18650 would start at 4.2V or so at full charge
and depending on the cell, is capable of providing 2-10Amps during normal usage. So during a short, at least as much.
It's much worse than you think...
Another point is that 1S Lioo batteries in the 18650 form factor can be found with some very high mAh ratings which means that, in a Lilo, the discharge current,, depending on the "C" rating , could be 45 or more times the "1C" mAh rating so a 3000 mAh rated 18650 1S battery ciuld source over 100A for a very brief period [. (3/135) * 60= 1.3 minutes.] 6.7 times the 1C rating:
Now DOUBLE that
6000 mAh 18650 1S Lipo
40000 mA
And it just gets worse...
High discharge 18650 batteries
208 Amps