Lowrance Elite 3 transducer

OK, I just ordered the box from Walmart. 
Yet another question, regarding chargers.  Is it safe to use the Battery Tender Jr. that I use for my motorcycle, or is it too powerful? 
I looked on amazon, but the charger they have had some not great reviews. 
Is there something else I should be using?

Tender is fine.

I ordered the waterproof box from Walmart, with a delivery date sometime week after next.  I had looked online and it showed that the box wasn't in stock in my area.  As luck would have it, I was in Walmart the other day and sure enough, they did have them in stock so I grabbed one.  Drilled a hole just big enough for the wires to fit through.  I ran the wires into the box, crimped on connectors, and then sealed the wires into the hole inside and out with silicone. 

If the weather cooperates, (we've had thunder storms and heavy rain everyday for a week), I'll hit Stampede for some kokanee on Thursday.  Gonna be fun actually seeing what's going on down there for a change!

Ron.

Update: 

I've used my setup a couple times now, trolling for kokes.  Both trips I ran the finder non-stop for about 5 hours.  Everything is working very well. 

The battery level only drops from 12.8 V down to 12.6 V during that time, and running the transducer through the scupper hole is convenient as well. 

Only down side is how frustrating it is to see a huge school of fish on the screen, troll right through them, and not get a bite!

Ron.