Is Tesla About To Offer Battery-Pack Swapping For Model S?

2013 Tesla Model S

2013 Tesla Model S

Enlarge Photo

Last week, one day after Consumer Reports called the Model S the best car it had tested since 2007, Tesla quietly announced that it will make the car a whole lot better.

On page 38 of a May 10 filing with the Securities & Exchange Commission, Tesla Motors [NSDQ:TSLA] discussed factors that may influence the adoption of electric vehicles.

Among the factors discussed was its ability to "rapidly swap out the Model S battery pack, and the development of specialized public facilities to perform such swapping, which do not currently exist but which we plan to introduce in the near future." (our emphasis)


We've heard this before

Tesla has discussed battery swapping as part of the Model S design at least since 2009. As recently as March, in its previous 10-K filing, it said it was considering implementing some version of the technology during 2013.

The latest information is the statement that "specialized public facilities" for conducting battery swaps are something that it "plan[s] to introduce in the near future". It essentially telegraphs an imminent announcement.

It also eliminates previous discussion of battery swaps occurring at "service centers" in favor of the far more interesting "specialized public facilities."

Beyond the SEC filing, CEO Elon Musk recently tweeted, "There is a way for the Tesla Model S to be recharged throughout the country faster than you could fill a gas tank."


Five-part trilogy

When asked what this tweet was about, he responded: "Don't forget the mystery announcement. Part 5 of the trilogy"--referring to earlier tweets promising imminent announcements, including the new Financing Plan and Service Plan recently announced.

Tesla Motors - Model S lithium-ion battery pack

Tesla Motors - Model S lithium-ion battery pack

Enlarge Photo

We still await word on an expansion of the network of SuperCharger quick-charging stations, as well as the "mystery announcement." Both are expected any day now.

Currently, the SuperCharger system offers the fastest charging installed on any electric car. It allows a Model S to add roughly 150 miles in 30 minutes under optimal conditions, and can even complete a full 265-mile "Range" charge of an 85-kWh Model S in a bit more than an hour--allowing owners to take long road trips.

But even SuperCharging is incapable of charging the large Tesla Model S battery pack "faster than you can fill a gas tank."

We are left to believe that the "mystery announcement" is related to the 10-K's battery-swap announcement.

Rapid battery swapping

So what is rapid battery swapping? Just what it sounds like: It replaces a depleted battery pack with a full one, rapidly.

Better Place Battery Swapping

Better Place Battery Swapping

Enlarge Photo

It may be best known among electric-car fans through the struggling Better Place service in Israel.

It would entail driving the Model S into a small automated facility, rather like an automated car wash. A robotic mechanism would remove the battery from under the floor and replace it with a fully charged pack.

Presumably after paying for the service through their touchscreen displays, Model S owners could drive away with fully charged batteries, ready to complete the next segment of their trips.

Musk has previously described this process as equivalent to the Better Place battery-swap process, which can swap out a battery pack in less than a minute.

Unlike Better Place, however, Tesla owners would then pick up their original batteries on the return trip.

Vigilance required

There has always been skepticism about whether Tesla would move forward with a battery-swap system, whether for functional or economic reasons.

Tesla Motors CEO Elon Musk at the wheel of a Tesla Roadster

Tesla Motors CEO Elon Musk at the wheel of a Tesla Roadster

Enlarge Photo

The company has announced $200 million in capital expenditure for 2013; a major investment in battery-swap infrastructure would clearly require substantial effort and resources.

But the statement in the 10-K and Musk's tweets appear to leave little room for doubt.

And perhaps the need was foreshadowed by Jake Fisher, head of automotive testing at Consumer Reports.

He said of the Model S: "If it could recharge in any gas station in three minutes, this car would score about 110" [out of 100].

Thomas Fisher is a performance-car enthusiast and Tesla Model S fan who lives in Southern California. He works as a business consultant and occasional writer..


Follow GreenCarReports on Facebook, Twitter and Google+.

Follow Us

Comments (49)
  1. How is the battery attached to the car? Does it look like an automatable quick release?

  2. It is flat against the floor of the car and attached by just a handful of bolts (8 or 12 maybe? I don't remember exactly.)

  3. I'm not sure of the details of the mechanical design; however, an automated, quick swap (about 2 min) capability was part of the original design of the car and has already been thoroughly tested.

  4. This is a liquid cooled pack, right.
    with connectors that don't look to be easily removeable from the bottom.

  5. Meant to post this picture.

  6. Some good pictures here too.

  7. I'm pretty sure they had to demo this ability to some regulatory body in CA in order to get the EV credits they are getting. So it can definitely be done in under 2 mins. I think they did it manually with a "pit stop" crew for that demo though.

    Also, part of Elon's bet with Dan Neil hinged on pack swapping. So presumably he got a similar demo before coughing up the cash.

  8. If it is liquid cooled, they would need double check valves to keep some of the fluid in the battery pack and the rest of it in the radiator. Hmmm.

  9. Yes. The rest is just a specialize jig, and all of the robotics to move the battery around. That issue was always the best reason to be skeptical.

    I don't know the volume of coolant in the radiator. Maybe there is a bladder inside of the battery that sucks the coolant back inside, lol.

    Regardless, it looks very much like Tesla is about to announce battery swapping. They have always claimed they could do it, so they must have a solution.

  10. There are more comments in this thread
    There are more comments in this thread
  11. I'd rather use the Super Charger, if I drove a Model S to the point it needed a charge I wouldn't need a 3 minute swap I'd need a break. I'd also hate to be far from home and have the swap process damage something on the car ending my trip in a rental car and having to head home early.

  12. Good point about needing a break by the time Model S runs out of juice.

    In all fairness: Better Place proves battery swaps can be done without risk of damaging anything. Also: the way the the Model S battery is bolted under the car seems pretty much ideal for the swapping concept.

  13. You never can tell what could happen to your car in an older station, swapping stations will need maintenance and if not kept up something could go wrong. Better Place is watching over their few stations, but if swapping was as widespread as gasoline you know you're bound to get a bad swap some day.

  14. I dont know. They should be able to create a reliable process for this. The jig and the robotics are quite simple. You can make the system physically unable to overtorque bolts or even start without being properly aligned.

    I'd be a lot more concerned about the system breaking down in mid swap. Getting stuck on top of one without a battery would be unpleasant.

  15. It could happen, what was only supposed to take three minutes could ruin your day. And though you could have a problem rapid charging it is in some cases easy to fix with a software update sent directly to the car or the charger.

  16. Few? 37 stations? Is fueling with gas trouble free? have you seen what happens when diesel fuel gets into a gasoline tank by error and thirty-fifty cars conk out?

  17. Yes I've heard of people doing this, but the problem there is the car owner making a mistake.

  18. Older station? They have to be built and used 1st and the mechanical tech required is well understood.
    And why wouldn't they be maintained? Yes, if swapping catches on in a big way, the chances of problems rises exponentially but worrying about fires and explosions didn't stop us from building 200,000 gasoline service stations.

  19. You can have the quick-charge system fry you battery, and shorten its life considerably. The Better Place batt-swap does it in cooled conditions, directly inspected, and checked on it way in and out. It works

  20. A quick charge frying your battery would be a rare event, but a big mechanically operated station breaking down could happen easily. Right now Better Place is keeping a close eye on their stations but they don't have a lot to watch. A larger aging swap network would be prone to problems just like older automated car washes.

  21. I doubt Tesla will take this route. The swap stations cost an absolute fortune to build and the density of the network needed wouldn't be any lower than that of the Superchargers that will need to be interspaced every 50 miles tops to offer drivers a safe and flexible driving experience. Also there is the practical matter of finding the real estate along highways to build these large structures. If you have to leave the highway to get to one, might as well spend some extra time at a fastcharger. In terms of cost this sounds like hydrogen infrastructure territory (okay, maybe not that bad...).

    What's really needed is to double the fast charge time at some point. 150 miles of extra range in 15 minutes seems perfectly acceptable.

  22. Yep, all good points.

    But of course, faster charging is also expensive. Right now superchargers charge at 90 kW, but Tesla has always planned on bumping that up to 120 kW, so it's quite possible that they are simply announcing 120 kW supercharging capability, though that is still far short of how fast one can pump gas.

    If one assumes that you can only pump gas at 5 gallons/min (pumps can go up to 10 gpm), that's 300 gallons/hour. Filling a 19 mpg car (MB S600 hwy), that's the equivalent of charging at 5,700 mph.

    Now assuming that the Tesla goes 100 miles on 38 kWh, so at 120 kW that's charging at only 316 mph - to match the the fill rate of gasoline, you'd have to charge nearly 20 times faster, or around 2 MW.

    That's a LOT of power!

  23. No need to match gasoline fill up speed. You start every mourning with a full battery, and by the time that's depleted you probably need a break anyway.

    Like I said: 150 miles in 15 minutes would be nice.Probably requires 250KW chargers. No problem at all from a charging viewpoint, it's just that current gen high energy density battery technology can't take it. Hopefully that will change soon.

  24. Yeah, I agree - 250 kW is fast enough for majority of uses. The 2 MW calc was really just an exercise to show how fast charging would need to be to match the charge rate of gasoline...

    Really, the only possible way to do that today is with battery swap, but then it's not really charging, is it?

  25. The speed isn't just about driver convenience, but turnover for the station owner. Can you imagine a typical 6-8 car queue at, say, the Vince Lombardi rest station on a football Sunday, but instead of taking 3-5m to fill up for each car it takes 30-60? So then you have to stripe across a # of dedicated spots that can accomodate peak usage, and feed 120kW to each of them? Call it 20 dedicated spots. Now the rest stop needs to have a 3MW substation and pay to maintain that even if it averages 10-15% utilization or else your 30m SuperCharger stop takes at least 2-3x longer than that.

    Of course, home charging may cut that demand in half, we'll see as the # of Teslas ramps.

  26. Hypothetically, let's say you can charge at 120 kW and you need 25 spots to handle peak demand of 50 cars/hour (each charge takes 30 minutes) with a peak demand of 3 MW.

    Now you have cars that can charge at 1 MW and you have 3 stations so your peak demand is still 3 MW.

    In both situations your peak demand will still be the same - 50 cars/hour, 60 kWh per charge, 3 MWh, but you will need more stations and sports to support the slower charge rate.

    But in the real world, utilization will be lower for the 3 1-MW station setup because inevitably a greater percentage of time time will be spent moving cars instead of charging cars as it takes a constant amount of time to park/start/stop/move regardless of how fast one can charge.

  27. However, if 5% of that 250Kw dissipates as heat you are looking at 12.5 Kw of heat, which is a whole house-full of airconditioning, all that in your four inch battery. not so good for the longevity of those poor cells. but charge it over one hour in a cooled environment which you drive off with a full battery, now that makes sense

  28. Agreed. The current battery is held in with about 20 bolts and has multiple connections for coolant, control and power. The reason for the many bolts, is that the battery pack is part of the structural design of the car. There is some risk to this each time a swap occurs.

    Shouldn't be long before we find out what Elon is talking about.

  29. Actually is a small structure that looks like a car wash. It costs far less than burying huge tanks of gasoline and diesel fuel underground, running those huge pipes, those complicated precision pumps that need to be calibrated every so often, and the very fact that you are dependent on them for day to day operations. Since most of the charging of the EV is doen at home or at work that actuall use of the swap-station is only for intercity, so the number drops considerably. If Israel requires 50 stations, which cost 50 million bucks the US will require 3000 such stations, 3 billion dollars, which is a rounding error on Obama's weekly deficit.

  30. "Unlike Better Place, however, Tesla owners would then pick up their original batteries on the return trip."

    What makes you believe this? I have never heard any convincing evidence of this and you have no citation (unlike the rest of the article which is pretty well cited).

  31. Sorry, my bad, thought it was cited -

    Here is his quote -

    “We’re designing the Model S to have switchable batteries,” said Musk, who has a solution to the problem of consumers not wanting to end up with an unknown pack in their expensive EV. “When people take an occasional two-way long distance trip, they’ll get a replacement pack and then pick up their original one on the way back. The issue of giving up your one-year-old pack for a three-old-one goes away.”

  32. As a soon to be MS40 owner, I'd happily rent an 85kwh or greater pack for a road trip, then pick up my own pack when I return. They could activate it and the Supercharger capability in software just for the rental.

  33. That is how I expect this to operate. There is no reason actually that they couldn't just activate an 85kWh software profile for the car giving you full access to the performance of the pack.

    Might make a nice upsell opportunity for them. I could totally imagine customers being allowed to purchase the new pack, while getting credit for the old one, similar to the way the loaner program works.

  34. I should add, that is all speculation. We need to wait for Elon to make his announcement. Based on his most recent tweet I suspect he moved it up to this week.

  35. What is the point of quick swapping a 85KWh battery pack?

    1. That is a lot of money sitting around waiting to swap.
    2. Messy system to deal with since the battery thermal control system have to be self contained.
    3. Limited use/need with quick chargers
    4. Lots of initial investment and cost
    5. Liability

  36. "That is a lot of money sitting around waiting to swap."
    "Lots of initial investment and cost"

    I don't know how much you think the batteries cost, but a lot of folks are citing prices that are far higher than what Tesla is paying.

    Fundamentally we need to wait to hear what Elon is proposing. But I think this at least has the potential of being an attractive route to pursue.

  37. @ even $350 per KWh, that is $30k per battery pack. Not counting cooling system, storage and swapping station.

  38. IIRC some of the details of the Better Place vision, the batteries in the cars AND the stations would participate in grid backup / storage.
    That would mitigate the cost of an expensive pack just sitting around and could even be profitable in some electricity market.s

  39. I think Tesla is not going to swap the main battery. Instead they will allow owners to use extra non-rechargeable aluminum-air battery (or batteries) placed in the Model S frunk (front trunk).

  40. Perhaps. But then, Tesla has repeatedly claimed that the main battery is swappable, and have not ever mentioned frunk cartridges as far as I am aware.

  41. China.

    Now got back and re-think.

  42. our capability to rapidly swap out the Model S batt
    ery pack and the development of specialized public
    facilities to perform such
    swapping, which do not currently exist but which we
    plan to introduce in the near future;
    Well, they dont need to invest anything. The Better Place system was designed to be flexible as to the size and type of battery. the system is deployed in Israel, and only the ferocious slanderous attacks of the traditional car importers stand in the way of making the batt-swap EV mainstream. However, 1% of the cars sold in Israel in April were the Batt-Swap EV Fluence ZE, which i drive, so skeptics are losing ground.

  43. One thing I've learned from owning an EV with a small battery is how much less of a problem this is. I'd say the 60kWh battery on the Tesla is way more than most people's daily needs and with increasing availability of even slow charging at destinations, it's just plenty. But only with infrastructure.

    It's exactly the same story with ownership of the battery as an asset. I just don't see this as an advantage.

    It might not be suitable for the US, but for Europe the 60 or even 40kWh Tesla S with switch stations would be a massive, runaway success. It would be almost ridiculous for most people to buy anything else at a similar price.

  44. Guys, the stuff about battery swapping was in the annual report as I mentioned in my blog back in March:

    "There was a hint in the annual report about battery-swapping stations"

  45. Given Better Place's recent bankruptcy filing, if Tesla truly plans to announce battery swap, that would be a welcome bit of good news for those who believe this to be a viable tech for EVs

  46. Battery exchange sounds quite labor-intensive, to me. It also sounds like it could take quite a bit of the owner's time, for each swap. Service stations' infrastructure might need quite an investment too.

    Why not increase the battery capacity, instead, allowing some increase in range beyond the claimed "300 miles"? Perhaps to 350 miles(?) "depending on "driving style'"? Extra space sounds generous, given the volume its electric drive train frees up.

    In case adding max. capacity beyond its current 85 kWh might increase the lithium battery’s fire potential, suppose it were built with internal cooling channels from front to back, to let air circulate past the cells?

  47. Might not cooling channels interfere with starting of overheating-related fires?

Commenting is closed for old articles.

Get FREE Dealer Quotes

From dealers near you

Find Green Cars


© 2015 Green Car Reports. All Rights Reserved. Green Car Reports is published by High Gear Media. Send us feedback. Stock photography by izmo, Inc.