Has anyone tried using a lawnmower battery  to run a sonar unit? What kind of life can I expect?  How about putting 8 D-cell batteries together, What kind of life can I expect out of a set of batteries.

I am using a Eagle Fishmark 320 and I only have 1 battery for the TM and sonar.  I am trying to clear up a little interference issue I am having.

Andy

Eagle sells that same unit in a portable model that runs on "D" cells.

http://www.eaglenav.com/en/Products/Fishfinders/FishMark-320-Portable/

I would recommend getting a small gel cell battery and charger so you do not have to worry about acid spills. I would think using "D" cells would empty your wallet pretty quick.

this battery should keep you on the water all day.

http://www.allelectronics.com/make-a-store/item/GC-1214/12-VOLT-12-AH-RECHARGEABLE-BATTERY/-/1.html

this charger should keep your battery topped off when your not using it.

http://www.allelectronics.com/make-a-store/item/BC-212/12VDC-500MA-2-STAGE-CHARGER-FOR-LEAD-ACID-BATTERIES/-/1.html

A little more compact is the 12 volt batterys for emergency lighting or pick up a battery for Acu View about $25 at BPS same thing. Then get a power point with clips to charge.

Using D's will cost.

Garnet

Some kayakers use 12V deer feeder batteries to run their fishfinders.  You can find them for less than $20 on the web.

I have a cheap locator on the pontoon and put a motorcycle battery to it.  Have the battery strapped down in the steering console storage.  Works fine.

I use a lawn tractor battery as a cranking battery for my 20 hp outboard. My livewell pump also runs off this battery. It was worked well for me, I just make sure to charge it fully after a few long days of use.