[Review] - Coocheer® 7500mAh Rugged Water Resistant Power Bank


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Feb 12, 2012
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As anyone who has followed my posts knows, I keep a spare charged battery with me, so that I don't have to hug a wall, and I don't want to drop the battery in my phone below 40%. And you also know that I keep my phone in an Otterbox Defender case. This has worked out for a long time, but opening the case on my lap (especially sitting in an airport lounge chair you're already sliding out of) to change the battery does get old.

I've been using the Coocheer 7,500mAh Power Bank for a few weeks. Much easier, just plug it into the microUSB connector on the phone. Why the Coocheer? To be completely honest, and in the interest of full disclosure, they contacted me and asked if I would review the power bank for them, and I get to keep it. Also, those of you who have been reading my posts know that I despise dishonesty, whether it's by a repair shop or a reviewer, so a $24 power bank isn't going to make me lie to you. You also know that I'm not easily impressed. I've stated my opinion of rave phones like the S6 - yawn - more than once.

That said, here goes.

When you first get the power bank, it's in a plain padded envelope. Normal, so far. Opening the envelope reveals the standard "box in a printed sleeve" packaging.

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Again, normal for the type of product. The sleeve is a little tight to get off intact (which I tried to do in case I had to take another picture later) but it's packaging and you're going to throw it in the trash.

Taking the box out of the sleeve, you get

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Again, the normal pull out the tab, pull out the end, open the box packaging. When you open the box, you find

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A plain piece of cardboard, folded to make compartments. They aren't wasting money on fancy packaging you're just going to throw out, they're spending it on build quality - and if you hold this power bank in your hand you'll know what the phrase means.

At this point, you're going to take the power bank out of the box. Careful - it's heavier than it looks. I've looked at and handled power banks of this capacity in stores. Plastic thin enough to make me careful not to hold them too hard. Very light. Not this one. Squeeze it all you like, but don't drop it on a bare toe - you'll probably break your toe. It's not too heavy to throw into a pants pocket (or purse I guess, ladies, although I've never carried one), but it's not a lightweight. It weighs over 9 ounces and it's only 4.5" X 2.7" X 1". Small but solid.

Oh, did I mention that it's solid? (I didn't say I'm never impressed). I won't drive over it - it may not withstand that kind of abuse, but it sure feels as if it would. This feels like a solid block of aluminum with what feels like silicone rubber around the edge. (Cellphone manufacturers - if you want to know how to give your phones "build quality" feel, buy one of these - it feels expensive. Not just the unexpected weight, but the touch and solidity of the power bank itself and the ports.)

It also says it's water resistant. I won't give it a bath (again - I want mine to keep working), but I've had it hanging from my belt when I got caught in one of the North Carolina Sandhills "afternoon showers" - expecting Noah to come floating by on the ark any minute. (It's the kind of rain that wets you to the bone in about 10 seconds and they issue flash flood warnings across the bottom of the TV screen as the storm approaches - but it's over in 15 minutes.) The power bank didn't just get drenched, it got drowned. And it's still working.

So how does it work? On one end is a flap, and under the flap are 3 ports, 2 USB ports, 1 with 1 dot, one with 2 dots, and a microUSB port.

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The one dot port, the one in the center, is the 1 Amp port, the one on the end, with the 2 dots, is the 2.1 Amp port. The microUSB port is evident. Those of you reading my posts also know how I feel about microUSB ports. It's so great that a shop no longer needs 62 chargers to cover all phones, but the microUSB port is too flimsy for every-day use. Not this one. Plug the cable in (an 11" cable comes with the power bank - please use that for charging both the power bank and the phone - the longer a cable is, the more copper it has to have to handle the same amount of current, and a cheap 2 foot cable may be too thin [the wire inside, not the cable diameter itself] to handle 2 Amps without dropping enough voltage that you aren't really getting 2 Amps - it's basic electricity, and nothing any manufacturer can change, except to make the cable short and/or thick enough to work properly) and wiggle it. Try to. It's in there solidly. Again, it's something I won't try, but (and the microUSB plug on the cable is good quality) I think that if you applied enough pressure, the plug would break before you caused any problem with the port.

And I'm not easily impressed. This end of the power bank is another thing about it that impressed me.

Oh, that little white thing on the left end? That's a flashlight. It's there if you need it, and you certainly have enough power to run one. Press the power switch and hold it for a couple of seconds and the light comes on. Do it again and it goes off. Not a super aircraft beacon, but it'll let you find the key hole on a dark night.

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Now, what about how it does what it does? When you first get the power bank it will probably be fully charged. How will you know? It has indicator lights.

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As you can see, one light is lit. That means about 25% charge (which I don't normally do, but this was during testing). If all 4 lights are lit, that's 100%. Plug it into a USB port or charger for half an hour. (Read my The Care and Feeding of Lithium Polymer Batteries guide to find out why you have to charge a lithium battery to more than "100%". That will ensure that the power bank is fully charged. Make it a habit - 15-30 minutes after "100%" is reached for any lithium battery larger than 100mAh. Maybe some company will come out with a "rate of change" charging chip, so it won't cost manufacturers a lot to give us a real 100% indication. [The battery is really at 100% when the voltage on its terminals stops rising during the constant current phase, which takes a little computer in the charging chip to do - in quantity it would probably cost manufacturers about 10 cents more per chip.])

Now for taking power out of the power bank. It holds 7,500mAh of power. That's how much you can get out of it. Can it fully charge a totally dead 7,500mAh battery? No. Why not? Because energy conversion, in this universe at least, is never 100% efficient. Some conversions, like a well designed electrical transformer, can get close - up to about 98%. Some are designed to have no efficiency at all - all the energy is converted to waste heat - like the brakes on your car. Charging a lithium battery is electrical to chemical conversion and, while I don't have a theoretical physics degree, and they didn't know about lithium batteries when I got my electrical engineering degree, I'd guess that the process is somewhere between 65%-80% efficient. That's why, even if your phone is turned off, if it's charging it gets warm. That loss of efficiency means the same as "some of the charging current is being lost as heat". That how the world works. Electrical to chemical (or chemical to electrical) conversion is low efficiency.

But it is nice to have more than 2 full charges for my Note 3 in my pocket when I leave the house, and without having to disassemble the case to get it. I'm a convert.

Any negatives? I have to find something wrong, don't I? I prefer carrying the power bank on a caribiner clip on my belt, not in my pocket. Why? Personal preference - my pockets are usually filled with other things. The smallest caribiner clip I can find that will fit into the lanyard hole (and that's what it was designed for - not caribiner clips) is too small to keep the power bank safe on my belt - a push on the bottom of the power bank and it'll come off the belt - and even then, it's a tight fit for the clip in the hole.

View attachment 187015

Once, and only once out of charging both my Note 3 and my wife's Note 3 many times, I found one slight problem. The power bank has an on-off switch which, of course, you normally keep off. I started by plugging the cable into the phone, then turning the power bank on. As I said, only once, the power bank switched on, then it switched off immediately. I unplugged it from the phone, turned it on, then plugged it in, and it charged the phone. I'm guessing it was the exact power level in the power bank and the exact power level in the phone that caused this. I doubt I'll ever see it again. (I still plug it in first, then turn it on, and it's worked every time.)

Boy, I had to dig for something, didn't I? It's solid, it's pretty water resistant by my test, it works, it's a very handy thing to have, and I'm complaining about 4mm more height on the little loop on top of the case. Sorry, but those are the only things I can find to complain about. Oh, and that I hope they come out with one with a capacity of about 15,000mAh that still fits in a pants pocket - and that I'm asked to review it.

This one wins the Rukbat Seal of "Get One". You'll find it at Coocheer's Amazon page if you want to order one. It's only $23.99 (which is cheaper than I've seen a lot of power banks of the same capacity in cheap plastic cases selling for), so if you don't have Amazon Plus, add something else you need for at least $11.01 and you'll get free shipping from Amazon.

If you order it by July 31, 2015, and use code 8VRGSYJ3, you'll get 15% off. That's $20.39 for 7,500mAh of portable Sherman Tank power.

Edit: Sorry, people, July is gone, so it's back to $23.95.

And if anyone knows of a really thin caribiner clip with a good spring that can clip on to a 1" wide belt, please post a link.
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