A battery idea for a depth finder in a kayak

I have a depth finder I bought for another project and considered how to mount it in my kayak. The first thing I was up against was finding a battery (and charger) to power it. I considered one of the AGM batteries but with the cost of the battery (≈ $30) and a charger (another ≈ $30) the cost became prohibitive. While in my shop I noticed my battery powered drill batteries in their chargers and it hit me. I already have a 12V battery and charger. All I had to do was figure out a way to connect my drill battery to my depth finder. That turned out to be easier than I thought. My drill is a Dewalt and the connections on the battery are two straight spades set down in the connector. I checked my electric junk drawer and found two straight terminals called Female Spade Connectors. I found two that were close and all it took was to insert a small screw driver to expand the width of the terminals so they would accept as the spade part in the battery as it is considerably thicker than the intended spade. The battery was not marked for polarity, so I had to use my multi-meter to determine that. Once I had the female connectors attached to the wires of the depth finder, a quick check showed that the kluge works. I am off to the local hardware store to find a plastic tool-box large enough to hold one battery and the excess cable and with a top flat enough to mount the depth finder display, and I will have a portable unit I can take in my yak or my Jon boat. I have the transducer mounted on a small float.

If you have a different brand drill make sure that whatever connectors you find to work that the connectors are firmly attached to the battery. And make sure you are certain of the polarity as reversing them can often cause damage to the depth finder and if left connected to the battery it will be harmed also.

Below are some pictures of the “almost” finished project. I opted for a small snap lid box. The second picture is the battery and excess cable inside the box and the third is the underside of the top. I used a thin piece of aluminum clad PVC sheet (Alucabond - locally made) to make the top stiff enough to take the screws and nuts to secure the bracket for the display unit. Not shown is the transducer which is presently mounted on a chunk of 2X4 as a float.

Fantastic!!! Thanks for sharing that idea…

Have you checked out the solar rechargers that are available for computers/cellphones? I have seen them in cabela’s catalogs, forestry suppliers catalog and the computer store. They appear small, flexible and light enough to place on your foredeck (correct name for a kayak?) There maybe a way to adapt one for you use. good luck and let us hear back from you on whether it is a feasible, do-able idea.gerri

Pictures added to the first post.

Those tool batteries are a little pricey aren’t they? I use one of these
http://www.homesecuritystore.com/p-239-bd412-12-volt-4ah-alarm-battery.aspx?affiliateid=10050&wm_ctID=359&wm_kwID=21942114&wm_mtID=1&wm_DefaultURL=http%3a%2f%2fwww.homesecuritystore.com%2f&source=pla&utm_source=google&utm_medium=cpc&utm_campaign=pla
I
bought three at a damaged and overstock outlet for $3.80 each the other day.

The original thought was, that I already had the 12V drill battery and the appropriate charger, which were not being used while I was out fishing.

I get that, but those batteries are more expensive than the tools they go on, you want to use it up on a sonar is your choice for sure.

He didn’t buy another battery, he is using one he has, if he is like most of us guys, there’s another in the drill at home. I would bet he can run the sonar half a day and then drill half a dozen holes in 2x4’s when he gets home.

I use a 12v deer feeder battery for the FF on my yak, can get 'em at Academy sports/Gander Mtn and the correct charger for $30-40. then build a battery box with a $5 dry box from walmart, some quick connect electrical connectors for the wiring, some goop, and it’s dependable, rugged, easily removed for transport and installes in 30 seconds at the ramp. These batteries will run a simple FF (Lowrance Mark 5 pro) for 4+ trips of 4+ hours/trip.

I will stick with my Alarm battery. Even at full price, just $14.00