AnkerDirect via Amazon offers the second-generation Anker Astro3 12,800mAh 3-Port External Battery Charger in Black for $39.99. Coupon code "ASTRO332" cuts it to $31.99. With free shipping, that's $60 off and the lowest total price we could find. It features PowerIQ Technology, which purports to detect your device to deliver the fastest possible charge. Deal ends March 29.