Sonar & Trolling Motor to Same Battery?

[Big Green Machine]

Hi all,

I used to run my Hummingbird Sonar (with fuse) off my main 12 V battery that is used to power my motor and downriggers. I noticed I was picking up some electrical interference so I switched to my other battery - the one I use for my 55 thrust bow mounted trolling motor. The first time out, I was able to troll most of the day, but as the battery was losing power, it was not able to handle both the trolling motor and sonar, and the trolling motors shut down. The second time out, things were fine until I drained the battery to about 20% left and this time the sonar gave me a warning message 'insufficeint power' and then after about 10 minutes shut down. For both trips, I did not fully charge the battery before I went (it was about 75%). The last time I went out, the battery was fully charged at 100% and I had no issues, except this time a lot of electric noise on the sonar screen.

Does anyone know if I can add a third rechargable battery (I have the room), perhaps a smaller 6 volt or something similar to the rechargable that came with my portable sonar. Would that solve my battery issues?

 

[spring fever]

I must be missing something here-most sonars take very little juice-in fact most are protected by a 3 or 5 amp fuse-could it be that your battery is the main problem and the sonar is masking another problem. Have your battery checked before anything else.

 

[Big Green Machine]

I must be missing something here-most sonars take very little juice-in fact most are protected by a 3 or 5 amp fuse-could it be that your battery is the main problem and the sonar is masking another problem. Have your battery checked before anything else.

Sonars do take very little juice, some portable ones run on D batteries. The problem I now have is electrical interference I get on the screen when running the trolling motor at the same time as the sonar. When I turn off the trolling motor the interference goes away.

 

[Fish Assassin]

Maybe get your self an alarm panel battery 12v7ah bat. its worth about $20. They will run a sonar for days and they are rechargable. Use it till you figure out your problem.

 

[Gunsmith]

I am not an expert in thjs matter but I understand that there are electronic filters available to correct the issue of interference, I would check with the electric motor manufacturer or the sonar manufacturer.

 

[profisher]

Your sounder shouldn't be connected directly to the battery. Go through a small fuse block...positive battery cable to master switch...positive cable from master switch to fuse block...then to your sounder's positive wire. Battery negative to bus bar....then to sounder's negative. Both bus and fuse block should me mounted somewhere easy to get to and where it will stay dry and clean.

 

[profisher]

How old are the batteries?

 

[Sharphooks]

Hey Profisher, if you are properly fused, what is the downside of wiring a sounder or GPS directly to a battery? I have always wired direct to the house battery on every boat I've ever owned. Last summer I went the bus bar route with both GPS/Sounder and antenna. For some reason the antenna intermittently would lose its signal (always at the worst possible time).

I finally cut to the chase and wired both the Furuno Navnet and its antenna direct to the house battery (the way I always did before) and that solved the problem. Both are properly fused with good clean connections to the terminals.

Why would an intermediary bus bar be more advisable as long as your fused properly?

 

[profisher]

Wiring off a master switch will prevent a dead battery from something left on by mistake. How many times have you walked by a boat at the marina that hasn't been used for a week or two and heard the VHF come to life when someone talks the channel it is set to? You still have to remember to turn off the master for this to work!!! On most boats the batteries aren't located in the driest of locations so having all your exposed terminal ends going to the battery post will likely result in corrosion issues eventually. Having a fuse block and bus bar that is properly labeled with individual mounting points allows for quick problem solving if a device goes down. Especially in an emergency situation. A cluster F&ck of wires back at the battery just means more aggravation at a time when you don't need more. Those are a few of my reasons for having my boat set up in this manner.

 

[Sharphooks]

Good points and noted, all of them, Profisher. As far as the cluster frick of wires coming off the battery you mentioned, I already have that up going on under the helm station--- a pile of half-arsed wiring jobs to multiple bus bars (all done by different owners at different times as they added or subtracted electronics)

Probably one of the reasons the bus bar approach left me with faulty connections-- Maybe a good argument for a complete re-wire of the boat...

 

[profisher]

I've owned my boat since new so that hasn't been an issue for me thankfully. I did rewire the entire boat 2 years ago and made some improvements over the original installation. Mostly in access, labeling, upgrade to all tinned copper wiring and better fuse block and bus bars. Rewiring is something anyone can do as you can just do it one wire at a time, especially if there unwanted joints or wires turning black or worse green.

 

[rendraW]

also try to make sure the transducer is as far away from the prop as possible.

 

[Big Green Machine]

Problem solved, just installed a small 12 v rechargeable for the sonar and the charge will last many many hours. Also bought a 'Battery Tender' and it can stay plugged in all the time unlike those chargers from Ukranian Tire that trickle. The tender will shut off when any battery is charged. And kick on when there is room.