Solar solution to recharge laptop, please help.

[Hugo Riendeau]

Hello,

I am about to go on a backpack trip and I would like to bring a small laptop to use with GPS / Mapping software. I have a long life battery but I would like to recharge it while hiking.

I read a few posts on the web about solar roll panel and solargorilla but I wanted if anyone had experience using such device and what would the the best optimal light weight option.

If someone already recently post about the subject please kindly give me the link.

Thanks for help!

Hugo

[Donald Browning]

I had your same idea. The way I approached it was with my MacBook Air, using an auxillary battery that I got from Quickertek. It's worked well with my small outings. I have no experience with solar, sorry.
Don

[George Geist]

I couldn't find a commercial solar charger that could fully recharge my GPS every day (that wasn't heavy and bulky). So built my own http://www.csm.ornl.gov/~geist/Philmont/
It kept everything charged during my two weeks at Philmont.

A laptop is another story. It typically draws around 10W to run. If you kept your usage time to less than an hour/day, you could possible get enough sunlight in a day to recharge it.

How long are your trips? For trips of a week or less, an extra laptop battery is a simpler, lighter solution.

[drowning in spam]

I've been thinking about this too, with the computer being a Fujitsu u810. I'm thinking the solar charger may not fully charge it everyday, but I don't think that's necessary at all. I'll fully charge it in town, which should give me 5-6 hours. If the solar charger can pad the battery life by another 5-6 hours, I think that will be more than enough for a week of camping with the way I intend to use it.

I'd love to hear from more people that have tried this, especially if they have successful solutions.

[Nick Gatel]

I have some experience with solar, as my tent trailer has a solar system that allows me to be self-contained indefinitely.

You need to perform some calculations. I will use the term panel to include any kind of solar material.

1. How amps or miliamps does your computer draw per hour.

2. How many amps or miliamps will your solar system charge per hour.

3. How many hours of useable sunlight will you have per day (you are going to need to charge the computer while hiking). You need to factor in overcast days, shade, etc.

4. Amp ratings for solar panels are optimum, and usually will only produce 90% max of specs, and this is in sunny locations, closer to the equator.

5. Using your calculations determine how many amps you need to replace per day and size your system based on the items above.

Problems I see while hiking

1. Hard to secure it to your pack and keep it oriented to the sun.

2. Does not work in shade or partial shade.

3. Suspect that a panel large enough to charge your laptop could weight as much as the laptop.

4. Potential of breaking the panel.

5. Not practical or desireable to stop on the trail and sit for an hour or two to let the system charge.

Now for the crux of the issue. Most small notebooks I have seen weigh at least 2 lbs. Not a lightweight piece of equipment (this is a lightweight backpacking website after all). 2 lbs is more than than any of my heaviest items (pack, sleeping bag, shelter, or shoes).

What can you do with the laptop that you cannot do with a topo map & compass? If you cannot do something critical with map & compass, that requires a computer then you could possibly get yourself into a pickle should the computer fail.

[drowning in spam]

I think one of the best options may be the Solio Mag for different types of devices. It says it gets a full charge in ~10 hours in full sunlight, so let's simplify and say it'd take 2 days to get a full charge if it's strapped on top of a pack of a PCT hiker. It weighs 7 oz.

I don't know what kind of computer the OP is planning on bringing, but I'll be using a computer that weighs 1.5 lbs. Add maybe 1/2 lb for the charger. As for what it can be used for: reading. I'll be scanning in more guidebooks than I wish to carry. I'll also have textbooks loaded in there so I can study while on the trail. Plus it'll be nice to have when hitting towns with wifi access. Anyway, it's not for everyone, but I don't think I can justify a thru-hike unless I have some way to study while I'm out there. It's 2.5 lbs that'll let me get out there.

[Dean F.]

One possible product, easy to attach to the outside of a pack:

http://www.brunton.com/product.php?id=256

These seem pretty popular with the extreme-expedition types.

The SolarROll 14 is described as "perfect for running satellite phones and charging laptops", but we all know how much marketing hype can be trusted. And they are expensive as heck.

I kinda have to agree- laptops draw a LOT of power. Good luck.

@Eugene-

Guidebooks? Get a Kindle from Amazon. Lighter (10.2 oz, 8×5.3×0.36"), better battery life (about a week of steady reading), easier on the eyes, and has free global wireless downloads- including Wikipedia access, I think. Download a guidebook if you need it. And if your guidebook is obscure just scan it as a PDF- the Kindles read PDF. $260 for the small one at the moment- not as expensive as a decent laptop. I've been very tempted by them but have yet to pull the trigger. I understand that they use a nonstandard recharger, though? Might want to look into that…

[drowning in spam]

Dean,

Have you tried viewing a book that is made up entirely of scanned images? It'd be garbage in so many ways. Just think about what that scanned pdf page is going to look like with the mediocre resolution that ebook readers have. It'd either resize the page, which would take a while and be illegible, or you'd have to scroll a lot. With the computer I have in mind, almost any book would be legible when viewed full page in full screen mode…the exceptions are some of the funky tiny symbols in calculus books. Hmm…I was just looking at the newer version of the computer I was, a u810, and it has built-in gps and longer battery life. I bet I could pull 12+ hours out of a single charge…

[Bob Gross]

I've been down this same road a few times.

Solar chargers are a poor power choice for a backpacker. If you are going to leave it in camp, and it is set for one direction, it can work somewhat. If you try to fix it onto your backpack, it generally doesn't work worth a darn, even if it is facing toward the sun all of the time. It is much more weight efficient to carry spare batteries. This especially applies to one week or less on the trail. As you get into longer periods of time, like a month, a fixed base-station solar charger makes more sense, e.g. Mount Everest Base Camp. They carry the rig in once, use it for a month or more, and then carry it out.

In fact, just be more economical in your power use, and you might be able to keep things going on one set of batteries for a long time. I did a 20-day trip in a remote land, and I used GPS very sparingly, and I used cameras very sparingly. I had lots of primary lithium batteries for backup, and they are very light.

–B.G.–

[Nia Schmald]

Deleted. Already covered by previous posters.

[Joe Kuster]

As mentioned above, solar solutions are limited. While not on the market just yet, there are promises of new Hydrogen cell chargers for mobile electronics that were released at the Consumer Electronics Show just a few days ago. These solutions looked very slick and could easily solve some recharging issues for hikers on short to moderate trips.

It really depends on what you think you need the laptop for but for now, I'd drop the laptop and look for a more compact device with lower battery requirements. In many cases, it would be lighter to carry an advanced GPS, smartphone, e-book reader and a bunch of spare batteries to do whatever you need.

[drowning in spam]

Once again, an ebook reader would be a paperweight for the books I'll be using.

Also, all those devices would still be pretty heavy and bulky when you're carrying around chargers for them too, or batteries. In my case, I'd definitely have to have a charger.

[Bob Gross]

If you are bound and determined that you need a solar charger, I suggest that you first determine the power requirements of your devices, and that means voltage, current, and time. Once you have a good grasp of those numbers, you can start to select a solar charger. A lot of them on the market do not even specify their power output, or if they do, they hide it. That is because many of the small/portable chargers have extremely small output. For a big rigid solar panel (photovoltaic panel), the price is about $5 per watt to $10 per watt. As you get down into the small/portable panels, especially the flexible ones, the per watt price goes up dramatically. Note that the highest-efficiency panels are rigid, and the lower efficiency ones can be flexible. Also consider the most efficient way to mount it for sun angle. It is not simple, but it isn't rocket science, either.
–B.G.–

[Joe Kuster]

Eugine, my post was targeted at Hugo's potential needs.

Compared to the weight of even a minimalistic laptop, an e-book reader is significantly lighter and the battery time is measured in days and even weeks for some users.

It really does sound like you've never used an e-book reader in person, they don't use scanned images but instead are a true text and line art based version of the book that is scalable, searchable and no scanning artifacts at all. That said, they aren't cheap and you usually have to re-buy the book you want. Then again solar power systems large enough to do what you're looking for are REALLY expensive.

If you wanna play with solar, don't let anyone stop you, it's fun to work with, but it's pretty limited on the amperage that you can get so you'd need a ultra-efficent laptop or only use it an absolute minimal amount.

How long of a trip are you seriously looking at? If your a weekend warrior or even a week long trekker, just carrying more battery power is pretty fail safe. On long trips, you can usually recharge at someplace where you resupply.

Battery packs for AC devices (Black and Decker makes a cheap one) can keep a laptop's life going, but OEM or aftermarket replacement batteries are the way to go for shorter trips and will likely be far cheaper than a solar solution that will keep you infinitely going.

There are also crank chargers, but I tend to consider those an unlikely candidate for more than cellphone charging. It took me thirty minutes to recharge my smartphone to one bar to make a call once, but it did work. There's one marketed by "The Weather Channel" that's actually pretty useful (radio, flashlight, weather radio etc).

By the way:
Bulky? Compared to a laptop?

As for text quality:

In no way am I endorsing the Kindle over anything else or saying it's perfect for your needs. I've played around with it and the Nook reader, both are actually pretty good for certain uses, most notably, reading books when on the trail as even with charger, it's lighter than a paperback.

[drowning in spam]

Joe,

I thought you were talking to me since I'm the one that mention e-books.

I do agree that e-book readers are light and very efficient. The thing is, I use scanned books books. I have for years. I'm a tabletpc user. Nothing beats a scanned book unless you can possibly get an unlocked pdf version from the publisher, which is basically never done, at least not legally.

Scanning a book means that I can digitally read any book I can physically get my hands on. It's simply not possible to get "true text and line art" versions of books of many books on e-book readers right now, and possibly ever. This is not a restriction for me whatsoever. I certainly don't have to buy books twice either. The book will look exactly the same on screen as it does in hand, at least down to 300 dpi. Because I will be using it on a tabletpc, I can search, highlight and annotate.

The thing I envy about e-book readers is that the black & white versions look great in bright light and have spectacular battery life. That's not really a factor for my trip though. If I get a u820 with gps, then I'll only turn it on during bright hours to locate myself…that is, if I don't bring a handheld gps, and if my compass/map navigation skills fail me. Most times I'll be using it at night or in the early morning to plan my hike for the next day, and hopefully to get a little studying done so I don't lose too much ground while I'm out.

The trip I'm looking at is the PCT. Carrying spare batteries, or external battery packs, creates its own problems. It's more weight, has to be charged sequentially or have another charging cord, depending if it's an internal or external battery, respectively.

When I mentioned bulk, I meant that it would be a smartphone (5.6 oz for Blackberry), plus it's charger, an e-book reader (10.2 oz for Kindle 2), plus its charger, an advanced gps (7.5 oz for Garmin 60CSx), plus its charger, and a bunch of spare batteries. Add the weight of the devices, plus chargers and spare batteries, and that could easily be over 2 lbs. The Fujitsu u820 is about 1.5 lbs with the extended battery. I estimate 1/2 lb for the charger. That puts it about even with the other devices. I don't care to pull up the specs for sizes right now, but the u820 is very small, very coat pocketable.

Here's the thing though–reading e-books is the primary goal. I need to be able to read scanned books that I created in full screen mode, in color. If the computer replaces other hardware, great, but that's not enough to sway my decision one way or another.

Find me an e-book reader with the resolution and processor to handle displaying color ebooks scanned at 300 dpi that I create myself and I'll give it a look. Storage may be an issue though. Scanned guide books are roughly 300 megs each, but three of the textbooks I'll be bringing are 2 gigs combined.

[Hugo Riendeau]

Thank you all for posting replies,

To add some more information I am planning to trek for a few weeks. I would like to resupply as less often as possible.

My first choice is to use a small laptop in order to read guidebooks and also mostly because I wanted to use google earth with gps device.

I might create another thread to the benefit of using laptop against other device or usint google earth against any standard garmin gps. If such thread doesn't already exist.

I will be bushwalking for some part of my trip so i figure out it was worth the trouble. I also liked the idea of satellite imagery navigation.

All remarks are quite useful.

[Joe Kuster]

Eugine: Most of the devices you mentioned can use a USB mini cord for charging a microUSB hub and really short USB cables would let you charge the whole mess at once if that was your fancy.

Frankly though for the PCT, you just change up your use a little and forget about it. Most people would ditch the electronics in favor of enjoying the outdoors and simply post x many chapters printed out of your books and pick them up at resupplies. Burn 'em for firestarter as you go and never carry more than you really need. Reprint it 2 to a page, front a back for maximum content. Low tech, but it certainly solves the expense of building a solar charger and is on average a lot lighter to carry.

If you've REALLY gotta have scanned books that you make yourself, simply load it on a smartphone and turn it to airplane mode for max battery life. HTC makes some that are quite capable of doing what you requested, but only a few have screens large enough for comfortable long term viewing. I'm sure there's similar apps from the iPhone, but maybe a little less open to supplying your own content – dunno there.

If you want, you can even go to town buying cheap additional batteries and there's even micro docking stations that'll charge spare batteries while your charging your main phone.

I'd bet if you swapped out your scanned file based format and swapped it to an OCR text based file that contained the color photos, you'd get it down to 30 – 100 megs / book.

You can get 16 or 32 gig cards in a Micro SD format and trust me, you won't complain about weight of those since it's basically the dirt under your toenails. You can even double use them with an adapter for your camera and then send the photos via email when your in town.

When your eyes get tired, swap it into "read" mode and let the little robotic voice read the book aloud to you. It works, I've got a ATT Fuze (HTC Diamond) and there's no end to what you can find apps for.

I'd need to throw it on a scale but the interwebs say mine is:
Smartphone: 5.82 oz
Battery: 165 grams
+ whatever charger you use, I'm sure you could fish around and find something light enough.

That's certainly one option, but there are color e-book readers that'll do what your asking, you just have to convert it into a PDF first. If you OCR it into a text based PDF that has embedded photos, you'll drastically reduce file size.

[Keith Selbo]

As everyone has said, you have to tell us the battery voltage and amp hours of your computer battery and how long the computer will run on a charge.

I use the flexible polymer panel charger pictured below (Silva Tech 40). It weighs just over 4 oz. I usually mount it on top of my rolled up sleeping pad on the top of my pack or sometimes hanging down the back as shown if the sun is to my back. The manufacturer claims it will charge 4 AA's in 10 hours. I'm not sure about that, but I was able to keep my smart phone and camera charged on a 50 mile hike through a temperate rain forest where I was in shade most of the day, every day. Most of the charging got done at meal times when I would find a pool of sunlight to set my pack in. If I knew more about your charging requirements, I could probably help you more.

I used a boost regulator to convert the AA voltage to USB (5V) for charging. I've seen a similar panel with the USB charger built in. If I remember where, I'll post the link.

[drowning in spam]

Joe,

Actually, I'm thinking about dropping the solar charger since the u820 gets such great battery life. With 12 hours of battery life, it shouldn't be much of an issue to charge it in town….I hope. I may even leave the handheld gps in a bounce box.

OCR is not a good solution. In many cases it does little to reduce file size. File size is really only a concern if trying to use it on an e-book reader. It's not an issue at all on something like the u820. The other issue is that OCR does a horrible job at getting characters right.

Viewing on a little cell phone screen isn't going to work very well either, unless those screens have way more resolution than I know about. They're maxed at what, 854×480? It'd have to be viewed sideways to have any hope of being legible, which means scrolling, and scrolling books sucks on pages that were formatted to be flipped.

It really comes down to resolution. No ebook reader or smartphone has the resolution to cut it. I won't scroll a page. The entire page has to be visible at once. This is something I can't compromise on.

If all I was reading was little novels that only had text, yeah, a phone or ebook reader might be the way to go. Try reading e-book textbooks for a couple years and let me know what you end up with. I bet it won't be any e-book reader or cell phone that's available right now.

The most savvy tabletpc users I know agree on two things: scan to pdf as an image and reading pages full screen is highly desirable. Again, this is because books are formatted for pages to be flipped and even if there was a good way to ocr to text and line art, it would still require more resolution than is available on currently available phones and ebook readers.

To stay on topic, I'm still planning to go with my Brunton SolarAA charger (7.8 oz) for my AA batteries…at least initially, and if it passes my field tests. Even if it took days to charge, that's more than enough for the my handheld gps, headlamp and camera.

[drowning in spam]

Keith,

The battery is 7.2V and 5200 mAh. Unfortunately I don't know of a way to charge it separately. Also, I think it has to be charged by a Fujitsu charger…I could be wrong, but I know some manufacturers are making "smart" chargers that make it impossible to use a generic charger with an adapter tip.

The output of the charger is 16V, 60W, 4.22A.

I sucked at the electronics section in physics…okay, all of physics….so I don't know what these numbers mean in regards to expected charging times with these solar chargers, or if it's even possible.

I'll see if I can dig for more info about the possibility of charging without the Fujitsu charger.

….

Holy moly, Fujitsu offers a solar charger…for $1400!! Ouch!
http://store.shopfujitsu.com/ca/EcomCA/SelectAccessoryDetail.jsp

Yeah, I think I'll just charge it in town.

[Roger Caffin]

How much silicon cell area you need depends on how much other junk you are carrying. OK, provocative and aggressive – but true.

I use a solar cell to recharge the batteries for my Steripen. Works great. LIGHT too.

Cheers

[Hugo Riendeau]

I have a LGX13 with a 9 cell battery. At the back of the pc it is written 20V.

Could anyone tell me whether the solar roll would do the job. I don't mind to charge it while walking all day. I expect to use the pc maybe 1 or 2 hours per day maximum.

Thanks for help!

[Keith Selbo]

Eugene, Hugo,

If you run your battery down by 20% or less a day, the Silva would be a candidate as far as power output goes, but the voltage makes it tough. I don't know of anything you can buy that would do the job. Sorry.

The only thing I can suggest is that you look for a computer that charges from 5 volts, or comes with a solar charger.

[Keith Selbo]

Roger,

Do you happen to know the weight and full sun power output of your solar cell?

[Roger Caffin]

> Do you happen to know the weight and full sun power output of your solar cell?

Sorry, no. Never bothered measuring.

I found it was able to recharge the two Tenergy CR123R batteries I use with my Steripen in maybe 4 – 6 hours, depending on the sky, after I had treated two litres of water. That took 1 amp for 2*90 seconds.

So … Steripen power consumption of 180 seconds at 1 amp draw at 6 V nominal: about 1,000 watt-seconds. Assume 50% recharge efficiency: 2,000 watt-seconds required. Spread that over 5 hours or 18,000 seconds: 0.11 watt output required (which is not all that much).

Assume 1 kW per squ metre sun power. The cell is about 0.13 m x 0.06 m or 0.0078 sq m. It should 'see' about 7.8 W under perfect conditions. Assume that the angle of the cell with respect to the sun, my movement, etc, gives 20% solar interception efficiency: about 1.56 W of sun power available. Assume a solar cell efficiency of about 7%: power output of 0.11 W. Matches requirement.

OK, the assumed efficiencies have been slightly fudged, but the numbers are quite realistic.

On the last trip I also used the same solar cell to recharge my mobile phone battery. I used the phone to ring ahead to Refuges a few times – I could have done just as well by taking one spare fully charged phone battery, but the weight of the adapter I made was extremely small.

This works for me. But I do not lug around all sorts of electronic devices when we are walking. I am quite capable of surviving without them – actually I don't own them anyhow. (Yeah – super-techie but no devices!). I have a log book – Rite in the Rain paper.

Cheers

[Author]

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