Hi @Sammy,
The LiPos you are referring to are not sufficient for this use case. You have to take 18650 cells.
50,4 V divided by 3,7 V = 14 Lipos in series
This is correct and brings us to “14S”
If you take good Sony VTC6 cells they offer 3000 mAh which leads to 10 cells parallel to reach the 30 Ah.
Now we are at “14S10P” = 140 cells.
You can get 150 cells at Ebay for around 747 EUR. See the picture:
Cheers
A.