If you've really wanted to try the NRG for your ICON Headlamp or your Apollo Lantern, but you thought a rechargeable battery would limit your use in the field, your answer is here.  The NRG Car Charger works for either NRG or NRG 2 and charges from any vehicle's 12 volt socket.  LED lights keep you appraised of the charging status.  Retail $24.95.