Riding the Flow

musings from the shire

Powering Your Gadgets in the Wilderness



In discussions with other gadgets users, often the problem of getting extra power comes up. Particularly when you are away from power outlets for prolonged time - e.g. on the nature hike.
Two "miracle solutions" always inevitably come up - using muscle power ("wind-up chargers") or using solar power. On first look, they appear to be perfect. However, they have very significant shortcomings in reality:


  • Wind-up chargers use energy of your body. When you may think its not significant, think again - usual mobile device consumes quite significant amount of power. If you want to actually charge it - you must provide more power than it consumes over all time you use it. Which you will quickly feel, when you have to wind this handle for such a long time and with such force. Law of conservation of energy also won't go anywhere - all this energy will come from your body, which will have to replenish it from food. Overall, this energy conversion process will be horrendously inefficient.
  • Solar chargers give you truly free energy, but in tiny amounts. Especially considering the fact that its not always possible to place them under perfect noon scorching sun. Even with that, realistically-sized panels (which are reasonable to carry around) won't give same current that your smartphone consumes as you use it - meaning they could only prolong the inevitable "battery has been discharged" message.
  • One less known solution would be using fuel cell or thermoelectric converter. While in theory, power/weight for chemical energy of usual fuels is magnitude better then even best batteries could offer, we still have to see efficient applications to appear in mainstream production.
So I always say - don't bother, just get a simple device like this - Varta Digital USB Charger.
Simple calculation - if you just carry this charger with 4x 3000+MAh NiMH rechargeable AA batteries, this will give you 12+Ah of power. If you just throw additional 4x AA batteries in your backpack - 24+Ah in total. You can estimate for yourself, how much your smartphone will hold on 24000 MAh, if its usual battery is about 1500 MAh. Need even more? Just carry more batteries, this will be much more efficient than carry extra food to replenish your energy from winding that charger handle ;)
Also such USB charger could be used to charge NiMH rechargeable batteries all around in home while you are not out exploring. Which could actually be its major usage, saving it from gathering dust in your cupboard.

Even more efficient and lightweight would be to carry extra pre-charged LiIon batteries for your exact device model - but nowadays not all devices give you swappable batteries, and this could become much more expensive comparing to USB charger, which uses off-the-shelf AA rechargeables.

Well all that unless some global cataclysm happens - then these solar or wind-up chargers could actually become usefull ;)

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