I'm planning an 8-day trip without resupply, which is a few days longer than the internal battery on an inReach SE will last.
My previous multi-day tests were on a long road trip, where the inReach was in the back of my truck, with most features turned on for maximum battery consumption. I got about 5 days per charge.
Sunday, I ran a different test, trying to extend battery life.
I went through all the settings to maximize battery life, except Tracking:
- Bluetooth: Off
- Message check interval: 20 minutes
- Ring until message is read: Off
- Tracking: 10 minutes (max battery life would be Off or 4 hours)
- Display brightness: 10%
This brightness is unusable in daylight, even in the shade. I turned brightness up and down each time I used it.
- Display timer: 15 seconds
- Sounds - Mute All: On
I sent two Preset messages, and one custom message that took 10 minutes of cursoring/cursing to enter ~90 characters.
After 11.5 hours of use (2.5 hours driving, 9 hours hiking), battery life was at 89%, starting from 100%. The driving and hiking were on roads and trails with pretty good exposure to the sky.
Extrapolating linearly indicates roughly 9 days of battery life.
Most of my days will be shorter than 11.5 hours on my planned 8 day trip, so I should be OK without a charger. I plan to turn off the inReach SE at camp each evening; and turn it back just as I start hiking the next day.
Note that realistic testing is challenging, because you must keep moving to keep the inReach SE awake.