Batteries have a current limit that is defined based upon the capacity of the battery. Typical low-cost lithium iron phosphate batteries (which is the chemistr

Batteries have a current limit that is defined based upon the capacity of the battery. Typical low-cost lithium iron phosphate batteries (which is the chemistry looks like they are using here) usually claim a top current limit of 10C, which would allow a full charge in just over 6 minutes. Really great lithium phosphate batteries can give you a current limit of 30C or higher, which basically means your charging times are limited by how large you want your battery wires to be. This is true for most electric cars. 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.