Pisen Electronics via Amazon offers the Pisen 20,000mAh Portable Battery Pack in Black or White for $29.99. Coupon code "PISENLCD" cuts the price to $19.79. With free shipping, that's tied with our mention from three weeks ago, $48 off list, and the lowest price we could find. It features one micro USB cable, 5V 2A input for quick charging, and a smart digital display LCD screen. Deal ends December 31.