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GreatShield PowerTank 10400mah Compact High Capacity Power Bank Portable External Battery Charger Pack (Dual 1.0A/2.1A USB Output with Metal Casing & LED's) - For iPhone 6 5s 5c 5, iPad Air mini, Galaxy S5 S4, Tab 2, Note 3 4, LG G3, Nexus 5 6, HTC One M8

    • Old price:$79.99
    • New price:$39.99
    • Percent off:-50%

Customer Reviews

Product Reviews

This is a powerful battery pack with a lot of features and it is packaged very professionally!

Length:: 5:34 Mins

This battery pack is beautifully packaged with a wraparound blue metal case and with white ends on it. It is a powerful battery pack rated at 10,400 mAh of capacity and capable of charging two devices simultaneously. I put together a video of the unit and the test results for your review.

The exterior shell is aluminum that looks fantastic. The battery weighs in at 10.5 ounces. The battery pack has two USB output ports that output 5 VDC at 1 Amp and the second one outputs 5 VDC at 2.1 Amps. This is ideal to allow you to charge two devices at the same time and one of them can be a tablet that requires 2.1 Amps to charge quickly.

During the testing the temperature of the battery pack never even exceeded ambient room temperature. To start your device charging you connect it with the proper cable and press the battery pack power button and charging starts. The charging will stop automatically when your device is fully charged or the battery pack is depleted.

This battery pack also features a dual LED flashlight built in that can stay on for up to 700 hours when the battery is fully charged. This is ideal for when you travel to have an emergency light in a hotel room, when looking for your keys or when in a dark movie theater.

This product is good and I rate it at 5 stars. If you are a business person or a student and have to depend on your tablet or smart phone for long periods of time without the ability to get to an AC power source then this is a good battery to own. This is good for those who travel a lot or camp out. Now you can watch your movies or listen to your music on those long airline flights.

You should note that I did not operate my tablets while I charged it. When I test a battery I do an extensive set of tests that fully charges the battery and then I use it to charge devices and make sure that it is fully depleted when my tests are done. I time each test and document the results as the test progresses. I then calculate the mAh of capacity that the battery supplied and I then calculate its charging efficiency. This process takes from 3 hours to, in very large batteries, about a day for testing. I don't take any short cuts or guess and every battery has these tests performed on it and documented. This is to assure that the battery is tested and it performs well. If a battery has performed poorly I then run the tests again to verify the results.

Items in the box:

* The GreatShield 10,400 mAh battery
* The battery pack comes with an instruction manual
* A USB to Micro USB charging cable that is 31 inches long
* It does not come with an AC wall charging adapter.

GreatShield 10400 mAh External Battery Pack Features:

* There are two USB power output ports and they are USB 1 rated at 5VDC at 1 Amp, USB 2 rated at 5VDC at 2.1 Amp for iPads and tablets.
* Press the ON button when you plug in a device and that begins the charging process of your device. There is an automatic OFF when your electronic device is charged.
* The battery pack uses Lithium-Ion battery technology and premium Samsung battery cells
* The battery pack can be recharged 500+ times
* Warranty is 18 months
* Powerful 10400 mAh capacity
* The unit is compact and weighs in at 10.5 ounces.
* Attractive design with nice white exterior and surrounding metal enclosure
* It has 3 blue LED status lights located on the side that indicate the battery charge level. One LED flashing means 0 to 10%, one LED on means 10 to 33%, two means 33 to 66%, three LEDs means 66 to 100%.
* When the battery pack is fully charged the three blue LEDs are on continuously while it is plugged into the AC power outlet.
* When pressing the power button or charging a device the LEDs light showing the amount of power still stored in the battery pack.
* The battery pack does not come with an AC wall charger.
* Charging it with a USB 2.0 port on your laptop or computer is not recommended by me as the battery would take too long to fully charge. (Approximately 20+ hours (Minimum) with a 500 mAh USB 2.0 Port.)
* It will take 10+ hours to charge the battery pack with a 5 VDC USB rated at 1 Amp.
* The battery pack can output 3.1 Amps max at one time so it can charge two devices simultaneously.
* The unit has a dual LED flashlight that can be turned on by quickly double pressing the power switch. It can be on for up to 700 hours continuously. You turn it off by double pressing the power switch again.

Charging my devices:

I charged the battery pack fully before I started my test. I started with a Kindle Fire charged at 1% and the GreatShield was fully charged at 3 LEDs.

* 30 min 23% and the battery pack was at 3 LEDs
* 60 min 44% and the battery pack was at 3 LEDs
* 90 min 64% and the battery pack was at 2 LEDs
* 120 min 83% and the battery pack was at 2 LEDs
* 150 min 95% and the battery pack was at 2 LEDs
* 180 min 100% and the battery pack was at 2 LEDs

I then charged an iPad 2 that was at 31% and the GreatShield battery back was at 2 LEDs.
* 30 min 44% and the battery pack was at 2 LEDs
* 60 min 56% and the battery pack was at 1 LED
* 90 min 68% and the battery pack was at 1 LED
* 120 min 77% and the battery pack was at 1 LED flashing and dead.

Summary of charging tests:

*Charge 99% of a kindle Fire = 4400 mAh x 99%= 4356 mAh
*Charge iPad 2 46% x 6944 mAh = 3194.24 mAh
*4356 mAh + 3194.24 mAh = 7550.24 mAh/10400 = 72.6%. That is a good result for this battery.

Here are some common devices and the amount of mAh of capacity they have when they are fully charged. This is just to give you an impression of how much energy it takes to charge your smart device:

* iPhone 4 battery 1,420 mAh battery capacity
* iPhone 4S battery 1,432 mAh battery capacity
* iPad 2 battery 6,944 mAh battery capacity
* iPad 3 battery 11,560 mAh battery capacity
* Kindle Fire battery 4400 mAh capacity
* Kindle Keyboard battery 1750 mAh capacity
* iPhone 5 is 3.8 VDC at 5.45 Wh = 1434 mAh battery
* iPad 4 battery is 11,486 mAh 3.7 VDC at 42.5 Wh
* iPad Mini battery is 4490 mAh at 3.72 VDC 16.7 Wh

When using an external battery you have to allow approximately 30 % of the battery capacity will be lost to heat, voltage conversion, powering the batteries electronics and the electronics of your electronics device's charging circuits. In addition you have to consider that your device is not truly off like a cell phone is still connected to the WIFI and phone networks and probably receiving emails, etc.

Real world examples of charging capability with this battery pack:

* iPhone 4 or 5 approximately 5.32 full charges out of a fully charged GreatShield 10400 mAh battery pack
* iPad 2 approximately 109% of a full charge
* iPad 3 or 4 approximately 65.3% of a full charge
* iPad Mini approximately 168% of a full charge
* Kindle Fire approximately 171% of a full charge
* A normal estimated usable storage is 70% of capacity or .70 * 10,400 mAh = 7,280 mAh charging capacity available for your electronic devices is considered normal for these styles of battery packs.
* In my testing I was able to use approximately 7550.24 mAh of capacity or roughly 72.6% of the 10,400 mAh capacity. This is a good result.

I received a sample product for evaluation and I promised to provide a fair and honest review.

Capacious, Elegant and Portable External Battery
The bottom line on the GreatShield battery is this: it works. In the past I've tried several different reserve power supplies for my gadgets, and I have had mixed results. However, there is no ambiguity about this battery: it's large, effective, versatile and well designed. It's one of the largest external battery that I've come across in terms of capacity (with impressive 10,400 mAh of charge), and yet it's much smaller in size than some of its larger near-competitors.

In order to test this battery charger I decided to completely drain my small electronic devices so that I get as clean of an idea of this battery's efficiency as I can. (As an aside, when you really want to discharge them, the consumer electronics has become really robust in recent year. It took me much longer than I thought it would. I had to blast music from my iPhone for hours and hours ...) I discover that I was able to fully charge all of my small electronic devices with plenty of power to spare. Most of them I was able to charge several times, and thanks to dual USB ports, was able to charge up to two devices at once. Full charging usually takes between one to two hours. I've tested this battery with iPhone 4S, iPhone 3G, Kindle Keyboard, Mobee Magic Bar, Jabra SPORT Bluetooth Stereo Headset, and the first generation iPad (32GB, Wifi + 3G). Oftentimes I was able to fully charge four or five devices with just one fully charged GreatShield battery. I was also able to charge my iPad to completely, and even charge it to almost half its capacity the second time around. If there was an easy way of connecting this battery to an ultrabook I would not be surprised if it would be possible to charge it to a decent amount as well.

The battery comes with a micro USB cable that allows you to charge it by either connecting it to a computer or a stand-alone USB charger. I think this would have been a much more effective product if it had two additions that some of its competitors already incorporate into their batteries/power banks: incorporated wall-outlet prongs for easy charging, and a permanently attached retractable micro USB cable. These two additions would make this battery stand out in the already very crowded field of external batteries/chargers.

This GreatShield battery is also beautifully designed. You would not be ashamed of being spotted with this battery at a trendy tech conference. The battery is very easy to use and operate, and overall vey intuitively designed.

Great Multi-Device Charger!
Product as described. With power outages, I know this charger will be very helpful! Also got it for when I'm traveling -- you never know when you'll need it until you wish you had it with you. Love the flashlight feature as well.

Excellent performance with Nexus 7 Tab, Galaxy Nexus Phone, Samsung Galaxy 7.7 Tablet and iPad Mini

Length:: 0:10 Mins

I am using GreatShield PowerTank 10400mah with Nexus 7 Tab (running ICS 4.3), Galaxy Nexus Phone (running ICS 4.2), Samsung Galaxy 7.7 Tablet (running ICS 4.0.4) and iPad Mini. Overall, this battery pack performs very well. It provided one of the best performances across the 4 devices compared with the other battery packs I have used. You can find the details of my tests below.

➨ General features:

GreatShield PowerTank 10400mah weighs 10.7 oz. Its size is 4.25" x 3.125" x 0.876". It has nice rounded edges and comes in Cyan blue and Grey colors. I thought it looked sleek and felt well made.

This external battery has 2 USB output port, labelled 5V1Amp and 5V2.1Amp. The package includes 31" USB to micro USB cable and a carrying pouch. Galaxy tab connector and lightening cable for iPad Mini are not included. The battery pack a double LED flash light built into it. To turn on the flash light you need to push the on button twice in in quick succession. Another double press will turn the flashlight off. The flash light is not very bright, but I found it handy to use in the car while driving at night without creating too much glare for the driver. The indicators on top of the battery pack indicate the charge level. When all three indicators are on the battery is fully charged.

When power bank is charging the output function (i.e. using the power bank to charge another device) does not work. This has not been the case the other external batteries I have tested, but I never use my external packs while charging them so it was not a significant difference for me.

➨ How I tested this battery pack:

I received this power bank from the manufacturer for an honest review be it positive or negative. Top reviewers are often asked to review new battery packs and one of the benefits of being asked to test different power banks is that it gives me an opportunity to compare them to each other using the same charging test, so I can compare them using "apples to apples" comparison. This set of tests allows me to provide unbiased results comparing the performance numbers.

My methodology is to charge each mobile device on each port of the unit for 10 minutes and measuring how much each unit was charge in that 10 minute period. In addition I tested charging two mobile devices at the same time. Each line in the table below represents a separate 10 minute test.

I use Battery App by Elvison to determine how each device recognized the charging source. 'AC' status means the charging is at full charging rate. 'USB' status indicates charging at a lower charging rate. 'Discharging' status means that the charging rate is below the power that the device is consuming so it slows down the discharge rate but does not re-charge.

➨ Test Results:

✔ Samsung Galaxy 7.7 tablet (using my own Galaxy tab connector cable)
Port 1A unit: AC ~~~~~~ 3% change in charge in 10 minutes
Port 2.1A unit: AC ~~~~ 4% change in charge in 10 minutes

✔ Nexus 7 Tab
Port 1A unit: AC ~~~~~~ 3% change in charge in 10 minutes
Port 2.1A unit: AC ~~~~ 3% change in charge in 10 minutes

✔ Galaxy Nexus Phone
Port 1A unit: AC ~~~~~~ 5% change in charge in 10 minutes
Port 2.1A unit: AC ~~~~ 6% change in charge in 10 minutes

✔ iPad Mini
Port 1A unit: AC ~~~~~~ 3% change in charge in 10 minutes
Port 2.1A unit: AC ~~~~ 3% change in charge in 10 minutes

✔ Galaxy Nexus Phone and Nexus 7 Tab at the same time
Port 1A unit: AC ~~~~~~ 6% change in charge in 10 minutes (Galaxy Nexus Phone)
Port 2.1A unit: AC ~~~~ 3% change in charge in 10 minutes (Nexus 7 Tab)

Port 1A unit: AC ~~~~~~ 4% change in charge in 10 minutes (Nexus 7 Tab)
Port 2.1A unit: AC ~~~~ 4% change in charge in 10 minutes (Galaxy Nexus Phone)

➨ Key finding:
✔ This external battery worked very well for all 4 devices I have tested. It was one of the fastest external packs I have tested. I also liked that it stayed totally cool charging all devices. All factors considered this external battery earned a 5 star rating.

Ali Julia review

Small but Mighty
In the middle of a conversation your cell phone gets a low battery warning... Plug it in to the Power Tank!!! Half way through your second movie on a long flight you get a low battery warning...Plug it into the Power Tank. Just a little thicker than you phone. Will really save the day. Solves a common problem.

Lifesaver!!! Literally!!!!! YOU NEED TO READ THIS REVIEW
My husband had purchased one of these power tanks to have as a back up charger for our family. We go camping a lot and of course we have smart phones which their battery's drain extremely quickly as we all know. We use it all the time for our cells, cameras, e-cigs and various other items that are charged with a USB or a micro USB and it has two ports so you can charge two items at the same time. The back up charging power tank lasts an extremely long time. I had mine fully charged and using it to charge our devices our entire camping trip which was 4 days without it dying on us. I actually used it to charge my cell phone for the rest of the next week and it didn't die. I eventually did plug it in and charge it but the device at that point was still charging anything I plugged into it.

Very impressed with the charging capabilities. This item is universal and charges almost any device.

**Here is the life saver part**
Now I forgot we had it in our SUV this winter because we had not been using it since summer.
Well we live in southern MN and this winter was insane. Blizzards and crazy amounts of snow with arctic temperatures, it's been crazy as well as dangerous.

We were driving home from my parents house for Christmas, they live about 100 miles from us and as we were almost halfway home the road conditions quickly deteriorated. One minute we could see the road the next minute there wasn't a road and it was just white. We quickly decided we needed to get off of the highway. This highway we were taking is a road that is not traveled as much. So traffic was far and few but none the less without being able to see we needed to pull off for safety.

So my husband pulls off at what we thought was the next exit road and it turned out to be a ditch. With a combination of the no visibility and icy road conditions we ended up deep in the ditch. This was a very deep ditch and we were not visible from the road now as well as we were trapped in our vehicle from all of the snow we were now in. It literally came up past our windows.
My phone had died before we left my parents and our car charger was in our other vehicle because the charger in that vehicle had died previously and I just forgot to put the charger back in our SUV.
I knew my husbands phone was almost dead at that point from using it to GPS the road conditions. So I go to call for help from his phone and of course as soon as I press call it died.
Our 6 month old son was with us in the car, even if anyone drove by they couldn't see us from the road, we couldn't get out of our vehicle and if we did get out the air temperature was -34 F and the windchill made it -50. That is frostbite within 5 minutes.
Both of our phones being dead I started to look around in our SUV for supplies. That's when I realized we had our Great Shield Battery Pack!
I was concerned it wouldn't have a power left because we hadn't charged it since August with our last camping trip and it had been in our car in the cold all of winter so far.
But I pushed the button and the light TURNED ON!!!!!
I was so relieved I could have cried. We were saved!!
We quickly plugged in both our phones turned them on and called for a tow truck and got home safely.

This GreatShield Power Tank saved our lives. LITERALLY!!

Thank you!

The GreatShield Power Tank is outstanding. It fits in my portfolio and keeps my phone and pad charged for those days when meetings are long and plugs are few. Holds it's charge for days. I've recommended this to 10 friends already. Great buy!

Great item at a great price
I actually bought this item as a gift for my girlfriend. I let it charge overnight and decided to see if this item was worth the money. I put my kindle and my phone on it, both I purposely let go dead, to charge. I had 100 percent charge on my phone in no time and though the kindle took some time, it did get it charged. When I was done I noticed that I was still on 3 bars, so I ran the experiment a few times. It took two charging cycles of both items to make it lose one bar. I'm sold. I am gonna purchase another one soon.

love, love, love it
I purchased 2 for Christmas presents but decided to try it out before I gave them away. It took a long while (overnight) to charge the charger itself but it is over 10,400 mah so I figured it was normal. I used it on my cell phone with a 1% charge each time and it took about 2 hours to charge to 100% but the best part is that I have charged it 3 times to a full charge and it barely went down one bar (it has 3 bars to show charge capacity). It is awesome so far. I would recommend highly. love, love, love it.

Great buy
Great product! Worth the money! Easy to use and charges faster than you would expect. Could not ask for a better product.


Technical data

  • High capacity rechargeable power bank is perfect for power-hungry smartphones, tablets and other devices - Reliable and stable lithium polymer core ensures longer battery life supplying more than 500 charge cycles
  • Dual charging USB ports lets you you charge up to two devices simultaneously - One 1.0 amp USB port and another 2.1 amp USB port allows for a maximum of 3.1 amps of total output
  • Built-in short circuit, over-charge and over-heat protection allows for safe, fast and reliable charge while on the go
  • Three LED lights work as charge indicators to show battery level or charging status - Convenient built in dual-LED flashlight provides light when you need it
  • Slim compact design with a hard, metal casing and LED lights


Product Description

GreatShield PowerTank charges up to two devices simultaneously with its dual 1A and 2.1A charging ports for 3.1A total output charging ability. Made with an aluminum casing and weighing in at 10.5oz and only 0.85 thick, the lithium polymer PowerTank supports over 500 charge cycles. It made with a built-in short circuit, over charge, and over-heat protection.

With 10400mAh capacity, your battery life will be extended by:

Apple iPhone 6/6 Plus/5/5S/5C/4/4S: Up to 5x complete charges
HTC One, Samsung Galaxy S4/S3: Up to 3x complete charges
Samsung Galaxy Note 3/2: Up to 2.5x complete charges
Apple iPad 4/3: Up to 0.7x complete charges
Apple iPad 2/1: Up to 1x complete charges
Apple iPad Mini: Up to 1.5x complete charges
Apple iPad Mini 2 with Retina Display: Up to 1.15 complete charges
Google Nexus 7: Up to 1.75x complete charges

GreatShield 12 month Limited Replacement Warranty

Product Specification:

Capacity: 10,400mAh
Maximum charging current: 1000mA - 1200mA
Storage temperature: -5F - 110F
Output: 5V/2.1A & 5V/1A
Input: 5V/1A
Size: 4.33x3.13x0.85in

Package includes: GreatShield PowerTank, Micro USB Charging Cable, Microfiber Pouch, Instructions (Charger/Adapter is NOT included)

Compatible with:
Apple - iPhone 6/6 Plus/5/5S/5C, 4/4S, iPad 2/3/4 mini 2, iPod Nano, Touch 4th/5th Generation (Lightning and 30-pin cables not included)
Samsung - Galaxy Note 3/2, S3/S4, S2 Skyrocket
Google - Nexus 4, 7 & 7FHD, 10
HTC - One M7, M4, EVO 4G, Thunderbolt, Incredible, Droid DNA
Motorola - Atrix, Droid, Moto X
Sony - Xperia series
Nokia - Lumia series
LG - Optimus series
And More!

NOTE: NOT compatible with Asus Transformer tablets and Galaxy Note 10.1

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