Walmart has the Stanley FatMax 140W Power Inverter with USB for only $11! (Reg. $25) This is perfect for charging up and powering smaller electronics like a cell phone or tablet computer, this inverter plugs in through your vehicle’s 12 Volt DC outlet. It uses a fan-free silent running design and a low-voltage feature that automatically shuts it off to prevent it from draining your vehicle’s battery. Plus, choose in-store pickup to save on shipping.