Best Mah to weight ratio battery backup for phone

Old list but possibly useful.  As a personal observation that’s a lot of charges.  On a trail like the PCT that would get me about 9 days of heavy use (for me) and about 18 days with conservative use.  Resupply/charging points are available before ever going that number of days.  I would suggest doing some analysis to determine your actual needs, then again maybe you already have.

Battery Stats

Christopher,

The published specifications for all battery chargers are WORTHLESS for determining the actual mAh/oz ratios! There are both charging and discharging losses that diminish the published capacities. To determine actual output capacities, you have to measure them with both an accurate constant current load (2A max which is ~what modern phones can accept) and charge current instruments.

I tested what Amazon had available as of 9/20/15. For an approximate actual output capacity of 6000 mAh, the unit that has the best ratio was the PowerGen 12000 (6364) at a 715 ratio. Other batteries of similar capacity were the PowerAdd 2GS 10,000 (5851 actual) at a 673 ratio; the Waka-Waka Base-10 (6473 actual) at a 568 ratio; and the Kayo Maxtar aka Mobil Power S16 – Gen II (6890 actual) at a 644 ratio.

For what it’s worth: I use a XTorm Power Bank Air, 6000 mAh.

It weighs 125 gram, or 4.4 ounces, fully charged.

To me, that’s the ideal capacity. I can get 3 full charges out of it for my iPhone 6.

I have a Galaxy so I just bought an extra battery that I charge and swap when needed.  Amazon says weighs 32g.

If you look at the fine print, the mAh rating is of the Lithium battery, which is 3.6 volts nominal.  It gets stepped up to 5 volts USB nominal.  Due to the conversion electronics inefficiency and this step up in voltage, the mAh of USB voltage is about half the mAh of the Lithium battery.

All manufacturers do this, so you can at least get an apples to apples comparison.  Though the electronics for one unit may be a little different than another.  I don’t think most people know how many mAh of USB voltage is required to charge their device, so maybe rating USB power banks this way is as good as anything else.

I have a generic 2200 mAh power bank that weighs 2.6 ounces.  That only delivers 500 mAh of USB voltage.  I don’t know if the electronics are bad or the Lithium battery is less than rated.  It was cheap.  190 mAh/oz (of USB voltage)..

I have a Brunton 4,000 mAh that weighs 5.8 ounces.  USB 2,000 mAh.  350 mAh/oz.  It has a shock proof water proof case which is why it weighs so much.

I have an Anker 10,000 mAh power bank that weighs 7.8 ounces.  5,000 mAh of USB voltage, so 640 mAh/oz.