Wednesday, October 16, 2019

Shorter Range Cars Saving the World

March 31, 2022
In what has been an accelerating trend of global decarbonization a spokeswoman for the VW group has made a surprise announcement on their rumored Project Maultier.  Speculations on Maultier have ranged from a new type of fuel cell to vehicle capable of assembling like Voltron into an even larger and more spacious vessel.  Instead of a giant mech, VW has unveiled a suite of solutions under the Maultier brand.

Maultier is being promoted as the solution ecosystem that will allow the world to make all cars electric.  The aspect of Maultier that will be most visible to consumers is the Burro a small trailer that could be described as a souped-up hoverboard.  The Burro is a semi-autonomous battery pack designed to dock with cars and provide extra range without needing to stop and recharge.  Using a sophisticated suite of sensors Burros has the ability to automatically dock and undock with vehicles moving along approved highways.  For regions where road laws prevent autonomous driving on highways, the Burros will need to be picked up and dropped off at certified servicing centers. 

In addition to the Burro hardware, there will be a suite of patents and software opened up to the global automotive industries.  The appropriate patients and schematics associated with charge ports that the Burro will require to safely connect with vehicles are being made open to any businesses that want them.  It is believed that the EU council will soon provide legal incentives for automotive manufacturers to...

(I'm having a hard time making this feel super sexy so here's some background)


One of the big challenges associated with making the world's cars electric is the cost of batteries.  Economists estimate that when electric car batteries get below $100/kWhr gas cars will be unable to compete on price in any meaningful fashion and the transition to an all-electric future would soon follow.  To put things in perspective for the "entry" Tesla Model 3 Costs $35,000, and it has a 50 kWhr battery.  At current battery prices, roughly $200/kWhr*, the battery pack alone costs about $10,000 for each vehicle.  This means about 28% of the car's cost is the battery pack.  The benefit of this large battery is a range of over 200 miles on a single charge, keeping customers pretty happy.  While this makes sense for a luxury car most consumers are unlikely to be able to afford the high sticker prices. 

The cost of batteries is more than their direct dollar amount, there is also a question on weight.  Lithium-ion batteries have an energy density of 100-265 watt-hours per kilogram.  For every kilowatt-hour of battery life, you want to add to an electric car you'll need to add 4-10 kilograms of battery cells, plus any additional packaging, and after that potentially make your frame that much stronger.  If we could get everyone to be ok with an electric car that could drive 100 miles on a full charge but have almost unlimited range while in the network of charging robots, we could do some really cool stuff.

Some considerations for implementing external electric batteries for electric cars

Pricing out the Burro.  While I do think this is a cool idea, there is always the question about money, the Burro is only making money when it is reselling electricity back to a customer, either through providing mobile power for vehicles going down the highway, or reselling electricity to the grid when demand for electricity is high, but driving demand is low.  Honestly, I don't currently have the info to even hope to estimate what costs would look like.  On the plus side, as the Burro makes the most sense as a service and not as a consumer purchase you don't have to think about sticker shock so long as the overall financing makes sense.

Societal Buy-in  As mentioned in the news from the future section, if only one brand of cars has a Burro compatible plug then its going to be hard for the financing to make sense, very much a chick and egg problem.  Plug compatibility goes beyond just the shape, but also positioning, the more variable the plug-in point for connecting car to Burro, the more complicated the Burros would need to be.  Ideally, you'd get something like the EU's guidelines on phone charger standardization.  In my current opinion, the ideal would be a charge port at the centerof either the front or rear bumper (or both, but at least one of the two).  There would also need to be a narrow-ish range of heights that the plug could be at.

(Semi-related, why don't more electric cars have charge points at the front or back of a car, it's not like you have the same fluid considerations of gas?  Or why isn't someone selling folks on multiple plug in locations on a vehicle so that people don't need to factor in how they park when they want to charge)

Battery Costs As battery prices continue to go down this idea could make less overall sense.  Once cell costs get low enough it's likely that consumer habits would lend themselves to buying a car with an oversized battery, vs buying a vehicle dependent on an additional ecosystem.  (this is similar to people buying SUVs over minivans even though the minivan is way more practical)


While sanity checking for this post I did find a design company that outlined a similar concept but instead had the extra batter using a single spherical wheel, which looks cool but makes zero engineering sense.

*there are a lot of different numbers associated with battery costs ranging from a low of $141/kWhr to $205 for an EIA study  (I'm using 200 because, well it makes the math clean)

I hope this was interesting, any questions, feedback are welcome.