Refrigerator Question

[J&RCruising]

Hi everyone,

Quick question from a fairly new guy.

Here is the issue. Plug the boat into shore power, all batteries are off, leave the ice maker switch on and walk away...thinking that everything in the fridge will stay cold. Come back the next day and everything in the fridge is actually at room temp/warm. Here is the question. Does the house battery need to be on to run the fridge even if i'm connected to shore power? I noticed the ice maker switch in the lower berth doesn't make a difference either way when the house battery is on. As a matter of fact, I really cant figure out what it really does.

Guess i'm also trying to figure out the role of shore power (as an engine substitute??) in running all the other items in the galley. Will the house battery always need to be on to run the fridge; how about the stove/oven/microwave? For some reason I think/thought the switches (microwave/stove/oven) in the lower berth bypass the house battery when hooked to shore power.

I have a 2018 30' CB.

BTW I've obviously always run everything with the boat running...engine providing AC current to the inverter to power the batteries to power everything. But now were at the dock a little more and some things I haven't done before are stumping me.

Any advice is appreciated.

Thanks

 

[Rocky]

Assuming your fridge is the same as mine, the short answer is yes. The house bank would need to be "on" to power the fridge (and other 12v systems) when hooked to shore power.

The Fridge is a 12v fridge - not 120/12v - so it will get its power from the house bank. The inverter/charger keep the battery topped off via the shore power, so the battery will stay full even though it is being used for power.

I hope that helps.

Rocky

 

[ethanbarnett]

Yes house batteries need to be on to run the fridge.

 

[Chimo]

Welcome to the forum. I think you have a couple of misconceptions about how your system works here that it would be good to clear up. Perhaps it would be good to try out the really excellent webinar put on by Ranger tugs that you can find at https://www.youtube.com/watch?v=Uj_am-ecSt4.

Hopefully these couple of tips will help with your immediate questions:

You may have a combined inverter/battery charger or separate units. It's good to know which and to read the manuals as a place to start.
Your engine alternator actually produces AC (as compared to a dynamo) which is rectified to DC. This is fed to your batteries through one or more bits of electronics like automatic charging relays (ACR's).

Your fridge is likely 12DC only and will be running off the batteries as long as your 'house' switch is on and the breaker on you DC panel is on.

When you plug in shorepower and activate the AC panel there are a number of things that run directly and are on marked breakers. One of these things is the battery charger. A good thing to have turned on if you have any load on the DC panel. There are also a few small loads that are independent of the panel.

When you activate the inverter it takes power from the batteries and gives you AC power at the outlets. That is limited by your battery capacity (See the YouTube) and must be carefully managed. Some things like to cooking top and water heater are too high load for a standard setup and are not usually wired to run off the inverter from the factory. There are also several threads on the subject on this board.

My apologies if I have covered items you already knew. It is not my intention to be anything but helpful.

 

[J&RCruising]

Rocky and Chimo,

Thank you for the information. I had figured most of it out but had a misperception that the fridge was hot wired to the battery when shore power is hooked up. Kind of a If This Then That (IFTTT) sort of thing. Guess we're not quite there yet.
Again thank you for your advice.

John