I'm glad to hear that your solar recharging system is working. However, you could have made an easily transportable box for your battery for a lot less cost than a solar system, and you wouldn't need to worry about somebody stealing the solar system. For example, here is a link to a post I did which describes an inexpensive waterproof battery box which connects to my fish finder or a battery charger with a SAE two-pin panel-mounted connector.
http://www.northwestkayakanglers.com/in ... #msg191025 .
If you're fishing from your Outback, carrying your fish finder battery to and from your kayak is the least of your problems. You probably also need to carry the fish finder head, rod holders, a stringer, and tools like a knife, fish bonker, and pliers, and lures and other tackle. I bought a plastic tool box and use it to transport all my fishing equipment in my vehicle, and to carry that equipment between my vehicle and the shore or boat ramp when I'm loading and unloading my kayak. The tool box keeps all that gear together, and makes it easy to carry. My battery box is just one of many items of equipment in the tool box.