Future EV batteries to charge 40 to 60 times faster

[LEAFguy]

Nanotechnology can bring charge times down to minutes instead of hours. A New York based research institute has developed a new nanomaterial that they call "nanoscoops". Due to the extremely small scale of material distribution, the stresses from fast charging are different than on current technology batteries. They are talking specifically about Lithium-ion (Li-ion) technology - the same technology used in the LEAF - along with laptops, cell phones, etc. This technology will not be available for some time, but knowing that it's in development is promising!

 

[mynameisjim]

What is the theoretical charging time limit for a car like the leaf? How much electricity can you move safely in the home environment?

 

[charlie1300]

I think the charging technology described here would make a difference for public DC charging, making it more like the time you spend to fill up the tank, and take a bathroom break. Home charging doesn't really need to be much quicker, unless you are an insomniac. :lol:

 

[DaveinOlyWA]

all kinds of charge storage research going at the "near cellular" level including the now infamous eestor EESU and Zenn research/scam/myth/drug induced hallucinations or whatever else you choose to categorize them as

 

[Smidge204]

The battery is not the limiting factor in charging rate. Improving the battery charge/discharge rate is good - it makes batteries more durable and capable of higher output - but it will not significantly decrease charging times. Even if the battery can handle it, charging sites with sufficient power will be hard to come by.

If you expect to recharge your battery in 5 minutes you can also expect about 700 amps of high voltage DC. That's not the kind of power just anyone is going to be handling. And that's assuming you'll find a location that can deliver the power you need.

It's not an unsolvable problem... but the dream of a 5-10 minute recharge is not going to become a reality any time soon, even with the perfect battery.
=Smidge=

 

[evnow]

Anything nano has one big problem cost. It is not always the case that cost will come down - some of the technologies are so expensive they never get to mass production and thus will remain in the labs.

Anyway, I still think the best we now have for fast charging is Li Titanate (SCiB by Toshiba). 5 Minute charging and very good thermal characteristics with very large # of cycles possible. On the -ve side we have lower energy density and higher cost. But WV is supposed to use it in their EV - so we will get to see how it works.

 

[LTLFTcomposite]

What is the theoretical charging time limit for a car like the leaf? How much electricity can you move safely in the home environment?

If you had a 100 amp branch circuit in your home, in theory a battery the size of the Leaf's could recharge in about an hour. Lot of things limiting charging below that level, but as an approximation to answer your question I'd think 22kW is probably about the max you could suck out residential service.

 

[Nubo]

The battery is not the limiting factor in charging rate. Improving the battery charge/discharge rate is good - it makes batteries more durable and capable of higher output - but it will not significantly decrease charging times. Even if the battery can handle it, charging sites with sufficient power will be hard to come by.

If you expect to recharge your battery in 5 minutes you can also expect about 700 amps of high voltage DC. That's not the kind of power just anyone is going to be handling. And that's assuming you'll find a location that can deliver the power you need.

It's not an unsolvable problem... but the dream of a 5-10 minute recharge is not going to become a reality any time soon, even with the perfect battery.
=Smidge=

One potential solution is flywheel energy storage. The charge station could spin up the rotors over time at a reasonable power draw, then dump a tremendous current when hooked up to an EV.

http://www.ifandp.com/article/001864.html

 

[smkettner]

What is the theoretical charging time limit for a car like the leaf? How much electricity can you move safely in the home environment?

If you had a 100 amp branch circuit in your home, in theory a battery the size of the Leaf's could recharge in about an hour. Lot of things limiting charging below that level, but as an approximation to answer your question I'd think 22kW is probably about the max you could suck out residential service.

Even with twice the battery I think the 3.3Kw charger is fine for home use. Very high speed charging would seem to be only needed on the road when travelling long distances.

 

[AndyH]

Current lithium cells - including the el-cheapos from China - have 'nano' (sub-micron/nanometer) carbon particles on the plates so nothing mysterious there. Sure, there are developments like nanotubes and such, but this is about charge/recharge speed not capacity or price.

Some of today's cells have a 2000 cycle life with a 4C charge - 15 minutes. Others, like A123-Systems' cells can handle a long life at 10C - 6 minutes. Charge rate isn't negatively impacting EVs - the complaint is energy density and price.

We're only pulling ~1-2C from our packs - replacing a 4C cell with a 10C cell won't get us down the road any farther or make us go any faster.

Faster charge/discharge is great for an electric drill but not necessary for a car.

 

[LEAFguy]

Some of today's cells have a 2000 cycle life with a 4C charge - 15 minutes. Others, like A123-Systems' cells can handle a long life at 10C - 6 minutes. Charge rate isn't negatively impacting EVs - the complaint is energy density and price.

We're only pulling ~1-2C from our packs - replacing a 4C cell with a 10C cell won't get us down the road any farther or make us go any faster.

Faster charge/discharge is great for an electric drill but not necessary for a car.

Andy - perhaps you can help me out here. What do you mean by "1-2C from our packs" and "4C charge - 15 minutes". I'm still trying to learn the language of EVs and their batteries.

Also, how do you mean that "Faster charge/discharge is great for an electric drill but not necessary for a car." For many, charging for 30 minutes to go 80 miles is not a good scenario. I think charging 5 minutes to go 200 miles (or more) would be of interest to many. Here the discharge rate is not important, but the charge rate is. Thanks.

 

[AndyH]

Andy - perhaps you can help me out here. What do you mean by "1-2C from our packs" and "4C charge - 15 minutes". I'm still trying to learn the language of EVs and their batteries.

Also, how do you mean that "Faster charge/discharge is great for an electric drill but not necessary for a car." For many, charging for 30 minutes to go 80 miles is not a good scenario. I think charging 5 minutes to go 200 miles (or more) would be of interest to many. Here the discharge rate is not important, but the charge rate is. Thanks.

I'll give it a shot.

Think of the C number as "how much energy can the cell accept or deliver in one hour." It's sorta 'hidden' in the definition of capacity - Ah = Amp*1 Hour.

Car start batteries and off-grid solar packs are usually quoted at the 20-hour rate while EV packs are usually quoted at the 1 hour discharge rate.

Here are some specs for a cylindrical LiFePO4 cell:

Nominal Capacity: 10Ah
Maximum Discharge Current: 100A Continuous, 130A (18 second pulse)
Maximum Charge Current: 40A

This 10Ah cell can deliver 10A for one hour (10Ah/10A=1h), 5A for two hours, or 20A for 30 minutes. The maximum continuous discharge current is 100A. 10Ah capacity divided by our 100A load gives us 0.1 hour - a six minute discharge. This is a 10C discharge rate - 10C X 10Ah = 100A. The 40A max charge rate is 4C - 4 times the cells 1-hour rate.

Charging or discharging a 10Ah cell at:
1C (10A) takes 1 hour
2C (20A) takes 30 minutes
3C (30A) takes 20 minutes
4C (40A) takes 15 minutes
10C (100A) takes 6 minutes

I see a six minute charge for an EV like 'range anxiety' - they're both myths born of the fear of something different from their current habit. (You gave me an opinion, I'll answer with one. :lol: )

Fast charging is good for power tools on construction sites, and applications like EV delivery vans - these devices aren't making money unless they're working. But there are more efficient ways to travel long distances without cycling the limited life out of a chemical storage device. Car-trains and inductive road surfaces are two.

Let's feed a 66Ah Leaf pack with energy for a 10C charge - 350-400VDC at 660A
For a 200 mile range, we'll need to more than double the pack size because we're carrying more weight and likely have pack cooling as well - let's say it's a 150Ah pack. 150Ah at 10C - 350-400VDC at 1500A? 525,000W? Think so?

Look at a diagram of the Tesla battery pack. Consider the surface area required to get the heat away from the cells. Consider the size of water cooling bath - or the plumbing for some esoteric coolant - and pumps and the radiator.

Here's a sorta-parallel from the airplane world. Start with a small mythical airplane that can cruise 100 miles at 100 mph on 100 lbs of fuel. The designer thinks people would want to go 200 miles on a fill-up - so he doubles the fuel to 200 lbs. Then he has to add more wing to carry the extra weight - but the airplane slows down from the drag. So he has to make the engine larger to carry the extra weight at the 100 mph speed. But the larger engine drinks fuel faster - so now it takes 250 lbs of fuel...which takes more wing and a larger engine and...welcome to the death spiral.

The batteries can handle it today. But people will not want to pay for the pack or the shorter pack life or the mini-nuke plants next to all the rest areas. :lol:

 

[Coffee_Slurry]

There you go. Some people leave capacity and current out of it altogether.

1C = 1 hour (charge or discharge)
2C = 30 minutes
3C = 20 minutes
etc

There's nothing that says charging, even at high current, has to generate heat in the battery pack. Some batteries (NiCd) actually get colder while absorbing charge.

An ideal battery would have very low internal resistance, or enough endothermic charging to keep it in check.

(This is one of those things that starts off great, and tends to get worse as the battery ages.)

 

[leafme]

Andy - perhaps you can help me out here. What do you mean by "1-2C from our packs" and "4C charge - 15 minutes". I'm still trying to learn the language of EVs and their batteries.

Also, how do you mean that "Faster charge/discharge is great for an electric drill but not necessary for a car." For many, charging for 30 minutes to go 80 miles is not a good scenario. I think charging 5 minutes to go 200 miles (or more) would be of interest to many. Here the discharge rate is not important, but the charge rate is. Thanks.

I'll give it a shot.

Think of the C number as "how much energy can the cell accept or deliver in one hour." It's sorta 'hidden' in the definition of capacity - Ah = Amp*1 Hour.

Car start batteries and off-grid solar packs are usually quoted at the 20-hour rate while EV packs are usually quoted at the 1 hour discharge rate.

Here are some specs for a cylindrical LiFePO4 cell:

Nominal Capacity: 10Ah
Maximum Discharge Current: 100A Continuous, 130A (18 second pulse)
Maximum Charge Current: 40A

Charging or discharging a 10Ah cell at:
1C (10A) takes 1 hour
2C (20A) takes 30 minutes
3C (30A) takes 20 minutes
4C (40A) takes 15 minutes
10C (100A) takes 6 minutes

Andy, According to professor Jay Whitacre of Carnegie Mellon Univ in an excellent video that was posted on this forum a while ago, the faster you take energy out of a Lithium battery the less you get (I believe it's true with other batteries as well). You are implying here that the energy quantity is fixed regardless of rate of withdrawal which goes against what Jay indicated in his presentation.

Malcolm

 

[LakeLeaf]

I thought there was a lot of talk of charging ultracapacitors - which charge extremely quickly and efficiently - and then using them to bleed charge into the batteries. Allows for the car to be recharged in a few minutes, and yet doesn't overstress the batteries.

 

[AndyH]

Andy, According to professor Jay Whitacre of Carnegie Mellon Univ in an excellent video that was posted on this forum a while ago, the faster you take energy out of a Lithium battery the less you get (I believe it's true with other batteries as well). You are implying here that the energy quantity is fixed regardless of rate of withdrawal which goes against what Jay indicated in his presentation.

Malcolm

Sure - you're right. I was attempting to look at only "C" rate then gave rough example with a 10Ah cell.

An old radar instructor told the class from time to time, "It always happens this way. Except when it doesn't."

Sealed lead-acid (note that the best return is at .05C...):
http://www.jlktechnicalsales.com/downloads/power-sonic/techman.pdf

For a 10C-rated LiFePO4 cell:
http://mvp090-1.104web.com.tw/cetacean/front/bin/ptdetail.phtml?Part=e40138f1

Cool so far. Check this out, though. This is for a cylindrical cell that I believe uses the same or very similar chemistry to the AESC cells used in the Leaf:
http://www.molicel.com/hq/download/DM/DM_IBR26700A.pdf

This is a 2.8Ah cell - we're looking at 1C thru 9C on the chart.

 

[garygid]

The faster you try to get the energy out, the more energy you lose in the process.

Likewise, in putting energy in, the faster you try to charge, the higher the losses.

 

[AndyH]

The faster you try to get the energy out, the more energy you lose in the process.

Likewise, in putting energy in, the faster you try to charge, the higher the losses.

In general yes - but did you look at the charts? The lightest load does not always deliver the longest distance traveled - unless we're using lead-acid.

 

[DaveinOlyWA]

its good to see this thread. great info. how long will it take us owners to determine that the QC charge to 80% has no detrimental effects to the longevity of the battery packs?

 

[EVDRIVER]

its good to see this thread. great info. how long will it take us owners to determine that the QC charge to 80% has no detrimental effects to the longevity of the battery packs?

Some are convinced Nissan did not use a 6.6 kw charger for that very reason.