Garrett Ace 350 Owner's Manual page 13

Battery Level Indicator—Indicates the current battery

condition. The detector will maintain full performance until
the batteries need to be replaced. Replace batteries when
there is only 1 segment remaining. NiMH rechargeable
batteries may be used, but may have a shorter life per charge.
You can expect 20 to 40 hours of operation depending on
battery type and quality.
Access and replace the batteries by sliding the cover off
the control housing. Remove batteries when the ACE 350 will
be stored for longer than 30 days.
Note: 1.5v/cell Lithium batteries can also be used, but the
use of 3.7v/cell Lithium batteries will damage the detector.
Sensitivity Indicator—The ACE 350 has eight (8) settings

for sensitivity. (See page 18 for information on when to adjust
your sensitivity settings.)
12 Garrett Metal Detectors