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Information Battery percentage and status

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The MagEx instrument and the MagNav app both display information about the state of the instrument's battery. Battery state and reporting exist in bands according to percentage of remaining battery capacity:

  • 30% or higher:
    The instrument has good remaining capacity.
    The LED on the instrument's power switch glows a solid green.
    MagNav displays the battery percentage or voltage in black text on a white background.
  • Between 20% and 30%:
    The instrument has capacity to survey for additional time, but if you will be surveying a significant amount more, start thinking about changing the battery.
    The LED on the power switch is blue.
    MagNav displays the battery percentage with a blue background.
  • Between 5% and 20%:
    You can continue to survey, but the battery is running low and you should consider changing the battery soon.
    The LED on the power switch is red.
    MagNav displays the battery percentage with a red background, and periodically notifies you that the battery is running low.
  • Below 5%:
    The battery is running low, and the instrument may turn off at any time in order to preserve battery health. You should change the battery as soon as possible.

Temperature-related effects:
Battery performance also changes as the temperature of the battery changes; as the temperature of a battery falls, the voltage it supplies also decreases, and the total energysupplied by the battery decreases. This means that in cold weather a battery will not last as long as in hot weather.

The battery percentages reported in the instrument are adjusted for the effect of temperature; at a given battery voltage a cold battery will display a higher percentage than a warm battery will report.

The effects of colder temperatures are not normally permanent; as a battery warms up, its output voltage and energy return to higher levels.

Notes about the calculation:
The MagEx instrument includes 2 batteries, and each battery includes 3 separate cells. Battery percentages are calculated from only one battery in the instrument - either the single battery if only one is connected, or from the better battery if two batteries are connected.

Reported battery percentage is an estimate, based on measurements of the behavior of healthy batteries in instruments in the field and in the lab. Battery performance may change as a battery ages and as the temperature changes.

The best practice for batteries is to use 2 healthy, fully charged batteries, and replace them both when the percentage falls below 20%.