question based on a dim memory and some updates

[Elton A Sanders]

20v Dewalt pack to 12V at say 1-5 amps general field and power outage use. The converter could be the same for most packs ( there are some 60-80 volt packs that might push using common electronics). Plastic would be different for each brand of pack. I don't see it adding more than 1 inch or so to the thickness of the pack ( on the 20v Dewalt packs, the packs with a pillar that sticks up in the tool handle would be bigger).
     Sandy
     WB5MMB

...................Sandy, can I ask for what kind of power tools battery and use case? I see the benefit of the idea, but wonder about all the different kinds of batteries and the battery terminals - requiring a different 'adapter cap' - unless there is a chance the converter PCB can be common to various kinds of terminal adapters (Black & Decker, DeWalt, Ryobi, Stihl, ...) and the applications might be medium duty current load so no loose connections. Also, the mass of a battery holder case could outweigh the advantages of field power conversion. 

Would you consider a battery power converter that comes with a rubber band / Velcro strap to be usable in the field? My guess it would weigh in grams with the safety and power converter electronics ?

It's interesting for me as well, as I see the batteries of my drill machine on the shelf. And a whopping big battery charger for it right next to it.