One unique feature of this external power pack is that it has a micro USB cable built into the side of the unit (see attached photo collage). It pops out of the side on a coiled cable, so if your mobile device takes a micro USB connector you don't need to carry any extra cables. This built-in cable delivers very rapid charging. It gave me faster charging than my own charging cable (see test results below). The power pack also has a port which allows you to connect other connectors, so it works with devices that have proprietary connectors as well.
This external battery pack is very compact. It is 3" long, 2" wide, and 0.75" thick. I like its shape. It weighs 4.6 oz. This battery pack has one port. 4 small green LED lights indicate the charge level.
I tested Lumsing 5200mAh external battery pack with Samsung Nexus phone, Samsung Galaxy 7.7 tablet and iPadMini. For testing Galaxy tab and iPadMini I used my own charging cables as the adapters for these devices were not included.
I tested the power pack both with a built-in cable and my own charging cable (using the Nexus phone which takes a micro USB charging cable). I saw much faster with a built-in cable, so for the devices that take a micro USB charging cable the built-in cable is the best choice.
I own a number of external batteries and to compare them I run the same set on tests on each of them, so they can be compared to each other using "apples to apples" comparison. This set of tests allows me to provide unbiased comparisons between different external batteries. For those who are interested in the details of the test I include at the end of this review.
★ How I tested this battery pack
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I use a USB current monitor and a charging test to test each port. The current monitor shows the voltage and the current flowing between the battery and the device.
The amount of energy transferred from the charger to the device is calculated by multiplying voltage and current. Most of the chargers are 5V devices and most devices show the voltage very close to 5V. The interesting number is the current as it varies from unit to unit and from port to port.
The current varies based on what the device requires and what battery provides. This communication happens using different protocols depending on OS. Newer Android OS versions have adapted their protocols to get better performance from ports aimed at Apple devices. An addition variable for Android devices is whether a data cable or charging cable is used to charge the device. The charging cables short the two data connections together (rendering them useless for data transfer), but this fools devices to see the cable as an AC power connection, and thus accept the higher current of the charging source.
The 10 minutes test consists of charging each mobile device on each port of the battery pack for 10 minutes and measure how much each unit was charge in that 10 minute period. Since the charging speed is non-linear I start charging each device from approximately the same charge level. 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:
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✔ Samsung Galaxy Nexus Phone
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AC charging rate ----- 7% change in charge in 10 minutes (built-in cable)
current monitor: ~~~~~ 0.92A and 4.99V (built-in cable)
AC charging rate ----- 4% change in charge in 10 minutes (my own cable)
current monitor: ~~~~~ 0.84A and 5.02V (my own cable)
✔ Samsung Galaxy 7.7 Tablet
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AC charging rate ----- 8% change in charge in 10 minutes (my own cable)
current monitor: ~~~~~ 1.01A and 4.75V (my own cable)
✔ iPadMini
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AC charging rate ----- 3% change in charge in 10 minutes
current monitor: ~~~~~ 1.03A and 5.02V
★ Summary
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This pack showed impressive performance especially with a built-in cable. The small size and the built-in cable make a great charger to have along as an emergency power back up.
You can find it on Amazon by following this link.
Ali Julia review ★★★★★
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