Quick Charge to 60% - Better Battery Life?

[ElectricVehicle]

I'm really struggling with the idea of Quick Charging. The expense of day time electricity and more importantly to me - the slight degradation to battery life from Quick Charging, means that I'll always take my Prius for trips over 150 miles round trip. (And the onboard 3.3 kW charger is too whimpy to get me to 100% charge in 5 hours - so you need the QC to make for the whimpy 3.3 kW onboard charger - 6.6 or 10 kW onboard would get to 100% while you are doing your half day vacation outing, meeting, etc... but with our current LEAFs we have to use QC even for that!)

The biggest problem is the slight degradation to battery life from Quick Charging.

At 65 mph, you get about 75 miles from a full charge. Allow 5 miles of range to get to your nearest Quick Charger (I can dream I'll be that close to on someday...), that LEAFs you with 70 miles for the first leg. Quick Charge to 80% gives you another 60 miles. So if you limit to one Quick Charge for the day, that's 130 miles roundtrip. Longer of course is you drive slower, but I'm thinking about casula driving with the family or friends in tht car and not explaining why I'm driving 50 mph, and even so, that just raises the number to (97 -5) + 97 * 80% = 170 miles.

So even with a single Quick Charge (QC) the round trip range is 130 - 170 miles.

Suppose I want to do 200 miles and need multiple QCs in a day?

Is the total number of Quick Charges the issue, or are multiple Quick Charges in the same day more damaging than the same number of QCs but spread out 1 per day?

I.e.
Degradation from 3 QC in one day = Degradation from 1 QC per day for 3 days ???

What if each QC is to 60% instead of 80%?

If you can QC twice in the same day to 60% with little or no battery degradation, then that gives you 120% charge from QC plus your starting charge giving a round trip 65 mph range of
75 starting charge + 45 QC1 + 45 QC2 - (2 * 5 miles to get to each QC) = 155 miles @ 65 mph

If QC to 60% (or 50%, 40%...) causes little or no battery degradation, then I can leave the Prius at home, take the LEAF, do a 60% QC on the way to the destination and then a 60% QC on the way back and not harm the LEAF battery. If that works, I'd take the LEAF!!! Otherwise, I'll use QC on rare occasion and take fewer of the longer trips in the LEAF.

QC is good for emergencies or the rare long trip. If we can find a way to do multiple QC in one day, without harming the battery, then it becomes a major increase in the utility of the LEAF and the Prius will be getting very lonely!!

Be interesting to find:
Relationship between QC end charge level (%) vs. amount of battery degradation.
Relationship between number of QC / day vs. amount of battery degradation.

 

[EVDRIVER]

What if the sky falls?

 

[ElectricVehicle]

How long will the battery pack last?

After 10 years, 70 to 80 percent of the pack’s capacity will be left. The exact amount will depend on how much (440-volt) fast charging is done—as well as environmental factors, such as extreme hot weather, which is tough on the battery.

Will the next-generation Leaf battery pack have much longer range?

Nissan is anticipating an improvement in capacity at about 8 to 10 percent year over year. This improvement could be applied to greater range or reducing the cost. If customers indicate that they are satisfied with 100 miles range, then future battery packs may be smaller with fewer cells, and therefore cheaper.

Will the DC fast chargers degrade the battery faster?

If fast charging is the primary way that a Leaf owner recharges, then the gradual capacity loss is about 10 percent more than 220-volt charging. In other words, it will bring the capacity loss closer to 70 percent after 10 years.

hybridcars.com Nissan LEAF battery pack Q&A

So extrapolating, if there is 70% capacity with mostly QC charging vs. 80% capacity with mostly Level 2 charging in 10 years, say a fast charge every other day would degrade the pack by an additional 10%. They also say "environmental factors, such as extreme hot weather, which is tough on the battery", so the predominate degradatoin from Quick Charging (QC), may be heat. Since more heat is generated as the battery reaches higher SOC, 2 QC to 60% in the same day, particulary if several hours apart may cause less degradation than a single QC to 80%. So QC during coooler times of the day, QC to lower charge levels, multiple QC in one day may not be bad of done to low states of charge and the battery is not allowed to get too hot.

Presuming that one QC every other day leads to 10% additional battery degradation, thats 182 QC/yr * 10 years = 1820 QC for 10% degradation. (note the 182 QC/year, is not far off from the number of QCs - 187 - that you would need to drive 15,000 mile/year in a LEAF on QC alone at 80 miles/QC) That translates to 0.0055% degradation per QC. Nissan's assumptions may be for a lower number of QC/year, say 90 which is one every 4 days, each QC would cause 0.011% degradation per QC, or you can look at it as 100 QCs will cause 1% battery degradation - more in extreme heat or hot pack to 80%, and less in cooler weather, with a cool pack to 40 or 60%. Doing the QC while the ambient temperature and the pack are hot probably causes 2+ times the damage of when they are cold, and ending theQC at less than 80% should reduce the degradation even further.

If a LEAF pack is $15,000, a 1% degradation is $150 and that's 90 QCs, so that's $1.66 of battery degradation per QC. Not trivial, level 2 is always preferrable where possible, but the degradation isn't nearly as bad as I though it might be.

Need more information, but I'm starting think a 150 mile round trip at 65 mph with 2 QVC stops to 50% charge, or less is some level 2 is available during the trip, could work very nicely, after allowing an extra 2 x 20 minute stops for partial QC, coffee and the restroom!

 

[cwerdna]

Do you actually anticipate you'll get the opportunity to run into this dilemma? It sure doesn't seem like there are many CHAdeMO stations in the US. http://www.chademo.com/" onclick="window.open(this.href);return false; lists (as of 9/16/11), 7 of these in "Other", which I'd assume is the US. Then there's the ongoing standards battle that I haven't followed.

If you go 70 miles, what happens if the station is out of order and there are no others nearby? Panic and look for L2 stations and wait for a LONG time? To me, it seems to be conservative, the QC stations need to be spaced a lot closer together, one might need to stop a lot more often than predicted range and one might need to have some accurate means of monitoring status of QC stations on your route (whether they work, it's not been vandalized w/copper cable stolen, etc.).

 

[jkirkebo]

Do you actually anticipate you'll get the opportunity to run into this dilemma? It sure doesn't seem like there are many CHAdeMO stations in the US. http://www.chademo.com/" onclick="window.open(this.href);return false; lists (as of 9/16/11), 7 of these in "Other", which I'd assume is the US.

Hmm, not a very updated site. They list zero for Norway even though we have at least 10 CHAdeMO stations operating now.

 

[DaveinOlyWA]

**completely unsubstantiated rumor alert**

there was a guy in Seattle who took his Leaf in for minor servicing and was told by technician that since the beginning of Summer, there has been two Leafs in AZ running on a test track 24/7 being quick charged and both have logged over 100,000 miles and neither has exhibited a shred of range degradation.

this would be done during the worst of possible environmental conditions which would include the 110+º temps of an AZ summer.

once again. nothing but hearsay from a Seattle Area Leaf owner as told to him by a Nissan tech.

now, we need to keep in mind that batteries suffer from two things, charging AND time. this "acid test" these two cars are ungoing only proves one aspect of battery pack longevity. the other which only time can tell is how fast they degrade if only charged a little bit daily.

keep in mind, these two cars being tested never sit with a full battery pack.

 

[Herm]

**completely unsubstantiated rumor alert**

I heard a rumor from my uncle Luis (may he rest in peace) that the 2015 Leaf will have a 35kWh pack with an MSRP just under $30k, not including the fed tax credit. I may have hallucinated this.

 

[surfingslovak]

I heard a rumor from my uncle Luis (may he rest in peace) that the 2015 Leaf will have a 35kWh pack with an MSRP just under $30k, not including the fed tax credit. I may have hallucinated this.

Is Nissan taking preorders for the 2015 model? I want one! But in all seriousness, I've been reading more Volt-related material lately and GM apparently hosted a web chat with their battery people on September 23. The concept of quick charging came up and the following has been said. Bill Wallace is the Director of Global Battery Systems at GM.

2:54 Comment From Guest
What is the effect on long term battery life due to routine rapid charging (>50kW)?

2:54 Bill Wallace
Rapid charging, while convenient for the customer, does decrease battery life. Therefore, the battery thermal management system can be designed to help reduce that performance loss.

 

[AndyH]

We've talked about this before, but it's scattered thru early threads. The quick charge is still relatively slow for modern lithium cells that can be charged in about 6 minutes (10C). I'm not concerned about degradation from quick charging per se.

I think the real issue, if we want to make it an issue, is that regular use of quick charging helps us use-up the cycle life sooner. 1000 or 2000 cycles can be used quickly or slowly...

60 or 80%? Either way, it's in the comfort zone for the cells as this is the 'constant current' stage where the cells can accept energy the fastest.

 

[ElectricVehicle]

We've talked about this before, but it's scattered thru early threads. The quick charge is still relatively slow for modern lithium cells that can be charged in about 6 minutes (10C). I'm not concerned about degradation from quick charging per se.

I think the real issue, if we want to make it an issue, is that regular use of quick charging helps us use-up the cycle life sooner. 1000 or 2000 cycles can be used quickly or slowly...

60 or 80%? Either way, it's in the comfort zone for the cells as this is the 'constant current' stage where the cells can accept energy the fastest.

I'm not sure 10C would apply to these large format prismatic cells, the way they are packaged in sanwuches and cooled with air cooling and radically unmatched themal conductivity - those modules in the middle of 24 under the seat, vs. the 2 deep modules under the feet. Nissan mentions the heat being an issue. If multiple QC per day is not an issue but just the total number of QC, why wouldn't Nissan state it that way? I think there's significant differences in utility between 1 QC/day max. vs. say 2000 QC over the 8 year battery warranty period...

If you wouldn't mind, please link the other threads here. We still have a lot to figure out, particularly with QC, to get the most out of our wonderful little LEAFs!

 

[LEAFfan]

**completely unsubstantiated rumor alert**
there was a guy in Seattle who took his Leaf in for minor servicing and was told by technician that since the beginning of Summer, there has been two Leafs in AZ running on a test track 24/7 being quick charged and both have logged over 100,000 miles and neither has exhibited a shred of range degradation.
this would be done during the worst of possible environmental conditions which would include the 110+º temps of an AZ summer.

Not completely unsubstantiated...before I received my LEAF in June, Brendon Jones, VP of Marketing and Sales told me he was here when they did the hot summer QC testing (simulated 8 years of use) and there was no battery degradation up to 6 QCs a day.

 

[LEAFfan]

It sure doesn't seem like there are many CHAdeMO stations in the US. http://www.chademo.com/" onclick="window.open(this.href);return false; lists (as of 9/16/11), 7 of these in "Other", which I'd assume is the US.

Just a few days ago, 2 CHAdeMOs were installed at the ECOtality building here in Phoenix so that info is definitely out of date. I'm going to check them out tomorrow! Also, there will be more along the interstates before the end of this year about 30 miles apart.

 

[AndyH]

We've talked about this before, but it's scattered thru early threads. The quick charge is still relatively slow for modern lithium cells that can be charged in about 6 minutes (10C). I'm not concerned about degradation from quick charging per se.

I think the real issue, if we want to make it an issue, is that regular use of quick charging helps us use-up the cycle life sooner. 1000 or 2000 cycles can be used quickly or slowly...

60 or 80%? Either way, it's in the comfort zone for the cells as this is the 'constant current' stage where the cells can accept energy the fastest.

I'm not sure 10C would apply to these large format prismatic cells, the way they are packaged in sanwuches and cooled with air cooling and radically unmatched themal conductivity - those modules in the middle of 24 under the seat, vs. the 2 deep modules under the feet. Nissan mentions the heat being an issue. If multiple QC per day is not an issue but just the total number of QC, why wouldn't Nissan state it that way? I think there's significant differences in utility between 1 QC/day max. vs. say 2000 QC over the 8 year battery warranty period...

If you wouldn't mind, please link the other threads here. We still have a lot to figure out, particularly with QC, to get the most out of our wonderful little LEAFs!

The Leaf cells are actually fairly small prismatics - especially compared with the 9000Ah Thunder Sky LiFePO4 cells used in some tourist submarines.

You're absolutely right that we're nowhere near 10C (a 6 minute recharge), but that was my point. Even quick charge is easy on modern cells. And with all the aluminum in the battery box and four temperature sensors, the car won't let us overheat the battery.

I think it's important to recall that cell life info from research papers talks about total cell capacity, not user capacity. The Leaf only lets us see/use the more restrictive end-user capacity - estimated to be about 84% of total. There might be some benefit to limiting the charge, but that's already handled by the car's 80% option. The capacity we can access should be about 84% of total, so 80% 'consumer' is already about 67% total/ultimate capacity.