I made my box the same way.. and I've found that you can set it to LiPo battery and use external power supply (Directly to one of my wheelchair batteries) if you make a jumper/patch cable with an xt(30 or 60 depending what's on your battery), connector on one end and a balance plug on the other and three 10k resistors in series in between and wire to the balance plug this way: You can then leave it in Lithium Polymer mode and vape on external PS... when you unplug the patch cable and plug in the battery just make sure you have unplugged the external This is my passthru with the patch cable on: there's the three 10k resistors in series in the black square wrap, I wrapped double sides foam tape around then black electricians tape over that just to make it sturdy when I up plug it for the battery... It works great this way, I've been using it like this for several weeks now... Note: if it ever starts saying "Check Battery" while on external, just unplug from ext ps, wait about 30 seconds and plug back in and it chugs on... Note 2: Use very high quality resistors, or the batt levels will fluctuate and it won't read correctly... I got this from an admin