AnkerDirect via Amazon offers its Anker PowerCore II 20000 20,000mAh 6-amp Portable Battery Pack for $43.99. Coupon code "ANK20AH3" cuts that to $32.99. With free shipping, that's tied with our May mention as the best price we've seen. (It's the lowest price we could find now by $18.) It features three PowerIQ fast-charging USB ports and can be fully charged in just under six hours via its dual microUSB inputs. Fully charged, it can charge an iPhone 7 almost seven times, Galaxy S7 four times, and most tablets almost twice.