Battery adapters for Makita, DeWalt, Milwaukee and others explained.

Word of caution: I have not tested all the adapter and it's your responsibility to check and make sure they work and won't damage your tool, this list is only to get you started, please let me know if there's any mistakes in the list. Also make sure you don't drain Lion batteries completely they can get damaged or worst not be recognized by the charger. And lastly batteries can only be charged with their manufacturer chargers, not through the adapters.
Dewalt 20v Battery to tool:
Older Dewalt 18v: extrafudge.com...
Makita 18v: extrafudge.com...
Milwaukee: extrafudge.com...
Ryobi: extrafudge.com...
Bosch: extrafudge.com...
Craftsman C3 19.2v: extrafudge.com...
Craftsman 20v Max: extrafudge.com...
Ridgid: extrafudge.com...
Harbor Freight Bauer 20v: extrafudge.com...
B&D or Porter Cable 20v Max: extrafudge.com...
Hitachi: extrafudge.com...
Make a Dewalt battery a USB battery pack: extrafudge.com...
Milwaukee M18 Battery to tool:
Older Nicad Milwaukee tools: extrafudge.com...
Dewalt: extrafudge.com...
Ryobi: extrafudge.com...
USB charger and power source: extrafudge.com...
Craftsman 20v MAX Battery to tool:
Dewalt 20v: extrafudge.com...
Milwaukee M18: extrafudge.com...
20v Porter Cable, Black and Decker and Stanley batteries(18v Bostitch):
Older Porter Cable 18v: extrafudge.com...
older Black & Decker 18v: extrafudge.com...
Ryobi: extrafudge.com...
Bosch: extrafudge.com...
Dewalt 20v: extrafudge.com...
Older Dewalt 18v: extrafudge.com...
Makita 18v: extrafudge.com...
Craftsman c3 19.2v: extrafudge.com...
Craftsman v20: extrafudge.com...
Makita 18v LXT Battery to tool:
14.4v Makita: extrafudge.com...
Older Makita 18v nicd: extrafudge.com...
Dewalt 20V max: extrafudge.com...
Milwaukee M18: extrafudge.com...
Metabo 18V: extrafudge.com...
Black & Decker 20V: extrafudge.com...
Bosch: extrafudge.com...
Ryobi: extrafudge.com...
Worx: extrafudge.com...
to USB: extrafudge.com...
Worx 20v Battery to tool:
Older 18v Worx: extrafudge.com...
Bosch 18v Battery to tool:
Makita: extrafudge.com...
Ryobi: extrafudge.com...
USB: extrafudge.com...
Ridgid 18v battery to tool:
Ryobi: extrafudge.com...
Milwaukee M18: extrafudge.com...
DeWalt 20v MAX: extrafudge.com...
USB: extrafudge.com...
Hitachi 18v battery to tool:
Ryobi 18v: extrafudge.com...
These links are amazon affiliate links and I might get a few pennies if you purchase.

[@tungadilla]

description links are very useful thanks. so far I use the dewalt to ryobi and bauer adapters and have had good luck.