What would prevent the battery from having a segmented design so that multiple segments can be charged in parallel? Is there something about the chemistry that requires the entire vehicle battery to be a single unit?
https://i.ytimg.com/vi/ga4L1w66AbU/maxresdefault.jpg
The problem is disgustingly parallel.
Edit: Oh I get it...the charging port is what you meant.
You can charge every single cell individually, simultaneously, if you design your connections to support it. IIRC our packs were wired to charge the internal cells in pairs.
If you think about it, though, with a given max current I = dQ/dt, you need the same amount of time to charge two cells each to a charge Q (mAh), no matter if you charge them simultaneously or one after the other. Because if you charge them simultaneously you can only supply I/2 each.