I recently tried this product:
its an SBEC you can get details here
I wanted to get 5V with high current out of simple 10-20Ah power banks like these
I then sealed them back up and added JST plugs onto each battery. Thi sway they can be removed and recharged individually using their own charging cables:
I then Connected 2 modules in series and connected 2 of these in parallel via a switch to the SBEC:
For the moment i have not had anything taking out more than 6A from the SBEC. Ill perform more tests as I test more LEDs at the same time!