Right now you can grab Aukey's 20000mAh power bank for just $23 at Amazon with coupon code AUPOWERQ. This saves you $7 on a power bank that you can charge with Micro-USB or your Lightning cable, and it has two outputs to charge multiple devices at the same time. With a capacity of 20000mAh, you'll easily be able to charge your phone or tablet at least two to three times per charge of the battery pack. The power button will change colors based on the charge of the pack, making it easy to know when it needs to be charged again.
Remember, you'll need coupon code AUPOWERQ for the full savings here. This deal should last through November 19, as long as the stock is available. If you are interested in grabbing one, be sure to do it sooner than later.