Battery swapping is one of those ideas that sounds good but has enough disadvantages that it's rarely worth it.
- Your vehicle design will be less efficient and more expensive than one without the constraint of an easily-removable battery.
- Just like with phones, removable batteries mean that you have more ingresses for water and dirt, hurting reliability.
- You have to standardize on battery sizes and interfaces. If some new battery technology comes along, or you want to change the chassis (to improve crash safety, for example) you'll have to create a new standard.
- In modern EVs, batteries have liquid coolant pumped through them. This lets the vehicle keep the battery at optimal temperatures for charging, discharging, and avoiding degradation in hot climates. Swapping batteries means coming up with another solution for controlling battery temperatures.
- In addition to specially-designed cars and batteries, you also need specially designed swapping stations. Again if you ever change the standards, you'll have to upgrade these stations.
All of these issues mean that battery swapping drastically increases cost and complexity for little benefit. A swap will take five minutes, while charging to 80% can take as little as 15 minutes. There's also the issue that batteries are valuable, and the owner of the vehicle probably wants their original battery back (or at least one without more wear & tear). Then you get into issues of compensating or charging people thousands of dollars depending on their new battery's degradation level. It's much simpler to give up on swapping and focus on improving charging speeds, which is exactly what Tesla did.
Good videos and point. The situation involved around battery swapping and how to do it matters, versus wholesale dismissing the idea because of a fondness for ICE or close-mindedness. The answer to the question, is not to be stuck on oil forever or until the climate is destroyed.
Yes, these are all issues for personal-use vehicles.
It's much less of a concern for trucking companies, many of which already have multiple depos across their routes and thus are already in a position to swap batteries from one truck they own to another truck they own.
Truck batteries are enormous and swapping them would be a huge logistical challenge / pain in the ass.
Better to just swap the whole tractor unit out if fast charging is not available for some reason. After all, it’s really just a battery (+motor and cab) on wheels.
You are mostly right for passenger vehicles, but in the specific context of commercial trucks most of those disadvantages are substantially reduced or eliminated.
> - Your vehicle design will be less efficient and more expensive than one without the constraint of an easily-removable battery.
Commercial trucks sold as a cab-and-chassis configuration, i.e. all the ones that you see the same basic truck under hundreds of different bodies, are already substantially standardized behind the cabin. They are less efficient and more expensive than integrated designs, but as a tradeoff they get the option to use any of those addon bodies that happens to fit length-wise.
This same compatible frame design benefits swappable batteries in that they can be built to go under a standard frame width.
> - Just like with phones, removable batteries mean that you have more ingresses for water and dirt, hurting reliability.
Reliable self-cleaning connectors are already a thing in industry, it's a factor that needs to be considered but it's not a real roadblock.
> - You have to standardize on battery sizes and interfaces. If some new battery technology comes along, or you want to change the chassis (to improve crash safety, for example) you'll have to create a new standard.
This class of trucks has been heavily standardized for decades, CAN still works great for the data link, there's no reason to believe substantial changes will be needed in ways that would be relevant.
> - In modern EVs, batteries have liquid coolant pumped through them. This lets the vehicle keep the battery at optimal temperatures for charging, discharging, and avoiding degradation in hot climates. Swapping batteries means coming up with another solution for controlling battery temperatures.
No it doesn't, plug-and-play dry break connections are already well known. This is a solved problem.
> - In addition to specially-designed cars and batteries, you also need specially designed swapping stations. Again if you ever change the standards, you'll have to upgrade these stations.
Most heavy truck swappable battery designs I've seen either go under or in the front, either way a forklift can do it.
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Again, for passenger cars I 100% agree, Tesla's one station that changed a dozen batteries was nothing but a mechanism to capture a tax benefit, it was never going to work in the big picture because passenger cars are so different. Commercial trucks are intentionally incredibly similar, so it's a different world.
Sure, there are all sorts of workarounds you can apply, but all those workarounds have costs. At the end of the day, economics rules, and if doing all those workarounds costs more than just putting in a bigger battery, they’ll just put in a bigger battery.
Also, you’re forgetting something important: most countries have laws limiting driver hours / mandating driver rest. As a practical matter, with appropriately spaced charging stations, a tractor like the one Tesla built effectively imposes no cost in terms of charging time. That’s because the mandatory driver rest periods are sufficient to charge the battery using today’s battery & charging technology. And on that topic, if you try swapping a battery with a forklift, you’ve already lost (in terms of time). You need a dedicated battery swap machine for the “time economics” of battery swap to make any sense.
So why bother with all kinds of expensive connectors, and the rest when you don’t need it anyway? That’s what you’re up against.
While I don't have a rosy view of swappable batteries in general, I must pick a nit. Drivers are mandated rests, but the trucks are not. A delivery company could operate swappable EVs at near 100% uptime.
In the medium and heavy vehicle industry one of the big discussions is on reuse of batteries at economic EOL. The idea is that after maybe 600 charge cycles a vehicle-sized battery will have a lot of life left but will no longer support the range that high-duty-cycle vehicles require. So they can be recycled into grid storage in a way that creates a virtuous cycle.
Battery swapping might even be a good way to jump start such a system since it could produce a flexible system for curve flattening both by charging in off-peak hours while still supporting fixed-installation vehicle packs.
The downside is that this makes battery systems less flexible, since batteries have to be of some fixed physical dimensions. This may not be practical for certain compact vehicles, but could be implemented more easily with straight trucks.
As long as the packs can be taken out of the vehicle without damaging either and the packs don't have DRM crap, packs can trivially be re-used by attaching them to a charge controller.
I think the idea is that it costs much more labor and energy to fully recycle a battery pack than to repurpose it, and you can always do the recycling later on.
If you're suggesting the time, energy, and safety and compromises required to design vehicles around modular batteries might not be offset by the cost delta of recycling I think that's a reasonable concern. Combining this with swappable packs might change the variables.
A system by which packs are routinely switched out and frequently tested could easily lead to a robust circular economy and could provide a better alternative to Vehicle To Grid solutions for load shifting.
I think vehicles should have replaceable packs for service, but not beyond that without a really strong argument. These batteries degrade over a few years to about 80% and just sort of stay there for a long time. So just making them big enough to allow them to remain useful for 10-20 years seems more than good enough.
I also really liked the idea, but some specialists have argued it would be hard to provide rigidity. Given the load that heavy trucks have to face, this sounds like a bigger problem for trucks than for cars.
I think we should focus on either:
- charging on the go if those trucks use highways for long-distance, maybe have self-driving trucks drive at night and charge on the way; or better:
- moving that cargo on train lines and using trucks with small batteries for the distance between the nearest train station and the final destination. That opens the possibility of using smaller trucks for many routes, which would really help with road safety, especially in dense areas. Trucks that can pull 15 tons or more are unsafe near children.
> I also really liked the idea, but some specialists have argued it would be hard to provide rigidity.
Do you happen to have any pointers to more info on this? I don't understand what would prevent the industry from standardizing on a structural battery pack rigid enough for the use case.
Then you overbuild the pack. The criticism of the new EV hummer's pack is an example, and it didn't even need swappability, is just trying to get the batteries to stay adequately in place. https://insideevs.com/news/668428/hummer-ev-battery-teardown...
Imo rigidity still feels like a semi bullshit gripe though. A lift should be able to rise up under the vehicle and uniformly support the batteries. The vehicle can then let them go. I imagine the batteries more or less suspended underneath the vehicle in this configuration, with a latching mechanism holding them up. Some cross bracing to provide structure.
Making sure the batteries stay attached though, that they don't give flying in a crash, is a significant & obvious problem though, now that I think of it.
When I've thought about swappable batteries for trucks it seems like you could locate them between the trailers frame rails. I'm sure there is enough structural meat on the frame rails to support a 4000lb battery.
My feeling is whether swappable batteries are viable or not is less of a engineering problem than an accounting and logistics one,
rektide is right to point at the need to over-build the pack: you need the car to be rigid without the batteries, essentially, and the battery to be sturdy on its own. You could argue that the car only goes through significant stress when the two are together, but every mechanical engineer is not liking that math.
Another argument is what Sandy Monroe [0] think is the biggest one: moving connectors. It’s not just high-energy cables, but possibly coolant, etc. Those will be the first thing to fail.
Sandy also mentions the risk of using someone else’s over-worn battery, but that’s more his atrabilar personality than something that could be engineered away: have the platform the battery regularly, even have the car do diagnostic and remove the worst ones from circulation.
Yeah... battery swapping seems like the next big thing for e-vecs. Imagine we shared batteries and all batteries must have some sort of reporting mechanism to report its life and charge holding and it must always be at 80% before being repurposed / fixed? Could be interesting...
Consumer car batteries charge 20->80% in under a half hour these days, and are warranted for a minimum of 8 years.
30 minutes seems slow until you realize that you hardly ever need to charge the car away from home. I do not miss going to the gas station!
I’d guess the mechanisms needed to swap the battery would be more maintenance than they are worth.
I guess for delivery vans, which drive during peak solar production, doubling the number of batteries so you can charge during the day might make sense.
"During snowstorm sometimes miles of the highway can be filled with stranded card. I wonder what will happen when all those cars are gasoline powered and the tanks depleted."
You can literally camp in an EV for days with a comfy temp inside. And if you're stuck in traffic for _days_, you've got bigger issues or you live in an area where you should never drive anywhere without a Get Home Bag anyway.
I live in Scandinavia where the temps get regularly below -20C and an EV is the best option to have by far. No car ever has been as warm as fast during winters.
Are you just inventing scenarios or is this something that actually happens somewhere in the world regularly? A massive amount of cars getting stuck in snow for so long they run out of fuel/electricity and need to be towed out one by one?
It's not exactly rocket science to bring in a generator on site to charge the EVs enough to get them to the nearest charger.
I could also invent a scenario out of my ass where the local gas station has run out of fuel because of a bank run style situation, but the electric grid still works just fine. How would gasoline powered cars work then?
People in the US regularly get stuck in snow on a highway for over 24 hours? In non-trivial amounts, not just isolated cases of people being idiots during the winter and driving a narrow mountain road on summer tires and getting stuck?
Those people really need a GHB and a propane cooker in their car at all times.
Given that Tesla tried battery swaps and canned it, and that venture funded startups already burned a billion dollars trying it and failing, I don't think many companies are eager to repeat the experiment.
China is doing it. The key thing is you need more than just a billion dollars, you need a dozen times that (or more, but the CCP doesn't need to worry about money) and credible political commitment that customers won't be left stuck with useless cars down the road.
NIO is doing some crazy crap, dunno how they pay for it.
They even have literal charging vans you can just order to come anywhere you want. You use an app to request one, they drive to your location and charge your car.
Plus they have the manned battery swap stations everyone has seen a video of.
China is throwing money at the problem, as simple as that. They're all too aware that their pollution issues need to be solved, and if it kickstarts an industry that can undercut Western competition, all the better..
Seems to be working well in Australia. They change batteries in 5 minutes using a fork lift, versus the ~20 minutes it takes to fill a truck with diesel.
The limiting factor for electric vehicle production is batteries. Trailers spend a lot more time sitting around than tractor units. It's more economically efficient to use the batteries as much as possible rather than have them sitting around.
Trailers come in many form factors: container, flat bet, end-dump. Heck, sometimes you just want to tow another tractor. Those different form factors have different constraints in terms of battery size and shape.
You'd still need big batteries in some tractor units so that they could drop off trailers. All tractor units would need small batteries so they could go short distances without a trailer.
