Connecting shark shield to FF battery...

The battery on my older SS seems to be running out of steam, as it only lasts a short time. According to SS, the battery cannot be replaced, so I'm going to try running my SS off of my fishfinder battery. My FF battery is a 9Ah LifePO4 battery (an older version of the Dakota batteries, that are fairly popular on this forum).

I took apart the SS, and measured the voltage of its (fully charged) battery at 12.41v. My FF battery says that it's 12.8v, but I measured 13.14v. It seems to me that the difference between 12.41 and 13.14 is slight, and I should be able to run my SS directly off the FF battery. It's been a long time since my high school electronics class (where we spent more time burning shunts than learning about electricity), so if I'm incorrect, let me know.

Assuming I can directly connect the SS to my FF battery, then I just need to find a good waterproof disconnect. For connecting my FF battery to my FF (inside the hull), I use these cheapo things:

https://www.amazon.com/LanHong-Waterproof-Electrical-Connector-Marine/dp/B01F54PFLE/

They're splash resistant, but definitely not sufficiently waterproof for connecting to the SS, which sits in the soak zone. Any recommendations for a truly waterproof disconnect?

What about just fully waterproof the housing inside another waterproof box?  Maybe even has a battery inside?

What about just fully waterproof the housing inside another waterproof box?  Maybe even has a battery inside?

The FF battery is inside the rear hatch, and I don't want to clutter the deck.

I will definitely be watching your project going forward. Will you be cutting the wires at the battery, and then running new wires through the casing to attach to them?

My newer model is 7.4 volts so if I decide to do something similar I will need a dedicated power source.

https://www.amazon.com/eBoot-Plastic-Waterproof-Adjustable-3-5-13mm/dp/B01GJ03AUQ/ref=asc_df_B01GJ03AUQ/?tag=hyprod-20&linkCode=df0&hvadid=194019628201&hvpos=&hvnetw=g&hvrand=128311638962346054&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9061323&hvtargid=pla-310445171939&psc=1

I believe this one is what Chet use:
https://www.amazon.com/YETOR-Waterproof-Connectors-Connector-Extension/dp/B07WDBLFDN/ref=sr_1_2_sspa?dchild=1&keywords=WATERPROOF+ELECTRICAL+CONNECTOR&qid=1629668079&s=hi&sr=1-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExNEpNOVpLUEwyODY4JmVuY3J5cHRlZElkPUEwMzc0MDc0M0xMMVVGQU1ITDdJVyZlbmNyeXB0ZWRBZElkPUEwNjAwODE0N1NWRzlIS0FIV1dWJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==


Waterproof connector housing:
https://www.amazon.com/dp/B08CMY4SJG/ref=sspa_dk_detail_5?psc=1&pd_rd_i=B08CMY4SJG&pd_rd_w=wVrgr&pf_rd_p=5d846283-ed3e-4512-a744-a30f97c5d738&pd_rd_wg=2RVvg&pf_rd_r=6MXJGSHQRR5RTCGJM1B0&pd_rd_r=df8fd869-8306-4322-a4ec-478f7beae385&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyMElHUjRCMVdDU0U3JmVuY3J5cHRlZElkPUExMDEyNDI3MllEQVdKTUhWQ1hERyZlbmNyeXB0ZWRBZElkPUEwNzY1NjUyMjhBV1czNDVMVFBTViZ3aWRnZXROYW1lPXNwX2RldGFpbF90aGVtYXRpYyZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=


Waterproof junction box:
https://www.amazon.com/dp/B07Q1YBFLP/ref=sspa_dk_detail_4?pd_rd_i=B07PVVDLCC&pd_rd_w=PYdX2&pf_rd_p=5d846283-ed3e-4512-a744-a30f97c5d738&pd_rd_wg=cLmvA&pf_rd_r=K6Q1B48Y1JHGTTV1BJVV&pd_rd_r=db505d16-674f-444f-b93b-9d3ce5d8db4a&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySjVNUTU2WFNPOVFXJmVuY3J5cHRlZElkPUEwMzA3NTgzNzVEQUVXVFhQRkg4JmVuY3J5cHRlZEFkSWQ9QTA0MjYwODMyVVRFOUhBSTBXVEpMJndpZGdldE5hbWU9c3BfZGV0YWlsX3RoZW1hdGljJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1

Also, before you disconnect the power from the board, try connecting it to the FF battery and make sure it works.  The circuit board may have some gate and be picky about power input.   

I will definitely be watching your project going forward. Will you be cutting the wires at the battery, and then running new wires through the casing to attach to them?

Yes, that's exactly the plan. If the voltage of my FF battery is close enough, it almost seems to easy to be true...

Thanks for the links, Y^3.

I've already got a few of those "eBoot" things, and that's what I'm planning to use to run the wire thru the SS case. Those "Chet" connectors look like they should work well for my purposes.

I'm not too concerned about damaging the SS, as it's not useful as it stands. I'll give it a try and see what happens...

Nice!  Please let us know how it goes!

I cut the wires and removed the battery from the SS, and then attached to (temporarily) to the FF batter leads. It seemed to work fine as normal.

The challenge will be to prevent any leakage into the SS where the wires exit, as even a tiny amount of moisture will surely ruin it.

I should have the parts I need tomorrow and, with luck, it'll be ready for testing by Friday...

I’m not sure exactly what you are trying to waterproof, but the connectors that yakyakyak posted work well, just make sure that you get the wiring that is the correct gauge for what you are running (no idea the gauge on SS wiring. If you are looking for a waterproof pass through (like if you are building a waterproof battery box) I’ve used these https://www.amazon.com/gp/aw/d/B01MXZ1M4I?psc=1&ref=ppx_pop_mob_b_asin_title

Just remember you want ip68 connections.

I'm a fan of the Delphi Weatherpack connectors.  They're readily available, and well tested in automotive and marine applications.  I buy from Joe over at CycleTerminal as he's super helpful via email and his prices are competitive.  http://www.cycleterminal.com/weatherpack-connectors.html

Maybe these, I’m using them on pops’ watersnake install.
SZJELEN SP21 2Pin~12Pin Panel Mount 21mm Connector,Aviation Cable Connector,IP67 Outdoor Waterproof Electrical Plug and Socket (2Pin) https://www.amazon.com/dp/B07DCKRTRQ/ref=cm_sw_r_cp_api_glt_fabc_13AR3CDM051A3CQZ1Q8S

Don’t get me started lol.

I cut the wires and removed the battery from the SS, and then attached to (temporarily) to the FF batter leads. It seemed to work fine as normal.

The challenge will be to prevent any leakage into the SS where the wires exit, as even a tiny amount of moisture will surely ruin it.

I should have the parts I need tomorrow and, with luck, it'll be ready for testing by Friday...

Waterproof connector, goop, and rubber liquid tape?  BTW, thanks for pioneering this for us 



https://www.homedepot.com/p/Gardner-Bender-Black-Liquid-Electrical-Tape-4-oz-LTB-400/100119178?source=shoppingads&locale=en-US&mtc=Shopping-VF-F_D27E-G-D27E-27_11_TOOLS_And_ACCESSORIES-NA-NA-Feed-SMART-2181312-WF-New_Engen+PL3&cm_mmc=Shopping-VF-F_D27E-G-D27E-27_11_TOOLS_And_ACCESSORIES-NA-NA-Feed-SMART-2181312-WF-New_Engen+PL3-71700000082410808-58700006989412257-92700062912530339&gclid=EAIaIQobChMIxcy4vaTI8gIVJQytBh3m0gRtEAQYASABEgL6o_D_BwE&gclsrc=aw.ds