Thread: Battery question for Livescope

Thanks Roy. I guess I will just unhook my fish finder and hook it to same battery, I thought I would just add new battery just for just the livescope wasn’t aware they should be wired to the same battery. Sorry about all the questions this is all new to me.

Dependable, interference-free sonar operation trumps considerations of convenience every time, when it comes to wiring. Do it right, do it once, go fishing. That's my opinion.

Originally Posted by jawjatek

Before I ponied up the cash for a LiFePO4 50 Ah Ionic, I was (and still do sometimes) using this battery: Duracell Ultra 12V 35AH Deep Cycle AGM SLA Battery - SLADC12-35J at Batteries Plus Bulbs

35 AH, a little heavy, but runs a 102sv and a PLS 6+ hours.

I'll spend that much on cable if i go to the back

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Can someone help me understand why you have to run both units off the same battery? I plan on adding livescope to my 93sv this spring and I hope to do it right the first time.


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I assumed it's in the installation instructions.
But i don't have one.

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You don't "have to". In electrical engineering we deal with a phenomena called a "ground loop" that can introduce common-mode noise between two devices that are at different ground potentials, or that share grounds with other signals. However, since the connection between your head and the GLS10 black box is ethernet, it may very well be transformer-coupled, which would attenuate the common-mode noise. Also, the ethernet signals are differential, which provides even more attenuation of common-mode noise.

Using two separate batteries on a boat means one battery's ground will be "floating" with respect to another battery, unless the grounds are bonded otherwise. As soon as you connect the 2 devices, the grounds will be connected by the shield or ground of the connecting cable. Any difference in ground potential will cause noise current to flow in the shield conductor. This tends to increase the common-mode noise. A common trick in audio engineering is to float one end of the shield, this is called a "ground lift".

In sonar/chartplotter installs, it is always best to avoid sharing a battery with a trolling motor, in case you were thinking of this, because the arcing inside the brushed DC motor, as well as the pulse-width modulation of the drive voltage, generates lots of wide-band noise which can couple into sensitive signals in the sonar system.

I'm not sure why you need to use different power sources for the head and the GLS 10 box. It may very well work fine. Try it.

A friend of mine had a Garmin Livescope installed at BPS. They connected the black box to a separate battery than the unit. After several trips on the water the unit kept losing connection between the unit and the black box. My friend was taking his boat back to BP to have both the unit and black box connected to the same battery as instructed by a Garmin tech. I hope this solves his issue. I'll post if I hear from him.