Amazon offers the Pisen 10,000mAh Portable Power Bank in Black for $18.99. Coupon code "8IL48AZC" cuts the price to $12.34. With free shipping for Prime members, that's $7 off list and the lowest price we could find. It can charge an iPhone 7 up to 3.6 times, a Galaxy S8 at least 2.3 times or an iPad Mini4 one time. Deal ends April 30.