Tesla has 500,000 reservations for the Model 3, Chevy has a $35,000, 200+ mile-range electric vehicle, a number of countries in Europe have set timelines to eliminate the sale of new combustion cars, and electric vehicles may end up being cheaper to build than dead-dinosaur-sauce-burning cars. It sure seems like electric cars are here to stay, but the truth is they’re still a pain in the ass to use when it comes to charging. I think I may have a workable stopgap solution.

The latest generation of electric cars have defined a 200-mile range as a new baseline, and it’s one that genuinely seems viable. Being able to drive 200 to 300 or so miles puts electric cars roughly in the ballpark of many gasoline cars people have been used to, as there’s been many cars with gas tanks around 12 gallons getting around 20-25 miles per gallon.

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The range for many electric cars is finally where it needs to be, but, like all good things, that range does eventually run out, and that’s where the problems begin. The charging infrastructure, while at least in some way extant, can in no way compete with the convenience of the robust gasoline-refueling infrastructure drivers are used to, and that’s going to be a problem for widespread adoption.

For most owners, charging is done every night, at home, and the cars, like the plot of a shitty sitcom, always end up back where they started once the day’s adventures are over.

This works fine for many people, but if you’re one of the millions of Americans who live in apartments without EV charging facilities, or if you just want to take a long road trip, the limitations of the current charging infrastructure become very, very clear.

As of June of this year, there were around 16,000 EV charging stations with about 44,000 connectors in the United States. That seems like a decent number, but most of those seem to be slow Level 2 charging stations, with the fast DC charging stations, like the Tesla Superchargers, only numbering 2,172 stations with 5,992 outlets. It’s these fast DC stations that are most suitable to long-distance travel, since they don’t take 6 or 8 hours to get your car back to a usuable charge.

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Now, for comparison, there’s about 168,000 gas stations in the United States, with each station having... well, a bunch of pumps. These numbers vary wildly, from tiny stations with 2 or 4 to huge truck stops with 32 or more pumps. We’ll guess conservatively that an average station has 12 pumps, giving a total of 2,016,000 available gas pumps in the U.S.

That’s a hell of a lot more. Gas stations are, as we all know, everywhere.

So, here’s where we are: electric cars are finally becoming affordable and practical enough to make sense to use, but if you want to do any significant traveling in one, it’s still a colossal ass-pain. But I think I have a decent stop-gap solution.

The key here is that to make a viable electric car charging infrastructure, we’ll need to piggyback on an existing infrastructure, and the most logical one to use is the gas station network. Trying to wire all gas stations or even one given chain of gas stations with the hardware needed for fast DC chargers would be expensive and slow. That type of network will need to come one day, but in the short term we need something fast and good enough.

That’s where Trunk Batteries come in.

Here’s what needs to happen: one (or more) of the major gas station franchises needs to partner with a hypothetical company that produces modular, rechargeable, swappable battery packs that can be placed into an electric car’s trunk, connect to the car’s charging system, and give the car a decent enough amount of range to be useful.

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It’d work like this: you’re taking your Model 3 or Bolt or Model S or whatever on a road trip, and you see you’re running out of battery power. Instead of hunting around to desperately find a charging station in range, you take the next exit, stop at a normal gas station, and back (or drive up, if you have a front trunk) up to the Trunk Battery kiosk.

Once there, you open your trunk and a forklift-like device places the ~250 lb battery pack in your trunk. The battery pack has a place to hold your hood or hatch nearly closed while allowing a cable room to snake out and plug into your car’s charging port.

You plug it in, check your range and see you have around 100 more miles of range, and off you go! When you exhaust the Trunk Battery, you stop at the next Trunk Battery-licensed gas station, and either drop off the battery or have it swapped for a fresh one. Easy!

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Thanks to the Tesla Model 3's new 21-70 battery cells, a viable battery pack of a size and weight suitable to most EV trunks with a range of around 95-100 miles is possible.

Here, I’ll walk you through the math: each 21-70 cell (named because it’s 21mm in diameter and 70mm in length) has a capacity of 21.275 Wh, and weighs 66 grams. If we get 1500 of these cells together, that makes a nearly 32 kWh battery pack with 218 lbs of battery weight.

Most sources say that you can expect an average of about 3 miles per kWh, so our 32 kWh battery pack should provide about 96 miles of range, which is close enough to my goal of 100 miles.

If we package these 1500 cells into an array of 25x10 sheets of cells and stack them six high, we get a package that’s about 20" wide by 27" long by around 6" high. If we factor in wiring and cooling devices and housing, we can probably end up with a ~250 lb box about 22"x 29" x 8" or so, which would just fit into the front trunk of a Tesla Model S, and should fit in the hatch or trunk area of pretty much any major EV available for sale.

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Any gas station franchise that decides to deal in Trunk Batteries would need a bit of equipment: a self-contained kiosk that stores and recharges battery packs, along with a lift/drop system for getting them easily into and out of car trunks.

These would take a bit of design and engineering work, but it’s by no means all that complicated.

Additionally, since the Trunk Battery system is, essentially, a third-party battery swapping system, the viability and benefits of a battery swapping solution would be made very clear. If Trunk Batteries became popular, carmakers may start including auxiliary charging ports right inside their trunks, or, even better, manufacturers would eventually agree on a standardized battery format and connector system to make all of the car’s batteries easily swappable by design, and without eating up precious luggage space.

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A solution like Trunk Batteries isn’t a long-term solution; it’s a stopgap that provides a way to leverage the existing robust gas station infrastructure in a quick-and-dirty way. Using a Trunk Battery means giving up a good chunk of your storage volume, and, at only about 100 miles, a long road trip would require a good amount of stops-and-swaps.

Even so, it would at least make an impromptu road trip possible, and allow for EVs to be used generally the same way combustion cars get used, without the route limitations and obsessive planning that’s usually required for any EV road trip.

Right now, though, I think a solution like Trunk Batteries is the most likely way the coming boom of electric car ownership will be served while a real charging infrastructure is slowly built. It’s a solution that should only be needed for about a decade or so, but, without it, EVs may not even be able to sell in the numbers needed to have a full charging network make sense.

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As always, investors are welcome to contact me here. Is ‘Sparky’ too obvious a name for the talking battery pack mascot?