I have a simple 2D Eagle fish finder on the small (12') tin boat. Use a Cabelas small sealed 12 v. battery to run it. Has always been very reliable (for many years). Today it quit on me totally. The battery was charged yesterday and the charger said it OK. I rechecked the connection leads and they were tight (push on friction connectors to the blades of the battery).

I'm thinking about connecting it directly to my main deep cycle (wet cell) series 27 battery, in the boat that we use for the trolling motor. If that turns on the sonar, does that necessarily mean that the battery is the source of the problem? Or could it be the transducer cable.....or, heaven forbid, the sonar itself?

Hoping some of you may be able to give me some guidance as to a diagnostic procedure to find out what the problem is. It started out running just fine when we were fishing today. A couple of hours in and she just quit! Thanks for any suggestions folks.