Electrial Question

Nov 9, 2004
110
Hunter Passage 420 Rock Hall, MD
We run our fridg and freezer 247. When we loose shore power from a storm or something our batteries are not being recharged by the charger and if the power is off for a prolonged time the batteries die due to the draw from the fridg and freezer.
I am looking for away to prevent this. I want to put something in the shore power line that if 120vac power is interrupted the 12dc power from the batteries to the disbribution panel will be shut down and then can be manually reset. It is cheaper to loose food than 3 4D batteries.
Any ideas will be much appreciated
 
Sep 25, 2008
7,076
Alden 50 Sarasota, Florida
You would be better served with a battery voltage sensing device which will cut power if the battery voltage lowers to a pre-set level. That will ensure power doesn’t stay off if/when shore power returns while still protecting the batteries from discharge beyond your selected pre-set. Using this method, when power is restored, so too are your refrigeration systems.

Power gates such as the above can be had for around $100. Some have wireless features to notify you of a power loss.

Among the options are Samplex battery backup module, West Mountain Radio’s powergates or MFJ makes a battery booster which serves the same purpose while also stabilizing battery voltage.
 
Jun 11, 2011
1,243
Hunter 41 Lewes
You can put in a relay that will do the same thing and for a lot less money. 120V coil and run all the loads you would like to drop through the the Normally Open contacts. As soon as the 120V supply drops then so do all the 12V loads. I would run this in parallel with the house battery switch so that the boat operates normally when you are aboard and can keep an eye on things. Once you are going to leave, plug in the 120V supply and turn off the house battery switch, the relay will power the devices around the switch right up until the power drops and then so does the loads.
 

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Blue Sea Systems Low Voltage Disconnect. Easy install. Place in series with refrigerator. It senses battery voltage and disconnects circuit when battery voltage has dropped to a preset value. Model m-lvd.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Blue Sea Systems Low Voltage Disconnect. Easy install. Place in series with refrigerator. It senses battery voltage and disconnects circuit when battery voltage has dropped to a preset value. Model m-lvd.
Bingo...
 
Feb 14, 2014
7,400
Hunter 430 Waveland, MS
12V units and don't require the inverter.
My H430 refrig is 120VAC [his is an H420].
I was going to add the Low Volt device too, until MaineSail told me to just turn off the Invert on my IC. Duhhh... MaineSail saved me some $$$.
Just Guessing...
Jim...
 
Nov 9, 2004
110
Hunter Passage 420 Rock Hall, MD
Don and Senang, that is true but at 11.7. It then continues to try to restart. It is not good for the batteries nor the fridge and freezer.
 
Jun 11, 2011
1,243
Hunter 41 Lewes
I have to replace $800.00 of batteries for this very reason. Marina lost power, 12V fridge and freezer, drain the batteries to 10V. They haven't been the same since. They were three years old and probably had another three to go. I wound up purchasing a Boat Command monitoring system. Best thing I ever did. I can "see" the boat any time any where providing it's in cell range. Caught another power outage, got a cell text, called the marina, they turned my DC panel off. 3 Hours later the power came back on, and I had make sure the charger was running and then turn on the DC panel. It allowed me to tough it out through the end of last season.

P.S. I don't represent Boat Command in any way but it's a really simple unit that works as advertised and is reasonably priced for what it does. A rare item now a days.