6

I mostly want to focus on the practical / mechanical perspective of this question.

I have thought already many times on buying a small electric motorcycle for daily commute etc but i wouldn't min to have small excursion/trip on it (even on these reduced speeds). What blocks me though is that it has such a limited range and such a big time of recharging that even i decided to take the (heavy and bulky) charger along with me and even i could find a power supply available anywhere, i would need to spend at least 2 hours of charging for every 100km of riding, reducing my average speed from 50km/h(an average small electric motorcycle speed) to a silly 25km/h.

So... if all vehicles manufacturers and batteries manufacturers had a standardized type of batteries (or a few if for some reason voltage cannot be the same in cars and motorcycles) that would fit all vehicles (or at least all vehicles of a given type) and would be modular in a way that a larger car would fit e.g 8 cells and a smaller car 5 cells and a motorcycle 3 cells etc, then if these cells would be produced in massive numbers (rendering them cheaper than normal vehicle batteries) could it be that they would be available in every gas station and/or remotely "desert" charging (via solar cells) stations so that it would be easy for a vehicle to pay and interchange it's empty battery with a full one without having to wait for long period?

These solar cells could be sold separately from the vehicle and thus piping the cost to the final consumer also when going to the charge station you could have your "empty" batteries overall state (age and capacity) examined and upon switching with the "charged" ones a small variance in price could be applied etc.

I can clearly see the financial and political implications of such a model but do you find this case to only belong in Worldbuilding???

put on hold as primarily opinion-based by Pᴀᴜʟsᴛᴇʀ2 Feb 11 at 18:46

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • I drive an electric car and I would not want to exchange batteries. I use slow charging (overnight) and rarely charge to 100% because I intend to keep the car for 20+ years -- I don't want to get a battery someone has done a bunch of fast charging on and abused. – Kathy Feb 11 at 15:31
  • How is this a question about motor vehicle maintenance and repair? – David Richerby Feb 11 at 17:53
  • @DavidRicherby The scope of the site is a bitter wider than the title implies. See related meta Are questions about automotive history on topic? – James Jenkins Feb 11 at 18:36

10 Answers 10

1

One of the biggest problems to solve in electric vehicles at the moment is battery - if the battery can be made more efficient, lighter the cumulative increases in efficiency makes the vehicle much more desirable to customers.

Sharing a standard battery is a good idea eventually but currently there are two forces against that:

  1. At a time of such investment in R&D to restrict the batteries to a standard could limit how easily these can be implemented into new vehicles
  2. The battery is one area that gives companies a competitive edge - if you're limited to share the innovation you make you see less of the profit

Once the improvements to be made here begin to peter off I'm sure you'll see a greater push towards standardised batteries - as you say, there is no other direction if we're to replace internal combustion cars - but I don't expect this is something we'll see in the near future.

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  • 1
    +1 from me for providing the most probable reasons why that has not yet happened. – kokobill Feb 11 at 13:41
  • Actually, a Tesla uses standard batteries, and they are made by Panasonic, not by Tesla. See my answer for details why you won't be changing batteries in a Tesla, however. – juhist Feb 11 at 13:45
  • @juhist Tesla's battery modules are custom, and in fact the cells are too, even though they're standard 18650 or 2170 sized and built in collaboration with Panasonic. The Tesla Model S is designed with battery swapping in mind, although they eventually decided against battery swapping stations. – user1908704 Feb 11 at 13:54
  • @user1908704 Interesting... I guess you could swap only Tesla Model S batteries with other Tesla Model S batteries? I mean, surely you can't be swapping Model S batteries with that of Model X or, say, Nissan Leaf? – juhist Feb 11 at 13:55
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    @juhist I think Model S and Model X are both swappable, but you can't swap one into another. The Model 3 isn't swappable (or rather it is, but you have to take apart the interior to do so, so not exactly feasible on the highway) – user1908704 Feb 11 at 14:00
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I'm not entirely sure that this question fits the primary purpose of this group BUT I have to say that I've long wondered why electric car manufacturers don't standardise on a battery format and devise some sort of unattended method of battery replacement.

I thought something that you drive the car onto and then the battery pack is ejected from underneath and a new one slotted in from underneath could work. From an engineering perspective, I guess the only risk is that when the battery is removed from the vehicle, the vehicle would be immobile until the new battery was fitted.

You could then re-engineer existing fuel stations to be equipped with some sort of charging rack in which incoming batteries would be installed and fully charged ones would be taken from.

I guess the biggest issue is that EV manufacturers have already established that they're going in another direction with the idea that batteries remain in the vehicle and are charged. Given that the format of the pins on the charging points vary wildly, the chances of getting manufacturers to standardise on a battery format are slim. I guess the thing stopping this is market forces, not engineering challenges. I guess that the only way that would change would be legislative changes from either one major or a small group of governments.

  • 3
    What you do if your fresh and brand new pack gets exchanged with an already heavily used one and your energy back just dies due to wear? Would it be like its kept track of where your former packs went and you can request to get your old pack back? Would there be some sort of insurance for it? Who would be supposed to pay that insurance? Or would it just be a lottery like system, where you can just hope the pack you get won't die till you have a new one, and if it does so, the damage is on you? Seems to be like an very financial risky system for the individual users, no matter how you solve it. – Zaibis Feb 11 at 11:33
  • 8
    @Zaibis Similar systems are already in place with items like compressed gas cannisters. Essentially the cannister/battery belongs to the system and the user pays a deposit to take temporary possession. Any time a user swaps one battery for another (which would almost always be the case with vehicle batteries) there is no need for a deposit. When each battery decays to a pre-determined performance point it's identified by the charging system and removed from service. – Dan Feb 11 at 11:45
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    @Dan: interesting. thanks for the analogy (if it is even one). – Zaibis Feb 11 at 11:49
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    @Dan Except that gas canisters have a very long life, canisters are very physically robust and hard to damage, the canister is relatively inexpensive to make, and there is little resale/scrap potential in a gas canister. All of those are the exact opposite for a battery pack. – Graham Feb 11 at 12:47
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    Using sealed battery assemblies, it would be possible to have the purchase price of the battery include a deposit and a wear credit, and then bill people based upon energy stored and retrieved. A home charger set up for use with such a system would credit people for energy stored, while charging for energy retrieved. The biggest difficulty would be the major incentive for people to create counterfeit battery packs and exchange them for legit ones. – supercat Feb 11 at 18:00
5

TL;DR:

This idea is old, like OLD (1890s), but so far nobody has been able to set it up in a financially viable way.

History

The steam car, the internal combustion engine automobile, and the electric car emerged as the main competing technologies in the late 1890s until the 1920s. The concept of exchangeable battery service was first proposed as early as 1896 in order to overcome the limited operating range of electric cars and trucks.

The concept was first put into practice by Hartford Electric Light Company through the GeVeCo battery service and was initially available for electric trucks. The vehicle owner purchased the vehicle from General Vehicle Company (GeVeCo, a subsidiary of the General Electric Company) without a battery and the electricity was purchased from Hartford Electric through an exchangeable battery. The owner paid a variable per-mile charge and a monthly service fee to cover maintenance and storage of the truck. Both vehicles and batteries were modified to facilitate a fast battery exchange. The service was provided between 1910 and 1924 and during that period vehicles using it covered more than 6 million miles. Beginning in 1917 a similar service was operated in Chicago for owners of Milburn Light Electric cars who also could buy the vehicle without the batteries.

Source: Wikipedia

Better Place company

Better Place was a venture-backed international company that developed and sold battery-charging and battery-switching services for electric cars. It was formally based in Palo Alto, California, but the bulk of its planning and operations were steered from Israel, where both its founder Shai Agassi and its chief investors resided.

[...] The company's financial difficulties were caused by mismanagement, wasteful efforts to establish toeholds and run pilots in too many countries, the high investment required to develop the charging and swapping infrastructure, and a market penetration far lower than originally predicted by Shai Agassi.

[...] The QuickDrop battery switch system would enable Renault Fluence Z.E.'s battery, the only vehicle deployed in the Better Place network, to be swapped in approximately three minutes at dedicated battery exchange stations.

Source: Wikipedia

A video of the process can be seen here: https://www.youtube.com/watch?v=qd0WPw3p2MQ

  • There was a similar scheme in... I want to say Saudi Arabia? It ran into the exact same problems. Each "station" ended up needing an entire warehouse to store/charge batteries, and cost five times (or more) greater than predicted to be built, and had higher running costs than expected too. – Baldrickk Feb 11 at 11:53
3

edit: as (I've just noticed that) @JamesJenkins has already pointed out:

Gogoro is everywhere in Taipei and now several other cities in Taiwan.

full disclosure; I'm not affiliated in any way and don't own one.

Spec sheet for electric scooter and battery:

System (including batteries) is waterproof:

  • IPX6, Above 30 mm:
  • IPX7, Below 30 mm

Taiwan currently has over 1,000 swap locations, you pick a nearby site on your phone, "reserve" a pair of batteries and go there and swap them in a few seconds.

enter image description here

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  • 1
    Yeah, posted my answer a couple minutes before you, but yours is better formatted. I suspect we were both writing at the same time. – James Jenkins Feb 11 at 16:46
2

One possible solution is a flow battery. Electrolyte could be replaced in very much the same way as we refill a car.

The downside though is that the electrolyte is some kind of strong acid. You think spilling flammable petroleum products are a problem? Try spilling acid which will eat through your clothes, your leg, your car bodywork, the concrete floor...

It's still a viable solution. The engineering to keep the acid in and the rest of the world out is non-trivial though, so we'd need a really good reason to do it.

2

This is currently in use in Taiwan for scooters.

A record 20,915 new electric scooters were registered last year, nearly double the previous year's number. Consumers were drawn in by government subsidies, along with a quick and convenient battery exchange system devised by a local startup. Source

And

Yamaha and Gogoro have both proven to be powerful forces in the light electric vehicle industry. Gogoro has a line of highly successful scooters based on their battery-swapping technology, and Yamaha just rolled their four latest electric bicycle models into shops in the US.

Now the two companies have announced that they will be joining forces on swappable-battery electric scooters, leveraging the strengths of both players. Source

CC image that I was not able to load correctly

  • I just noticed your answer after I posted; I live in Taipei and these look really fun! Scooters are so widely used here and have such a high density that it has a good business model that might not scale easily to other countries. – uhoh Feb 11 at 16:45
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    @uhoh It could work regionally we have bike share and electric scooter rental here in Pittsburgh PA, that seem to be doing ok. – James Jenkins Feb 11 at 16:49
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    Excellent! I really miss the snow; I grew up in upstate NY but I've been away for decades. – uhoh Feb 11 at 16:55
1

The problem with standarized, replacable batteries is with their size. In common electric cars, battery(-pack) is as big as the whole car:

enter image description here

I don't see the way to easily swap it to charged one on the battery gas station. It is possible to place different kind of batteries in, for example, trunk, but low placement of battery pack has additional benefit of lowering the mass center.

Honda apparently is working on charging-by-replacing batteries in their bikes (smaller batteries than in cars):

https://www.electrive.com/2018/11/30/honda-launches-pcx-electric-scooter-with-battery-swapping/

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  • also an interesting answer. I had no idea that the battery in electric cars was THAT big, but still even if it was to be consisted out of 50 "cell pieces" it would be faster to switch these than wait for 2 (or i guess even more for a car) hours. – kokobill Feb 11 at 13:39
  • To swap them, you'd have to lie on the ground and get dirty. Then, you'd have to somehow extract those 50 cells, meaning they would have to be in some kind of safe container with handles (larger cell, less cells in car). Battery backs are also cooled/heated (at least in Tesla). Replacable batteries seem to be possible only in small vehicles, such as bikes. – crueltear Feb 11 at 13:44
  • my whole question initiated on the bike domain but i still get your point... – kokobill Feb 11 at 13:48
  • Honda is currently checking electric/hybrid bikes in Asian countries, and are going to use swappable batteries. They are going to see how people use those bikes - experimental phase seems to be too early for standarization (why standarize, when nobody is going to use it?). Also, electirc Honda PCX has no storage space, due to batteries - not exactly best thing in bike used for daily commute. – crueltear Feb 11 at 13:51
1

Not going to happen.

It is widely accepted that the best electric cars today are Tesla. While somebody could argue their frameless door windows, big external size, big wheels with practically no tire left, etc. are just for show and not for go, the technology in Teslas exceeds that of the technology in other electric cars.

So, let's take a look how Tesla uses batteries.

The batteries in Tesla are cylindrical cells, 18650 or 2170. 18650 has approximately 3 Ah of capacity, whereas 2170 has approximately 6 Ah. It watt-hours it's 10.8 or 21.6 watt hours, or in kilojoules it's 38.9 kJ or 77.8 kJ. A liter of gasoline is 36 MJ, so these figures correspond to about 1 or 2 milliliters of gasoline. So, if you are going to change these batteries, you will be changing energy 1 or 2 milliliters at a time. See the problem?

Ok, somebody could claim that best gasoline vehicles (=hybrid) are only 33% efficient, so in reality you will be changing energy 3 or 6 milliliters gasoline equivalent at a time.

These batteries in Tesla are hidden under the floor of the car, giving low center of gravity (thus safe and good handling), good behaviour in a car crash, huge electric range, a front trunk (frunk) where you can store stuff, etc. Although in theory the cells can be changed, in practice you don't do it. The Tesla cells typically last for the life of the vehicle, because you are using only tiny fraction of the cell capacities in typical driving.

Now, could you make the cells into larger multi-cell units? Yep, perhaps you could. In fact, Toyota has made the NiMH battery into a single unit. The trouble is that the tiny 1.6 kWh unit in RAV4 hybrid weighs about 70 kilograms and in this particular Toyota it takes some trunk space in the rear because it's not under the floor of the vehicle. Also, the units would differ in ideal dimensions between cars (and between different locations in the same car) to make use of the available space most efficient, making standardization difficult. Additionally, you need to lift the car up to change the cells in Tesla under the floor of the car.

Changeable batteries thus are not going to happen. The situation is similar to mobile phones. Making the battery difficult to change allows thin phones, which customers prefer. Making the cells difficult to change in a car allows low center of gravity even in a SUV, good and safe handling, crash safety, lots of storage space, long range, etc., which customers prefer, again.

In some manner, the cells actually are standardized in Tesla. They are very similar in size to common laptop cells, just use a slightly different chemistry that has been optimized for automotive use and for low cost. But, this standardized size means a single Tesla has a huge number of cells in difficult to access places.

However, there are several things that are going to happen, making electric passenger vehicles a reality:

  • Battery cost will go down and size will go up.
  • Quick charging will become more prevalent, allowing you to charge your car partially (not to 100% level, though, as the last few percent will be slow) while on a coffee break
  • A secondary market will form for cells that have lost half or so of their capacity, and are thus not ideal for automotive use, but can be used to store wind and solar power in an electric grid for the rest of their useful life. Thus, the battery replacement will be cheaper than it is now, because you get a refund for partially useful cells.
0

There is a reliability problem with this idea that might not be obvious. To give a real-world analogy, four-engine planes have more engine problems per flying hour that two-engine planes, simply because there are twice as many engines for the faults to occur in.

If you split the "car battery" into multiple replaceable units, you multiply the reliability problems caused by bad connectors and bad individual units. If a problem like that leaves the car stranded somewhere, who pays to sort the problem out? The charging station doesn't "own" the batteries it charges and swaps, and neither does the car owner. So who picks up the cost arising from the faulty battery?

One good feature of conventional fuels is that they are a very standardized product - you can buy gas anywhere without even considering whether there going to be a problem with the fuel you just bought. You would need to make swappable batteries as reliable as that, which might be a hard engineering problem. Of course gas stations do sometimes screw up and have pumps dispensing the wrong fuel, but this is so rare and the consequences happen so quickly that it's clear where the blame lies.

  • This is one of the reasons I really like the idea of hydrogen fuel cell powered cars - you could fill them like you do a petrol car. Unfortunately physics hasn't been so "enthusiastic" at letting us figure out a way to properly make them feasible for mass market. – Baldrickk Feb 11 at 11:55
  • Of course having some sort of system which swaps over batteries could have diagnostic testing built into it so if a battery is removed from a vehicle and found to be bad, it could be removed from circulation at that point. Depending on the system design, a vehicle with a single bad battery could potentially be driven at reduced power and display a message to return to the nearest "fuel" station. – Steve Matthews Feb 11 at 12:15
  • @alphazero VERY interesting approach... I guess the end user is responsible in such a case but still a "modular" type battery with per say 8 cells one of which would fail for some technical reason would still work just with 7/8 of it's original capacity, thus requiring only a sooner re-charge – kokobill Feb 11 at 13:35
  • Actually, a Tesla has the battery made from a huge number of 18650 / 2170 units. I don't see them failing at a great rate. – juhist Feb 11 at 13:48
0

Tesla at a point did feature a way to swap the entire empty battery assembly for a fully loaded one. The showcased process required only a prepared station the car would roll over and about 90 seconds later it could roll off with a full battery.

But then the abundance of free and fast superchargers offered a more compelling alternative and the project never really moved out of the pilot phase. Especially when considering that the ACTUAL process instead of 90 seconds took about seven minutes, was partially automated but partially still manual work (that can go wrong), required a pre-negotiated appointment and the car owner had to pay for it. On top of that, the vehicle did not recognize the new battery as such and continued to count the distance achieved with a supposedly single charge. Owners also were worried about the possibility of giving away their brand new but empty batteries for an old and worn out, albeit full one and thereby losing on maximum charge capacity, and thus vehicle price.

So probably all of these has lead to the state in which we are now, where the program is effectively dead, and based on the experiences no other vendor is rushing to implement their own version of it. In Musk's own words:

"People don’t care about pack swap. The superchargers are fast enough. Based on what we’re seeing here, it’s unlikely to be something that’s worth expanding in the future unless something changes."

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