I was thinking of light weight, not back and joints straining lead acid batteries and spanners being needed.
Batteries will evolve. Like we have for cordless tools now, Lithium Ion, weigh barely anything. So changing the ones to power a car may become easy and quick to do.
It might be a small pack on it's own wheels which drop out like Thunderbird two, floats away on a mag lev in the forecourt floor and the replacement floats into the car chassis and clamps itself in place whilst your paying the bill.
The spent battery then joins a queue of other batteries in the building and is contactlessly inductively charged as it passes toward the front, ready to be dispensed into the next car.
Friction free and with no mechanical parts to wear out and no need for a human other than perhaps taking the cash at the til.