#90% or w/e of the required charge if they're too old they get withdrawn and recycled

[stumblngrumbl]

IMO instead of charging, electric cars should have standard sized modular battery packs (small / short range cars have one, bigger & longer distance vehicles may have many) and service stations should swap the packs when you pull up and you go on your merry way moments later, and the station plugs the packs in.

These *may* be able to be automated, or you could have attendants do part of the work since different vehicles may have the packs mounted in different places.

This system would be a huge boon to electric car buyers as you're never stuck having to pay for a failed battery - you subscribe to the service similar to those propane tank swaps, but in such a way that the actual costs of the battery pack are spread over the predicted number of users.

In addition, since the battery is paid for during its use, a brand new car would be sold without the ownership of a battery - it would be delivered with a battery that's understood to be going back to the general swap :: new cars would cost much less (battery is paid for over the life of the battery).

Basically over the long haul yes you've paid for a battery and the charging, but you'll never be stuck with a bill for an entire new battery - this would allow used electric cars to have a reasonable resale value as well; today I wouldn't touch a older electric car or hybrid unless it was super cheap since I have to assume the risk that the battery will be toast any time and even smaller hybrid batteries are very large cost.

There could be different networks of battery swaps services, but I think it would be best served as a state-run enterprise so that any station can serve any car.

Depending on the stock a station has of batteries, they could be potentially be charged when the grid has the most excess power (typically night time) rather than *right now* when someone needs a charged battery.