It's tempting to grab the biggest battery you can find, but that often means a heavier, bulkier device. If you're someone who likes to slip your vape into a shirt pocket or a small bag, a 1000mAh brick is going to be a pain. You don't need a week of battery life if you're near a charger most of the day.

Also, high capacity doesn't always mean better performance. A well-engineered 350mAh battery can outlast a poorly designed 600mAh one. Look at the brand's reputation and read user reviews about real-world battery life, not just the spec sheet.

And remember: you're buying a device, not a power bank. A battery that lasts two days but feels awful in your hand is a bad trade. Prioritize the overall experience.