How long will the batteries last? NMP Support Center December 14, 2011 21:39 Follow The average overall life, based on normal use, is between 25 and 30 hours of operation. Related articles Live action use of the DT1H Would be possible to use the handheld sonar just for measuring distance/range of fish in front of the diver ? All I get is "---" readings on my depth sounder in certain places. I've noticed that these places have very soft/muddy bottoms and/or very dirty/silty water. I see a small amount of water leaking from near the activation button and display screen after submerging my Handheld Sonar. Is that normal? Can I use gorilla glue or silicone to fasten my transducer to my hull? Comments 0 comments Please sign in to leave a comment.