The first, the myCharge Peak 6000, I picked up in 2013, for a trip I was planning to take. I was traveling by train, to visit a friend in Oregon and I didn't know if the train would have outlets or not. The myCharge Peak 6000 was the strongest battery I could find at the local best buy on short notice. Fortunately for me, Amtrak's Empire Builder has a pair of outlets right beside the seat, and the battery wasn't needed for that part of the trip. It did however come in hand wandering around Eugene Oregon and sometimes spending the night someplace where I didn't have a charger with me.
The myCharge Peak has numerous outputs, a built-in micro USB connector for charging most android devices or other electronics that take a charge over micro USB, an iPod connector for the older models of iPod, a USB Port to attach a cable that fits connectors other than those two, and two input methods, a built in USB cable to recharge the Peak, and a pair of prongs that flip out from the underside, and plug directly into an outlet. Impressively, the rubber flap with an embedded magnet that shields the charging USB plug has endured my tendency to flip it open and shut when bored. The myCharge Peak has a multi-function button that serves as both an on/off switch, and a information button. if you hold it long enough, you can force the unit off. if you press it while the unit is off, it powers back on. if you press it briefly while it is on, it will report the status of the battery. By default this is done with both light and sound. a recessed button can be pressed with the help of a paperclip or pin, and the mode by which it informs you can be changed if you don't want the battery to talk to you.
The second, the more powerful Mophie Powerstation XL was purchased for roughly the same price as the myCharge. You see, I had misplaced the myCharge, and another trip was coming up (Again, to Oregon). I decided that the thing that could best help me find what I had done with my old battery pack would be to buy a new one and invoke murphy's law. It did not turn up immediately, in fact it didn't turn back up until February of this year. I was headed out for a birthday celebration when I grabbed a leather jacket I hadn't worn in some time... Infact, not since my previous birthday celebration. But it was curiously heavy on one side. Digging into the pocket, I found the old battery pack hiding in there.
While the Peak is bristling with connectors the Mophie is comparatively spartan. It has three connectors, two of them usb ports that will accept the USB cable of your choosing and one micro USB input port, for recharging the battery pack itsself. It comes with nothing in the way of instructions and only a USB A to Micro USB cable. Initially I had mistaken the micro USB port for a security lock port, and thought I needed some manner of USB A to A cable to charge it. After a bit of furtive searching online I determined no, that smaller hole WAS a micro USB port, and that must be how it recharged. Carrying twice the stock charge as the myCharge pack, I do find myself going longer between recharges on the Mophie. The lack of built in connectors is a bit of a bummer, but the slightly smaller size of the unit can be nicer for fitting into a pocket.
Would I recommend them? Probably. I think there are more economical battery packs now available, and perusing the camping section of a local fleet farm store I did see a Coghlan's Battery Pack that I thought rather desirable. I don't know how well it works, but like the myCharge, it's 6k mAh, includes a small solar panel, and has a crank charging function as well. I don't imagine it crank-charges very fast, but every little bit helps. I definitely recommend having a battery pack or two of some kind, if you're going to use your electronics out in the wild. Especially if you're going to charge off of a BioLite Stove. Doubly so if you wanted to, say, use a power pot on a biolite stove and charge the battery at both ends, as it were.
Buy the myCharge Peak 6000 Here!
Buy the Mophie Powerstation XL here!
Buy the Coghlan's Power Pack before me, and tell me if it's any good!
Mophie in Black, myCharge in White: