Thursday, May 14, 2009

Better Place Battery Swap

According To Paul

I've written on Better Place's battery swapping plan before, but since they've actually demonstrated it now, I thought it was worth another look. This link will take you to a 2 minute video of the "switching station" in operation. It's kind of slick, but I still have questions.

When  I first got my RAV EV in 2002, there was talk on the EV lists about how future EVs could drive across the country. One camp favored battery swapping, much like demonstrated here. The engineers of the group favored fast charging. Still others, actually it was mostly just Felix Kramer, who thought these "plug-in hybrids" were the way to go. Turns out he had the best idea, although all three ideas seemed plausible to me at the time.

But since Better Place went to the trouble of building this thing, how well does it work?

If you watch the video, it shows a Nissan sport utility vehicle driving into a small facility where a mechanized device unlatches the battery pack and replaces it with a fully charged one. The whole operation takes slightly over a minute, two minutes if you count driving into and out of the facility. Presumedly, payment is automated, so you never need to get out of the car, well, unless you gotta pee.

That sure compares well with filling up a gas tank, but I still wonder about its feasibility.

Consider that for this to work from a financial perspective, many, if not most car companies, would have to standardize the design of their battery packs so the same machine could replace packs on any vehicle. Given what I've learned about the auto industry these past 6 years, I don't see that happening.

Also, the various car companies are cutting deals with a wide variety of LiIon battery makers and all of them are making their own specific type of LiIon battery. Each of these batteries has unique characteristics of voltage, energy density and power. From what the engineers tell me, the power electronics, or controller, is specifically designed to work with a certain battery, and that car or SUV will not be able to operate with just any old battery.

Further, the economics of battery swapping are going to be very tough since all you're selling the customer are the 20 or 30 kWh of electricity stored in the pack. The U.S. average for a kWh is 10.4 cents. So, for a sale of $2-$3, only part of which is profit, the swapping station will have to purchase, charge and store hundreds of batteries of various kinds. These battery packs today cost $750-$1000/kWh, although some are saying they'll be down to $500/kWh soon and eventually down to $300/kWh.

As daunting as that sounds, keep in mind that people who really want an EV that can go long distances will probably buy a PHEV Prius, Volt, Ford Escape PHEV or one of those BYD or Fisker Karma plug-in hybrids.

And fast charging is quite viable as well. Aerovironment of Monrovia, CA has been making industrial fast chargers for over a decade. About 12 years ago, some of their engineers set out to see how far they could drive an EV1 in 24 hours, using a fast charger. They managed just over 1200 miles, a record that still stands. Of course, all the EV1s were crushed a few years later, so no more attempts were made with that car.

The point being that viable alternatives to battery swapping exist today, and they will only get better, making the need for an expensive infrastructure unnecessary.

So, while I'm happy that Better Place has demonstrated this battery swapping idea, I hope they don't spend a lot of time or money on the concept. Money that could be better used to actually get cars on the road.



May 13, 2009, 12:54 PM
Better Place Unveils Battery Swap Station
Better Place, a company working to build infrastructure for electric cars, hasreleased a video showing how its technology for swapping spent car batteries works.

Swapping stations, the company said, would facilitate longer trips for battery-powered cars — say over 100 miles or so — by allowing drivers to roll up and swap out a spent battery for a freshly charged one. (For shorter distances – commuting for example – the cars can simply be recharged at home or at work.)

The video, taken from a demonstration on Wednesday in Yokohama, Japan, shows a white Nissan electric crossover sport-utility vehicle driving onto a ramp in a tidy, covered white station. Machines remove the battery from the bottom of the car and click in a replacement, amid whirring and clinking sounds.

The company says that the entire process takes 80 seconds, though that’s difficult to verify from the slickly cut video.

Better Place plans on beginning construction of more battery swap stations, which it calls “Switch Stations,” later this year — though unlike in the video, ramps will not be used in the future deployment of the swap machines, according to a Better Place representative.

One hundred of the stations — which cost around $500,000 apiece — will be rolled out in Israel by 2011, with additional stations slated for Denmark and later, Australia, California, Hawaii and Ontario.

Though it uses a sport-utility vehicle for the demonstration – not the greenest choice – the company said that it can recharge the batteries using solar panels, “creating a truly zero-emission solution,” according to an e-mailed comment from Sidney Goodman, a Better Place vice president.

“It will be as quick (if not quicker) than refueling a traditional gas-powered vehicle,” Mr. Goodman said, “but will be much cleaner and convenient, allowing consumers the opportunity to either get out of the vehicle during battery switch or remain inside the vehicle while the operation is completed.”

1 comment:

Falstaff said...

Paul -

I'm an engineer and have looked fairly carefully at some of the issues you address w/ the BP concept. As I see it, the only valid one is the issue of the standardized battery, that is, a standard that will allow exchange with several different vehicle makes. There are some technical difficulties there: standard form factor, standard voltage, standard latch, standard temperature control (forced air? water?), standard IT interface (the BP concept requires a small computer in the battery). These are all perhaps solvable, but those aside the car mfns still have to want to play along. So far BP just has Rennault-Nissan, and even that consists of a Memorandum of Understanding. R-N has also made recent moves (e.g. Arizona) suggesting they can go it alone.

Regarding the other issues you mention:
-Battery Cost. The price now is more like $400/kWh, with lower quotes coming out of China. But the overlooked key figure is cycle life. It is cycle life that enables the BP plan. The LiFePO4 batteries certainly do 3000 cycles, with A123 reporting as much as 7000. For a 22kWh, 100mi battery pack, that's 300,000 miles. That didn't matter much before BP's exchange concept appeared as the battery cost was tied to the life of the vehicle. BP undoes that coupling and stands to use the entire 300k miles. So now the $9,000 up front battery cost becomes ~4 cents a mile. Add ~3 cents a mile for the energy, another 1 cent for the infrastructure and BP is well ahead of European combustion vehicle per mile costs already, and the advantage can only get better. BTW, this per mile calculus holds for most any type of vehicle - even an 18 wheeler, though admittedly the up front cost becomes daunting. And the estimated 'hundreds' of batteries at an exchange station is high. Consider that the number of batteries stored need only be the backroom automated charge time (~20mins) divided by the exchange time (2 mins), or about ten, and that's worse case. Statistically that number can shrink further.

-Fast Charging. There are several serious technical challenges here, which to my mind puts FC much more 'out there' as a practical concept than battery exchange. First, if fast charging is to become the long term answer for EVs then it must anticipate higher capacity, longer range capacity batteries as the economics and technology enable them. Lets say a 300 mile, 75 kWh battery becomes feasible in 2020. To charge that 75 kWh pack in ~ 5mins requires nearly a one megawatt electrical service. A fast charge 'station' then becomes a multi-megawatt electrical substation. Second, a 440V service won't accommodate the required amps, and the standard insulation mechanicals on cables and connectors at ~14KV are not meant to be commonly handled. High voltage applies stress insulators, and some work is required yet to provide an all weather, safe, high voltage self charge point. Note that battery exchange does not share this scaling problem, more capable batteries have little impact. Third, fast charging batteries are not quite out of the lab yet. Existing off the shelf battery chemistries can indeed be charged in minutes as your 1200 mile EV1 anecdote illustrates, but it kills the life cycle- they can not be charged at those rates again and again and last, not yet.

-Competition from a PHEV Prius. Those dual power train vehicles will always be more expensive than a pure BEV play, and they retain all of the maintenance problems of combustion engines and drive trains. The BEV without the battery, a 'nice' one, should easily cost $15k to $20k. The US tax break of $7500 drops the price nearly half again. Eventually the PHEV's, which include the battery cost, just won't compete.