Oh well. The battery is 604 Wh nominal. There are two types of Li-Ion cells commonly used in e-bikes: the older 18650 (65 x 18 mm) and the newer 21700 (70 x 21mm). The 21700 was first released in 2015 with the special focus on using it in e-bikes. It is used in newer Tesla cars as well. The 21700 cell has the nominal voltage of 3.7 V; to achieve 36 V nominal, you use 10 cells in series. The 604 Wh battery of the Vado has the charge of 16.8 Ah. I believe 4 rows of cells are connected in parallel, giving the single cell nominal charge of 4200 mAh. So it is the 10s4p battery layout.
Note some Vado models have had the 460 Wh battery (3.0) and some have got 500 Wh batteries (4.0). Since the external size of the battery is the same in all bike models, it means less capable (and less expensive) cells were used in the less expensive models of the Vado: 3200 mAh cells in the 3.0 and 3470 mAh in the 4.0.
The way the battery charge is calculated and reported is rather obscure. The 604 Wh is the nominal value but actual batteries differ in the capacity because the cells are unfortunately not identical. It is hard to draw conclusions. Only a test of a battery in a discharging apparatus as used by custom battery makers would be a proof.
I have noticed that the pedal assistance in my Vado drops down significantly at 5% battery left. The support is greatly reduced to keep the lights and the display operating; I think the pedalling is still assisted at very low level, so I can ride for 1-2 km more to find a safe place at which I can swap the batteries. Switching the support to OFF makes the bike feel even heavier. I have never gone down to less than 4% though so I cannot tell what happens at the 2% of battery left.
Lowest percentage I've dropped to is 9% remaining after 62 miles. 
