As people rely more and more on their smartphones for more tasks throughout the day, it can become increasingly difficult to get through the day without needing to top off at some point. There's no shortage of power bricks out there, but many of them are the size of drinking flasks and hold enough battery power to charge a smartphone fully two to three times. That may be great for a short camping trip but probably is overkill for a particularly busy day making calls and using a portable hotspot.

Fortunately, a number of charging devices no bigger than a credit card have improved significantly over the past few years and now offer higher capacity and more ports than in the past to give your smartphone the energy hug that they need. Consider these credit card-sized devices a sort of retail therapy for phones. Here are some of the most versatile options.

Flexion. The Flexion is a small flat portable battery that covers the basics, maintains a slim profile and packs a punch. The same card includes both microUSB and Lightning connectors so iPhone and Android users can help out colleagues regardless of their phone preference. It also packs a 2500 mAH battery--pretty beefy for this type of product--that should charge most phones in the market fully, including the iPhone 6 (and get you to mostly charged on an iPhone 6 Plus.

Thinium. The Thinium answers the question, "What do you do if your portable battery runs out? While a bit thicker than the Flexion (and twice as expensive), it includes a flip-out outlet prong and can cradle most phones withou the need of an extra dock. The Thinium can also act as a charging cable to connect yoru phone to a USB port on a PC. However, the device itself does not include a battery.

Skinny Charge. The Swiss Army Knife of credit card-style portable chargers, the Skinny Charge houses three different types of connectors (Lightning, micruUSB and even the old 30-pin iPod connector). It also includes an LED to serve as a flashlight if some illumination is needed and the phone's flash can't be used because the battery is dead. Between that and the charging light, it can be a little bright when charging, but at least the company put both lights on the same side so one can put the device face down to minimize distraction