WARNING: If you use rechargeable batteries in your WowWee robot you do so at your own risk. WowWee only recommends the use of standard non-rechargeable alkaline batteries. Read the manual for more important tips about battery usage and your robot
Rechargeable and non-rechargeable batteries
Femisapien is very easy on batteries so using standard non-rechargeable AA batteries shouldn't set your wallet or purse back too badly. However, the flip side to that equation is that you will want to play with Femisapien a lot more than you might imagine so perhaps you will start running up a big battery bill like me. If you do, you should know about a terrific line of batteries I found called Juice Alkaline Rechargeables. Normally I wouldn't go into this kind of detail on batteries but it's important.
Most rechargeable batteries are nominally rated at 1.2 volts. When I tried my usual Duracell NiMH (Nickel Metal Hydride) rechargeable batteries in Femisapien, I discovered that she was somewhat sluggish especially when compared to her wonderfully snappy performance with standard non-rechargeable alkaline batteries which are rated at 1.5 volts. Fortunately Juice Alkaline rechargeables share the same 1.5 volts rating as non-rechargeables do. With these batteries Femisapien was quite happy and I didn't have to continually buy new sets of batteries to service the long dancing and acting sessions I put her through. In addition, I have the peace of mind of using batteries that I will not have to throw away and therefore am helping the environment (Wall-E would be proud!).
TIP: Unlike NiMH batteries where they recommend you run them until they're nearly but not completely discharged before recharging, the Juice rechargeable batteries will last a LOT longer if you keep them "topped off". By "topped off" I mean that you recharge them the instant you see Femisapien get a little sluggish. This works out well because her dance movments and her walking are a lot more fun when she's at full charge then when she's a bit tuckered out.