Amps draw on freezer and Fridge?

[Capt. Rodbone]

78 Grand Banks 42 Classic. The best I can tell both are original however, those are items I don’t have any paperwork on in the manuals I inherited from the prior owner. We are having a few little things done while at a marina/boat yard and I am considering another project. Can someone estimate to me what these units pictured below likely draw?

 

[ranger58sb]

Sub-Zero has fairly decent documentation available through their Customer Service guys. And they answered the phone.

Mid-Atlantic Parts are the go-to folks for parts relative to your specific serial-numbered units.

Or if one of your systems happen to be a 249FF (or FFI) under-counter freezer, I have that manual. (Although I don't find many electrical details. All I see is projected Annual Energy Usage as 479 kWh.)

Our under-counter fridge is a two-drawer unit, apparently not like yours...

-Chris

 

[TBill36]

Small refig or freezer should be around 60 watts when it's running which is about 1/3 of the time. Momentary start up can be 10X and will be what limits your system.

If you don't have one, get a clamp on amp meter that measures both AC and DC. Great tool for determining where all your electrity is going.

 

[Comodave]

We have a portable freezer that uses 80 watts when running.

 

[High Wire]

5-6 amp at 12 vdc each when running for a estimated guess.

 

[Comodave]

Depending on the installation they may run from 50 to 80% of the time. I find it is way more efficient to have a small 12 volt fan running to help evacuate the heat from the cabinet so the refer doesn’t have to work as long and hard to cool. The power for the fan is well offset by shorter run time for the compressor. Also have 2 air vents, 1 low for cool air to enter and 1 high for hot air to exit. By doing this you should be able to turn down the setting on the thermostat and still maintain cool enough.

 

[C lectric]

I also agree about the clamp on ammeters. They used to be high dollar tools but no more. A decent meter that is TRMS rated , and can read DC amps will be of lots of use, around $100.00 CDN.

As far as the units go likely about 4-6 amps at 12VDC. However, just as important is duty cycle. Installation can affect that hugely.

Take heed of Commodaves suggestions. one vent low for air entry, one vent high for exit. I will add that the fan should BLOW OUT and be at the top vent.

Poor circulation and exit of the heat will cause long running times and as I found out the outright failure of the poor fridge to be able to cycle at all meaning high power use.

 

[Comodave]

Our last boat had a Vitrifugo refer that didn’t cool well and ran all the time it seemed. Vitrifugo nicely put a terminal on the main board for power up to .5 amps for a fan to run whenever the compressor was running. The boatbuilder had put a very nice looking vent for the refer but put it on the side so it led to nowhere that air could get to the compressor area. I added a low intake vent and put a 5” 50 mAmp fan on the intake blowing cool air into the cabinet. I also added a vent at the top of the cabinet for the hot air to escape. The refer that didn’t cool well then cooled very well and would actually freeze ice cream. I could have actually hooked up 10 of the fans to the circuit board since the fan draw was so low. Just getting cool air in and the hot air out will improve the working of the refer dramatically. I would have like to put the fan on the hot exhaust air vent but it would not fit so I used it to push cool air in instead.

 

[Insequent]

While a clamp-on meter is useful, and worth having on board, but you should also get a "kill a watt" type meter. The AC ones are easy - plug into wall then plug appliance into them. Leave it for 24 hours (or week if you want...) and get much more useful info.
For DC, its a bit more mucking around as you need the (different) meter in series with the appliance, but its very much worth doing.

Having 24 hour consumption for everything on board enables you to size house bank and charging systems to match cruising needs. And decide what needs replacing....

Obviously a freezer uses a lot more energy than a fridge. Here is some test result info for a portable Waeco (Dometic) 110 litre fridge freezer, with an efficient Danfoss compressor The unit specs were 120VAC 1.2 A, 12VDC 7A. So, for a 24 hour run: 3°C hold 21 Ah. For -5°C hold 62.4 Ah. For -10°C hold 131.4Ah.

For a 40 litre Engel (40 years old) it was kinda similar: 0.5° hold 55.3Ah, -3.8°C hold 101.6Ah.

My main galley fridge is a Norcold DE0061 (Danfoss compressor) with freezer up top and fridge below. It used 80Ah in 24 hours, which is reasonable IMO. As Commodave notes, better venting would likely improve it, but it does have reasonable vents already so I have not changed it yet.

On the other hand, the older style bar fridge in the pilothouse (with tiny little freezer for a couple of ice trays and much smaller fridge compartment) used 163.3Ah. It was ditched within a short time of me collecting the data! A power hog like that is a house bank killer!