After months of evaluating my XYL’s iPad and then buying and returning a Kindle Fire HD, I finally settled on a Nexus tablet and started downloading and reading books on it via Kindle.
I also use my smart phone as a mobile hotspot at times so that I can go online with the Nexus when I’m away from my home router.
All this eats up power of course so I recently ordered a highly-rated battery pack/charger to power these devices.
At just under $50, the Anker Astro E4 is cheaper than an extra battery for my phone and offers the added flexibility of being able to power just about anything that can accept power from a USB port. It also comes with three jacks, one of which is for iPads.
I haven’t opened the charger up so I can only speculate about what’s inside – two Li-Ion cells and a DC-DC converter.
The specs for the Anker say that it will provide an output of 5VDC at 2 amps and would do so for 6-1/2 hours. Of course that’s too good to be true…and it isn’t true, but I still like the device and consider it well worth the money. On a single charge, it will completely charge my smart phone three times. Or my phone once and my Nexus once. It will even charge them simultaneously at a slower rate.
My impetus for buying this thing in the first place was to be able to power my Nexus and the XYL’s iPad on our flight to Hawaii. We’d both downloaded movies to watch, books to read and MP3′s to listen to during the long flight and I didn’t want us to run out of power.
The Anker filled the bill and I was looking forward to measuring its actual capacity once I got home. The results of tests with my West Mountain Radio battery analyzer are a bit surprising.
In the graph below, the green trace represents a 1-amp discharge rate and the red trace represents a 2-amp discharge rate. Neither discharge rate delivers 13,000 mAH nor do they indicate curves typical of Li-Ion batteries. Clearly there is a DC-DC converter or something similar at work. But what determines end-of-life for a charge? A timer?
Regardless of discharge rate, actual capacity of this battery pack is about 9000 mAH.
Note also that the higher discharge rate of 2 amps produced power for a longer period – and a higher capacity.
Despite not meeting its claimed specs, I very much consider it worth the money spent on it.