Calling on ttmott and the electrical experts

[ocgrant]

Ok I need to wire in something 12v to be "hot" all the time even with the batteries switched off (5.3 amp load). On my 48DA where do i go? Are my 2 8D's House and Engine or do they share duty via some computer? Please give me your advice on the best solution. I want to be able to leave the boat with panel battery switches off and this circuit still "hot".

 

[LTD.330]

5.3 amps is a significant draw. An 8D battery rated at 245 Amp Hours (WestMarine AGM) would be dead in just over 46 hours. You'll definitely have to leave your battery charger on all of the time.

You'll have to wire your fused circuit directly to the battery, the battery side of the battery switch, or the output of the battery charger (assuming it bypasses the battery switch).

 

[TNT8808]

I don't believe they share duty, and I don't see a computer. Here's a pic for Tom from our owner's manual.

 

[ocgrant]

Yes, Battery charger will be on at the dock when plugged into shore power all the time so draw is not a concern. I just don't want to be on the hook all day and go to start the engines and have no power. So what does the emergency start switch do? Where does the "house 12v" come from?

 

[dtfeld]

Wire direct to the battery with a fuse no further than 18" from the battery terminal. You could add an accessory terminal to the battery and wire to that.

 

[dtfeld]

What draw 5.3 Amps...marine fridge?

 

[Jeremygavin]

I just did this for my cockpit fridge. It is a isotherm drawer fridge that is DC only so it won’t run off shore power and it was wired into the DC panel in the salon that is switched off with the battery switches. When I leave the boat for the week I like to turn off the main battery switches.
On my boat there is a main DC breaker panel in the lazarette that has the breakers for bilge blowers, bilge pumps, air horn pump, bilge pump and a variety of other things as well. They are safety breakers so you need a flathead screw driver to turn them off. About 1/2 this panel is constant DC power and the other 1/2 is switched power from the battery switches in the salon. I added a new breaker to the non switched side and wired the cockpit fridge into that so it would not turn off with the battery switches. It has and on/off/temp knob on fridge so I can turn it off from there if I need to. This is what the label looks like on my boat.

 

[dtfeld]

Just redo the breaker big enough to handle both fridges....i'd imagine a 20A would allow both to start simultaneously ...

 

[ocgrant]

I just did this for my cockpit fridge. It is a isotherm drawer fridge that is DC only so it won’t run off shore power and it was wired into the DC pane in the salon that is switched off with the battery switches. When I leave the boat for the week I like to turn off the main battery switches.
On my boat there is a main DC breaker panel in the lazarette that has the breakers for bilge blowers, bilge pumps, air horn pump, bilge pump and a variety of other things as well. They are safety breakers so you need a flathead screw driver to turn them off. About 1/2 this panel is constant DC power and the other 1/2 is switched power from the battery switches in the salon. I added a new breaker to the non switched side and wired the cockpit fridge into that so it would not turn off with the battery switches. It has and on/off/temp knob on fridge so I can turn it off from there if I need to. This is what the label looks like on my boat.
View attachment 83934

That is perfect... I have the same panel. I have to check if I have an empty breaker slot. Where do you get extra breakers?

 

[ocgrant]

Got it FP had them in stock....

 

[Jeremygavin]

That is perfect... I have the same panel. I have to check if I have an empty breaker slot. Where do you get extra breakers?

I had 4-5 empty slots so I would assume you have one. Use a test light or meter to make sure you are on the unswitched side of the panel (it was the bottom half of mine).
I got the breakers from Flounder pounder. They are Carlin guarded breakers. Here is the list from my panel. Sea Ray # 826578 for 10amp which should work if you are running something that needs 5.3amps. If you google Searay part # 826578 they will come up.

 

[NotHerDecision]

Just redo the breaker big enough to handle both fridges....i'd imagine a 20A would allow both to start simultaneously ...

This is Bad advice. Breakers protect wires. If you put a larger breaker without upgrading the wiring to that breaker you are at risk of a fire.

 

[dtfeld]

This is Bad advice. Breakers protect wires. If you put a larger breaker without upgrading the wiring to that breaker you are at risk of a fire.

You are correct. Had the same thought this morning. Find 2 spots add 2 breakers wire direct.

Edit: Assuming this is a new install, so wiring will have to be sized accordingly regardless, Could be 1 run of heavier gauge, or 2 of smaller. Wiresizing chart.

https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1:_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit

 

[ttmott]

I think you will find for both the starboard and the port circuits that there are switched loads and un-switched loads. The switched loads are those that the main disconnect solenoids will remove power when they are turned off and the un-switched are always on regardless of the main disconnect solenoids.
You should also find that the un-switched loads are protected with unique 100 amp circuit breakers called the "Line Side Panel Feed" in the Main Disconnect Panel, one for the port battery and one for the starboard battery, then the wires from those circuit breakers feed the corresponding port and starboard un-switched circuit breakers in the main circuit breaker panel. Usually the lower rows (port and starboard) circuit breakers in that panel are un-switched and the upper are switched (see the picture). Always the bilge pumps, memories, blowers, and other critical circuits are un-switched.
So, If you want a circuit that will not be turned off when the disconnect solenoids are de-energized install a new circuit breaker in this lower section of the main circuit breaker panel. When you open the panel up it is quite obvious looking at the copper buss bars where that demarcation is. Hope this helps - Tom

 

[ocgrant]

I think you will find for both the starboard and the port circuits that there are switched loads and un-switched loads. The switched loads are those that the main disconnect solenoids will remove power when they are turned off and the un-switched are always on regardless of the main disconnect solenoids.
You should also find that the un-switched loads are protected with unique 100 amp circuit breakers called the "Line Side Panel Feed" in the Main Disconnect Panel, one for the port battery and one for the starboard battery, then the wires from those circuit breakers feed the corresponding port and starboard un-switched circuit breakers in the main circuit breaker panel. Usually the lower rows (port and starboard) circuit breakers in that panel are un-switched and the upper are switched (see the picture). Always the bilge pumps, memories, blowers, and other critical circuits are un-switched.
So, If you want a circuit that will not be turned off when the disconnect solenoids are de-energized install a new circuit breaker in this lower section of the main circuit breaker panel. When you open the panel up it is quite obvious looking at the copper buss bars where that demarcation is. Hope this helps - Tom
View attachment 83980 View attachment 83979

Tom,
Thank you, that picture of the buss tells me everything. I ordered a breaker last night from FP so this should be simple now. One question what is the access to the panel to run the wire into it? Any thing special I need to get my cable into that box?

 

[Jeremygavin]

When I did it there was no factory way to get the wire into the box so I used a water proof electrical box connector from HD. I had to drill a hole in the side of the box to run it through. This is what I used. I painted it for keep it from corroding before is installing it. There may be a proper marine fitting for this but what I did is sealed so it will work fine IMO.

https://www.homedepot.com/p/100170032

 

[ttmott]

Tom,
Thank you, that picture of the buss tells me everything. I ordered a breaker last night from FP so this should be simple now. One question what is the access to the panel to run the wire into it? Any thing special I need to get my cable into that box?

I've added a couple of circuits to the breaker panel. I drilled a hole in the bottom and installed a liquid-tight cable gland -

 

[ocgrant]

I've added a couple of circuits to the breaker panel. I drilled a hole in the bottom and installed a liquid-tight cable gland -
View attachment 83985

Perfect, thanks. Amazon and will be here tomorrow.

 

[ocgrant]

Well thank you all for the help...Parts arrived & Mission complete. 12V Ice maker installed and wired as recommended. Working perfect right now making ice.