Ford: Li-Ion Cells Can Be Charged In 2 Minutes Without Undue Stress

Ford electric door sill

MAR 8 2017 BY MARK KANE 66

Ford Focus Electric (new ~115 mile/DCFC equipped)

Ford Motor Company’s Xiao Yang and Ted Miller will present an interesting paper about fast charging of lithium-ion batteries at the WCX 17: SAE World Congress Experience in April. According to a teaser about the talk, the 5-Ah laboratory sample cell revealed great charge/discharge capabilities without capacity loss. Specifically, charging takes only a few minutes “without undue stresses“:

  • full recharge in 3 minutes under a constant rate of 20C (100 A)
  • From 0% to 85% state of charge in 2 minutes at 25.5C (127.5 A)

There is no details about the magic yet, but after 50 test cycles, the cells were apparently unharmed:

“We try to understand the fast recharge capability of Li-ion batteries and its effect on capacity degradation. We find out that 5 Ah prismatic Li-ion cells can be fully recharged in 3 minutes under a constant rate of 20C, or in 2 min (25.5C) from 0% to 85% SOC (state of charge) without undue stresses. We cycle the battery at 16C charge rate from 0 to 100%SOC and do not see any unexpected battery capacity loss in 50 cycles, where half of the cycles are 1C-rate charge as a reference capacity check. We realize that the batteries under the fast charge study do not experience mass transport limitations in either solid electrodes or the electrolyte system.”

Source: SAE via Green Car Congress

Categories: Battery Tech, Charging, Ford


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66 Comments on "Ford: Li-Ion Cells Can Be Charged In 2 Minutes Without Undue Stress"

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Attn Oil Companies: It’s Happening.

We already got a president who will take care of this dare situation, but thank you for the heads up.

Att: Big Oil

I don’t think they are worried. Total already bought SAFT…

Nothing is happening. 99% of new cars are still gas cars.

If you live in America… Slightly different if you live in Norway, I imagine their petrol station owners are pretty much inconsolable at the moment.

Probably not because Norway makes so much money from drilling and exporting…wait for it. OIL!

500 cycles would have been nice but looks very promising !

It would only take a week to test for 500 cycles. It smells fishy.

I agree. 50 cycles is not validation.

Was going to post the same thing. At such high C rates, why not cycle more?

I’m guessing there’s a cliff in the full capacity-cycle chart, possibly varying a lot from one battery sample to another.


Or that cliff is at 51 cycles for all samoles.


Exactly what I was going to post. Who stops a li-ion battery cycling test after only 50 cycles? Perhaps they just don’t want to report what happens after those 50 cycles.

There have been a lot of reports of lab prototype batteries demonstrated that have remarkable properties, such as being able to be charged quickly; properties which fade quickly after just 100-200 cycles or so. Perhaps this is merely one more of those. If so, then this is far less significant than what is suggested in the article.

At 12 minutes / cycle 50 cycles would only take 5 hours and 500 cycles just over 2 days. I remember some battery manufacturers boasting their batteries went for 8000 cycles. If you charge your car every day, 365 days a year and expect 10 to 20 year life then 3650 to 7300 cycles is a reasonable goal.

500 cycles in a Chevy Bolt will give you almost 120,000 miles.

Other car parts will fall apart before you reach 3650 or even 7300 cycles… With a 250 mile range this is 900k to 1800k miles…

So they can charge tiny battery cells really fast using monstrous power supplies.

Good for small electronics devices using these batteries.
But what about cars with large battery packs capable of driving 400+km ?
Car charging times are limited by the power supply capabilities, not the battery degradation.
It’s been the case since the very first Tesla Model S with supercharging capability.

If you use dump packs, you only need to supply the average power level needed for a days worth of charging to the super charger.

K-lein, I’m not sure if I follow you when you are saying:
“Car charging times are limited by the power supply capabilities, not the battery degradation.”
Can you elaborate on that further?

A simple calculation: Charging 100kWh in 3 minutes is 2MW. That is 2000kW. Charging 85% in 2 minutes is 2.55MW. This is at a time where we are thrilled when people talk about fast chargers delivering 350kW, that is.35MW.

Fors is talking about taking fast charging to a whole new level.

Charging will probably never be 100% efficient. So how will these chargers deal with the huge amount of heat generated? They will need to dissipate a huge amount of BTUs after each fast charge. It is possible, but it will be difficult and likely expensive.

I still believe that battery swap will one of the charging options going forward or perhaps someone will figure out electrolyte replacement.

The heat dissipation for really fast charging is a problem as is the safety of something that puts out that much power.

Battery swap schemes are difficult to make if the batteries are not rented, and people want to own the whole car. Charging at 1MW will make charging as fast as putting petrol in a car, and people tolerate that.

A battery swap system would have to be standardized either so that all car producers would have to chose from a little selection of battery sizes or so that each car producers would have to have their own standards. The first option would stifle competition and make it hard to introduce new and better battery technologies. The second option would mean lots of battery change stations. There are a two digit number of car producers (I am talking car producers not brands) and they would all have to have their own set of battery charging stations.

I consider the battery swap idea dead.

“Car charging times are limited by the power supply capabilities, not the battery degradation.”

That’s not entirely true. Some DC fast chargers, most notably Tesla Superchargers, taper off the charging power because the battery overheats if you charge it at high power (that is, a high “C” rate) for very long. And for current EVs, a “high rate” would be much, much lower than 20C.

If they’re charging at a rate of 20C-25.5C, then it looks like they’ve reduced the internal resistance in the battery cell, which means it can be charged faster without excessive overheating. Try that charging rate, or even a third of that, with a typical EV li-ion cell, and it will likely burst into flames.

We definitely need EV batteries that can be charged much faster without overheating. But we also need them to last for 2000+ cycles, which the batteries under discussion likely don’t.

“After 50 test cycles…”

500 cycles would be a minimum for a complete test, 2000 – 3000 is more common to test Lithium battery failure.

It is great Ford is working on research and making it public, but this is a long way from existing in a production vehicle.

Just a reminder, RC LiPo batteries are all rated for 20C – 25C charge/discharge rate and have been for 10 years. Somebody with more battery engineering experience than me would need to read the paper to find the real advancement.

Many published industry papers are people trying to get a free trip to their favorite conference or pad their resume for the next job opportunity.

Fellow RC hobbyist here. You are correct on discharge rates but charge rates are still typically in the 2C to 5C range.

I have yet to see double-digit charge rates recommended by any LiPo manufacturer.

Turnigy’s lithium grapheme RC batteries are @ 15C now. Check out HobbyKing for fun.
I have used them in E-bikes and they don’t even warm up. Crazy.

Thanks for the correction.

This was my memory from some spec sheets when designing a system using off the shelf RC batteries. It was a German company explaining the difference between their cells and the Asian built cells claiming much higher specs.

Recharging a 50kWh car battery in 3 minutes (20C) would require a charer that provides 1000kW. Once we go to 50-60 kWh battery packs the max charging rate of the cells will no longer matter. The bottleneck will be the charging infrastructure.
This article only shows that Ford isn’t able to see the important technical chalanges in the EV world.

Porsche claiming the 6.8 available KWh aboard the 918 can discharge at 200KW (~29C), and charge in a half hour (20KW), is another indication there are better batteries than what Panasonic are delivering. That was from the 918 brochure, and marks an important feature for race tracks: socking high kinetic energy back into limited numbers of batteries. In fairness, I don’t think anyone has proved that battery lasts. Ford may be on to something?

Two words: Dump pack.

As Nick said. A capacitor rack to level the load. Could just run 240 @ 200 amps, which is less than current superchargers. Capacitor bank reloads between vehicles. Think bigger. The capacitor bank or “dump pack” is large enough to handle several vehicles in a row. It really is that easy.

That assumes that the charger usage is low enough.

I want to calculate the cost… Please specify the voltage rating and capacity of your ‘dump bank’ capacitors.

“Recharging a 50kWh car battery in 3 minutes (20C) would require a charer that provides 1000kW. Once we go to 50-60 kWh battery packs the max charging rate of the cells will no longer matter. The bottleneck will be the charging infrastructure.”

ProTerra EV bus chargers already charge at a 500 kW rate. Future EV superfast chargers almost certainly will charge at a 1000 kW rate… or even faster. If we want to get down to the range of 300 miles of charge in 5-10 minutes, then we will need 1000+kW chargers.

As someone pointed out in an earlier discussion, the most practical place for a superfast EV charger is right next to an electrical substation, so high power can be carried directly into the EV superfast charger using a minimal distance of high tension transmission lines.

Hey Ford, those are called power cells and you likely found them in an HEV. They can accept really high charge and discharge rates. The only issue is their energy density is garbage so you will be limited to a sub 100mi bev.

Someone is forgetting about the specific requirements for li-ion charging – CC-CV.
Keeping a cell @CC rate of 20C won’t get it to be 100% charged.
The 85% is more likely to believe.

I am skeptical but I’m happy to be wrong. Or are they using Lithium Titanate cells? Those are well known to take 20C+ but they are expensive and isn’t very energy dense so that wouldn’t really be news.

Lithium Titanate (LTO) is already used for buses that quickly recharge at bus stops while picking up passengers. Those buses usually only have a handful of miles of range because they are expected to recharge often and because LTO cells are expensive. LTO is not a solution for cars unless Ford has figured out how to drastically increase the energy density and reduce the price of them.
Well, they might be a solution if you added a system for charging during driving but that would likely be far more expensive than building a nation-wide network of fast chargers.

Gg fool cell

No mention of cost.
No mention of density.

The technical challenge is not making a cell:
– you can charge quickly
– you can discharge quickly
– with high gravimetric density
– with high volumetric density
– with high durability
– that’s cheap

The challenge is making a call with a satisfactory combination of all of those characteristics.

Exactly. And in reality a C rate of 3-4 would be enough. From all appearances we are headed there by 2025.

So in 8 years lithium ion battery technology will be around these specs:

400 watts per kg. (200 currently)
Not sure on watts per liter.. anyone fill in?
$80 per kWh (currently at $170)

The $170 figure is from the end of 2016, and includes both cell and pack prices.


The Prius could get 1300 W/kg. I think we are beyond that now. If that’s an important figure for you there are always supercapacitors, which go up to 15000 W/kg.

Lithium ion batteries are lighter than water so their W/l is greater than their W/kg, probably by something close to double. I’m not sure about supercapacitors.

Actually, cylindrical cells are currently around 270 watts per kg, while pouch cells are around 200 watts per kg.


You appear to confusing energy and power. He was asking about power.

I think he means Wh/kg. SparkEV battery is about 450 lb (205 kg) and 105 kW, which is over 500 W/kg. That’s pack weight which includes the housing and cooling stuff.

Correction: power out of the battery is over 120 kW, so SparkEV pack including housing, BMS, etc. is close to 600 W/kg.

So watts per kg are used as a measure of power output as well as energy density? There must be some way to avoid confusing them, not?

Power density: watts per kilogram (W/kg)
Energy density: watt-hours per kilogram (Wh/kg)

Thank you sir!!

If he meant Wh/kg he should have said so. I can’t read minds. W/kg are an important measure for some.

> So in 8 years lithium ion battery technology will be around these specs:

Never assume that the rate of progress achieved in the recent past, will continue to be achieved in the near future.

Note, I find it interesting that none of this battery enthusiasm extends to the hydrogen car. That’s always stuck at the most inefficient method possible.

I’m not sure if you looked at the linked article or not, but it has a chart showing the expected increase in watts per kg for cylindrical cells and pouch cells, and other similar projections exist.

But, let’s not go into HFCV here. I’m sure there’ll be a clickbait HFCV article come along when the site goes a bit quiet. 😉

? No doubt FCVs are improving their efficiency as well, but hydrogen production doesn’t have much room to get more efficient. Its physics.

Quite meaningless post I would say.
Lithium titanate batteries are already in use, for example in battery buses, can charge in minutes or seconds at bus stops, nothing new here. The problem – expensive and low specific energy.

Regular NMC or NCA batteries probably can be abused this way too. Problem – dendrites forming, shorting cells, and eventually it may end up Samsung Note 7 way, which is not good for battery car publicity.

We also have to consider heat. If there is a loss of 10% during charging, then you would loose 10kWh in 2-3 minutes. That is so much heat that it can bring 107 liter (28 US gallons) from room temperature (20C) to boiling point.

The cooling system of the battery would have to be designed to remove that king of heat.

+1. Didn’t see your post before I posted mine. Heat will be a bear to deal with. It is doable but it adds complexity.

“We also have to consider heat. If there is a loss of 10% during charging, then you would [lose] 10kWh in 2-3 minutes.”

Yes, but it’s only the internal loss inside the cell which is a real engineering challenge, and rechargeable batteries are at least 98% in charging efficiency.

Losses in the charger and the power cables can be reduced by simply increasing the diameter of the wires to lower resistance, or by increasing the voltage. Larger diameter wires/cables also have the added benefit of greater thermal mass, which means they can absorb more waste heat without getting too hot.

If its a Lithium Titanate (LTO) battery then its not a big deal.

Lithium Titanate batteries have been around for a long while, can take very high C-rates, and are durable for 5,000+ cycles.

The downsides is that they aren’t as energy dense, they operate at lower voltages (2.1V instead of 3.6V+) so for a given Ah battery rating, they store less energy.

Unless Ford has figured out a way to make LTO batteries as energy dense as contemporary cells, then it could be a flash in the pan.

My first thoughts exactly. I believe ford has been working with LTO cells so this would be my guess.

My personal opinion is that cars with LTO packs that have smaller range (perhaps a 30kWh pack) but can charge much fast may have a space in the EV world. In particular in places like the UK where there is a good density of fast chargers – although these would have to get significantly bigger to cope with going from sub 30min for 80% to sub 8min to 80%.

This is absolutely fantastic, charging at 16 C or even more is bringing us much closer to ev that can charge at Megawatt level in a few minutes. 150 KWh charged in 10 minutes using a Megacharger, the final frontier. Really amazing good job by Ford, I hope they carry on this time.

What about the GRID. That would be a huge load on the GRID for just a few minutes. It could cause Brown outs and Blackouts.
What’s the big hurry anyway. Slow down a little and enjoy life.
QUOTE=Charging 100kWh in 3 minutes is 2MW. That is 2000kW. Charging 85% in 2 minutes is 2.55MW.

2550kW at 400V is 6375A divided by 8A per mm2 pure copper gives us a handy 800 mm2 cross section wire…what’s in your water, guys?