Battery dies way too quick, hopefully some 3rd party battery straps come out soon
Use some hairbands, elasticated strap, velcro cable ties etc, to tie a powerbank onto the back of the headstrap. I bought a £2-3 attachment that's just an elasticated strap basically, put it round the strap and tighten it around the powerbank. Doesn't fall out, but easy enough to slide in and out if I need to replace it. Obviously also means you can use any powerbank.