Best Energy Pack for Ultra-light, Long-Distance Backpacking Spoiler: It's the Just Mobile Gum++

Obviously, the best ultalight battery pack is no battery pack, but on our trip we’re going to be bringing a phone, a camera, an MP3 player and two headlamps. The phone doubles as our GPS and the headlamps might be USB rechargeable. Having spare energy to get us through longer sections is important.

I’ve completed some research, investigating which are the best options. As I was reviewing the many battery pack and solar charger solutions that are out there, I came to a few conclusions right off the bat:

• The models with turbines, like the Eton BoostTurbine2000 are crap. I called Eton to ask them how many cranks it would take to charge a phone. The technical support guy’s response: “You’d be at it all day. These are meant for emergency use only.” So turbines are out.
• The idea of using a solar panel is great, but doing so will suck. I looked far and wide for an ultralight solar panel, but they’re all heavier than just getting a battery pack. The problem with solar panels is that they need to have their own battery packs, so you end up carrying the extra battery pack and the panel itself. If you’re out for really long trips, these are probably worth it, but for trips where you’ll be in and out of towns, there are lighter options.
• There are a million wannabe battery pack manufacturers, like Timetec, Powergen, Rokit and Unu. They’re strong on branding, but when you go to their website — if they have one — you’ll find more marketing but not much real innovation or information. For example, in my attached chart, there are many blank spots and questions marks for these brands.

Looking for battery packs for backpackers means finding one that’s light, durable and efficient. There are a few features you probably want in particular:

• You want a battery pack that will charge your devices as quickly as they support. Many battery packs, particularly the small ones, only provide 1 amp of output from a single USB port. If you have a device that can handle more (like a tablet), it’ll charge quite slowly. The best ones have as much as 2.5A output, and will adapt to send the right amount of power to your device.
• You want a battery pack that charges quickly when you plug it into the wall. You don’t want to get stuck in town overnight because of how slowly your battery pack charges.
• You want a battery pack that offers “pass through charging”. This allows you to plug the battery into the wall, and plug your device into the battery — simultaneously — allowing you to charge both at the same time. Most battery packs don’t offer this.
• Finally, you want the most energy packed into the smallest, lightest device.

When looking at all these features, there are three standout energy packs, the Innergie PocketCell Duo, the Anker Astro 5600 and the Just Mobile Gum++.

The Anker Astro ($30) is the lightest of the bunch, but it also is complex, charges slowly when plugged in, and has a complex body. It has a flashlight, for what that’s worth, and, at 4.2 ounces, has an energy density of 1333 mAh/oz. It does not appear to have passthrough functionality.

The Just Mobile Gum++ ($90) is a very simple, lightweight and durable option. At 4.6 ounces, it’s still very light. It has a slightly lower energy density from the Astro (1304 mAh/oz), but boasts an ABS shell, the fastest charge rate when plugged in (2500 mA), and just generally looks like a good, simple option.

Finally is the Innergie PocketCell Duo ($90). This is the most powerful of the bunch, at 6800 mAh, has the highest energy density at 1456 mAh/oz) and has two output ports (both at 2100 mA). Unfortunately, unlike the Gum++, it only chargest at 1500 mA, so it will take longer to charge.

The PocketCell and Gum++ are both very new products, and don’t have many reviews. The Anker has been around awhile and has decent reviews, though some upset people that aren’t happy with their products.

Here’s my recommendation: If you need a battery pack that can charge two devices at the same time, get the Innergie PocketCell Duo. If not, get the Just Mobile Gum++. If you want to do your own analysis, check out the attached spreadsheet and go wild.

Update: Since Innergie does not mention whether their device supports pass through, I’ve contacted them via their contact form and via Twitter. After more than two months, they’ve been entirely non-responsive. There is another person on their Twitter stream that is complaining (loudly) that they never responded to a broken device complaint that he had. I can’t recommend Innergie despite their slick device, great marketing, etc. Something is going wrong with that company.