When the time comes to buy a portable external battery, you have to choose between the largest one you can afford or going for a smaller one. I'm here to argue that smaller is better. Don't get me wrong—big batteries are great. I have portable batteries big enough to power my house . But I've surrounded those batteries with a bunch of small ones. You won't want to carry that big battery around Credit: Jerome Thomas / How-To Geek The reason is in the name. These are portable battery banks, and their utility depends first and foremost on how portable they actually are. Battery banks with larger capacities aren't carrying around the same size "tank" with more energy poured inside. That's not how this works. They're typically made with the same size batteries, just more of them. This is often why they are called battery banks, because they're a bank of batteries. Larger battery banks weigh more, and they are thicker.…