Spare Airshield Battery

I wanted another battery for my Airshield, so I went to Radio Shack and bought a four battery clip for AA size batteries, and a coaxial power plug the same size as is on the Airshield battery. I cut one of the battery cells off the battery clip to make it for three AA batteries and that way it will fit the space in the hood. I soldered the clip so the batteries were in series and added the plug on a short wire (be sure to check polarity). I bought a pack of 2000 mAh rechargeable NiCd batteries and installed three. I charge this using the same Airshield charger and use a timer to make sure it is not on more than about six hours. This works better than the Airshield battery—it has more power and lasts longer.