This pump used 2 D-Cell batteries and is not rechargeable. 

Engel 2nd Generation 2X2 Portable Air Pump for Engel and other live bait coolers and buckets. Includes 12v DC car adapter, flexible hose and weighted air stone. Alkaline Batteries (2 x size D) are not included.  Top quality alkaline batteries last up 45 hours of continuous use.  Air flow volume is 0.8L/Min (slow speed) and 1.0 L/Min (fast speed).

Optional