Not saying this cant be done but I left it alone, I made a mod for the Xiaomi mi and had it powered onboard the tello, rather than use the tello battery. This worked well.
Tried many variations for this mod. From small coins cells in parallel, tello extra battery etc. From what I've found there is limited ways of achieving this without motors overheating or the tello struggling and getting error 13 codes
It's hard enough for us guys to fly a small drone like the tello in the UK as it is. I GUESS there is a reason they (the protesters at heathrow) are protesting. But why use a tello!!!! Annoyed, very sad and a little dumbfounded...