I know that some of you use 3M AirStream or BreatheEasy respirators.
I finally got around to making a video that shows the way I am using an alternative to the stock 3M NiCad battery.
This tiny rechargeable lithium battery lasts longer, and is a small fraction of the weight and cost of the original.
Because of its size and USB connectors, it lends itself to mounting on the helmet, eliminating a cord going to your belt.
I hope this gives some folk ideas for use in their own configurations.