Rechargeable NiCad and NiMh batteries that come with these cameras only have a short life span, are very expensive and usually hard to find. 9V batteries are very cheap and easy to obtain. As rechargeable batteries get older, their charge may only last for a couple rolls of film. Many times the rechargeable batteries can die without warning which is terrible if you are on a shoot and your battery goes dead.The rechargeables usually take 14 hours or more to charge. With our system, you can just pop in a new 9V battery. Rechargables are notorious for blowing the battery doors off the 500 series cameras when their fragile internal chemistry goes bad. 9V batteries are much more stable and reliable. A 9V battery runs about $2 versus the rechargeables which can run close to $100.