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Mobility Digest Review: USB Battery Backup Power Cells


A few hours after I got my new HTC Surround home on launch day I discovered I had an issue that needed a quick solution. Think it was during my second full battery charge in less than 12 hours! Granted, I have not had the device long enough, and lack the required utilities to determine what the real life is for the supplied 1230 mAh battery so I am in no way knocking the battery. Problem is, despite Microsoft’s marketing spiel it is a fun device to play with and I have had it in my hands almost every waking minute for the past week, so the poor battery has been taking a big hit. I know that extended batteries are a long way off (even a spare battery from AT&T is on backorder) and I can forget about a manufacturer making anything as slick as the Proporta Turbocharger BackPack for iPhone 4 reviewed here, for a Windows Phone device anytime in the near future. Even with a handful of spare batteries, I would not look forward to popping off the back of my hard shell, popping off the back cover of my phone (after powering it off), and then reversing the process. For one its a PITA and second, I don’t really like the way the back cover on the Surround is made as it pries off rather than the familiar slide and click on my Fuze and Tilt2’s. So aside from being near a car or AC outlet 24/7 what is one to do.

I decided to look in backup battery packs and subsequently have three different models to tell you about today. Hey, a good scout is always prepared. BTW, now I have 5700 mAh of reserve power so I am ready for the next hurricane or whatever else comes along. In no particular order:


Energizer XP1000 Portable Charger


This is the smallest of the three devices and as the model number indicates it is rated at 1000 mAh. It measures a svelte 3.40” x 2.20” x 0.30” and weighs in under 1.5oz. Included with the battery pack is; a carry bag, a 11” cable with micro USB at one end a Y at the other with a std USB and a round pin plug to accommodate the 4 phone tips provided. The tips included in the kit are; iPhone/iPod, mini USB, micro USB and a really tiny round one I suppose for a Blackberry device. They also offer a TipFit Guarantee for Life. So if one of the provided tips don’t work with your phone or you need a different tip for a new phone they will send it to you for free. Good deal.

The micro USB end of the cable plugs into the battery pack and the std USB plugs into your PC’s USB port. They recommend 8 hours for the initial charge. Subsequent charges have taken 3-5 hours. An indicator light will change from red to green when it has reached full charge. There is a button on the end of the unit labeled, “LED Activation Button”, and when I press it a green LED lights up, I suppose indicating that the device has a charge. Not sure if this light changes status under different conditions as there is no explanation in the instructions and so far, it’s just a green light, not flashing, not yellow. The XP1000 is rated for up to 500 full charges and claims that it will stay charged for a full year. It uses a lithium polymer battery with a rated output of DC 5V and Max 500mA.

I have used this charger through two or three full cycles, once when my device low battery indicator turned on, and it did what it is supposed to do, but because of its limited capacity it may conk out on you before it can fully charge your device. Actually, that’s exactly what happened during my low battery event. I continued to use my phone off an on and after about 45 minutes this “little battery that couldn’t”, gave up. It did get my phone close (85-95% est) to a full charge though. In the other instances, my phone was only down to 60-70% so the XP1000 was able to top off the battery before dying. But if you are just looking for some emergency power or need to walk around while you are topping off the charge on your phone this little guy may just do the trick. You can find it for $19.95 at office supply stores and other retail outlets.


DigiPower EBP-TM21 Power Plus 2 in 1


This next step up in chargers is rated at 1700 mAh so it has enough punch to fully charge most phones on a single cycle. It also has a fold out AC plug for fast and easy recharging. The Power Plus measured 3.75” x 2.20” x 0.75” and weighs in around 3oz. In the package you get the device and….that’s it. Unless you want to call the fold out instruction sheet something. The plan here is for you to use your existing USB to whatever cable and simply plug it into the Power Plus. Works for me. The device provides two USB ports so theoretically you can charge two devices at the same time, but after reading some Amazon reviews that may not be entirely true. Of course your mileage may vary, based on amperage draw, etc.

The device has a power button on top that toggles through; charger on (indicated by a blue LED) & flashlight, flashlight only, charger on only and off. Yes, I said flashlight. A novel idea but several reviewers have complained that the button is easily pressed while bouncing around in a bag or backpack only to turn the fully charged device into a dead battery, probably when you need it the most. There are two LED’s; one to tell you the battery pack is charging and a second to let you know that your device is charging. While the battery pack is charging the LED will glow red until fully charged and then change to blue indicating “good to go”. The device also has the ability to be a pass thru charger so you can use this as your primary charging block. Just add your preferred cable and this becomes your daily AC charger but can also be the take along for those days away from civilization.  Output voltage is DC 5.3V and Max current 500 mA.. Full charging time for the battery pack is 4 to 5 hours.

For the first test my phone was somewhere between 10-15% I think (damn, I hate that battery icon, % readout please!) when I plugged in the fully charged Power Plus. Over the course of the next 2+ hours usage was light to moderate, turning the device on every 5-10 minutes, checking/reading some mail and using the eBay app to setup my account on the phone. Unfortunately the Power Plus conked out at about 2.5 hours and just short of 100% on the battery. That was about twice the normal charge time, which makes sense based on the 500mA output. Might have been because it was the first charge for the new battery or the 1700 mAh rating is a bit high. For the second test, I left the Power Plus connected to my phone for exactly 90 minutes to determine what it could do in a set period of time. Started at about 25-30% and with some light to moderate use, including a bunch of texting, the phone battery looked to be at about 75-80% when I disconnected. So a decent charge while still allowing you to move about with the phone. Available through only retailers for about $37.00


DigiPower JS-Smart Mobile Charger


Saved the best for last. This bad boy packs a whopping 3000mAh so it keeps going and going, at least for a couple full or multiple partial charges. It is made up of dual 1500 mAh lithium polymer batteries. The package includes: the mobile charger,  a carry bag, and two 3ft cables, USB to mini USB and USB to micro USB. I really like the nice touch of adding little Velcro wraps with the DigiPower logo to each of the cables. Damn, it should be a law. The charger measures 4.25” x 2.60” x 0.65” and weighs about 3.5oz. It has soft rounded edges making it look a bit like a cell phone. The Mobile Charger has a mini USB input port for charging the battery pack and a std USB port, protected by a rubber boot for connecting one of the supplied cables to your phone or other device. The two ports are clearly marked on the back of the charger.

While the JS-Smart is charging, four blue LED’s flash in sequence. When all four are flashing the charge is below 25%, one on and the rest flashing – 25 to 50%, and so on until you are fully charged when all 4 LED’s remain lit. Although you can charge the JS-Smart through a PC’s USB port they highly recommend using an AC power pack, like the one that came with your phone, or the Power Plus mentioned above. Otherwise, you may wait a very long time for this battery pack to fully charge. To charge your phone, plug it in with one of the supplied cables and press/hold the Mobile Charger’s power button until you see one or more of the display’s LEDs illuminate.  The number of LED’s that come on will indicate the current capacity. Any time during your device charge cycle, you can press the power button to see how much power is remaining in the Mobile Charger. Note that this charger will not allow pass-thru charging. You much unplug the Mobile Charger from an AC or USB input before the output port will become active. If one of the LED’s starts blinking during the charge cycle this indicates that you are almost out of juice. The Mobile Charger will automatically shut off when your device is fully charged. A full recharge of the JS-Smart takes about 8 hours. It is rated for about 300 full charge cycles. Output voltage is DC 5V at Max 600 mA.

It took 2.45 hours for the JS-Smart to bring my device up to full 100% charge after starting at about 25-30% with light to moderate usage, including a couple web searches/views and a whole bunch of email reads and sends. And as advertised, as soon as my device’s LED turned from red to green, the JS-Smart powered down. When I checked the remaining power in the Mobile Charger, I got 2 lights, indicating between 25 & 50% remaining, which is about right. In all fairness, during this test as well as the tests of the other units, the charge got up into the 80-90% area (again, only a guess based on the icon) in about an hour, but these devices really struggle with that last 10-20%, so the results are actually better than a full charge test might reveal. For my follow up test I I plugged  fully charged Mobile Charger into my phone, which had about 20% remaining and left it connect for 90 minutes. During that period usage was moderate, reading/writing several emails, downloading a couple apps and playing around with a new tool to access our forums (very nice BTW). I would estimate a 70% charge at the end of the test, so a decent boost with fairly moderate activity. Still only had two lights after the test, indicating between 25-50% remaining power in the Mobile Charger. Would definitely take this big daddy along on a trip if I knew I would be away from a plug for an extended period. Available through online retailers for $49.99.



I know its hard for manufacturers to justify sled type power packs for every Android/WM7 and other platform device released, but with mini/micro USB ports becoming standard and always in the same place (don’t get me started on OEM’s who put the charging port on the side or elsewhere – just dumb) its not as hard as it appears. Make a sled with a 3000mAh battery onboard. Make the sled back just wide and tall enough for a 4.3” device, but still able to handle everything down to 3.5” (sorry Dell) which would cover about 98% of all (except iPhones-different port) Smartphones. Put a ledge at the bottom with a USB connector. On the back add a ratcheting wheel that would allow you to move the connector in/out about 1/4”, more than enough to accommodate different device thicknesses. Add a lock so you can set it and forget it. Now add two little fingers with a little spring tension at the top, like those bars that keep you in the roller coaster seat, to make sure your device stays in place when placed in the sled. No, its probably not pocketable, but you can walk around the house or office all day with it and when you popped it out, your device would still have a full charge. Add a USB port to the sled so you can charge your device in place. Wouldn’t cost much to make and at most you would need two models. Plus, it could be used through multiple generations of devices, or until the sled battery died. Guess I just spend too much time thinking about this stuff though. Don’t want any royalties for this. Just a prototype please. And hurry.

My focus with these chargers is to have the freedom to walk around without being tethered to an AC outlet, which was reasonably practical with all three. One thing I didn’t like though was the 36” long USB cable dangling from the two DigiPower units. I fear that the cable will get hooked on something and yank on my device connector potentially causing damage, or worse yanking it off the table and flinging it onto my tile floor. Ouch! So I found some nice 12” USB to Micro cables at They offer a whole range of styles; straight, right/left angle, forward/back, etc. in; 6”, 12”, 24” and 36” lengths. Going to try the straight and right angle to see which works better for me. My guess is 12” will be the perfect size to move my device/charger around while also being able to pick my device off the desk to use while the portable charger is connected.

As some of the initial novelty of my new Windows Phone wears off I suppose my stock battery will make it through a typical day, but with these portable devices I know that I can plug in anywhere and start to juice back up. I would much prefer some type of portable dock or plutonium powercell, but these battery packs are a good alternative. And it’s not as if I can’t find other uses for them. Pretty much everything, thankfully, is using the DC 5V standard these days. Don’t let the lights go out on your device. Stay charged!

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