Your smartphone's battery life is no doubt very important to you, but its charging time matters, too -- just ask anyone who's had mere minutes to top up a phone before heading out. So who offers the best recharge rates, then? Tom's Guide might have an answer. It recently conducted a charging speed test to determine which phones will deliver the most energy when you're in a rush. In short, you'll probably want to make a beeline toward either ASUS' Zenfone 2 or Samsung's Galaxy S6. The Zenfone 2 is the fastest in short bursts, giving you 32 percent power in just 15 minutes. The Galaxy S6 is faster overall, however, hitting 100 percent after 1 hour and 22 minutes.