You're on a photo shoot and your DSLR camera batteries die. Digital cameras really do drain battery life quite fast, especially with flash photography, which is why you have spare rechargeable Powerex camera batteries in your kit bag. These are a lifesaver and you continue your shoot as any professional photographer would.
You could've used standard non-rechargeable batteries, but you value buying the best rechargeable camera batteries like Powerex precharged AAA1000 mAh and AA 2600mAh / 2700mAh NiMH batteries. These batteries are capable of being stored for extended periods of time and still remain full or nearly fully charged - after a year, for instance, they will retain up to 85% of their capacity. The batteries come precharged and can be recharged hundreds of times. Rechargeable batteries save you money since you won't need to buy endless supplies of non-rechargeable alkaline batteries.