The only reason a Tesla Roadster can't charge in 2 minutes is because Tesla didn't want to / couldn't engineer a low cost solution that dealt with customers buying two packs (one for the garage, one for the car), which were connected by a wire doing thousands of amps at many hundreds of volts. That kind of connection can be literally explosive, much less potentially fatal to creatures that use electricity to regulate their internal fluid pumps. It's all about how fast you can shove electrons down a wire, and very little to do with the batteries themselves for this kind of pack. Rewiring a pack in parallel to put out / accept that kind of current is trivial.