AUKEY 14W Solar Charger

I like to go backpacking.  My backpacking trips generally only last a weekend.  Keeping phones, GPS, and other devices alive for that amount of time isn't an issue.  It will become a problem on longer treks.  Carrying backup batteries can help, but on long enough treks even those won't last.

I have a 20,000 mAh Limefuel battery pack with two USB ports.  (Amazon only sells a 15,000 mAh version now.)  I charged my phone from it for several days to get it down to 10%.  I wish I had counted how many charges I got from it.  That would have been useful information.

Limefuel 20,000 mAh USB battery pack.

To charge this battery pack on the trail I intend to use a solar panel.  I bought a 14w Aukey, dual port, charger.  I set it up in my garden at noon and pointed it west towards the sun.

Then I plugged in a digital meter so I'd have some idea of what it was actually doing.  My initial results were not good.  It was cloudy so the panel only produced 0.5 watts.

An hour later it was producing 1.45 watts.  At least it was something, but not much.

The battery showed that it was at 30% of capacity.  I was actually pleased with this.  It went from 10% to 30% in 3 hours with a cloudy sky.

Less than an hour later things were happening.  The clouds went away and the solar charger was putting out 7.66 watts.  That's nowhere near the claimed 14 watt capacity, but I'll take it.  I live in North Carolina, not the desert of Arizona.  

After 5 hours my battery was at 48%.  Assuming that it actually holds 20,000 mAh, and that the display is correct, then it went from 2000 mAh to 9600 mAh.  That's enough to charge my cell phone 3 times. 

This battery pack and solar charger look like a winning combination for the trail.  The biggest downside is the weight.  I haven't put either on a scale, but Amazon lists the solar charger at 1.1 lbs. and the battery at 12 oz.  That's a lot of additional weight just to keep your phone charged.