Friday, July 6, 2018

Solar for backpackers

I get this question all the time. "I am going on a four day backpacking trip, and I need to charge my phone. Tell me about solar options."

There a large number of problems with this whole situation. The first and the biggest is, maybe you don't need that much access to your phone? Maybe the point of backpacking is to get away from your phone? The counter argument is "I am using it as my camera." Not surprisingly I have a problem with this answer as well. Yes, phones have become amazing cameras. Truly. Easy to use, incredible resolution. Your phone isn't particularly waterproof , which of course can be mitigated with a waterproof phone case, but the real problem is this. If something bad were to happen, you really should have a working phone with a full battery.

But, okay, you're going to bring your phone and you need to charge it. People have this image of "I will put a solar panel on the back of my backpack and it will charge my phone while I hike." I hate to be negative, but a solar panel needs to be facing the sun, which means it really needs to be on the top of your pack, and it needs to be pointed directly at the sun to be as efficient as possible.

Gregory actually released an update of their classic Baltoro backpack, with a solar panel and battery mounted on the top of the pack. They did this in conjunction with Goal Zero.

You see how the sun is directly in front of the hiker, and the solar panel is on the back? Yeah, this setup doesn't work very well. A setup like this will work best at 12 noon and there can't be any trees.

Okay, so that won't work so well, but how about on rest days. I can plant the solar panel in the sun, and charge my phone directly. This isn't a bad idea, you do need to stay on top of it though, about every twenty minutes it would be best if re-align the panel with the sun. It is all about maximum efficiency. This is essentially how we charged batteries during the AGAP trip. every 4 days or so we would take a rest day, and charge batteries, both literally and figuratively. OH! But in the first line of this post I said four days. There probably won't be any rest days.

But if there were, you have to take into account that it will take a few hours to charge the battery in your phone, and during that time you can't actually use your phone.

Okay, option 2 is a little different. You don't actually need a solar panel. really all you need is a battery. For a four day trip how many times are you going to need to charge your phone? twice maybe? Unfortunately we need to do a little math.

An iPhone 6 plus battery has a capacity of 2915 milliamp hours (mAH). That is what we need to charge. If we take a battery pack with us it needs to be able to charge that twice, and good first option is the Goal Zero Flip 20. It has a battery capacity of 5200 milliamp hours (mAH). With this size battery we will just charge it before we go on our trip, and at night when we wouldn't be using the phone anyway, by plugging it into the battery via USB cable. This is far less expensive than a solar panel and far more practical. It costs less too!

If you need more power than that, the Sherpa 40 holds a whopping 12000 mAH. That is enough to charge an iPad mini 2.5 times.

This is essentially how we did the AGAP trip, we had two Sherpa power units and a large solar panel. On rest days we charged the sherpas, and at night we charged our batteries from the sherpas. It worked flawlessly. Let me know how you solve your backcountry power problems.

One final tip, if you are bringing your phone into the backcountry to use as a camera, keep it in airplane mode. This will dramatically extend your devices battery life, and it will also help you separate from the front county. Which is the reason we are in the backcountry after all, isn't it?

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