Thread: Graph Power Source Question

I have a HB 798ciSI unit and wondering if a 12v 9 Ah AGM sealed battery would be a sufficient power source?

T.I.A.

Do you mean nothing but the 798 on that battery? Plenty big enough. You just don't want the power source on the same battery that is currently running a motor. So if this unit is at the console and you want to watch while using the big motor, then you would want the power to be from the trolling battery. If this unit will be on the bow of the boat, then the power should come from the cranking battery.

Yes only the graph on the battery.I'll be moving the graph from front to back (2 different quick connects mounting stations and 2 different Xducers 1 on Tmotor and 1 on transom) so I want a different compact power source so there is no interference from anything.Would the 12v 9AH AGM rechargeable battery be sufficient for 12-15 continious operating hours?

The only issue I've seen on this type battery, is that they seem to have less than long life. Works fine for a year, usually, but after that it's a guess as to how much longer it will go. That is with heavy usage, tho, so maybe it will last longer for you. I'm sure it will do what you want for a while.

I've never had a problem with interference running my DFs off the start battery. I tried using the TM battery for one I had up front and that did not work because the TM caused a lot of interference but I've never had problems with the outboard motors.

My concern is running the starting battery down or getting the battery below the reccomended cranking amps on a Tohatsu TLDI.
So I figured on a designated graph and accessories battery. Which brings to mind another question,will other accessories such as lights,pumps,etc. create interference on a graph?

Originally Posted by SeaRay

I've never had a problem with interference running my DFs off the start battery. I tried using the TM battery for one I had up front and that did not work because the TM caused a lot of interference but I've never had problems with the outboard motors.

None of the associated items such as aerator, lights, bilge pump have caused me problems with interference. I also have never run down the start battery by running two DFs for 6 hours solid along with my aerator cycling on and off. They are not a big power drain. I use the 27 series marine starting battery and I've never had a problem with power drain. I've had similar results with Interstate and Walmart marine batteries. I keep a set of jumper cables in the boat but I have never needed them.
(Probably go home today and have a dead battery since I said that.)

Originally Posted by SeaRay

None of the associated items such as aerator, lights, bilge pump have caused me problems with interference. I also have never run down the start battery by running two DFs for 6 hours solid along with my aerator cycling on and off. They are not a big power drain. I use the 27 series marine starting battery and I've never had a problem with power drain. I've had similar results with Interstate and Walmart marine batteries. I keep a set of jumper cables in the boat but I have never needed them.
(Probably go home today and have a dead battery since I said that.)

I'm in the same boat except I run a 31 series battery for a starting battery. My motor is a 140hp. I've run two fish finders, my cycling aerator, bilge on and off, and nav lights for a little over 7 hours one morning without starting the motor to charge the battery. I do use a cabelas AGM 31 series as my cranking battery. I use the same two batteries for my 24 v trolling motor setup without issues.

Brand new, a 9AH battery will probably get the job done. Without details on how the AH spec was measured, just roughly guess that the battery will run your unit for 9 hours -- but you shouldn't run an AGM down below about 80% discharge, so your maximum run time is 7.2 hours.

As the battery ages, it gets smaller, so at some point it won't make it through the day. A larger battery will last longer before it gets too small. Very much a trade off of battery weight, price and life.