If they must do $10 increments, would that mean to try using one account?
I'm not sure what you mean by "one account". One Chargepoint account? I don't see any other way. Only one credit card account attached to it? Yes, I guess, since it's intended to connect and bill to it automatically when you activate the station, where you don't futz through choosing which credit card to use for that session, so it just needs one linked in.
I wasn't aware they do this.
Yeah, credit card transaction fees can be really annoying for vendors on small purchases, so this is a sensible way to reduce the number of transactions, to reduce the amount of credit card fees.
I just don't wanna be overcharged or pay more than what I expected / get.
Then look at the price first, before deciding if you want to use it or not.
If its based on time, will it guarantee how many KWH you gain during your charge?
There's an attitude coming across with the use of the word "guarantee". But it works how it works, and yes, it's more confusing and harder to tell when it's time based. If it's like a 30A station on 208V, then that's about 6.2kW power. If you ran that for 2 hours, you'd get about 12 kWh. But yes, there's more figuring you have to do, so it's not as straightforward.
If someone left their car and somehow forgot to unplug it for a week or a month, will they get billed for that entire time?
That all depends on the policies of that particular station, and as
@ucmndd mentioned, those are set by the property owner.
The most I'd do is overnight if it takes 6-8 hours for a full charge.
I was at a hotel last year where I wanted to use their Chargepoint stations overnight, but read their fee structure and decided I couldn't. They had a 5 hour maximum limit, and then $2 per hour idle fees after it cut off. I was low, so 5 hours wouldn't have filled my car, and then I would have had to pay an extra $10 for 5 more hours of idle fees. That's not how overnight hotel charging is supposed to be set up. I haven't gotten around to calling the hotel to explain to them how that's a stupid configuration.