Saturday, April 2, 2011

lessons learned #3: the forgotten topic

Earlier, I'd listed some of the topics I wanted to talk about, but I forgot to include a rather crucial one: power. So while it's on my mind, let's talk about it.

By "power," I mean electricity for various high- and low-tech devices on the route. Flashlights need power, for example, and so do smart phones. In fact, smart phones require a lot of power: battery technology hasn't had a chance to catch up with the amount of electricity a typical smart phone consumes. Even when I use my own Droid X in a very limited manner, I still need to charge it by the end of any given 24-hour period. It's greedier than my old BlackBerry was, and that's going to be a problem when I'm in the middle of a 25-mile schlep, out in the boonies.

During the 2008 walk, I brought along with me a solar-powered cell phone charger that I had purchased from REI. It proved to be worthless. There were days, especially in the high desert, where I had plenty of sun and plenty of time on the road to absorb crazy amounts of solar energy, but the device failed to perform. At best-- and this was after an entire day of charging-- the device produced only about a minute or two of power for the BlackBerry. I'm not blaming REI for this; REI sells a wide range of products from all sorts of manufacturers; most will be good, but some will inevitably be duds. This solar charger just happened to be one of the worst of the products I had bought. I don't know whether the charger itself was defective or whether solar chargers in general are simply not worth the purchase cost, but my intuition, based on my experience, is that such chargers are inherently problematic.

The first warning sign, I now know, is that the literature and commentary on solar chargers is wildly varied in its assessment of their performance. Some people love solar chargers; others hate them. I finally understand what that means: for your own safety, stay far away from any product about which no clearly positive opinion has emerged. Compare the user/expert comments about solar chargers to, say, comments about Nalgene water bottles, which are almost universally loved. (Later on, however, I'll talk about one of the problems with those bottles.)

Anyone who's listened even partially to the debates over solar power knows that solar energy has distinct disadvantages. One of them, perhaps the biggest disadvantage of them all, is the inconsistent availability of sunlight. All it takes is a few clouds to reduce the performance of a solar cell. Coupled with that problem is the second-biggest disadvantage: the solar cell itself is a delicate, finicky piece of technology. Tiny scratches and even a small amount of dust can cut down on a cell's ability to absorb sunlight. Add this to the first problem, and you've already got a product of dubious worth, especially out on the road.

But there's more. As I was walking, I also learned of a third disadvantage: angle of exposure. In the best of all possible worlds, a solar cell should absorb sunlight that's striking its surface at a clean 90-degree angle. This angle can't be guaranteed, however, when the cell is sitting atop your backpack, bouncing along while you walk. The sun itself prevents one from keeping an ideal angle of exposure, because its position in the sky is constantly changing. The likelihood of enjoying optimal angle of exposure while walking is practically zero.

Finally, there's the problem of energy storage: even as the solar energy's being absorbed, it's draining steadily out of the cell. By the time you flop down at the end of seven hours' walking and try to charge your cell phone, you aren't enjoying the benefit of every single possible watt: much of the electricity has disappeared while you were walking.

My view of solar cells for hiking, then, is quite negative. Unless you're willing to spend money on a ridiculously huge welcome mat of solar cells, I don't see how any modest-sized device can possibly power something like a Droid X, day after day, on the road.

So what are the alternatives if we assume that (1) I'll be needing and using a cell phone on a regular basis, and (2) I'll be walking long stretches without the benefit of an electric socket or a car charger?

My first thought is to go with a hand-cranked charger this time around. These types of chargers generally work for flashlights, but many (or even most) of the newer ones also work for cell phones. The problem, of course, is that they're very labor-intensive and provide only a few minutes' power after all that effort (see here, for example). In other words, hand-cranked chargers are really meant for emergencies, not as a day-by-day resource for a Droid X's electricity needs.

A better alternative, at least for a cell phone, might be a kinetic charger, i.e., a device that takes advantage of the body's natural motions to generate small but steady amounts of electricity over time. The concept has been incarnated various ways; one company, nPower, makes a peg-like device that's supposed to sit upright in the pocket of one's backpack; the walker's up-and-down motion is what generates power. The nPower PEG device ("PEG" stands for "personal energy generator") supposedly produces "about a minute of iPhone 3G talk time from 10 minutes of walking, or one minute of MP3 playback from one minute of walking." To me, that's plenty, especially after walking all day long.

My two concerns about kinetic chargers (see more charger ideas here) are their cost and their durability. Because so much of this tech is new and hasn't been embraced by the public at large, I can't imagine that it would be cheap. Sure enough, it turns out that the nPower PEG is a whopping $150. I also need to know how well such a device can endure variations in temperature and humidity, how well it can withstand being stored inside the confines of a backpack, or how well it might survive an accidental drop of 3 or 4 feet onto asphalt. Could I walk past a waterfall, get soaked, and still rely on the device? Could I use it in the rain, several days in a row? How well would it survive extreme cold, or 110 degrees in the high desert? These are all important questions. In principle, at least, kinetic chargers strike me as the way to go if I'm planning to take my smart phone with me (and why wouldn't I, given how useful it is?), but I have a ton of questions about them, practically speaking.

I'm not as concerned about the power needs of a flashlight. It was, in my experience last time around, very rare for me to be stumbling about at night with a flashlight. These days, there are so many tiny, economical alternatives to the traditional camper's flashlight that I have no worries about my possible nocturnal lighting needs. Still, when my thoughts turn back to that hand-cranked charger, I can't help thinking that a 2-in-one device would be a smarter purchase than a single-purpose device.

Meanwhile, the smart phone is a huge concern. The Droid X is a power sink, and I'm not sure a hand-cranked device, even if used three or four times a day during a 20- or 25-mile walk, would provide enough power for me to do much more than send brief tweets as opposed to blogging at any length. The nPower PEG, on the other hand, keeps your cell phone's battery "topped off" all day long, or so the claim goes. I'd love to road-test one of these devices before buying it. Maybe I should do some research into whether that's possible. If it is, you might be in for some very interesting blogging.


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4 comments:

surprises aplenty said...

I think adapting your behavior might be the best solution. Turn the phone off at night or even turn it on for only one hour or so in a day. If you need to tweet or post something everyday or a few times a day for safety reasons or the like, keep it short.

I enjoy this blog and your other one and your writing makes even quotidian events seem interesting so I'll read your blog everyday, given the chance, but that doesn't mean you really need to produce material everyday.

On the other hand, I learned of a prototype device that fits like a brace around your knee. In walking, people actually use muscular effort to stop our knees from overextending and this device does that mechanically. It must weigh something and needs to be lugged around, but in action, it creates electrical energy and saves you metabolic energy: win-win.
I think this is it:
http://ns.umich.edu/htdocs/releases/story.php?id=6325

Kevin Kim said...

I did something like that with the BlackBerry, i.e., kept the phone off most of the time. I also suspect I'll be doing a lot more tweeting than blogging this time around, perhaps reserving the blogging for whenever I'm in a town and have access to an electric socket.

Yes, the knee device is something I'd like to look into as well. In fact, the first time I'd ever heard the term "kinetic charger," that was the design I'd envisioned before I'd even read about such chargers in detail.

Stafford said...

What is the maximum time you will have between electric wall sockets?
For me it is practically zero, but inevitably the iPhone, iPad, Galaxy Tab or nexus one runs out of juice. So I carry around an Energizer Universal charger power pack just in case.
http://www.amazon.com/Energizer-XP4001-Universal-Rechargeable-Power/dp/B0029U2WUA/ref=pd_cp_cps_1
In my most extreme case the power pack lay in my bag for three days after a full charge and managed to bring my iPhone back to life for another 6 hours.
Personally I wouldn't trust anything that doesn't come directly from an electrical outlet

Kevin Kim said...

Stafford,

There may, at some points along the route, be days between sockets. That happened to me last time, during the latter part of my route when I was in the high desert. Had I continued the walk through Idaho and Utah and Wyoming, the time between sockets could have been weeks.