GPS Battery Life Calculator
Predicts runtime for a handheld GPS given temperature, sample rate, and backlight use.
Inputs
Result
A natural placement between the calculator and the explanation.
What this solves — and what it doesn't
GPS handhelds have wildly variable battery life depending on how you use them: sample rate, backlight, cold, battery age. A Garmin 65s might last 16 hours at 10-second sampling in summer but under 8 hours at 1-second sampling in winter. This tool predicts runtime from those factors so you can carry the right number of AAs or know whether to keep the GPS off most of the time.
How to read the result
The result is total runtime from full charge. Plan for 60% of that as ‘safe usable time’ — leaving buffer for the unexpected. If the number is too low, drop sampling to 30 seconds (saves ~30%) or carry spare batteries.
Cold is the silent killer. Below freezing, lithium AAs hold more charge than alkaline; below -10 C, store the GPS in an inner pocket.
Limitations
- Battery draw varies by device; we approximate from a Garmin-class baseline.
- Doesn’t model barometric altimeter or compass draw separately.
- Age estimate is linear; lithium batteries hold voltage longer than predicted.
Frequently asked questions
Should I carry lithium or alkaline?
Lithium. They weigh less per mAh, last 5 to 10x longer in storage, and hold up in cold.
Is the backlight a big deal?
Yes — it can double draw. Use auto-dim or short timeout.
Does the GPS work under tree cover?
Yes, with reduced accuracy. Heavy canopy can extend fix times and burn more power.