I already have an older 36# thrust trolling motor running off of this battery and will be installing one fishfinder and one combo unit on the boat. Will I be able to run all three off the same battery for a day of fishing? I only use the TM to go around spots (have a bigger 8 hp motor on my jon boat to get from spot to spot). If not can I run the two fishfinder units off a smaller battery. The thing is weigh is a huge issue for me with my 8hp i dont want my jon boat to be too much slower and batteries weight a lot.

I'm running two (same age and size) batteries in parell on a 15ft Ranger. Keeps the trolling motor and fish finder running all day 12 to 14 hours with full power even when the wind is blowing.

I don't use the gas motor much I'll fish my way to the next spot I want to try.

I had 1 battery powering a 30lb TM(only source of propulsion) and depthfinder on a 12ft jon boat.  I've fished many 8-10 hour days without any problems.  I've recently bought a 9hp gas motor, now I can't even feel any loss in TM power after 8 hours of fishing.

The depth finders draw so little power that you wiil have no problem  running them off your TM battery.

great news thank you it will save me some weight and speed.

check out those small 12volt batteries used in vexilars. I have gone two full days running the depthfinder on one charge and they only weigh like 5 pounds

I run a trolling motor, fish finder, bilge pump, deck lights and navigation lights off of ONE of the everstart deep cycle... the biggest one. My fish finder tells me volts at the battery. Its only dropped below 12 once after running all that gear for probably 5 hours.

Most batterys have a life cycle of three to five years plus if it is a marine battery they are deep cycling and have alot of power. You can take the battery to a car repair place and ask them to do a carbon pile draw test on it that will tell you if the battery can hold up under load.