Field equipment is judged differently from equipment used indoors, because the cost of failure is not inconvenience. This page covers environmental ratings, power budgeting, and redundancy for carried and outdoor-use devices.
01Environmental ratings and what they omit
Ingress protection ratings are a standardised two-digit scheme. The first digit describes protection against solid particles, the second against liquids, and a higher digit indicates a more demanding test. The rating is meaningful because the tests are defined, but it is narrower than it is usually read as.
What a rating does not tell you:
- It is a test result on a new unit. Seals, gaskets, and adhesives degrade with age, heat, and
impact. A rating describes the device as manufactured, not as carried for two seasons.
- Water tests are usually fresh water. Salt water is chemically harsher and is generally out of
scope.
- Pressure and movement are not the same as immersion. Immersion testing is static. Moving water
and high-pressure spray apply forces the test does not model.
- Dust and liquid are not shock, altitude, or temperature. Those are separate ratings, tested
separately, and often not published at all.
Operating temperature range is frequently the specification that matters most in the field and the one least often stated. Batteries, displays, and adhesives all behave differently in cold, and sustained heat is the more common cause of permanent damage.
02Power is the binding constraint
Away from a supply, every device competes for the same finite energy, and the plan should be built in energy terms rather than device terms.
- Battery capacity is rated under laboratory conditions. Cold, high-draw use, and age all reduce
the usable figure, sometimes substantially.
- Recharging is not free of loss. Energy moved from a pack into a device is reduced by conversion
losses at both ends, so a pack does not deliver its nominal capacity to your devices.
- Solar collection is highly dependent on angle, shading, and conditions, and realistic output is
well below rated output. It extends a power budget; it rarely replaces one.
- Charging a cold battery can damage it. Warming a pack before charging is standard practice in
cold conditions.
Build the budget from measured consumption over a realistic day, add margin for cold and for the unexpected, and know which single device you would keep powered if everything else had to be switched off.
03Navigation, communication, and redundancy
Satellite positioning receivers determine position by receiving signals; a basic receiver does not transmit and cannot summon help. Devices that can request assistance are a separate category with their own subscription, registration, and coverage requirements, and those requirements should be confirmed as active before departure rather than assumed.
Terrain, tree cover, and structures degrade both positioning accuracy and communication reliability. Coverage maps describe favourable conditions.
The general principle across all of it is that a single electronic device is a single point of failure with a battery attached. Redundancy in this context does not mean a second identical device, because an identical device shares the same failure modes and the same power dependency. It means a fallback that fails differently: a paper map and compass alongside a receiver, a non-electronic light source, a way to signal that does not need a network. Carrying the fallback is only half of it; being able to use it without the primary device is the other half.