Are those king kong 26650s? If so the problem is not your battery.
looks interesting .
Yes they are the 26650 King kongs. The long runs of 18ga wire maybe causing my trouble time for a little more homework on wire sizing I guess. The batteries are in parallel not series so would that still cause the heat issues?
Series wouldn’t work at all with these emitters. The term ‘instaflash’ comes to mind. The two large high discharge cells In parallel don’t sag much voltage under load, and the voltage is the only limiter in a FET driver on high.
What exactly happens if you try to run them all on high?
The other one will almost immediately step down to what looks like moonlight mode.