It's come to my attention that many people don't really understand what they are buying when they buy a power bank, also known as an external battery. So I'd like to start with a brief class on what a power bank is and what the various terms mean that are used when discussing them. If you're already an expert on this topic, please skip the next paragraph to read my experience with this product.
A power bank is nothing more than an external battery that you can use to power and / or charge just about any device that has a cord that connects to a power source via a standard USB port. They come in a variety of shapes and sizes, but there are really only three things to look for when looking at performance. One is the number of USB ports on the device, another is the amperage (listed in milliamps or amps) available through each port and lastly, the total amount of energy stored in the battery, which may be referred to as "capacity" and the units are usually referred to in milliamps per hour or mAh. If you have a newer Android smartphone or tablet that you want to charge, then you want a power bank that offers a 2 amp USB port. If you have an iPod or iPhone, you can get away with a single 1 amp port, but I always recommend having at least one 2 amp port. A power bank with more than one port will, in theory, allow you to charge more than one device at a time. The thing to keep in mind when shopping for a power bank is that manufacturer claims are often inflated to at least some degree. The most often exaggerated feature is the mAh capacity of a power bank. Capacity is important because more capacity allows you more device "up-time" per charge on the bank.
Over the past year, I've been asked by a variety of sellers to test and review their power banks, and while I always did my best to accurately review each item, it was impossible to get precise, quantitative data on the performance of the banks because the only way to do so is if you have proper testing equipment. You can give anecdotal evidence like "It charged my tablet quickly," but you really can't measure the mAh capacity and the amperage put out at the USB ports with any kind of accuracy. I recently acquired testing equipment that allows me to get precise and accurate data regarding the capabilities of a power bank or charger; and I have to admit I'm excited to finally know without a doubt that I'm giving accurate information about a product.
All that being said, here's what I found with this Eachine power bank...
I received my sample of this product and fully charged it. Then, using a Centech USB Power Load Inducer
and a Centech USB Power Meter
to verify output, in conjunction with a Portapow power monitor to measure total power consumed, I placed 2.0 amp load on the power bank, and it took about 47 minutes to overload and turn off. I turned the unit back on, placed a 1.8 amp load on it and it took about an 80 minutes to kick off. I turned the unit back on, placed a 1.5 amp load on it and it ran until all energy was depleted. At the end of the test, the Portapow power monitor indicated the power bank had put out a total of 6,942 mAh (at 5 volts). I charged the unit back up and ran the test again, this time with just the monitor and the load inducer drawing 1.5 amps, and after putting out 6,860 mAh (5 volts), the bank was completely drained. After recharging, I tested the 1 amp USB port and it did handle 1.0 amps for over ten minutes, when I ended the test.
Power banks use a 3.7 volt battery, as do most cell phones, to understand the results, we have to convert the mAh test results from 5 volt (USB standard voltage) to 3.7 volts. When we do this, we find that this power bank puts out an average of 9,325 mAh, or roughly 90% of stated capacity. Because of the voltage conversion and other factors involved, there will always be some energy lost, so no power bank will put out 100% of stated capacity to the device to be charged. So in summation, this power bank is capable of putting out 2 full amps, but not indefinitely and even 1.8 amps will overload the bank after a time. Still, this is common with power banks and I'm not going to gig the rating for that. I like the looks of the unit. Having a power button helps keep the bank from slow draining when not in use, and the blue backlit LCD screen indicating percent of power remaining and charge status is definitely a big plus. 9,325 mAh at 1.5 or 1.8 amps is enough to greatly extend the battery life of a tablet, and charge pretty much any phone several times. This Eachine power bank comparatively does an excellent job. In fact, considering the "curve", it deserves five stars.
********** Complimentary Product Received for Testing and Unbiased Review **********