic maintenance. Compared to loss of range and premature pack replacement the trade maybe well worth it.

 

[dhanson865]

Cool the battery pack any time it is above 80F and that power draw won't come on up north. You'll haul around a couple of pounds of tubing and a pump or fan that would be a non issue for range (imagine 20 pounds out of 3600 something on the order of a half of 1 percent of the weight of the car).

Heck cooling the pack at >80F would only happen for me 4 months out of the year but it would allow me to charge the car in the heat of the day without worrying about it.

Range could be preserved by having a higher threshold while running on battery power only. So for the sake of argument let's say 86F would kick the TMS in when unplugged.
When plugged in it could kick in at 72F.

A 72F pack would stay that way for quite sometime before getting up into the 80's

As I left the garage this morning my pack was 83F and that was after it cooled overnight with garage doors opened to ensure the air temp gets as low as possible. With a TMS the pack could have been be 72F instead.

Other than additional cost, the only downside from a TMS is it's something else to go wrong and require periodic maintenance. Compared to loss of range and premature pack replacement the trade maybe well worth it.

I left the garage this morning with my pack around 74/75 degrees. High today will be mid 90s so I skipped free charging at work and at lunch.

I'm plugging in at home and charging around 4am - 5am.

In addition to having different temps for plugged in vs unplugged they could have a preference slider / radio button for short term efficiency (less cooling) vs long term health (more cooling). People that know they don't need it could let the system have a higher threshold, people that live in AZ could switch it so that it comes on at a lower temp.

I'd also argue that you should have a third mode to separate driving vs parked. I think a lot of people don't want to risk losing range while parked.

So say you have a Plugged / unplugged driving / unplugged parked

Low could be 65 / 70 / 75 (good for those AZ, CA, TX, FL types that really need it)
Med could be 70 / 75 / 80 ( good for those of us that see some degradation but aren't in the group above)
High could be 75 / 80 / 85 (good for those pacific northwestern types that don't need it, want to disable it)

 

[Jedlacks]

The article that I didn't bother to discuss, and the one you are probably referring to talks about Casa Grande in 2012. I am referring to when they put batteries in the Jukes and was driving around Japan. They ran "simulations" to predict the effect of the heat and cold in the hottest and the coldest. And my memory might be slipping, but their "coldest" was Boston. None of these automakers want to spend the money on real world testing because computer simulations along with their legal department will find a cheaper solution all the time.

None of us should be shocked that Nissan, Mitsubishi and Toyota all use simulations to predict real world conditions. Mitsubishi was in the news recently, Toyota had to walk back their promises on the Prius, and Nissan on the batteries.

 

[QueenBee]

Yes. Exactly. Its not the qc but the temps. Use qc such that you dont get excessive temps and you should be fine. Qc is not really that fast a charge in reality its just fast compared to what we are used to. Now once we get into 10 to 15 minute 60kwr type fast charging. Now that would actually be fast and might strain batteries. Ours of course could not handle that.

These ideas that DCQC doesn't cause additional heat and temperature rise completely ignores basic physics and electrical theory. Two things are different. For one second pretend that fully charging the battery creates X heat. If you apply X heat over 45 minutes or over 7 hours. Which scenario is going to cause a higher temperature rise?

Then as you may know the heat is caused by resistance. One feature of resistance is that it increases as current and temperature increase. So above we know which scenario has a higher temperature but which has a higher current and thus higher restiance and thus more heat? Say 100 amps or 10 amps?

 

[nerys]

No one is ignoring basic physics. You (please no insult intended) are ignoring basic reading comprehension.

Not one person i am aware of has stated what you claim. Not one.

I personally only state (within my extremely limite knowledge of the subject) that qc charging of a normal level under typical conditions will simply not cause enough heating for it to be a problem for battery life degredation.

Nothing more. Qc charging is not an issue heating is an issue so qc charging only becomes a problem if it generates enough heat to be a problem. Ie if you can qc without generating unsafe heat then the qc is not necessarily damaging to the battery for the most part.

You are inventing statements that as best i can tell exist no where but in your post alone (again absolutely no insult intended)

 

[QueenBee]

No one is ignoring basic physics. You (please no insult intended) are ignoring basic reading comprehension.

Not one person i am aware of has stated what you claim. Not one.

Before you start "not insulting" people about reading comprehension I would suggest you reread this thread...

I've found the temperature increase from DCFC to be about the same as L2 charging for the same amount of energy input.

Nothing more. Qc charging is not an issue heating is an issue so qc charging only becomes a problem if it generates enough heat to be a problem. Ie if you can qc without generating unsafe heat then the qc is not necessarily damaging to the battery for the most part.

What you are saying is like saying "Living in Phoenix is not an issue heating is an issue so living in Phoenix only becomes a problem if it generates enough heat to be a problem. ie if you can live in Phoenix without generating unsafe heat then living in Phoenix is not necessarily damaging to the battery for the most part."

In my experience as these batteries age and pack resistance increases they really start to heat up with DCQC, freeway driving, etc. and it becomes really easy to get them outside of comfortable temperatures even in the so called "mild" Pacific Northwest.

 

[nerys]

Again. Comprehension. Again non ok nsult intended.

Your comparison is invalid. Phoenix is a geo once its hot it stays hot. Constant temp soak.

While qc only heats "WHILE" you qc. Once you disconnect theee is no more additional heat energy being added.

Again the heat is the problem. Not the qc necessarily.

 

[JPWhite]

If you apply X heat over 45 minutes or over 7 hours. Which scenario is going to cause a higher temperature rise?

In my experience is that the increase in temperature is comparable either way,

The speed of the temp increase is clearly faster with DCFC. I think you are maybe mixing speed with absolute temp rise.

I contend it doesn't matter if the battery gets hotter more quickly if the ultimate top temperature is about the same. Remember the LEAF battery is well enclosed and cools by radiation only, sloooowwwwlllyyyyyy.

 

[DaveinOlyWA]

Be that as it may my best battery numbers happens when I drive enough to fast charge twice a day. Granted heat was not an issue. First charge usually happened at 3 AM, the 2nd at 11 AM so plenty of time to cool off.

Keep in mind; a "mildly" hot Summer day will generate more heat. In my 6 day experiment, my highest temp was in the low to mid 80's. The other day, the battery temps were in the high 80's (OAT was mid 90's) so charge however you see fit but don't discount parking in the shade!

 

[QueenBee]

If you apply X heat over 45 minutes or over 7 hours. Which scenario is going to cause a higher temperature rise?

In my experience is that the increase in temperature is comparable either way,

The speed of the temp increase is clearly faster with DCFC. I think you are maybe mixing speed with absolute temp rise.

I contend it doesn't matter if the battery gets hotter more quickly if the ultimate top temperature is about the same. Remember the LEAF battery is well enclosed and cools by radiation only, sloooowwwwlllyyyyyy.

Nope no confusion I contend that DCQC causes more heat to be added to the battery and in a quicker amount of time thus giving the battery less time to radiate slowly and thus there is a higher absolute temp rise.

 

[nerys]

Irrelevant without factoring in time unless the absolute rise takes you immediately into dangerous territory.

Qc at 104'f with a cqr heat aoaked at 104'f is not temotely the same thing as qc at 85'f in pennsylvania. Hell i could probably qc 3 or 4 times a day in the middle of winter and barely warm the battery up. Takes 5 hours of hard driving and charging to get to 3 or 4 battery bars.

I am not sure why this is hard to grasp for you.

Absolute temp rise is the issue as you state but you for some reason ignore the time it takes to get their and the geo temp soak in place.

My car has a range of about 70 miles currently. I l2 charge the entire day when not on a run at 90'f putting aeound 140 miles a day on the car. Never over 6 temp bars.

The reason is onbvious. The car can "cool" between chargi g seasions.

When you are in summer in phienix the car can not cool so qc will raise your temp but being off qc might not lower this increase meaning a subsequent qc might be additive.

While if you do the same thing in pa you will end the day with the battery never getting as hot as the phoenix car before it even qc'd the very first time.

I am not sure why this is difficult to understand i assume i am simply not explaining it properly. Hopefully this post accomplishes that.

 

[Valdemar]

I don't have any experimental or scientific data to prove it but I think it's very likely that temperature at the cell level can be significantly higher than that registered by the temp sensors even if it doesn't last long, and if true it surely adds to battery wear over time even if the overall perceived temperature rise is not big after a QC session.

 

[nerys]

Ahhhh now that is interesting. Where are the sensor probes for the battery? What are they actually measuring? I think there are 3 probes??

Yes actual cell temperature is the critical temperaturi doubt a single qc in mild geo is going to raise it dangerously but itnwould bebinteresting to know what it does actually do.

 

[DaveinOlyWA]

If you apply X heat over 45 minutes or over 7 hours. Which scenario is going to cause a higher temperature rise?

In my experience is that the increase in temperature is comparable either way,

The speed of the temp increase is clearly faster with DCFC. I think you are maybe mixing speed with absolute temp rise.

I contend it doesn't matter if the battery gets hotter more quickly if the ultimate top temperature is about the same. Remember the LEAF battery is well enclosed and cools by radiation only, sloooowwwwlllyyyyyy.

Nope no confusion I contend that DCQC causes more heat to be added to the battery and in a quicker amount of time thus giving the battery less time to radiate slowly and thus there is a higher absolute temp rise.

yes this is true and like any scenario, high heat will degrade the pack quicker and it doesn't matter where the heat came from.

in all things equal, you add 12 kwh by fast charge, you might see a rise of 10º that may drop 8º in several hours.

charge on 240 (which generate more heat per unit of charge received) and you might see a 10º rise masked by the same 8º drop in the same several hours. Which is better?

doesn't matter. what does matter is what the temperature gets to. so 240 charging in 110º ambient heat is going to degrade your battery quick... there is no getting around that

 

[JPWhite]

Nope no confusion I contend that DCQC causes more heat to be added to the battery and in a quicker amount of time thus giving the battery less time to radiate slowly and thus there is a higher absolute temp rise.

We'll have to agree to disagree. That hasn't been my observation.

 

[QueenBee]

Nope no confusion I contend that DCQC causes more heat to be added to the battery and in a quicker amount of time thus giving the battery less time to radiate slowly and thus there is a higher absolute temp rise.

We'll have to agree to disagree. That hasn't been my observation.

I'm happy with that since I don't have actual data comparing the two controlled for starting SOC and temp as well as ambient temp so I'm just basing it on theory and I'm not smart enough to be able to come up with any sort of estimates as to how much of a difference one should expect.