Fridge: 12V or DC
- Thread starter xavpil
- Start date
Hello,
Congratulations on the new boat. I have a SO 409, very similar to your 419. I'm very happy with my boat.
I guess I'm a little confused. You are off grid. How do you generate electricity? Do you have solar panels that produce DC power? Do you have a generator that produces AC power?
As far as I know, it's better to NOT convert electricity from AC to DC or vice versa. There are losses incurred when it is converted. So, if you are generating DC power with alternator, wind generator, solar, etc, then run the fridge on DC. If you are generating AC power with a diesel or gasoline generator, then run the fridge on AC power.
It is less efficient to generate DC power with solar, convert it to AC with an inverter and then run the fridge off AC.
Understand?
Barry
Congratulations on the new boat. I have a SO 409, very similar to your 419. I'm very happy with my boat.
I guess I'm a little confused. You are off grid. How do you generate electricity? Do you have solar panels that produce DC power? Do you have a generator that produces AC power?
As far as I know, it's better to NOT convert electricity from AC to DC or vice versa. There are losses incurred when it is converted. So, if you are generating DC power with alternator, wind generator, solar, etc, then run the fridge on DC. If you are generating AC power with a diesel or gasoline generator, then run the fridge on AC power.
It is less efficient to generate DC power with solar, convert it to AC with an inverter and then run the fridge off AC.
Understand?
Barry
Thx Barry!! Glad you enjoy your 409!!
So yes, off grid. 800 w solar, 400 lithium. Multiplus Victron inverter charger
DC would be better then, right?
DC is better because it is more efficient. Electricity onboard is stored as a direct current (DC). To get AC it is necessary to turn the DC into AC with a converter an inverter. Converters Inverter introduce more inefficiency, most are only 90to 95% efficient. If the refrigerator uses 700 watt hours a day, it will take about 700wh of DC or 770wh if the DC is first converted to AC. Electricity on a cruising sailboat is precious, use it wisely.
The convenience of a refrigerator using dual power (AC/DC) is so when afloat away from the shore power you can use your onboard DC power to keep your food cold. When in a marina plugged into the AC shore power the refrigerator can switch off DC to AC and keep food cold.
Using “”inverted AC” will drain your DC battery storage more quickly than if you use DC directly to power the refrigerator. The process converting DC to AC consumes some of your stored DC power to function.
Using “”inverted AC” will drain your DC battery storage more quickly than if you use DC directly to power the refrigerator. The process converting DC to AC consumes some of your stored DC power to function.
Wow. Such a clear answer!!! Thank you!
Now I have to decide if it’s worth me running the 12v plug all the way to the panel, when I’ve never done that before.
What kind of refrigerator are we talking about? One of those portable ones?
In general long term use of the 12v cigaret lighter style plugs is not reccomended. They are prone to corrosion which can cause all sorts of trouble that you really don't want. It is best to hard wire the device and properly fuse it.
Sorry Dave, not True.
Try to run a DC air conditioner.
It is all in the Amps it pulls and resistance to power is your efficiency.
Jim... [aka Engineer]
James, read the whole post. Storing electricity as DC in a battery, then inverting it to be AC induces a ~ 10% loss right off the bat in the process. Amps is only part of the story, as I"m sure you know amps is not a measure of work done, watts are and as you know watts is a function of both amps and volts. Yes, low voltage DC uses more amps than high voltage AC, however the power draw use can be the same, 1a @120vac is roughly equivalent to 10a @ 12vdc.Sorry Dave, not True.
Try to run a DC air conditioner.
It is all in the Amps it pulls and resistance to power is your efficiency.
Jim... [aka Engineer]
Why would the OP, invert his power when he has 120 VAC?
Oh well, enough Said by me.
Jim...
PS: Energy Out / Energy In = Efficiency
Just kidding you a little bit.... but perhaps you should try to drink better beer!When set just right, the beer has an ice sludge on it.
Well the Admiral likes CoorsLite in a can.
Captain Jim loves Land Shark in a bottle.
So we kinda TIE on beer in our 120VAC freezer , even "OFF the GRID".
We can do 120VAC with our on board Generator without "Inverting" off house Batteries.
Oh well perhaps @xavpil has an Genset too.
Captain Jim...
How often does your fridge cycle and how long will it stay cold if it’s not run? My 12V fridge cycles about 10 minutes on / 10 minutes off in moderate temperatures. It could probably stay cold longer than 10 minutes but I presume the designers programmed it that way for efficiency or some reason like that.We can do 120VAC with our on board Generator without "Inverting" off house Batteries.
If I had a choice I’d rather have a 12V fridge that runs whenever it needs to than a 120V fridge that only runs when I don’t mind the noise and fuel consumption of a generator.
A DC refrigerator will run anytime the battery is sufficiently charged to provide the power. If the engine is running the refrigerator will still run and the alternator will charge the battery. If the generator is running, presumably it is also feeding the charger and that will provide the power to the refrigerator. And if you are plugged into shore power the charger will provide the power to run the refrigerator through the battery.
An AC only refrigerator will only run off an inefficient inverter, a generator, or shore power.
An AC only refrigerator will only run off an inefficient inverter, a generator, or shore power.