# bow/second sonar power



## ezbite (May 25, 2006)

I want to put a sonar up on the bow of my boat, its a helix 12, pretty big unit, will draw some juice. I've already got a helix 10 on my starting battery, running lights and bilge pump. I don't want to put anymore draw on the starting battery (in fact I'd like to get the helix 10 off it). anyhow, I've got 2 options, either add another deep cycle battery and run both sonars off it (that will be 4 battery's) or hook into my 24v trolling motor battery's. I've read online that you shouldn't run sonars off trolling motor battery's because if you do you will drain the voltage down lower on one causing a shorter lifespan and you should replace both battery's at the same time. is this true? I would think since they are wired in a series the draw would be the same on both battery's and if I choose this route, will I have a problem tapping off one battery in a 24v series? won't one battery still be 12v? how do you have your bow/second sonar wired?


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## rockytop (Mar 19, 2008)

Tom I doubt you would drain one battery more then the other to worry about. But if you have a variable speed trolling motor you might experience noise or interference. Try it hooked up to one battery,if you get noise you have to run wires to your starting battery. I don't have a trolling motor. But this summer I was anchored at west branch , stereo on and 2 fishfinders on for 5 to 6 hours and that battery started my chevy 350 right up. But I have a switch for a second battery if needed. Another option is them small 12v 15 amp hour batteries,there cheap but might be a pain to charge. Bob


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## ezbite (May 25, 2006)

i've been reading about the interference issue, I think i'm going to go with a 4th battery for the radios, sonars and lights. i'll just leave the starting battery for just that and the bilge pump only.

I've been looking at those little tractor starting battery's but not sure if they can take the constant discharging/recharging? I cant find them in deep cycle and I've been looking.


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## rockytop (Mar 19, 2008)

Plus so many conflicting views on witch battery to tap into.the unit is 12 volt hooking into a 24volts. Some say either battery some say the battery with the negative connected to the positive of the other is always 24 volts.


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## crappiedude (Mar 12, 2006)

I run both my HDS7 & 8 off my staring battery along with the lights, livewell and bilge pumps.
Only issue I ever had was at first I had the electronics running through the fuse panel. When ever I started the outboard the electronics would shut off. I solved that problem by running separate 10 ga wires directly from the starting battery to the electronics wiring at the console and I've haven't had that problem again.
Personally I would try adding the bow unit and see how it all performed before I added a 4th battery. I'm not saying the extra battery isn't needed but why fix a problem you may not have.


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## firemanmike2127 (Mar 17, 2013)

I run a 998 & 999si on my boat. The stereo, aerator, interior lighting, & bilge pump are all on the Group 27 Interstate primary battery. It starts the 225 Mercury O/B with no problem. For night fishing I will switch over to primary battery # 2 (a group 24 Interstate) to ensure that my Group 27 is ready to fire the engine when it's time to go home. That's the only time I ever use my back-up battery. Mike


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## bobk (Apr 30, 2004)

Just buy a bigger battery.


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## JamesF (May 20, 2016)

Your gonna need a bigger boat!


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## dwmikemx (Mar 22, 2008)

Don't wire your sonar units to the trolling motor batteries. 
Just go to Sam's and get a Duracell AGM Group 31 marine battery ($179) for a starting battery and wire your sonars direct to it using no less than #12 wire.

I had the Interstate group 29 starting battery with my HB 1199 & 998. Always had issues with running down the battery while running my electronics all day without starting my outboard. 
Went to the group 31 and have had no more problems with low voltage from the electronics draw.


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## ezbite (May 25, 2006)

dwmikemx said:


> Don't wire your sonar units to the trolling motor batteries.
> Just go to Sam's and get a Duracell AGM Group 31 marine battery ($179) for a starting battery and wire your sonars direct to it using no less than #12 wire.
> 
> I had the Interstate group 29 starting battery with my HB 1199 & 998. Always had issues with running down the battery while running my electronics all day without starting my outboard.
> Went to the group 31 and have had no more problems with low voltage from the electronics draw.


change of plans just going to go with the G31 battery.


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## dwmikemx (Mar 22, 2008)

ezbite said:


> change of plans just going to go with the G31 battery.


@ezbite... I'll also add that I charge my starting and TM batteries with my on board charger after every time out fishing, so I'm always starting the day out with a fully charged battery.


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## JamesF (May 20, 2016)

I really like the onboard charger. I just unplug TM and electronics, plug in the charger and ready for fishing!


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## ezbite (May 25, 2006)

i have a 2200 minn kota 2 bank just for the TM batterys and a $20 ever start 3 amp charger/ maintainer for the main battery. i never go on the water without fully charged batterys.


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## JamesF (May 20, 2016)

I knew that I was going to have three batteries, and at the time I had the bucks for a 330 MK. Before that I had one battery and a 12volt.charger. Now life is ez.!


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## Shortdrift (Apr 5, 2004)

ezbite said:


> change of plans just going to go with the G31 battery.


Good decision. I have a 27 as my starting battery for my small 20hp motor and run my sonars of it without problems.


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