Find a Good Quality Power Bank?

 When it comes to batteries there's a lot of specs for example
if you are looking for longer use out there, the larger the AmpHours or mAh the more power is stored there. Some will debate if the numbers are believable but let's go with what is in your post. I'd get the larger 7000mAh unit for this and one more reason.
Second reason. The life span of these things is finite. Only so machine charge cycles so a bigger battery will get more work done over time and have a longer life span compared to a smaller battery.

for a Galaxy Note 3, with a 3200mah battery. 50000 mAh is huge. A 10000 mAh is sufficient and it is not the capacity that makes a power bank charge a smartphone fast rather the input current rating. When it is 2.1 A at 5 V, you would find it better/faster charging your phone than a 1A 5V rating provided the smartphone has a 2.1A current drawing ability.

Google Nexus, specifically, has approximately a 3220 mAh battery. Power banks will typically start around the 5000 mAh range and get higher. If you're to purchase a 10,000 mAh power bank, you will essentially be able to charge your phone 2.5 times before you need to recharge the bank.


You can always get a higher capacity power bank, but with higher capactity comes bigger physical size, longer charge times, and higher cost. For a decent 10,000 mAh power bank, you should expect to pay in the $20 range.