They show about 20 cells. For cheap lithium ion batteries, that will be something like 150 to 200 watt hours. This is not a ridiculous figure relative to the stated range.
I counted 22. I'm suspecting thats either a 35.2V 11S2P LiFePO4 pack with probably under 100Whr, or a 40.7V LiPo pack which could be upwards of 250WHr (and could get ~200Whr quite inexpensively). Another possibility it that it's a 37V 10S2P motive power battery and a 7.2V 2S pack to power the non-motive electronics (microcontroller/gps/bluetooth/…)
