Many of us have external battery chargers for our smartphones when the battery life is running low. They are convenient, since they can be recharged and serve as a backup power source when plugging your phone into a wall socket isn't an option. But what do you do with the external charger when it's time to replace it? Most rechargeable batteries can be used up to 1,000 times, but when they no longer hold a charge, be sure to recycle them. The nonprofit Call2Recycle program has thousands of free recycling boxes in stores like Best Buy, Lowe's and the Home Depot, where you simply drop them off. The batteries get stripped and recycled into new products.