I came by 3 6S* 60A LiPo batteryblocks. But those are boxes made from 2mm thin glassfibre plating (kind of PCB , lacking the copper layer).
Dimensions, 290x210x120mm and about 10 kg each.
I want to use 2 to power a Bafang midmotor on a Streetfox.
First idea I had was to use panniers. But no...