Caffeine is our power source, whether it’s from coffee or tea or BAWLS. What better way for us to visualize our batteries being charged than a mug with a battery that powers up when we fill it with our piping hot caffeinated libation of choice? This ceramic mug is classic black with a white outline of a battery on it. Pour in your hot liquid – anything over 96.8F (36C) – and watch the green cells within the battery light up. As your beverage cools (or is ingested) the battery will fade into emptiness, reminding you that you need a refill.