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Taking a five day hike, and I want to take a bazillion pictures. It would be nice to have the compass & GPS functionality too, and I want something really small. The obvious choice is my iPhone.

As everyone knows, however, an iPhone sucks juice like a baby waking up from a night's sleep. Even if I turn off all the radio transmitters, I just can't imagine my iPhone holding a charge for more than a day.

I've poked around looking at hand-crank chargers (not recommended for smart phones), and solar panels seem to have really mixed results. I've also seen chargers that take 9-volt batteries and convert them into juice, but realistically don't know how many batteries I'd need to drain to keep my electronics going.

So, what is my best option for having this device last the whole hike, with no recharge?

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Seems impossible with no recharge? I mean, turn it off... that'll make it last :) –  Ryley Mar 15 '12 at 5:31
Bring a real camera. –  whatsisname Mar 21 '12 at 18:16
@whatsisname if you're not a photographer, an iPhone 4+ camera takes excellent pictures considering all the other functionality it provides (and pretty damn light too). Obviously it's no DSLR, but it is surprisingly good! –  Ryley Mar 23 '12 at 16:00
Related question: outdoors.stackexchange.com/q/873/3143 –  Paul Paulsen Jul 22 '14 at 12:13

5 Answers 5

up vote 14 down vote accepted

If the GPS is mostly off (i.e. you're only rarely using your GPS app), I think you will get ~2 days of battery life. To get that much battery life, you'd need to do these things:

  • Keep the GPS off as much as possible (i.e. use it no more that 5-6 times a day)
  • Turn it off at night completely
  • keep brightness to a minimum
  • Disable all cellular antennas (may need to jailbreak to do this)
  • remove unnecessary apps, especially anything that wants to run in the background
  • turn it off during the day as much as possible

So even with all that, you're looking at 2 days.

What can you do beyond that? I think the simplest solution to get you the recharge you'd need is to buy an iPhone battery case - usually this is just an external Li-ion battery that plugs into your iPhone. These are pretty common, fairly light, and generally easy to use. They also have the advantage of often combining in a waterproof case (so you can take pictures even if it is raining). The limitation might be that it doesn't actually get you enough charges for what you want to do (a bazillion pictures are a lot!)

I agree that hand-cranks and solar chargers are not nearly reliable enough.

So the only other solution that I might consider is something that eats AA Li-ion disposable batteries (or if you feel environmentally friendly, the best AA rechargeables you can find) and spits out power via USB. Tekkeon makes a couple products that might be the right kind of thing (I've used one before that worked perfectly)... You might try this one. Li-ion AAs are very light, although expensive, and each set of 2 will charge your iPhone 1-2 times (depends on which AA charger you get and which iPhone you have... might be best to test this before you leave!).

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Airplane mode should disable all the antennas. –  Kevin Mar 15 '12 at 14:31
It does... unfortunately, that includes the GPS! –  Ryley Mar 15 '12 at 15:48
When traveling well-established trails I've generally found GPS to be completely unnecessary. It wouldn't even occur to me to enable it unless there was some sort of emergency. –  Michael Hampton May 10 '14 at 16:25
@MichaelHampton - I'm just saying it's a tradeoff - if you don't need the GPS, great... In that case, airplane mode will save you battery. If you aren't on well-established trails and you need occasional GPS, then it's worth knowing that you're going to sacrifice some battery life. –  Ryley May 22 '14 at 20:54

My solution is to let the phone be a phone (and GPS and web browser and ...) and take a camera to be a camera. My camera uses AA batteries, it's simple enough to bring spares, and I have a solar recharger for them too. I can take hundreds of pictures before I need to recharge the batteries. I can turn the phone on once a day or so to use the GPS or whatever, and I'm not using up phone battery when I'm taking pictures. Similarly, I'm not using up camera batteries when I'm checking to see if anyone phoned me.

I know it appears counter-intuitive - why take two things when one can meet both functions? But it works for me.

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You could consider looking into something like the PowerPot. They are currently accepting pre-orders on Kickstarter. It is described as follows:

Simply put, the PowerPot transforms the heat from cooking into electricity (…) using a technology called thermoelectric power generation.

PowerPot V prototype

I’m not sure how well it will work, but from their description it seems like it could do exactly what you’re looking for. The only thing is that it doesn’t look like it’s on the market yet, although the Kickstarter site mentions deliveries for pre-orders should start in July 2012.

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I was looking that over a few days ago - I found it suspiciously lacking in the hard details of how it would perform... most other chargers I've dealt with offer a pretty straightforward table of "charge for X minutes for Y% of battery for an iPhone Z". I hope that this thing does turn out to be great though! –  Ryley Apr 19 '12 at 19:56
Yes, I know what you mean. All they say is that it can produce 5W in "optimal" conditions. Hopefully the lack of details is just because they are still in the development stage... –  Big General Apr 19 '12 at 22:39
See the biolite camp stove as well, does something similar. biolitestove.com –  Benzo Mar 21 '14 at 19:34
If you are in an area where fires are not allowed then these are trading the weight of batteries for the weight of cooker fuel. –  Greenstone Walker Mar 23 '14 at 23:49

Take an external rechargeable powerpack like one of these:-


Choose the size of powerpack according to your trip length and needs, as these things are not lightweight. Obviously, these tend to be bigger and heavier than the device you're looking to charge :-(

As an alternative, look at an Android phone. You'll get much the same feature set (GPS, compass, phone) but with the advantage of field-swappable batteries. So you can just purchase a few extra batteries, charge them up, tape over the contacts and stick them in a ziploc bag.

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good point. I have one of these amazon.com/PowerGen-External-UltraSlim-Motorola-Blackberry/dp/… (also by PowerGen) and it claims to hold 3 full phone charges. It's smaller and lighter than my phone and works like a charm (plus it's a flashlight.) –  Kate Gregory Sep 17 '12 at 15:43
Battery cases are also available to extend battery life. See a comparison at wirecutter. thewirecutter.com/reviews/best-iphone-5-battery-case –  Benzo Mar 21 '14 at 19:37

Have a look at these solar charger options. Solar charger solio, power traveller, brown dog, snow lizard, Bushnell Bear Grylls SolarWrap Freeloader pro / freeloader, links http://www.instructables.com/id/DYI-iPhone-5-Solar-Charger-with-CAD/ http://www.outdoorgearlab.com/Solar-Charger-Reviews

In the end I went with an option by a company called Portapow and on Amazon they were doing a 11w solar panel and usb battery bundle for £80. Batteries by Anker also come with a good reputation and portapow also have an AA USB battery charger.

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