Right now I'm running my bow mount t-motor with battery in back of boat. I've run 6ga wire from battery to t-motor. I've also got my graph up front but I run it on one of those little Cabelas batteries.
Is there a way to tap in to the 6ga wire and run the graph off the main battery, or do I need to run seperate wires to the back?

There are several ways to splice in your graph wires to the trolling motor wires. 6ga is pretty big so you're probably not going to want to use wire nuts. You could put in an inline splice and just put the smaller wire for your graph in to the crimp along with the big wire. If it were me I probably would just strip off some insulation and solder the smaller wire right onto the trolling motor wire and cover the area with electrical tape.

Be careful running you graph and t-motor on the same battery. It can (not necessarily will) cause interference on your graph while you are running your t-motor

Ditto on wiring the graph on the trolling motor battery. I don't know how the newer trolling motors / graphs behave together but every time I've tried it in the past I got interference. I use a small Cabelas 12v battery to power my graph instead. You can get the battery and charger for $30.

http://www.cabelas.com/cabelas/en/content/Item/01/80/49/i018049sq01.jpg

Rob, thats the same battery I have, It only lasts abou 3/4 of the day. Maybe I need a new one.

Thanks

hm, you know what is wierd... With my old graph (Lowrance X-91) my battery only lasted about 2 years and then it was like you said, the battery would die after 3/4 of a day or 1/2 a day.

With my new graph (Lowrance LCX-17M) I got a new battery like that and it has lasted much longer and it still powers it all day no problem. I don't know why a larger graph would last longer but it seems like there's some variation in how much electricity these graphs draw.

Isn't have a boat fun :) It seems like there is always something to fix.

I would advise against using the same wiring and battery for the graph and trolling motor. You will more than likely get interference when you are using the trolling motor. You can buy an inexpensive battery to run your graph like a small motorcycle battery. The problem is they are typically not a deep cycle battery. Running it down and charging all the time will kill the battery over time. I just bought a cheapy deep cycle battery from the local parts store for $50 or less with a warranty. If it dies I take it back and get a new one for pretty cheap. Walmart sells deep cycle batteries for pretty cheap also. I think less than $40 for the smallest and cheapest battery. Run some small gague wires and you're done.

In my 14' Aluminum I use a 12v motorcycle battery for the graph. The battery is about 6" X 4" and about 4" deep. It has never run out of juice while on the water and I have taken it out two days in a row with no charging in between.