Why is it electric cars where found to have a maximum possible range of 520 miles? Do gas cars have a similar limit?
As you may recall from looking at our electric truck, it could never reach a range of 521 miles. There’s a physical limit to it’s range that cannot be overcome (with current technology).
Before looking at whether the maximum range math would apply to other types of fuel, we have to understand where the limit comes from.
Why Is There a Limit At All?
The short answer is that as we add batteries to our electric car, it takes power to move those batteries. That means we need to add more batteries. Those batteries will require energy to move as well, so we’ll need to add batteries for our battery’s batteries.
I had expected this to make the vehicles too costly for any meaningful range, but instead stumbled upon what appears to be a limit to any vehicle’s range.
Why a 520 Mile Limit?
I took some time to explore the convergence in the formulas, and found the answer (which also makes good intuitive sense). Rather than boring you with the derivation, I’ll give you the answer. The limit is a ratio of…
How energy efficient is the vehicle
(how many pounds can we move one mile on one kWh)
What is the energy density of the fuel
(how many pounds does it take to store one kWh of power)
In the case of a modern electric vehicle the answer is
Pound) × (Mile)) ÷ ( kWh) ÷ 19.71 (( Pound) ÷ ( kWh)) = 520.6 (Mile)
What Happens at the Limit?
As we reach our limit, the fuel we add is essentially providing the power to move itself (in addition to the rest of the vehicle and fuel) and no more. Thus, no matter how much fuel we add we’re just adding the ability to move our fuel and not the vehicle.
So EV Ranges Will Never Reach 521 Miles?
That is not exactly true.
The ratio is not a universal property, it’s simply the limit of current technology. There are two ways to increase this limit (which will certainly increase with every generation).
The best way would be to make batteries lighter.
The other method is any engineering effort to make cars more efficient. However, this would also benefit any kind of car by simply allowing them to go further per kWh.
How Does this Impact Gas Cars?
That’s a good question. We’ll tackle that one next.