FeatherSticks · Gear
Power Bank for Camping: Sizes, Phone Battery in the Cold and Solar Chargers
Your power bank holds about a third less than the number printed on it.
Quick facts
- Weekend (2–3 days)
- About 10,000 mAh (37 Wh) for phone + headlamp
- Usable capacity
- Roughly 60–70 % of the printed figure
- Reserve
- Keep 20–30 % of the phone for emergency calls
- Cold
- Inner pocket by day, sleeping bag at night
What you need
- Power bank sized to the trip (5,000–20,000 mAh)
- Short charging cable plus a spare on longer trips
- Spare lithium AA/AAA cells for devices that take them
- Clear zip bag for the phone
- Small roll-top dry bag for electronics
- Thin touch-screen gloves for winter
- Folding solar panel (only for long, sunny trips in open terrain)
Step by step
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1 List what needs power
Phone as map and emergency phone, headlamp, GPS and anything else. Note the battery size of each and how much you use it per day.
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2 Convert mAh to Wh, minus losses
mAh × 3.7 V ÷ 1,000 gives watt-hours. About a third is lost in conversion, so plan with 60–70 % of the printed capacity.
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3 Pick the power bank size
Rule of thumb: 5,000 mAh for one night, 10,000 for two to three days, 20,000 for four to five. In the cold or with heavy use, go one size up.
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4 Make the phone last
Download offline maps at home, use flight mode on the trail, keep the screen dim and off while walking, and close apps you do not need.
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5 Keep batteries warm
Carry phone and power bank in an inner pocket by day and in the sleeping bag at night. Charge lithium batteries only above 0 °C.
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6 Pack dry, keep a reserve
Electronics go into a zip bag or dry bag. Keep 20–30 % of the phone battery for an emergency call and stop navigating with it at that point.
Common mistakes
- Buying by the mAh on the box without allowing for conversion losses.
- Using the phone as map, camera and torch until it is empty, with no reserve for an emergency call.
- Carrying phone and power bank in an outside pocket in frost.
- Charging lithium batteries below 0 °C or warming them next to the fire.
- Relying on a solar panel for a trip in the forest or in winter.
- Charging the large power bank on the morning of departure.
- Carrying spare cells loose with keys and coins.