It seems like battery swapping could potentially make battery charging a side issue.
- 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.
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.
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.
Nio is doing it: https://www.youtube.com/watch?v=VmWL1hZQmD0
Gogoro is doing it: https://www.youtube.com/watch?v=i5ddtHj_N2E
Janus Trucks is doing it: https://www.youtube.com/watch?v=9eYLtPSf7PY
Paying attention to what's going on in the real world is more useful than internet theorizing.
> - 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.
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.
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.
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 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.
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.
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.
My feeling is whether swappable batteries are viable or not is less of a engineering problem than an accounting and logistics one,
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.
https://fullycharged.show/episodes/this-giant-electric-semi-...
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.
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.
Tesla and the major automakers can't risk their name and reputation on a crap product.
Full Self Driving has entered the chat...
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.