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Comment by patall | Hacker News Reader

Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened.

I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 200 miles and then on the way back home do the same and get your old battery back at your last stop and keep that pack for all your short day to day trips. But somehow, this idea seems to be 100% abandoned.

Edit: Follow up conspiracy: Could it actually be because the battery is the one component of an EV that degrades the fastest and thus cars would last much longer (and no manufacturer would want that) if you could just swap the main battery every 100.000 miles or so?

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It was abandoned because fast charging stations keep improving, and are much simpler and cheaper to operate than battery swap stations. It's already at the point where you can take a 400-500 mile road trip in a Model 3 with maybe a single twenty minute charging stop, which is just not that much extra time, and most people like to take a short break every few hours anyway.

I suspect Tesla knew this would probably happen, but IIRC there was a rule for a while with the California ZEV credit program where manufacturers qualified for extra credits if a vehicle could be "refueled" in under five minutes. Tesla set up a single swapping station to prove it could be done and therefore qualify for the extra credits, but it was always kind of inconvenient and expensive and very few people actually used it.

I see, that actually makes sense. To bad most affordable cars actually operate in much lower ranges.

A car with a 40 mile range would be cheaper to buy, and a lot lighter so also more efficient. You could swap in a 400 mile battery when you actually need it.

The problem I have with the 40 mile range is that is highly dependent on

1. temperature. Extreme cold lowers range 2. topography. Inclines can drain a battery quickly. Declines can add range. 3. driving style. Do you have a lead foot? 4. Driving type. Are you on a highway?

You're nitpicking here. 60 mile range. 100 mile range. Whatever customer needs daily is far different from their outlier use cases. Most people with home/work charging never go below 40 miles from full.

fair enough. It is an innovative idea.

I’d still like to be able to tow a battery behind me for extended trips.

I don’t know how running the AC impacts range, I would like to know. Places with extreme weather and major population centers can make an otherwise short drive really taxing on resources through ac use or just being stuck in place for extended periods of time. Like how peak LV traffic can turn a 15 min drive into a 50 minute drive in 120f+ heat.

Tow-able batteries would make wide use cases like apartments more viable too.

Edit-typo

That seems like a fantastic idea. This way, the car's internal battery can be smaller and lighter for day-to-day use (and therefore more efficient), and whenever longer range is needed you can just rent a fully-charged tow-a-battery, which you can swap out like propane tanks, or recharge yourself at home. These tow-a-batteries would work with any electric car with standard secure hook-ups.

Since these batteries would be rather expensive, I imagine that you would have to pay a refundable deposit to the tow-a-battery network (Shell, Esso, etc.) that covers the full cost of the tow-a-battery in order to rent one.

The biggest down-side is that a rear-end crash could be rather dangerous. I don't see a way around that without making the tow-a-battery a vehicle in itself.

by the time you've added enough protection (ie, extra mass and drag) to the towed battery, it seems like you would be pretty deep into diminishing returns. a large amount of the extra energy would be spent on moving the trailer itself.

Not really. Yes batteries add lots of weight. But electric motors have lots of torque and are known to climb hills easily. Like how Tesla’s forthcoming truck can tow up to 14000 pounds. I’m not doing the calculus, but I suspect the power characteristics of electric motors more than make up for a towable battery.

Edit-here’s an article about a company doing this

https://electrek.co/2020/02/19/french-startup-proposes-batte...

energy, not power. I'm sure the motors have enough torque to tow the battery, what I'm doubting is how efficiently that extra battery capacity gets converted to range.

as an aside, the cybertruck is (probably) pretty bad at towing. see this video for an interesting argument: https://www.youtube.com/watch?v=S4W-P5aCWJs

Very slow video. Wish it were transcripted.

It also allows for faster retrofitting of old vehicles with new battery tech.

It does sound like a very intriguing idea, and one that I believe requires some research.

However, in practice I think this would be equivilent to towing a small tanker trailer full of chemicals or gasoline. It would require plaques indicating the contents, special insurance, and all kinds of BS at the RMV. Imaging if one decoupled on the highway and drove into oncoming traffic at 60mph? It would essentially be a rolling bomb. This happens quite often with camper trailers.

I think engineers would need to emphasize redundancy, failsafe measures, and automated attachment/detachment capability that does not require human interaction to safely accomplish. Then you will convince CA that it doesn't need a ream of paperwork to register and then the rest of the country will adopt it.

So here’s a company doing it for fleet vehicles in China. Granted, it’s not a guarantee it can get through the US regulatory system, but there are definitely more dangerous factors on the road.

Personally I see this as completely new tech from the ICE. That means it really ought to open up new usage and user experiences than the outgoing tech. And those changes should be perceived as better in some way to really take off.

Edit-forgot the link: https://electrek.co/2020/05/06/mobile-ev-chargers-and-vans-g...

Towing would annoying but dropping a block into the Cybertruck bed or the Y back cargo area would be pretty neat.

Most drivers aren't competent to tow a trailer, especially not at high speed or reversing.

Most apartment sized AC units top out at a few kW - that's the peak power, just maintaining the already cooled apartment is going to be consuming much less power.

A car cruising at highway speed is lconsuming something on order of 10x as much power. Given how much smaller cars are than apartments, it's an even greater difference.

So to answer your question: not much. Heating in cold weather is much worse on range, as it's not just the cabin but also the battery that needs to be maintained at an adequate operational temperature.

unless manufacturers implement some sort of standardized battery pack, it seems like this would be a logistical headache. simple enough to store and charge your original battery for when you return, but how do they have the correct battery for you to pick up on the outgoing leg? is the "gas" station supposed to keep a stock of charged batteries for every type of EV?

Immediate concern for me would be safety. My impression is the battery pack provides a lot of the rigidity necessary to keep the car in one piece, and swapping the battery out introduces new hazards.

There's also the concern about liability, whether the battery pack you're getting is as good as the one you're trading in (what if it's older and has a lower overall capacity), and how that might impact resale value.

Third would be logistics, keeping the flow of batteries through the stations and having enough batteries on hand to swap on demand, and keeping compatibility with different makes and models, is a challenge.

That's why you would only use those for long distance trips and for everything else you would own that one old pack.

Rigidity could indeed be a problem but so has been gasoline safety. There would need to be standards but there are also standards for charging plugs so, it is not like this never happened before.

Or have a built in battery and battery swap bay. Both can happen and no reason not do have both.

Nobody who actually owns a car wanted to swap batteries.

There are many reasons: ownership of the battery, logistics of the swap and swap back, required payment for convenience, need to stop anyway, range of vehicle, etc.

Well if you want to see one way the battery swapping model can fail work, check out the book Totaled, which is about the Israeli EV startup Better Place that tried battery swapping before Tesla was a thing. Granted there were a lot of complicating factors that may not apply in the Tesla case (securing battery swapping locations in Israel came with specific challenges), but it may provide some insight.

Increased capacity and high speed charging have made it not worth the cost/complexity.

I've read the Rivian truck can have an additional battery dropped in the truck bed but I don't think it is something you can buy yet.

Correct-ish. Rivian has a patent for such an ability, but no announcement even of planned availability.

Continued battery improvements pretty much obviate any more complicated range extending efforts, IMO, other than perhaps road embedded magnetic chargers, which are fairly simple.

Probably the same reason why smartphone battery is not swappable. For various reason we don't have swappable smartphone battery even though it is technically much easier problem to solve.

What reason would that be? I always assumed that was because of the pursuit of slimmer phones and to discourage repair.

It’s also a more complex and expensive. Swapping cellphone batteries means you need to own another battery which few people did once capacity increased. With cellphones people that want a swappable battery can just get an external battery pack but most people can simply recharge daily.

Hmmm... is this not also an option with an electric car? A "long distance" battery pack trailer of some sort? Lose some sleekness, but gain a ton in utility, and storage space for those long trips.

> Swapping cellphone batteries means you need to own another battery which few people did once capacity increased.

That doesn't make sense to me. Sure, maybe you can't get an OEM battery, but I've owned cell phones in the last 5 years that I easily swapped out the old battery with an aftermarket battery for about $12. I think people have the ability to buy batteries.

> With cellphones people that want a swappable battery can just get an external battery pack but most people can simply recharge daily.

My OG Pixel phone is on its last legs in terms of battery capacity, which means it will probably get scrapped(even if I trade it in somehow or get it "recycled"). I would have swapped the battery with a new one, but I don't have that option. At least without risking damaging the phone on disassembly. Recharging daily isn't a solution because it runs out of power in about 5 hours without even using it.

Have you considered a battery case like: “Google Pixel 2 Battery Case, 4700mAh“ https://www.amazon.com/Rechargeable-External-Protective-Port...

From reviews that product is likely terrible, but I know people that are happy with their iPhone battery cases.

In theory we should be able to have external battery packs for electric cars, but I think the power density would have to about double before that happens. How many miles can you fit in a 30 lbs battery right now? Not very many.

I think that gets you about 10 miles in a Tesla. If it got you 20 miles it might be worth building a few slots into the trunk for extended range.

Discouraging isn't something that affects next quarter's earnings. Reducing the cost of water-related repairs, warranty replacements etc., though.

even those two reason still make sense for car.

It depends on the smartphone, there are still (very few) around that have one.

Beside the possible "planned obsolescence", I believe that the change was mostly because of waterproof or almost waterproof design, and (IMHO senseless) "let's make it thinner".

I am imagining a scenario where an autonomous vehicle zooms toward the car at high speed and then from underneath the car swaps out the batteries then zooms away.

That's because it's not "cool". We wanted our flying cars, so if we aren't getting those, we at least want our cars to do wild and unbelievable things like flock together and fuel each other like jet planes. Who's going to invest in battery swapping technology? It's effectively a solved problem and not exciting.

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