Image: Anker Your iPhone has great battery life, but if you’re going to be away for a while, it’s always best to leave the house with a power bank tucked away in your bag. And today’s a great day to grab one: This Amazon Black Friday sale drops the price on the 10K Anker magnetic power bank to just $36, a savings of $24, and the best price we’ve ever seen. Even better, all three colors — black, white, and sky blue — are on sale for the same price, so you don’t have to settle for a...