Why are we not already able to “instant-charge” EVs, smartphones or other batteries?
In: Physics
As compared to other posts that already explain all of the relevant factors: it is possible to have electric vehicles that can “instantly” recharge, but not with existing systems, both in the vehicle, and the charging infrastructure. We would need even more powerful “instant discharge” charging stations that wouldn’t catch on fire, and capacitors rather than batteries.
We could, in theory, use capacitors rather than batteries to charge vehicles. Capacitors can charge up to full capacity almost instantly, but they do not have the same energy density as a battery and are meant to only hold a charge for a very small amount of time.
In a nutshell, a capacitor collects voltage, and amperage of varying charges, stores it up in a battery like device, and then outputs a known value of V and A consistently and reliably. This is generally used for electronics like computers that require relatively precise and accurate values to operate. Your wall socket in your house may output as low as 100V up to 135V at any given time. A capacitor constantly receives the incomming and variable voltage at a speed greater than it depletes, and sends out a perfect and constant 120v to the power circuit of the device it’s plugged into.
So, in theory, we could make a car that uses a capacitor as a battery, that has a very high and fast energy input, with an energy output limiter to slow and regulate the release of energy to power a car.
But, due to a very low energy density, you wouldn’t be able to fit as much energy into the physical size of the “capacitor” battery. Capacitors are also not great at storing energy, only temporarily holding it. They discharge quickly, so you would lose nearly all of your charge immediately after charging, like 25% per 10 minutes, unlike a battery that can store energy at a 5% loss per month.
This could result in being able to fully charge your vehicle’s capacitor in 5 seconds??? and could enable a driving range of 20km??? This is speculation/theory.. not real or known numbers, just pulled them out of my ass.
So, you could spend 5 seconds charging for 20km of range, or the equivalent of 25 seconds per 100km of vehicle range.
So, you would need to charge your car before leaving, and immediately drive it 20km to repeat the process. If you got out of it to go shopping and there wasn’t a charger, whatever charge you had left in it wouldxbe gone by the time you got back to the car, and you would be stranded.
The current system of charging speed vs travel distance is in place to be a reasonable balance. 20 minutes on a super charger can get someone a few hundred kilometers, and gives you a normal battery that doesn’t naturally dissipate its charge within minutes or hours.
Ideally, having a battery that can charge 80% in 3-5 minutes would be the ultimate goal of the tech, as this is how long it takes to put gas in most vehicles. It may just result in less distance than a gas vehicle can drive on a tank, and you may need to fill up 2/3x more frequently. We are already accustomed to the inconvenience and time to put gas in a car. If we can match that time to a reasonable driving distance, most people wouldn’t ever notice the difference between gas/electric.
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