I converted mine to work with a lithium ion battery you use to charge iPhones. Connects to the helmet via a retractable usb and the batteries can be had for $20 so I got three of them. They are small enough to just mount on the top of the helmet with velcro.
I’ve looked into that, if I don’t sell it I think that’s what I’m gonna go ahead and do. I figured whoever bought it that’s what they would end up doing as well. It’s an incredible helmet and has seen very little use. I purchased it for safety on the lathe however, I’ve sold my lathe.