I am planning to use the Panasonic NCR-18650 cylindrical cells for a BEV (Battery Electrical Vehicle). As it would be easier to buy ready-made modules, I have found a supplier selling a Li-ion pack that delivers 417 Wh(or in other words 11.6 Ah) at 36 V (something like what this guy uses... http://www.electricbicycleworld.com/36V-11-6Ah-Lithium-Ion-Frame-Bottle-Mount-p/hx-bb-11.6ah-36v.htm ). Upon further inquiry, he says its a 10S4P i.e 10 in series and 4 "strings"(whatever that means) in parellel. The Voltage and Energy density calculation part is where I get confused: The panasonic datasheet says that each individual cell has 10.44 Wh of energy and supplies it at 3.6 V. So, 10 cells in Series → 36 V and 10.44 Wh IF I arrange these cells in 4 "parallel" rows, I get → 36 V and 41.76 Wh. But, the guy claims 10S4P supplies 417Wh. Where am I going wrong?