Inside the Samebike LO26 type battery pack 

A view inside a 48V battery pack, showing the layout of the battery connections. This is a 13S4P battery wired in a type of ladder style. It is quite complicated to get 52 batteries inside the metal case.
Sorry I said 4 batteries in series when I meant in parallel.
If you connect 13 X 3.7V batteries in series you get 48.1V across them. This is the nominal voltage, when fully charged it will be about 54V and when discharged about 41V.
The current rating of the 18650 batteries will probably range from 2Ah to 3.5Ah. So 4
X 2.6Ah batteries in parallel gives 10.4Ah.
So a 13S 4P battery, using 2.6Ah batteries gives a 48V 10.4Ah battery.