I have just finished making up a battery box for my new Raymarine Dragonfly 5 pro. Prior to this I had just been using a dry bag but wanted to switch to something a bit more sturdy.
First up was finding a suitable box. I found the Pelican 1120 to be the perfect size for my 12v 7ah battery. In addition to the size, it comes with foam included that has perforated edges so can be cut to size very easily to make a nice snug fit so that the battery doesn’t move around.
The Peli 1120 case is not cheap. A new case with foam will set you back around £35-40. The good news is that they regularly appear second hand on EBay. I managed to purchase 2 in a week both for lesson than £20. This is still quite expensive but the box feels very sturdy and is completely water tight.
You can remove the perforated edges of the foam to give a really close fit to your battery. This will prevent any movement whilst out paddling your kayak.
Once the battery was in place I fitted some female crimp terminals to some short lengths of cable. I included an in line fuse that can take micro fuse blades. This is recommended by most fish finders in their installation manual and will prevent any spikes in voltage causing any damage to your expensive fish finder.
I connected the live and neutral cable to an index marine bulgin low flange socket (http://www.indexmarine.co.uk/bulgin-connectors.html). These are expensive (approx £10) but they are so simple to install and offer a watertight seal. Combine this with the index marine plug connected to the fish finder power cable and you have an easy way to connect the fish finder to the battery box.
The finished result is shown below:
I’ve been really happy with how the battery box ended up and see it lasting longer than I will!