Portable USB Power Bank (min. 10000 mAh)
With today’s technological and communication needs, you might as well carry a Portable USB Power Bank. I recommend one that has between 10000mAh to 26400mAh capacity.
I personally carry the Anker PowerCore II, 10000 mAh battery as it is small, light and can be fully recharged using a portable folding solar panel, and offers up the Qualcomm 2.0 fast-charge technology which seems to charge my iphone a bit faster than non-fast-charge power banks.
Power Banks can obviously be used 24h a day, specifically in the evening, when you want to re-charge your devices. Needless to say, you should also carry the following its with the Power Bank:
- the appropriate short-length (less than 2 foot; 6″ to 1 foot) charger cable for your mobile phone
- the charging cable (typically a micro USB) to recharge the actual power bank
- a quick charge (min. 2.4A) compact wall charger, and
- a quick charge (min. 2.4A) car charger
Anker, RAVPower, and PrimeCables are all good reliable brands for all of these items. The Qualcomm 3.0 charging spec is today’s leading industry high-speed charging standard designed to push up to 3.0A of power into your device (fully charges most phones under 1 hour), although 2.4A chargers are the most cost-effective at this time.
AN IMPORTANT NOTE ON RATED CAPACITIES (10000mAh, 26400mAh, etc):
The dirty little secret that most consumers do not know is that the industry standard output for portable power banks is measured at 3.7V, while smartphones (samsung, iphone, etc) draw power at 5V.
So, in order to charge the phone, a power bank must convert 3.7V to 5V, otherwise known as the “boost conversion rate” factor which is calculated simply as: 3.7V / 5V = 0.74
This means that the 10000mAh power bank is actually a 7400mAh power bank when outputting at 5V.
The second important secret is that this conversion does not come for free. There is an inherent power loss on the PCBA (printed circuit board assembly), or the “electronics” in the power bank — meaning the circuitry is only between 85% to 92% efficient in doing this power conversion. This actually makes the 10000mAh –> 7400mAh power bank capacity further reduced to around 6500mAh (7400mAh x 88%). The power conversion percentage varies among manufacturers (a marketing feature of the product), while the boost conversion rate factor is a mathematical constant.
So while there’s no false advertising happening, the lack of consumer knowledge makes some customers think they are being shortchanged because they feel that the power bank they just purchased is not performing or lasting as long as expected. With that said, any “slim” or cylinder-style (single “premium” battery) power bank with a nominal rating of 3300mAh or less should never be purchased, no matter how attractive the price point, since it will offer at best, only a meager single smartphone charge or less (3300mAh x 0.74 x 0.88 = 2100mAh)
To calculate how many times your phone can be re-charged, lookup you phone’s battery capacity in mAh and divide that into the adjusted power bank number. In our 10000mAh –> 6500mAh example, an iPhone 8 Plus 2675mAh battery can be recharged 2.4 times (and not 3.7 times) with a typical 10000mAh advertised power bank.
Caveat emptor — do your homework, and use those Grade 4 math skills to get the appropriate power bank you need.
