Nice setup db, I wouldn't have thought to use velcro.  Simple but effective.

I had picked up an x-4 unit locally off FB marketplace earlier this year for $35, thinking it might be a good idea to grab one of these low power B&W units while they can still be found.  Here is my take on making it portable with a Ryobi battery for power.  I have a 9Ah in the picture, but I'm thinking a 4Ah size would last more than a week of fishing given the low power draw of the unit.  I haven't tested run time with it yet.
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I have looked at power draw with the transducer out of water vs in water and the current draw doesn't noticeably change.  I know Magicpaddler was the one that initially told me about not running the transducer out of water, but I have since seen the same advice given in other online forums and groups.  Transducers seem pretty robust, but they are the moving part of the unit, even if you can't see it moving, you can hear the clicks.  Like brake pads on a car, they eventually wear out.  Hours and how you drive makes a difference in how long they last.  I do run my transducer in a through hull configuration consisting of a foam block with a transducer shaped hole cutout siliconed to my canoe floor which I then fill with water and seat the transducer.  I don't know if this is considered sufficient to prevent damage, but I haven't had an issue so far. 

Magicpaddler,

For the down converter, I considered three different units: ZK-J5X, LM2596 & the Mini360.  They are all advertised as highly efficient, but I decided to test them out to see which would be the best fit.  For testing I dialed each one in to 14.5V and I used a 1.3 Ah Ryobi battery and recorded run time of my Fishfinder(no transducer). I used the same battery for each test.

ZK-J5X: ($8-$10)This is the fanciest of the three, with a LCD screen which can show input/output voltage and current draw.  It features 4 buttons and is quite easy to adjust and use.  It is rated at a maximum 5 amps, which works since my unit draws under 1 amp.  I really like this downconverter overall, as it gives you a lot of information.  It's downfall for this application is that the screen cannot be turned off without also turning off the downconverter itself.  My 1.3 Ah battery lasted 3:58 using this converter.

LM2596: ($1) Less frills with this unit, with just a screw adjustment potentiometer and a blue LED status light.  This unit is rated at a max of 3 amps, again adequate for this application.  My 1.3Ah battery lasted 4:09 using this converter.
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Mini360: (<$1) Also rated at a max 3 amps.  This thing is tiny(fingernail size).  It's almost hard to work with, it's so small.  The pot adjustment is sensitive and a bit futzy.  But once wired and setup, this unit seems to be the best fit.  My 1.3 Ah battery lasted 4:39.  Winner, winner, chicken dinner. 

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db wrote on Jun 1^st, 2021 at 5:14pm:

DOH! Wrong link. So many links, so little time...

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I use velcro strips to attach it to a thwart.

"Sound travels faster underwater, so perhaps it pings or listens harder out of water, I'm not sure. "

Hence my question.

Mine is an X-4 portable.
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Judging from memories of my old green box with the two knobs, muddy bottoms in deep water required a higher setting than hard bottoms in shallow water. Does that also equate to more current draw?

The last three I've used had a manual and an auto setting for depth. Auto was fine by me. My theory is when the ducer is attached to the hull of an overturned canoe all night, it was striving to ping the moon at full blast. The same ducer in a bucket would be minimal current draw as my theory goes. This was probably the fullest feature one I've used and it was also siliconed to the hull. Batteries were totally dead the next day.
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I've never heard the ducer out of water worry before. You guys all shoot through the hull right?

I was curious is all. Glad I don't have to worry that I knowingly damaged anyone's transducer.
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No worries. That mapping feature you figured out is pretty cool.

What would be really cool in my book is a bluetooth transducer and an app or two for my phone that uses Tesla's wireless power grid, and WiFi! No wait, maybe just depth maps of all the Q lakes...

db, which fish finder unit do you use?  You mentioned, no frills, so I'm guessing it might be a black and white unit.  Those do draw a lot less power, maybe 1/4 what my Hook 4 uses. This unit replaces a Lowrance Elite 4x, which consumed about half as much power.  The x in the unit name for Lowrance units means it has no chart plotter mapping/GPS function.  Color and GPS and screen size all contribute to power draw. 

The Ryobi lithium battery is certainly rechargeable and that is part of the beauty of using it. It has protection built in, so you cannot over discharge and ruin the battery.  I have a number of tools that use 18V Ryobi batteries.  These bigger ones don't get much use though, I use them mainly in my weed wacker and a brushless chainsaw.  To be honest, if I didn't already have these batteries I probably would use a LIFePO4 battery as they are less expensive. 

I have one of these 16Ah LIFePO4 batteries which I've used though about a half dozen charges so far and it has preformed well.  It's hard to beat for the price, but it is physically larger with almost twice the Ah.   It's an option if you need some of the added frills of a power hungry fish finder and don't mind the weight. (You need to Login or Register to view media files and links)

I was using a 12.8V 10Ah LIFePO4 battery for the last 8 years, but last winter I noticed it wasn't charging fully.  I took it apart and found one cell of 3 batteries were leaking.  That forced me to start looking at other options.

The Lowrance Hook 4 unit is no longer in production, having been replaced by the Hook2 and then Hook Reveal model.  The Hook 4 is superior in that it has the ability to display Raster as well as Vector map images. Lowrance turned off Raster image mapping in their lower tier units, namely the Hook2 and Hook Reveal models. I had been using a Garmin GPSMap 62s in addition to my Elite 4x unit, but it always seemed like a disjointed system for fishing.  The Garmin is definitely they way to go if you are bushwhacking or using seldom used portages, as it's a hiking GPS.  Yeah, I could mark waypoints on the Garmin, but it wasn't on a detailed map.  The Hook 4  unit allows me to view Navionics (Vector) maps if the lakes have been mapped(a few in Quetico), or as I have shown it can display Raster satellite imagery.

I have heard that it is not good for the transducer to run it out of water, so I try not to do so intentionally.  I'm not sure if it causes overheating of the element or if it just needs a denser medium to flex against to reduce wear.  I know some people epoxy or silicone their transducers in their boat, so perhaps it's not a cooling issue.  I don't think running the transducer in or out of water would affect power consumption, it is pinging either way.  Sound travels faster underwater, so perhaps it pings or listens harder out of water, I'm not sure. 

Don’t run a ducer in open air.  It can crack the crystal or separate the casing.
With the down converter that brings the current up to about 375mA still less than other have reported.  Most down converters are 95% + efficiency.

arnesr wrote on May 29^th, 2021 at 4:17pm:

You guys are talking way over my head but as far as battery life goes, I know load matters.

Assuming a Ryobi 9Ah Lithium battery is rechargeable, I have a test request. Lose the bucket and let the ducer ping the open air for the test.

I ask this because with my no-frills finder running off 8 disposable AAs, I can get easily get two trips out of the batteries. If I forget to turn it off at night, which I've done more than once, I consider myself lucky to hear a tick tick tick the next morning.

Maybe another test for the backlight level would be interesting with the ducer turned off.

I got 29 hours, 40 Minutes and 18 seconds out of my 9Ah battery to be exact.  Real world results might vary, as this was just a static "on" test with the transducer in a bucket. I can turn the unit off when not in use or turn the backlight down. Just the GPS cannot be turned off, but I can turn off the transducer, though I'm not sure I will bother.  I believe the screen itself uses the most power, dimming the backlight to 6 or 7 should help save juice.  My test was run at a full, level 10, backlight

For testing I used one of those Chinese battery load testers. 
(You need to Login or Register to view media files and links) I was able to plug the fish finder in and use that instead of the artificial load generated by the board.  The board logs the time a load is drawn and the Ah. It works slick for the price, plus I can test batteries with it.

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Here is my rig:
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It consists of a thin cutting board with a lock-n-lock container for dry battery storage, zip tied down with a inverted plastic electrical box sandwiched between a Ram mount and the cutting board.  The electrical box houses a switch and a bright blue LED, for power on status, and serves as a riser allowing me to fold the screen flat against the battery box for transport.  The yellow cord is a 3 foot extension, allowing me to mount the unit to my thwart and have the battery elsewhere. 

On the business end of the battery I have a 3D printed sleeve that connects to the battery terminals.  Wired to that is a 2A breaker in place of a fuse and a tiny buck converter to bring the voltage of the Ryobi battery down to 14.5V.  This is all wrapped tightly in electrical tape, not pretty but it works.  Even though the Ryobi system is 18V, a fully charged battery is over 20 volts, and I did not feel comfortable feeding that to my unit.  14.5V sounded more reasonable and there is very little heat generated by the buck converter at this voltage differential. 

One other modification I made to the unit is that I ditched the Lowrance power connector and soldered .062" pin connectors to a LED power cable. Only two pins are used for power, the rest are for NMEA, which almost no one uses, and certainly not in a canoe.  The two larger pins are the power pins, and the black negative pin is located between the two plastic notches. I will be installing some heat shrink to protect the connection from the elements a bit. It may be hard to see in the pic, but I have a small zip tie securing the wire to the threads of the connector so the wire cannot pull loose.
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You stated 30 hours of operation on a 9Ah battery.  Can the fish detector or the GPS functions be shut off when you are not using them to save battery? 30 hours on 9Ah is about 300mA.  That is better than others have reported. Good info.

arnesr wrote on May 28^th, 2021 at 2:41am:


Thanks!

It does still work.  I haven't tried the latest QGIS version, as far as printing, but you can definitely load the satellite imagery and overlay it with the PCD info from Paddle Planner.

I don't plan on printing maps for my upcoming BWCA trip in June, as I have upgraded my fish finder to one with a chart plotter function, a Lowrance Hook 4 model.  I used QGIS and a few other free software programs to create a zoomable satellite imagery map with the PCD layer from PP overlaid on top. When I put the crosshairs over the campsite it shows the condensed campsite info.  Likewise, the portages show the length in rods. There is a layer detailing the US/CAN border and the Quetico perimeter as well.

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A couple more screen shots taken with the fish finder itself. You can really pick out some shallow structure areas and even downed trees to target for fishing.   

LLC - Tiger Bay:
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The pros of this are I don't have to spend money on paper and ink and the data is imbedded.  The cons are my maps only last as long as my battery and of course the weight of the battery.  I am using a Ryobi 9Ah Lithium battery to power the fish finder and I tested it at just shy of 30 hours runtime at full brightness.

If there is interest, I could put together a tutorial for how I generated this map for my Lowrance unit.