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February 01, 2015 - Monoprice 5200mAh Battery Backup and Flashlight, #10576 All this winter I'd been using my phone as a flashlight, sometimes in pretty harsh situations. Each time I turned on its LED, I was keenly aware that there was only one unfortunate slip between my phone and an untimely demise. I wanted a wearable/carryable solution for this and other applications that was a bit more durable than my phone, so on the 5th last month I got a wonderful new gadget: one of several strong offerings in Monoprice's line of Battery Backups. I used it and loved it. Then I broke it, took it apart, fixed it, and took a close look at the internals while I had it open. I identified everything I could and commented on things like circuit design choices, build quality, and the usefulness of these products as a base for DIY designs. Overall, a whole lot of fun with a great little gadget!

This winter I've been filling a wood-fired furnace at least once a day, inspecting industrial equipment, navigating underground stations and generally doing some hands-on work that's not very suited to my unprotected smartphone. I've never been very comfortable with this arrangement, so when a few Monoprice sales caught my eye I looked through their line of Battery Backups for something to fit that need. I've been interested in wearable/carryable electronics for quite some time, and my relationship with Monoprice has always been excellent so they were one of the first places I looked.



I was pleasantly surprised to find an entire set of brand-new designs! This line of gadgets all represent a real consumer need that I've seen everywhere in society, but especially where high durability is a priority: all devices accumulate damage like scratches or cracks, but smartphones are very valuable. It doesn't make much sense to pull out a $600 item when you need to see what's in a grease trap or under a truck. This is where wearable/carryable electronics come in! A second, more rugged multifunction device can allow the more fragile smartphone to avoid damage and even offer additional functions like

Eventually I chose the 10576, for a few reasons: The proportions looked like something easy to use as a flashlight and easy to carry in jeans or a jacket.

A battery capacity of 5200mAh is enough for a weekend of extensive use.

Several LEDs and what appears to be a good reflector behind them.

I love the build quality of aluminum as a housing material.

The retail price of $17.99 fit nicely below my $20.00 limit, and this option met or exceeded all my criteria. I ordered one and it came on the 5th of January this year, and it's my pleasure to offer a brief review of the device!

Build Quality and Design Language Monoprice has been moving decisively into personal electronics - and I've watched their catalog develop with interest. Their previous offerings were strong, but this line feels more consistent as a "Monoprice brand" and definitely matches my expectation of Monoprice products. The whole experience has been no-nonsense, with a utilitarian design that provides commonsense purpose to the device without taking away from a simple elegance that makes it really attractive. The overall gadget is an extruded oval shape, which is bold and simple but still has great curves. I'm a big fan of the minimalistic design (it was one of the reasons I bought this model) and it distinguishes itself from other competitors very nicely. The oval shape also fits great in your hand or pocket, and the button placement on one side makes there only one active face for interaction. The glossy plastic and sparkle-finish aluminum also offers a wonderful shine under nearly any light source. On the flashlight side, the array of 7 LEDs is arranged tastefully and glitters through a glossy reflective shield.

I'm incredibly impressed with the build quality. The plastic head and tail fit onto what appears to be an aluminum shell, but I couldn't find a seam or wiggle anywhere. The design is tight, and I'm strongly reminded of Apple's monolithic approach to devices. The USB ports don't have a single bit of give to them, and the faceplate button has the nice satisfying click of the tact switches we've all come to love. One thing I would note is that the four LEDs that display the battery's SOC (State Of Charge) are surface mounted LEDs on the circuit board - they can be seen because the glossy finish is actually similar to a two-way mirror and allows their light to pass through. At some angles, the brightness of individual LEDs can change due to absorption from a reinforcing rib that runs through the center of the unit's plastic head. It's also possible to see glimpses of the circuit board from reflecting light inside the head unit. (In the linked photo, all four LEDs are on at the same brightness. This is the most extreme example I was able to find.)

Use in a Low-Stress Setting For my first few weeks with the device I used it gently and carefully, in everyday urban settings where the device was comfortably within its designed specs. I kept it nicely in the side pocket of carpenter pants or in my jacket, where it fit securely and left a satisfying weight without feeling bulky or awkward. The unit is stylish and easily carried, especially in a winter wardrobe! The raised edge around the tact switch is great for finding the orientation of the device blind in a pocket, and the smooth finish feels secure in my hand. When navigating a dark room the light is strong. I'm especially happy with the power capacity of the pack, because even with several power cycles of the Razr Maxx battery crammed into my phone I still wasn't able to put a dent in it. If I had the tools I could get a more precise measurement of the actual watt-hours delivered, but let's be honest: this thing is a powerhouse.

Use in a High-Stress Setting I really wanted to push the device to its reasonable limits - after all, I bought it to stand in for my phone in stressful lighting situations! So I started carrying it around whenever I could, just to see how much I'd use it. I wanted to see how the plastic and aluminum would accumulate scratches or dirt, and also to identify any failure points. Again the 10576 exceeded many of my expectations. The flashlight can stand vertically to illuminate a room (on nighttime trips to the wood furnace) or lay on its side to illuminate a working space (inspecting pipes and tracing plumbing through crawlspaces) and in pretty much any setting, it works very nicely. The beam is wide and strong for a good overall coverage that makes working under this light very easy. I was able to find one complaint: when holding it over the opening to a 750 gallon in-ground grease trap, I found myself fervently wishing for a wrist strap. The glossy finish on the body gives it a secure grip against a bare hand, but it's frequently slipped out from between a leather work glove. (This may be more a fault of my gloves than the unit) Drilling a pair of holes for a metal ring into one side may interrupt the smooth lines of the unit, but many flashlights come with them and it wouldn't be unreasonable for customers who want a more streamlined look to leave the holes unused.

Construction and Teardown The higher stresses of daily use didn't seem to bother the 10576 much at all, until it took a spill out of my jacket onto hard concrete and landed directly on the plastic head unit. All the devices functions worked just fine, but the shock knocked off its faceplate and the head unit now wobbled by ~0.5mm about the center of its axis. To be honest, I had expected the plastic to shatter or crack on a sharp impact like that. I was proven wrong - although the head unit feels rigid, it must be plastic enough (pun intended, heh) to deform and absorb the entire unit's impact without serious damage. It appears most of the force was concentrated where the plastic head joins to the aluminum body.

The faceplate came off, and you can see some stress deformations in the upper right-hand corner from the impact. The plastic is still in one piece though! The two holes at top and bottom center of the face lead to screws ~1.5cm deep, at the back of the head unit.

I almost couldn't find a Phillips driver that could reach that far down a small shaft. I never realized how many of my drivers used those short-shaft interchangeable bits!

Two screws, and the head unit comes cleanly off.

The entire assembly slides out at this point, although not without a bit of tugging. It's snug in there! ...are those 18650 cells I see?

Yes they are! Two ICR18650-26H M Samsung SDIEH TEV2 cells - available online for $6.68 - so with this unit's price point at $17.99 a full three-quarters of your money goes straight to battery power! This teardown has done nothing but confirm my expectations: Monoprice offers high quality electronics with the best performance for your dollar, hands down.

Here's a close-up shot of the head unit and its mounting point on the aluminum body. The aluminum body appears to be cut from a single piece of extruded aluminum - the screws thread themselves into the ribs running along the top and bottom of the body. I was also pleasantly surprised to find, during scratch tests, that the plastic's mirror finish is not painted on, but instead penetrates the entire unit. That must be why it handled high-stress scratches without flaking or peeling. Nice attention to detail from Monoprice's design engineers!

Warning: hacking things open can sometimes be dangerous. When I was testing voltages on the LEDs, I burned myself on the surface-mount resistors as they dissipated heat. Some amount of heat is to be expected any time there's a power resistor being driven, but leaving the LEDs on for 60 seconds brought the lighting PCB from an ambient 17.6 to 54.4 °C on my IR thermometer! This doesn't strike me as a fault or design flaw - after all, high power LEDs need heatsinks - but definitely something to be aware of for anyone pulling their units apart!

I wish I could comment on things like soldering quality or circuit design merits, but I'd be way out of my league. I'll leave those comments to others more qualified and simply say that the entire board looks clean and well-fabricated.

Use as a DIY Power Platform During my teardown and reviewing process, I began to realize just how approachable this unit is. That approachability itself is a feature - there are lots of people who buy things just to use the goodies inside for other purposes. The easy disassembly, excellent pricing and simple electronics are a perfect platform for DIY hackers to use this as a ready-made project kit! Need a power supply for a robotics project? How about one that provides a regulated 5V line, comes in a rugged aluminum case, lasts for hours, recharges safely and comes pre-built by professionals for only $17.99! Seriously guys. People need to know how awesome this is. The power supply of your next robotics project could be as simple as a screwdriver and a hookup wire.