Main battery solenoids

Steven C

New Member
Nov 19, 2021
6
Astor Fl
Boat Info
2002 380 Sundancer
Engines
8.1S Mercury horizon
7kw Westerbeke
When docked and hooked up to shore power should you leave the main battery solenoid switches on or off or does it matter, I have been leaving the port side on so I can turn light on when I walk down into the salon.
Thanks in advance.
 
73901361-D96D-4B6E-98D2-F6B41FA76D40.jpeg
 
I used to leave them on but don’t need to when on Shore power
They only need to be on for engines. you should have seperate breakers for lights etc where these are only engine
I have to confirm next trip to the boat, but I don’t think my lights work unless those solenoids are on.
 
On our boat, the solenoid must be on for any 12 volt devices to work (except a few wired directly to the battery). To provide power to the engines, also need to turn the keys to on and finally press engine switch at helm
 
On our boat, the solenoid must be on for any 12 volt devices to work (except a few wired directly to the battery). To provide power to the engines, also need to turn the keys to on and finally press engine switch at helm


I will confirm the same on a 07 44DA and 08 58DB with the minor caveat that the 58 has a bunch of 24v systems, but act in same manor.
 
Also confirmed. Port side battery bank supplies 12 V to the cockpit. Starboard supplies 12 V to the cabin.
 
My boat at the dock if the shore power is connected and on the batteries are fully connected. If the shore power is disconnected the batteries are turned off.
Switching the battery solenoids off only turns off some of the loads like lighting, nav equipment, engine starters, refrigeration, windlass, etc. What remains connected with the battery switches off are battery charger, bilge pumps, electronic memory power, engine ECM's, SR Monitor system, CO monitors, Fire detection/suppression, and other emergency systems.
Here is how the Main Circuit Breaker Panel is divided for the 52DB.
Main Breaker Panel Loads.jpg
 
So it seems everyone , except me, needs to have engine solenoids on.
One thing I do have on the boat besides 2x lead batteries for each engine is 2x lithium batteries for house.
It could be that my lights and other items are bypassing the engine batteries and straight to the seperate house batteries.

sorry for confusion and I learnt something today.
 
Yes those lithium batteries are not OEM. Someone added those and bypassed the solenoids while wiring them in.

Do those batteries also start your generator?
 
So it seems everyone , except me, needs to have engine solenoids on.

Most of our boats are set up so the battery banks service both engine and house. So for most of us, the Main Battery Solenoids aren't "engine" solenoids but instead are for combined functions.

In our case, 12VDC/24VDC loads don't work unless the Main Battery Solenoids are ON.

-Chris
 
I’m curious about your lithium battery house setup. Do you have the wiring schematic for that? How is it charged?
 
Going back to the OP's question, this section is important:
.... What remains connected with the battery switches off are battery charger, bilge pumps, electronic memory power, engine ECM's, SR Monitor system, CO monitors, Fire detection/suppression, and other emergency systems. ....

IF you do remember to shut all the other loads off and don't leave an errant light on somewhere that would drain the batteries (that would be prevented if you had shut down the main breakers/solenoids), you still do have that list of loads connected to the batteries. They are VERY SMALL loads, but those VERY SMALL LOADS are a drain on the batteries that are in storage. That's why it's good to periodically charge the batteries over the winter unless you disconnect them entirely or shut down the breakers to those very small loads.

The biggest reason to shut down the mains though, is to prevent that errant load (like a cabin light) that you might not notice you left on. That's a relatively big load if left on for days and weeks at a time, without a charger being active. That could definitely deplete your battery. If you're plugged into shore and your charger is working, that alone wouldn't be any more of an issue than your fridge running.
 

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