Tag Archives: Green Energy

Solar Phone Chargers Suck

A few nights ago, in bed and unable to sleep (like always) I had a drunken idea. I wasn’t drunk at the time but that doesn’t mean it wasn’t a classic drunken idea. You might know exactly what I’m talking about; it’s one of those ideas that sounds amazingly amazing at the time but upon waking up and mulling over the idea ten hours later you realize it sounds kinda silly, undoable, and stupid.

I want to go live in the woods for a week.

I don’t want to get too much into my reasoning here, but I think I need a break from life in general. Just to get away. Being poor means I can’t hop in an airplane and fly away for a vacation, and I don’t have any scheduled vacations until July, so living in the woods seems great because it’s cheap and doable. And I can’t think of a better way to escape life than to live in the woods like a bum.

My main issue is this: I don’t want to totally abandon society. Writing is part of the introspection process for me, and there is no goddamn way I’m going to write in a notebook. I want to make some progress with my stories and continue blogging and transferring notebook writings to a computer is a time consuming mess. Most of the time I can’t even read my writing, especially the hastily written scrawl that appears when I’m in the zone. To live in the woods I need my phone and preferably my computer. Sounds easy enough, right?

I’m going to ignore all the other logistical problems here like where I’m going to sleep, what I’m going to eat, where I’m going to park my car so I can still get to work, etc. and focus on the phone and computer problem here. It’s a pain in the ass to solve.

The main problem is going to be charging the damn things. I’m totally ignoring the WiFi needed for my computer here by the way. A phone is easy enough to charge given a power source (the obvious one here is a car) but the computer is different. It requires a 120 volt AC source to charge. The easiest solution would be to use a car inverter (which I have) to charge it, but these options involve the car again. I want to live in the woods far enough away that if I am doing this project illegally in the park that I’m well hidden. Camping too close to a parking lot might get me booted from the park straight away.

Ideally I could charge my stuff via something that is usually present when living outdoors: the sun. It’s big, it’s bright, it’s in the sky for about half the day, and it’s the primary source of power for everything on earth. It’s an obvious choice. And I also have about three solar panels.

The one I want to use is a larger maybe 1.5 sq. ft. solar panel that puts out about 20 volts max. The other two are smaller 6 volt panels. It’s this guy right here:

AA battery pack for scale.

Any project that you attempt should start as simply as possible, only adding complexity to solve a problem. The most obvious way to charge my phone (and let’s worry about charging that piece of hardware before even worrying about the laptop) is to connect the solar panel directly to the phone. But seeing as the panel puts out like 20 volts in direct sunlight and the phone charges from a 5 volt USB supply I’m terrified to do this. It might not even work and in the worst case scenario I might blow my phone up or destroy it. Do I want to risk my Samsung S7 by hooking a panel directly to it? No way.

This is probably a good way to fry the circuits in your phone.

Luckily I also have an LM7805 integrated circuit (IC for short: this basically means there’s a bunch of shit in the chip to make it do what you need it to do without working out the details on your own) which takes some input voltage and outputs 5 volts: perfect for a USB charger. So now the plan is this: hook solar panel up to the LM7805 and hook that to my phone. Here’s a poorly-drawn example:

The LM7805 is not really this large.

And the phone did charge! But damn did it charge slowly. I started charging it (while off to save power) at 59%; about 45 minutes later it was at 62%. Jeez. This wasn’t going to work at all.

Back to the drawing board. Solar panels don’t put out a whole lot of current. They provide free electricity, but it takes a huge solar collection area to do anything useful with it and this is why the phone was charging so slowly. I was directly trying to capture energy into the phone, and it was slow indeed. If only I could store the energy into another battery passively to use later. Collect power all day in the sunlight and then charge quickly when I needed to. So here’s the plan now:

Another good question is how all of this shit is supposed to survive in the woods for a week.

I’m going to take eight rechargeable nickel-metal hydride batteries and charge them via the panel. (Note: These things are great. I use them in gaming remotes, TV remotes, and anything else that eats through batteries. When they die, you charge them, and you don’t need to constantly have a stack of alkaline AAs laying around the house.) Since each battery provides 1.4 volts, the entire pack should be around 11.2 volts; 12 volts from the panel (regulated by a charge controller. I know I said 20 volts earlier) should be perfect to charge them. And when I want to charge the phone, I use them along with the LM7805 circuit to give the USB line, and the phone, 5 volts. The batteries should store all the energy passively through the day, and I can charge (hopefully) quickly when I need to. I don’t know if this will work as well as I hope it should. I currently have the batteries charging and after the sun goes down I’ll see how charging the phone works.

The full setup so far. I would have my phone in the picture charging, but guess what I had to use to take the picture?

An easy work around here would be to grab a car battery and haul that around with me, but car batteries are heavy. I don’t want hauling a 50 pound battery around to be part of my living in the woods project.

I charged the 8 rechargeables with the panel for about two or three hours. I was then able to charge my phone with those from 43% to 49% in about a half-hour at a half-amp of current. This isn’t too bad even if it is slow for a phone. It’s doable at least. Obviously I need to start with freshly charged batteries so all the panel has to do is “top them off” periodically instead of doing all the heavy lifting of charging them in the first place. I’d like to stress again how little current a solar panel puts out. To do anything you need a large solar panel.

And to close this really boring post: let me bitch about solar powered cell phone chargers, like the kind you buy in a store. My mother-in-law kept talking about them today. Apparently there’s one that’s about the size of a cell phone and can charge a phone very quickly. It even works in the shade! she mentioned. I call bullshit on this. If it has a tiny, phone-sized solar panel, it won’t be able to do jack shit. The product probably has a big, fat, lithium-ion battery which can likely charge a phone multiple times before it dies. The solar panel is there to charge it in the meantime, just like my shitty setup detailed here. The problem: the panel is too small! To charge the internal battery I’m guessing this shitty, tiny device must be left in direct sunlight for at least three days, probably more. While it might work great if the internal battery is fully charged, the solar panel will be unable to top it off even under low use. This is simply physics and can’t be worked around. Charging your phone by solar power fucking sucks.