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?

  • 1
    Seems impossible with no recharge? I mean, turn it off... that'll make it last :)
    – Ryley
    Commented Mar 15, 2012 at 5:31
  • 2
    Bring a real camera. Commented Mar 21, 2012 at 18:16
  • 1
    @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
    Commented Mar 23, 2012 at 16:00
  • Related question: outdoors.stackexchange.com/q/873/3143 Commented Jul 22, 2014 at 12:13
  • Not worth an entire answer, but I've brought both an iPhone 4 and 5s on trips like these and they do actually last a good time longer than you'd expect in airplane mode. I'm not sure about the GPS function but when just occasionally taking pictures without also browsing them a lot, you can last 5 days without too much effort. Commented May 22, 2015 at 11:32

9 Answers 9


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!).

  • 6
    Airplane mode should disable all the antennas.
    – Kevin
    Commented Mar 15, 2012 at 14:31
  • It does... unfortunately, that includes the GPS!
    – Ryley
    Commented Mar 15, 2012 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. Commented May 10, 2014 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
    Commented May 22, 2014 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.

  • There are specialized appliances for GPS as well. So let your phone be a phone, your GPS be GPS, etc.
    – anatolyg
    Commented Dec 19, 2019 at 8:26

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.

  • 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
    Commented Apr 19, 2012 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... Commented Apr 19, 2012 at 22:39
  • See the biolite camp stove as well, does something similar. biolitestove.com
    – Benzo
    Commented Mar 21, 2014 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. Commented Mar 23, 2014 at 23:49
  • It takes < 5 mins to boil up a pan of water to cook a meal. Is that long enough to charge an iPhone with this?
    – QuentinUK
    Commented Jun 3, 2015 at 12:55

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.


Ideally you want an independent device for your navigation. Such as a Garmin Dakota 20 or a Garmin Foretrex 401 which are both considerably cheap. On established trails you don't need that at all.

However if things go south, murphys law suggests, that your cellphone will be dead by then as well.

An external power bank (plenty of links above already) can hold up to 4+ charges and is good to have around in your normal urban life as well.

If you run your phone on airplane mode and have one of these powerbanks you should be good for up to 14 days without a gridbased power source.

Using the GPS on your phone WILL drain your battery in no time. I have an app for topographic maps. However it will use the GPS constantly, resulting in your phone being dead in 3-4 hours.


I'd recommend getting a solar powered charger. I go for multi-day hiking trips and I use one all the time. I ordered mine from aliexpress.com, waterproof, for less than $20. It's really inexpensive because you're ordering it directly from China and it's free shipping since China ships so many goods all around the world.


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.


You're a little too late for this kickstarter campaign, which covers your exact use case:


It's a fuel cell that converts lighter or camping gas from standard containers to electricity for USB charging with outdoors in mind. However fuel cells aren't new. What's new is the support for standard gas containers in a portable and somewhat robust device. Earlier products required hydrogen, specific containers and/or a fixed orientation to operate.

Hope it'll hit the market in mid 2016.

Disclaimer: I'm a backer but not affiliated to eZelleron otherwise.


Most items have been mentioned (and I will not repeat them), but some obvious I didn't see are:

  • Turn off Bluetooth
  • Turn off WIFI
  • Already mentioned was making the screen brightness lower. A screen is using up a lot of power. Related are:
    • Don't look more than needed on the display.
    • I assume you can define the time before the screen blank timeout (after you looked at the screen, it will turn off after some time). Minimize this time, or better, switch the screen off manually.

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