Wondering how folks prefer to keep Square readers charged at events

[TYKG2017]

I'm about start selling at conventions and the first thing I'm trying to figure out is the best approach to keep the contactless chip reader powered.  

I noticed there is a USB to AC charger so that's an option.  And you can keep the reader or the dock plugged into a computer, tablet or laptop to keep a charge correct?    So I could just keep my laptop/tablet plugged in and wouldn't have to buy the extra USB wall adapter.

I'm basically curious if people have a preference one way or another, or it really makes no difference?

Thanks!

[VanKalkerFarms]

yeah, you can charge it off a computer also.  but you shouldn't need to, I have 3 that make it multiple days before needing charging and they get 50-100 charges on them.