Given I spend most summer weekends under canvas, maintaining charge in electrical items like my mobile phone and ipod, can be a challenge.

To eke out the power in my phone, I tend to keep it on flight mode unless I absolutely need to use it, whilst use of my iPod is strictly rationed, allowing for just a few hours of music each day.

I love spending time in the natural world, and I'm largely glad to be free from digital distractions, but relaxing in the sunshine with an interesting audiobook can be a pleasure, and on a cold wet evening I love disappearing into my sleeping bag with a good film to watch on my tablet.

For families with small children who rely heavily on things like iPads to keep them entertained, I'm sure camping can be a bit of a trial. For safety reasons too, it's good to know that your smartphone is there for you, even if it is just to use GPS to check the route of a walk or find out the opening times of a nearby attraction.

To overcome the problem of spending so much time without any electricity, I bought myself a Power Monkey Powertraveller many years ago. It had a 2200mAh battery pack, which is approximately half the power of the 4000mAh iSIS at peak power. The Power Monkey claims to be able to fully charge a mobile phone three times, though in use I've found it is capable of just one and a bit full smartphone charges.

Of course, it's important to understand that different batteries will have different storage capacities - and one gadget will use power at a different rate to another. For example, an iPhone 6 battery stores around 1800 mAh, whereas the original iPhone was 1400mAh, the Samsung Galaxy S5 is 2900mAh and the iPad Air is 8820mAh.

I'd been looking for a more powerful replacement for some time, and another camper friend of mine had been singing the praises of her Freeloader solar charger, so I was keen to test out the iSIS.

When the device arrived, it was smaller than I'd imagined and included the main unit, which has built in charging ports (micro and standard USB) as well as two integrated flexible charging arms (lightening and micro USB), there was also a rubberised protective case, a separate mini USB cable and a carry strap.

With a 220mA solar panel, the iSIS uses a powercell that Freeloader claim is upto 50% more efficient than competitor products. The unit is also built for extreme environments, working effectively down to a teeth chattering -20 degrees, up to a sweltering 60 degrees.

The iSlS has a good solid feel to it and is beautifully made - a two year warranty is a rare thing in this day and age and Freeloader are clearly confident in the build quality and longevity of the device. Size wise, I have a Sony Xperia Z2 smartphone, and the iSIS is the same width, but is actually shorter in length though approximately double the thickness.

The unit arrived with a factory charge, which showed two bars on the little LCD screen, indicating the battery was approximately 30% full. I immediately used it charge my dead smartphone from 4% up to full charge, and I still had one bar showing on the screen.

I then topped up my iPod using the USB port which drained the battery fully. An impressive start though.

Plugging it into the mains, I left it to fully charge back up to five bars, which took approximately three hours. Keen to see how the charger would fare with a higher powered device, I plugged my Hudl2 tablet it. The official blurb claims you'll get one hours use, but I managed an impressive hour and 20 minutes of use.

As the battery was fully drained again, I decided to give solar energy a try. I left it in direct sunlight at home on a winters day. It was bright, but there were clouds and no consistently bright sunshine. When I returned home (10 hours later) the unit was showing one bar of power, which honestly, I was quite pleasantly surprised by.

The following day we took it outdoors on a walk with us. The unit comes with a strap which has an adjustable velcro fastening, which can be attached to the rubberised carry case. Our walk lasted a few hours, and I used the velcro strap to attach the iSlS to my daysack, where it sat securely, soaking up what little there was of the winter sun.

Unfortunately the battery didn't make it up past one bar, but that's hardly surprising given the weather.

My advice would be to rely on mains power for full charges wherever possible, and top up with sunlight as necessary when out and about. In winter weather, conditions are far from ideal to expect a solar charger to work at optimum efficiency.

It's worth understanding the maths here.

This solar panel is rated at 220mA and, at peak performance in the height of summer, will therefore charge a 4000mAh in just over 18 hours. With less sun, or less powerful sun, the charging will take longer. In spring sunshine, you might be operating at about 50% of that.

So the rating of the solar panel determines how quickly it can charge your battery, and surface area is king.

Instead of storing it away when not in use, I now keep it next to my south facing kitchen window, to minimise the need to charge it from the mains. I don't doubt that the solar charging function will be much improved in summer with more, and far stronger direct sunlight available.

That said, it's also important to note that glass (particularly in windscreens, double glazing in conservatories and the like) tends to filter out the UV light which solar panels need. Solar panels won't tend to charge quite as well when sat behind a window.

All said, I think the iSIS is a superb little gadget and ideal for my needs. A device that can charge my phone and iPod, and allow me to use my tablet for an hour or so suits my needs perfectly.

Whilst there are solar devices which are more powerful, the benefit of the Freeloader iSIS is it's excellent build quality and compact size. I already take such a large amount of gear with me when I camp, that anything new I get needs to be as small as possible.

The iSIS does a great job of providing a good amount of power in relation to its size.


A beautiful looking and simple to use gadget, with the flexibility to charge via the mains or solar panel. The build quality is excellent and the built-in charging arms are handy.


The flip-out arm could be more stable, and LCD screens can be hard to view in daylight.

Recommended Use

I'd recommend this for campers, hikers, festival goers and backpackers. Anyone really who spends more than a day or two outdoors in the summer.

Ease of use:
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