Reddit reviews Nekteck 21W Portable Solar Panel Charger, Waterproof Camping Gear Solar Powered Charger with 2 USB Port for iPhone X/8 Plus, Samsung Galaxy s9/s8,iPad, Tablet and Any USB Devices

Honestly I wouldn't get a solar battery pack. They're too small and sometimes don't even charge past 50%. Look for a usb solar panel (Anker or Nektech) and add a good battery pack (again anker or ravpower) 20,000 mAh or more. Charge your phone and battery pack during the day. At night use the battery pack.

FYI, those chinesium power banks would struggle to charge at 20mA, which could optimistically recover about 2-5% of your battery over 8 hours of direct sun. Don't buy one.

Assuming the phone's 3500mAh

2x2400mAh = 4800mAh

0.5x3500mAh = 1750mAh

You'll need >6550mAh or 25 watt-hours per day.

If you want the option of solar charging I'd recommend buying a solar mat instead, and a battery at least double your daily power requirement.

Here's one option:

This 21w solar mat should be able to recharge all your devices in a couple of hours of direct sun. Pair that with a 20,000mAh power bank and you're pretty well set.

Note: The math works here because all your batteries and the power banks are 3.7v nominal. Power is being up and down converted to 5v, so that cancels itself, apart from entropic loss. If you're trying to figure out power requirements you must use watt-hours instead of amp-hours when comparing different voltages. VxA=W W/A=V W/V=A

Pretty standard stuff (though I did like the video).

Bigger panels are better. Don't expect much if it's shady.

As far as adding solar to a BOB, I don't think I'd invest much in it. A really cheap (Sub-$100) way would be the $55 Nekteck from the video, plus a Nitecore F1 charger ($10), and some 18650's ($10). It'd allow you to charge the battery while walking or not really paying attention to it.

You can charge your phone (or any USB-powered device) off the NiteCore, it shows the battery voltage and charging status (though with some sort-of-confusing tiny lights. RTFM.), plus the batteries work in really good flashlights/headlamps/WML's and have the highest energy density on the market right now (most power for least weight). Plus, unlike those 'power pack' things, with individual cells you don't lose the whole pack if one goes bad (most of those packs are just 6x18650's in a case anyway).

And if SHTF, most laptop batteries contain 18650's for scavenging.

___

You could also use 26650 batteries ($13.99), but they're larger and harder to package than 18650's. The NiteCore charger works with both though. They do provide more mAh (3400 vs 5200) which means more energy storage, per battery.

Energy-density wise, the 18650's are a much better value. 26650's are roughly twice the area/weight of an 18650, but don't provide twice the energy storage. You'd be better off with 2x18650's than 1x26650 in most cases, but I could see how, from a "I'll forget to change the battery on the charger halfway through the day" point of view, a 26650 might make sense.

This is mine and puts out about 1000ma love it to death. Has ancher http points and i just attatch it to my 1 day pack and go. :) https://www.amazon.com/gp/aw/d/B017GQ7OEA?vs=1&vs=1

So there are quite a few options in the space, but I'll link the one I got below.

So the budget ones start at about 30 bucks, typically have built in batteries, and require about 9 hours to provide ~10 amp-hours worth of power. Your average phone takes between 3 and 8 amp-hours, so it will charge a 1-2 phones in 9 hours of sunshine. Now that's 9 hours of direct sun, so on cloudy winter days you could run short (if it's really cloudy). From my tests with it, even on a cloudy day it could charge my phone 30% in about 2 hours of summer sun, so you could probably charge one phone a day in the winter. This is what I got with my 200 dollar budget, but they sell some nicer ones if you're willing to spend a bit more. The big thing to look for is one that has a standard USB port, and can output at least 5 Watts.

The next tier up have foldable solar panels, and can provide 15-21 Watts, enough to charge tablets. These are typically used by backpackers and people that live in remote areas or off grid, but if you're wanting to be ready for anything, or keep your e-reader charged, they're worth looking at. These start at about 50 bucks and can run as high as 100. Most of these do not have internal batteries, so a charge pack is recommended if you want to be able to store power without having the device connected.

What I got was the basic tier: https://www.amazon.com/Charger-Portable-Flashlight-Including-Compatible/dp/B07W6CQ7ZV

Cheap option if you want to charge tablets (doesn't store power): https://www.amazon.com/Nekteck-Waterproof-Portable-Efficiency-Compatible/dp/B017GQ7OEA. If you want a power bank, get a large one, at least 25000 mAh. They run about 35 bucks.

is there a reason you didn't test this popular option

I honestly got one for my 9-day trip from Denver to Glenwood Springs and expected it to not work out so well with the same negativity I am seeing in some of these posts from people with no personal experience.

BUT... I was pleasantly surprised as my old phone that already didn't hold a charge very well was at 100% the entire trip. However, I have since taken it camping and on cloudy days it doesn't charge so well on those days.

This is the charger I got: https://www.amazon.com/Nekteck-Waterproof-Portable-Efficiency-Compatible/dp/B017GQ7OEA/ref=zg_bs_2407762011_5?_encoding=UTF8&psc=1&refRID=VEC9CG751KWTT9Y1T0BJ

It sat over my dry bag that ran along the top of my rear rack.

This is the solar charger.
and this is the battery.

Get him a set of hiking clothes from REI.

Or a solar charging setup for his technology.

Or a travel wallet.

^ Basically came to post this. LEDs have mostly swept away the other lighting methods- with the possible exception of oil lanterns, which can sit for decades and be ready for use.

You can cobble together an entire solar + battery + charger + flashlight system for $100-150 USD, if you shop around online (which isn't bad, if you buy an item or two here and there). I will also vouch for Anker, they make really good charging gear.

• Solar panel
  
• USB battery pack
  
• USB AA/AAA charger
  
• eneloops
  
• Flashlights: good n' cheap | better | hardcore
  
• Headlamps: simple | fancier

Sweet dude I got this one:

https://www.amazon.com/gp/aw/d/B017GQ7OEA/ref=sxts1?ie=UTF8&qid=1469054354&sr=1&pi=AC_SX236_SY340_QL65

It's purdy good except if you try to plug two things in at once, obviously.