Formula E wants to add fast charging

I'll admit I don't watch Formula E, but I know all the cool kids are doing it. The series is starting to get more technically interesting as the rules open up - and this year, the cars could actually do an entire race without a mid-race car change.

But apparently this is somehow boring, and Formula E wants to add fast charging.

This could be really interesting. Let's see if we can throw some numbers out there and attract some engineers who are actually good at this.

Those are 54 kWh batteries. Let's say we want to get half a charge in a stop. That means 27 kWh. A Tesla Supercharger can pump out 150 kW, which means it would take about 11 minutes. Nope, this is not acceptable. If we want a 1 minute pit stop, we're going to need 1500 kW.

This is what a 1500 kW generator looks like.

What's the efficiency of EV chargers? Well, this study shows it to be in the mid 80s and it's better on higher power chargers. So let's say the engineers can get it to, say 90%. That means we're losing 150 kW (the entire output of that Tesla Supercharger) which is apparently equivalent to 200 hp according to an online calculator. Or half a million BTUs. So we're going to have to deal with that somehow. 

How big is the cabling for this? What sort of grounding do we need? What sort of voltage? Is this going to have to be inserted by a Giant Pit Robot because of sheer mass? Will there be a nimbus of glowing ozone around the whole car? Will the TV cameras get overwhelmed by static until we see a steaming car burn out leaving a red glowing heat sink behind?

I know the reality will likely be very mundane and boring - this is a series that actually had drivers changing cars - but man, wouldn't that be fun?

Keith Tanner said:

How big is the cabling for this?

I was going to try to be funny and post a picture of a copper cable the diameter of a large coffee can.  Turns out I can't find one.  Hmmmmmm.....If they try, I suspect that this might involve liquid nitrogen cooling to achieve superconductor reductions in resistance.   

It would be more reasonable to have hot-swappable battery packs that are exchanged as part of a pit stop.  

Not sure why hot swapping battery packs wouldn't make more sense. Even without a back of the napkin calculation the heat dissipation aspect of charging that in <1min will be very challenging.

All I know is I've been having serious thoughts about a run at that $50k lemons prize. 

I'd be curious if the batteries could handle that much power being thrown at them. I know they don't need to live for years and tens of thousands of miles, but still. I wish I could make myself follow televised racing, the tech here is very interesting, and the different challenges faced by racing EVs are fascinating. Cool stuff. But seriously, how do you charge anything that fast? Wild.

I think the CEO guy was saying, the point of fast charging would be to show off how fast they can charge...in other words, swapping battery packs wouldn't have that same level of "look at how feasible electric cars are for regular people" that they want to promote. Similar to when they didn't have to switch cars anymore and they could say "look our range is much better now."

I also think he was just speculating, which is to say, it may not be possible to do it yet but he wanted to put the idea out there.

Battery swapping is boring, it's basically just a tire swap when you get down to it. I want to see them actually push the boundaries. How do you get a battery to accept power that quickly? What does the infrastructure look like? I don't care if the battery is slag at the end of the race. Find a way!

I want this aspect of the rules wiiiiide open so the guys who figure it out have a massive competitive advantage - and this is tech that is seriously beneficial to the automotive world in general. The OEs are there, let's put their motorsport budget to good use.

According to the September 2019 issue of Race Tech Magazine, Formula E cars can go for a full race right now.  There was a battery breakthrough by a company called Atieva which allows the cars a full race distance with better performance to boot.

It was also a regulatory breakthrough. The season that just ended was doing full distance races, I believe. But the F1 guys want refuelling back. What would it look like if FE added it?

It's highly unlikely it'll actually happen in an exciting way. But let's play "what if" :)

I hear you on the battery swapping being "boring" but if I was the guy trying to get back on the track that's the answer. Found this link in my archives which could be helpful to put some of the tech in context https://trs.jpl.nasa.gov/bitstream/handle/2014/41485/08-0012.pdf?sequence=1&isAllowed=y

In reply to JoeyM :

More likely liquid helium, as I believe that's what used in medical imaging devices. I read an article and the author did say that liquid cooling of the cable would be required for the super fast charging, and for Keith robotics were also mentioned.

Not to stray too far off-topic but, after reading Steve Matchett's book The Mechanic's Tale, I hope F1 doesn't bring refueling back.  Their fuels are way more volatile than Indycar and present a greater hazard.  If they want more exciting pit stops, perhaps they should limit the people "over the wall" like Indycar does, rather than the 275 people they currently allow.

I think it more important that Formula E showcase the high performance level on a single charge over the course of a race, rather than a rules-mandated recharge mid-race.

In reply to Keith Tanner :

Doing the math, it's closer to 1600kW of power needed.  But since Power = volts * current, 1600kW=1,600,000 W = 1000V*1600A.

And IIRC, the modern state of the art racing batteries are close to 1000V, so it's quite conceivable that it's on the order more than 1500A.

When we were melting dirt in the Idaho desert, it was 500V*500A to melt dirt (dirt becomes a conductor at high temps, with nice an high resistance, so the heat would propagate the dirt melting.)

Yea, that's a LOT of power.  Needing some serious cooling.

No way they'd put a 1500kW generator next to each car - much more likely to have a powerwall-type stack of batteries in the pit that they charge slowly during the race and discharge quickly into the car during a pit stop. Commercially available pantograph charging for buses currently supports 600kW charging, but word on the street is 1000kW is within reach with higher voltages.

The cars wouldn't be plugged in, but a mobile setup like this would be pretty badass.

https://new.siemens.com/global/en/products/mobility/road-solutions/electromobility/ebus-charging.html

As far as the cables go, typically for big generators like that you run multiple smaller cables in parallel instead of a single giant set of cables (as an EE I have on occasion designed systems that use big generators.)

Having said that, I think the solution for race cars would be to swap in fresh batteries during a pit stop, rather than recharging them.  I'd think they could collaborate on the design so there was a common style battery pack that could be pulled out and replaced quickly, and then it wouldn't be much different than a refueling stop for an internal combustion engine car.

Gratuitous photo of a generator setup my boss designed some years back...five 2.5MW generators in parallel:

Instead of a robot plugging them in I'm picturing this:

In reply to dculberson :

I watch formula E when I travel to the other side of the world for work.  It is definitely the future of motorsports.  It won't be long before someone claims that lemons prize money.

alfadriver said:

When we were melting dirt in the Idaho desert...

More info needed!

I didn't really expect to see a stack of 1500 kW generators, that was mostly to provide a mental picture of scale. 

Okay, the bus charging is pretty cool. Can we use bus technology in Formula E?

Why would they need to make the battery half the size?  What if it was a mandatory pit stop that they had to only had to "half charge".  Wouldn't that bring the necessary current way down to do it in a timely manner?

I wonder how much more insanely dangerous it would be to charge at the necessary rate vs refueling with methanol or something. 

dculberson said:

Instead of a robot plugging them in I'm picturing this:

The bus company I may or may not work for beat you to that idea by a few years too... A superior solution to the pantograph but not what the standards agencies chose. 

https://www.youtube.com/watch?v=pwdl4HFkyUg

https://www.youtube.com/watch?v=dp3_zUgD6KE

They also hold the range for longest distance traveled by an EV on a single charge and have already sold 800V architecture buses to customers (sorry Porsche, not first). Some neat stuff happening in the transit bus space. There is a contingent of us in the office that want to swap some old bus stuff into a pickup and make a run at that Lemons money...

wvumtnbkr said:

Why would they need to make the battery half the size?  What if it was a mandatory pit stop that they had to only had to "half charge".  Wouldn't that bring the necessary current way down to do it in a timely manner?

My numbers were based on putting a half charge into the existing "full size" battery. The rate of charge tapers off as you get close to full, so I assume they'd leave that on the table.

Ah gotcha.  Thanks for the clarification!

Keith Tanner said:

alfadriver said:

When we were melting dirt in the Idaho desert...

More info needed!

In Situ Vitrification- https://www.sciencedirect.com/science/article/pii/0191815X88900514 we were melting dirt to encapsulate waste into glass.  That paper was from Oak Ridge, we were at the Idaho National Engineering Lab, and there was another team at Hanford trying the same thing.  4 large carbon electrodes stuck in the ground fed by just under a MW would melt the dirt into glass.

And that's my frame of reference for the amount of power that would be needed for 1500kW charging rate.  To absorb that energy would be incredible.

Heh heh heh, I think I've come up with some ideas. Now all I have to go is get Musk's attention so he'll throw me some spare parts and we can go win Lemons.