How many volts does the livescope transducer need to produce a good picture and how many volts does the ff need to produce a good picture? Or does it even matter with either one?

Anything over 12v. They should work with 11ish, but 12+ is better and the claim that they work better with more voltage is unproven.

Garmin fish finders and livescope systems will operate from 10-32 vdc.

The graphs stop at 18v, the lvs module can run up to 32v. I don’t know what happens to the graphs above 18v though, we need a lab rat to test it. I see guys running their graph on 20v DeWalt batteries, but they claim the 20v battery is really only 18v.

I have a 1222 GPS Map with my livescope. Specs for it and several other units I looked up all say voltage range is 10-32vdc.



Connections
NMEA 0183 INPUT PORTS
1

VIDEO INPUT PORTS
1 (BNC composite)

VIDEO OUTPUT PORTS
none

BLUETOOTH®
Electrical

POWER INPUT 10 to 32 Vdc

How weird, here is the spec page for the Ultra series, wonder why they would have a different range? I’m curious about their other models now, kinda bored, guess I’ll look them up. (Pic below is the Echomap ultra specs)


So the 86** series is like your 1022 and uses 10-32v while the entire Echomap series uses 9-18v. Must have something to do with being a touch screen only on the Echomaps. I remember Russell marine products doing a video of the gls module being run on 12v-24v, but I don’t remember what graph they were using in the video. Might as well look it up too now.


Edit: apparently RMP is confused on the graphs too, they said not put 24v into any Garmin graphs. Now the OP has me curious if the 10** or 86** series would work better on higher voltage.