Anker PowerCore II 20000 | $36 | Amazon | Use code Y18A1260

Anker’s PowerCore line of battery packs have been our readers’ favorites since they debuted, and now you can get the new Anker PowerCore II 20,000 for $36 with enter promo code Y18A1260.

Cosmetically, the PowerCore II look very similar to the original PowerCores, but with more precise eight-dot charge indicators so you know how much juice you have left. But inside, they’ve been upgraded with Anker’s new PowerIQ 2.0 charging technology, which delivers the fastest possible charging speed to your devices, including Quick Charge-compatible phones. That speed works both ways, as the entire battery will recharge in five hours if you plug them into a QC wall charger.