Portable Power for Climbers and Mountaineers

Power Article HeaderCGR takes a look at using the latest portable power devices to help power your adventures.

Smartphones have become an essential accessory for climbers and mountaineers, they have so many uses that I can’t imagine being without one. Don’t get me wrong, I love being ‘off grid’ for periods of time and there are benefits: being closely connected to my environment, having great people experiences and generally enjoying time without any distractions.

There are times, however, that I need one professionally and I like having one recreationally. I enjoying posting photos and updating status on expeditions and climbing adventures. Satellite phones are also becoming more essential on international expeditions as well as a dedicated GPS device that is separate from my smartphone. Professionally I would never be out with clients without some serious extra power for my phone.

My usual expedition length is three to four weeks and a typical climbing trip will be for 10 days, during those times I will often have access to electricity but it can be several days in between. My travels usually include my iPhone 4s, Garmin Fenix 2 and an iPad Mini 2 so these are what I need to power with priority going to the iPhone. On longer and more remote or professional expeditions I can also have Garmin Oregon 600 as well as a satellite phone or my DeLorme InReach that will also need power.  I definitely need to consider the harsh environments I am often using my devices in: sub zero temperatures, humidity, wind and rain all have an effect on the battery life of my smartphone – always adverse!.

Alpine routes with bivvies are also an activity where small portable power devices are useful. If you are on a route for several days then extra power can help keep you in contact with base and keep that social media feed sated.

So what should you look for to power your devices for small periods of time? Here are some tips from CGR reviewers who are out all year around in all weathers. We list what we think is important, we then suggest and compare devices from the major players.  All the devices tested are suitable for short trips into the mountains for a few days.


The device should be light enough for you to think about including it in your kit list. If it’s too heavy then the temptation is to ditch it and leave it at home. However, there is a direct link between weight and power. If the device is super light it will not have enough power for several charges.


The power of a portable power device is measured in mAh, that means milliampere hours. Basically the higher the mAh the more power the device has and the more charges it can put into your phone or tablet. Remember that link though, the more powerful devices can be heavier. Always look for an output of 5V and more than 2A as these will recharge you device at a quicker rate. Also check out the input you want at least 1A to charge the device in a reasonable time.


You will need to have a robust device and some of our test models have been specifically designed to be very robust with thick casings. Some models have passed an IP test and have an IP rating. This is an International Protection rating that explains a devices splashproof, dustproof and shockproof. The first number gives a dustproof rating and the second number give a water ingress rating. IP57 is good and fairly normal and IP68 is top notch. All ports should have water resistant seals for a decent IP rated devices. If a device is rated IP7X that means there is no rating for the water resistance but the device has good dustproof properties.

Charge displays

These are often a series of LED lights that simply show how much charge is left in the device. Typically a device will have 4 or 5 lights which flash when the device is charging or discharging. They are also good for letting you know how much charge is left so that you can monitor and control its use.

Charge time

This is only really crucial if you are charging the device from solar panels on longer expeditions or trips in wild areas where you will be camping without access to electricity. Our tests assume that the device is being charged at an electricity socket and then being used until it is drained. Although knowing how long a device will take to charge is useful if you have limited time. It is also important to note that these types of battery – Lithium Ion or Polymer need to be totally discharged and recharged several times before they achieve peak capacity.

Auto shut off

This is important so that the device maintains as much charge as possible. Smart devices will even recognise what type of phone is connected and charge accordingly. It should then shut of promptly to conserve charge.


We asked the main players to submit an appropriate device from their range and we tested them out in the field for a variety of activities. We give a short description of each, possible uses and our thoughts on whether they are fit for purpose. We then give them an overall CGR star rating. We just weighed the unit and not the accessories to offer an even playing field.


Brunton Revolt 4000

Brunton REVOLT



The Brunton Revolt 4000 is a very rugged device and very much looks the part. It has a 4000mAh Lithium Polymer  battery which is totally encased in shock absorbing silicon and it even has a Vibram base, it has an IPX5 rating. There is a large central button with 5 yellow LEDs to show how much charge is available and how much charge is left. The display flashes when the battery is being charged. The input is 5V 1A and is via the micro USB and the output is a respectable 5V 2.1A via a normal USB so everything was nice and simple with leads I always have available. The sockets are well sealed with a solid clicking closure which makes them rain resistant. It weighs 164g so light enough to be considered a pack accessory for a short expedition.

One of the great features of the Brunton is the supplied 3 in 1 lead which is supplied as an accessory. This is a normal USB at one end and an iPhone 30 pin, Lighting and micro USB leads going into it which makes it very versatile. A great addition and well thought through so no need to carry anything thing else as it’s all there and in a neat and robust package.

Charging times were reasonable at 4.5 hours from dead and the unit charged my iPhone 1.5 times from dead. It gave me about a 50% charge to my iPad Mini. The yellow display was easy to read and the unit shut off promptly.

I would recommend the Brunton Revolt 4000 for overnight bivvies or long days out on the hill when you are intending to use you phone as a GPS. It has become a staple in my pack for work and recreation alike.

SRP: £45.00  Stockists.


Varta Indestructible 6000


CGR Rating 4

The German company Varta make a huge variety of batteries and electronic paraphernalia. We featured them in last season Headtorch article where they scored highly with their excellent low cost Indestructible 1W headtorch which was great value for money. The Indestructible 6000 is in the same range and is an excellent powerpack for the money. It comes with a fabric case and a micro USB lead so you will need to supply your own iPhone leads.

It is a monster, packing 6000mAh and sporting two output sockets: one 2.4A and one 1A so you can choose how fast you want to charge your device (remembering . The unit is very robust and has an IP67 rating, which is a good as it gets. It is fully encased in metal and hard rubber with a solid flip lid that protects the sockets from dust and water. It is heavy too weighing in at 236g but you should remember that it packs a power punch with the amount of charges it can offer.

The charging display is via 4 small blue LEDs and the charging time was a hefty 7 hours through the micro USB input. There is also an on/off button and the unit was prompt with the auto shut off. The big battery was very useful for my iPad mini and I managed to get a full charge from dead – but I only had enough charge left over to put 65% charge into my watch. I could get three iPhone charges and I made my phone last 4 days as long as I charged from 50%.

The Varta Indestructible 6000 is definitely a good choice for trips of up to three days and as long as you are sensible with your power management you will get up to 4 days out of it. It is very robust too and will easily stand up the rigours of living in a climbing pack

SRP: £34.99      Stockists.


Freeloader iSIS

iSIS - Contents

CGR Rating 4

Although this test does not include solar we included the Freeloader iSIS as they are an established British brand that offer high quality power. We should add that other manufacturers make solar chargers and we will be featuring them during the Spring when we take a closer look at expedition power. We featured the Freeloader iSIS as it was the best, equivalent item from the range. I should also point out that I tested the iSIS from mains charging only.

The Freeloader iSIS is 4000mAh Lithium Polymer battery that has a good sized solar pv panel incorporated into it. It is a nice, compact unit that comes with protective cover, Velcro straps so it can be attached to a pack and a micro USB lead. It weighed in at 234g and measured 7.5 x 12.8cm so was one of the larger test pieces, about the same size as a large smartphone. The pack comes with a rubber case, micro usb lead and Velcro strap to attach the iSIS to your pack.

The unit came across as a robust and rugged charger with a micro USB input and a standard USB output so you can attach most modern smartphones or tablets. The sides of the iSIS had two leads, a micro USB and an Apple lightning lead. The unclip from the top corners and as long as you are using modern devices there is no need to carry extra leads. There is also a small information display in the bottom right hand corner that gives information on the amount of charge left and where the charge is coming from (whether from the mains or solar). The input/output at the bottom of the iSIS has two ports that have rubber covers, these proved a little flimsy and the smaller one detached quite easily, it was easy to replace and did stay in the port so I never felt I was going to lose it – I probably would on an extended expedition though. A small blue on/off button finished off the unit as well as a small stand at the back for solar charging.

The Freeloader iSIS had a charge time of 4.5 hours from fully discharged and I managed almost two iPhone 4s charges from dead and three quarters of an iPad mini charge, I would expect this to improve with more charges/discharges. So more than enough for a three day trip and with the integrated solar charger it can be topped up (as long as you’re not climbing a north face).

The Freeloader iSIS is a rugged charger that is designed for outdoor use, it would be great for shorter trips where you feel you only need an extra one or two charges or you are planning to use your phone as a GPS for the day.

SRP £64.99            Stockists


Anker Astro E1

Anker Astro E1

CGR Rating 3I’ve had one of these for a while and it has been a standard in my pack for about a year. Rich also uses one so we felt that it was only fair to include it. Anker are a US company that manufactures a wide variety of chargers and Solar PV panels.

The Anker Astro E1 is a very compact 5200mAh charger that charges from mains via a micro USB port and discharges through the standard USB port. It has 4 small blue LED’s that display how much charge is available and flashes to indicate it is charging. You will also need to carry whatever leads you will need to charge, it comes with a micro USB lead and a mesh case as standard.

It also has an LED to let you know it is fully charged by turning from amber to green together with a small on/off button. The Astro E1 also boasts Power IQ which detects what type of device is connected and discharges just the right amount of charge needed.

It has no IP rating and isn’t weatherproof at all so you will need to keep it in a waterproof bag (I’ve used a standard  Exped bag for a while with no problems) and it has a glossy case. It is fairly lightweight weighing in at 122g so was the lightest in test.

Charging times are good – it took the Anker Astro E1 4hrs to fully charge from dead and I have managed to fully charge my iPhone 4s twice and have a little left for a watch charge. It gave my iPad mini a 90% charge from dead.

I’ve included the Anker Astro E1 as I have used it for a while: the compact nature of the device make and it’s price make it a good choice for day out with a good forecast.

Stockists         SRP £19.99 (but often cheaper)


Power Traveller Minigorilla

Image 995

 CGR Rating 3

Power Traveller are another UK company and the Minigorilla is part of their Professional range is the beast of the bunch, with a 9000mAh battery, a good sized display screen which shows the voltage being discharged and the amount of charge left and the vast array of connectors means that there isn’t anything the Minigorilla won’t charge. I was, however, surprised that I couldn’t find any micro USB, Lighting or 30 pin leads but there were sufficient connectors to charge a netbook and most sorts of mobile device you have. There is, however, a standard USB output so you can charge iPhones and most android phones that need a micro USB. The device is also water resistant but doesn’t have an IP rating.

The Minigorilla has a dedicated charging lead whereas all the other devices charged through a micro USB port and to charge this device you will need to carry the charger as an extra. The charger came with a selection of international pins so it can be changed according to the country/continent you are planning to visit.

The Minigorilla is a very robust device with a hard plastic case and rubber grips along the length. Considering that the battery is so powerful I was nicely surprised to find the device weighed only 249g so would break your back in a pack. Charging times was 5.75 hours from dead and it charged my iPhone 3 times, my iPad Mini from 50% and fully charged my watch with still one bar left! So this really does provide plenty of power.

The Power Traveller Minigorilla is perfect for trips of 3-4 days and will provide plenty of power for a whole range of mobile dev ices and netbooks. The only downside is that it has its own charger and doesn’t charge from a micro USB so you will have to carry this for extended use.

SRP £99 (currently on offer for £70.00 on the Power Traveller website.). Stockists


Finally here are a few tips to extend the life of your gadgets whilst out in the mountains.

  • Make sure all your devices are fully charged before you set out on your adventure.
  • Never let your device go below 50% power if you can help it – trickle the charge in from there.
  • Switch your phone on to airplane mode when you are not using it.
  • Close all background apps – these really do eat up power. If your device has a way to switch off the background app refresh then do so.
  • Switch to 2G when not up or downloading – you can still make calls and send texts
  • Send texts rather than call or iMessage/ Messenger.
  • Reduce the screen brightness and enable any power saving settings the device has.


And last but not least your device is only as good as your lead – the lead is often the weak link in the whole system and is the most likely item to break. Buy a high quality lead – my preferences are for the Brunton Power Knife and the brilliant Mophie Travel USB Kit. The MOS Spring Cable also looks like it would fit the bill but I haven’t been able to get one in the UK. A longer cable is useful as I can keep the power in my pack and still use my phone as the Brunton and Mophie cables are very short.

About the author:

Dave bio shot

Dave Sarkar has tested and reviewed climbing, mountaineering and outdoor equipment for almost 10 years. He works as a qualified MIA and aspirant IML: working full time as a mountaineering instructor and expedition leader for his company Wild Spaces. When he isn’t working in the mountains he’s playing in the mountains and enjoys all aspects climbing and mountain sports whether bouldering at his local crag or ice climbing; as long as he’s going upwards he’s happy!


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  1. Technology is such a wonderful thing. We wouldn’t have all these conveniences half a century ago and now look at us, charing our mobile devices in the middle of nowhere! I’m definitely investing on some of those equipment, it’s pretty useful in camping and trekking. Thanks for the review. Any personal favorites Dave?

    1. Yep, my favourite it the Freeloader iSIS. I’ve been using in with the larger 5w Supercharger and it’s been perfect. My mate uses the Anker with an Anker solar panel, this also works well. I use the Freeloader as they are a British company. All the best, Dave.

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