I would love to see some kind of standardized way of supplementing an electric car's battery. Most people don't need massive EV range all of the time, just when going on long trips. Being able to buy or rent an extra battery pack and throw it in the trunk, frunk, or back seats to add more range seems ideal for those cases.

I've thought it would be great if there were rentable battery trailers that had an extra full charge or two built in, plus maybe some extra storage.

uHaul could make a killing off of them for people who want to take their EV on a road trip. If you could get 600 miles off of a single combined full charge you would be in the range of reasonable American road trip distance, and you could make the choice to stop and eat and occupy two chargers to get another 480 miles or so out of a 30 minute stop.

I usually clock about 900-1100 miles a day when I'm doing a destination road trip, so I would still chafe at that limit, but it would beat the heck out of sub-300 mile limits between long breaks for me.

But of course uHaul can’t do this without the full cooperation of the electric vehicle manufacturers. As a first order approximation of course there is nothing tricky about suplementing the power of a running EV, but on a practical level I would expect the firmware to throw a hissy fit if it does not expects this.

Also, why a battery trailer? Why not a gas tank plus generator trailer?

Because electricity can be sourced renewable very easy and the gas for a generator cannot. It would defeat the primary reason why people buy EVs.

But I guess if you need it once every few years as opposed to daily, it's ok.

Even with a smaller trailer, though, I'd expect a 33% or so range penalty-- it's just not too much of a win. You don't make it anywhere near twice as far.

Even so, assuming there were a nationwide network of them, you could pull in, swap trailers, and be on your way in 15 minutes.

Of course, this is in an ideal world where everything goes my way. I wonder if the penalty would be as high as 33%. Seems like it would be simple to make a maximally aerodynamic battery trailer since human comfort doesn't have to be considered. Then you're only adding the weight and drag of a few hundred lbs of trailer and battery.

I would think the penalty would be in the high single digits or at most in the very low double digits which could be offset by having 1.5x or 2x normal battery capacity in the trailer.

*Ninja edit, I decided to look this up. The Model Y's battery is 1700 lbs, so you are absolutely right that there would be a significant distance penalty adding that much weight to the vehicle plus the trailer weight and the battery armor as well if that isn't included in the weight.

https://www.carparts.com/blog/how-heavy-is-a-tesla-battery/

Curb weight of the Model Y is also 4400 lbs, so having to tow a 2500 lb trailer would be a significant hassle.

Perhaps that could be offset by making the trailer smart and adding motors to it that the main brain could control through the power link. If it could push its own weight and it had a 1.5x battery, and if it also had regenerative braking, then it could get close to doubling the distance.

Then again, each trailer would cost right about the same as a full vehicle, and would require an entire factory to be spun up to make them, and it would be an incredibly valuable product and therefore ripe for theft.

Lots of negatives, not a lot of positives.

It would be better all in all to be able to hot swap the batteries then. With standardized batteries put onto an integrated sled system, a robot at the fuel pump could pull the discharged battery and put it on a battery tester/charger and insert a fresh charged battery in its place.

I guess that would be more like an oil change or system flush, but the advantages would be manifold. Batteries wouldn't be the weak spot in the system any longer. The likelihood of people keeping batteries until they degraded would be significantly reduced, problematic batteries could be identified and repaired or recycled before they erupted, and assuming that the system was in wide usage it could enable road trippers to stay on the road longer quicker and waste less daylight.

Plus, for manufacturers, fuel stations, and mechanics, it would be an opportunity to make more money off of vehicle owners while providing safer, longer lasting vehicles to customers.

It's probably still a post-scarcity pipe dream though.

> It would be better all in all to be able to hot swap the batteries then. With standardized batteries put onto an integrated sled system, a robot at the fuel pump could pull the discharged battery and put it on a battery tester/charger and insert a fresh charged battery in its place.

This has been discussed/proposed/Tesla said they were going to do this long ago.

The big downside is that no one wants to exchange their battery for someone else's. Pretty soon all the batteries end up in crappy shape.

The only way you could really do this is by having the swap stations own the batteries--- but this is so capital intensive that it's really a non-starter. Not to mention that it is a bit mechanically fraught.

The big upside is that we could use a lot more solar/daytime power for charging.

There's also the safety issue, since 1700 lbs of lithium is dangerous if mishandled.

If the glass pack batteries make it to market, with their 2x capacity boost and lack of dangerous chemicals, it might make more sense, but purportedly they also work better with quick charge and can handle more charge cycles, so it may be a moot point anyway.