12v Refidgerators

[KLYoung]

I have been looking at new TTs and have found that quite a few have 12v only refriderators. Has anyone used these while boondocking? How long will they run on solar? I have 400w of solar panels and 2 100a Battleborn batteries.

[bikendan]

KLYoung wrote:
4x4van, that is interesting because my dealer here in the midwest called the company and was told that the 12v was the only thing available.

that's because the West Coast version is only sold by dealers, from Colorado and west.

from the website:
"West Coast Models
"Of all the paths you take in life, make sure a few of them are dirt..." -Muir

At Surveyor, Customer Satisfaction is #1 and these models were specifically requested by RV Customer and dealers from Colorado, Westward. We're glad we listened. Built regionally in Oregon."

[KLYoung]

4x4van, that is interesting because my dealer here in the midwest called the company and was told that the 12v was the only thing available.

[4x4van]

Interestingly, Forest River's brochure lists 2 different "Surveyor Luxury" models. The Surveyor Luxury shows a 10 cu.ft. 12v residential fridge, while the Surveyor Luxury West Coast shows an 8 cu.ft. gas/elec fridge.

[ajriding]

2oldman wrote:

ajriding wrote:
I did the math of how little power I would need to cook for a few minutes each day, and concluded I could use inefficient electricity to cook with and still have plenty to run the fridge and fan and lights and charge a phone...

In theory, yes, but when drawing huge amounts of amps like for an electric burner, a small complement of batteries can't maintain enough voltage to keep the inverter online. I'm not sure what kind of electric stove cooking is done for a 'few minutes.' Frying eggs?

The new-style induction cooktops are more efficient than those coil-things of the past. People are using induction off batteries with no issues, even up to 45 minutes with a fridge running, and yes, eggs and coffee in the morning is about all I would do, and the evening would be a little more, but I would not plan something complicated that requires lengthy stove use when running off batteries. That is all for another discussion, though. You can start a new thread about this topic, but lets not continue...

[MEXICOWANDERER]

Subject line refrigerators

Vacuum panels minimize insulation space. And insulation is 90% the key of successful electric refrigerator energy success. The others being motor compressor lifespan and door integrity.

[2oldman]

ajriding wrote:
I did the math of how little power I would need to cook for a few minutes each day, and concluded I could use inefficient electricity to cook with and still have plenty to run the fridge and fan and lights and charge a phone...

In theory, yes, but when drawing huge amounts of amps like for an electric burner, a small complement of batteries can't maintain enough voltage to keep the inverter online. I'm not sure what kind of electric stove cooking is done for a 'few minutes.' Frying eggs?

[ajriding]

A residential fridge, in the case of an RV, can mean two things:

1. It is only referring to the size; a residential size fridge, as opposed to the much smaller fridges found in RVs. i.e., as big as the fridge in your house kitchen.
or

2. Literally some people put a walmart/homedepot $100 house fridge in their Rv because its is $100 and not $1,000.

2 is really dumb unless you are parked at a trailer park and have already taken the wheels off the camper, so 1 is usually what Residential is referring to. You see this a lot when shopping for used campers as the seller ruined the absorption fridge and is putting in the cheapest option to have a working fridge hoping the buyer does not know anything.

On amp hours, be careful when calculating. A Danfoss compressor that pulls 3 or 5 amps, does not mean it pulls 3 or 5 amps for the entire hour. Those might typically only run 10 minutes total out of every hour, so it would take 6 hours to get a full 3 or 5 amp hour total (10 mins at 3 amps times 6 equals one hour at 3 amps).
So, I am guessing the calculation from a previous post was wrong.

One battery is not ideal for running a fridge as you need the extra battery to help with overcast days. Depending on other demands on the batteries you should be able to go 3 days even with a big compressor fridge, if you have a small one then you can go a very long time. The solar does work on cloudy days, but just at a reduced output, so you do always get some charging.

People do run these compressor fridges (like ARB or Dometic etc) off the car starting battery all afternoon and can still crank the vehicle, keep this in mind for reference to how little power it uses.

If I had it to do over I would have 3 four-volt batteries, or two bigger 6 volt (I have two golf cart now) and have an electric stove top instead of propane. I did the math of how little power I would need to cook for a few minutes each day, and concluded I could use inefficient electricity to cook with and still have plenty to run the fridge and fan and lights and charge a phone...

Propane is still king for heating water and is in a tie with the diesel heaters for heating the air.

[DrewE]

2oldman wrote:

wolfe10 wrote:
Double the voltage and amps are halved to produce the same watts.

Yes, but he said "amp hours"

12v at 1 amp for one hour= 12 ah
24v at .5 amp for one hour= 12 ah

A more appropriate unit would be watt-hours if you want to get technical. Please tell me if I am wrong.

Amp-hours are a measure of charge, not energy; one amp-hour is 3600 Coulombs (as a Coulomb is defined as an amp-second). At a basic level, charge is a count of electrons; one amp-hour is equivalent to 2.25 x 10^22 electrons. As such, the voltage is not involved at all.

1 A for 1 hour = 1 A * 1 h = 1 Ah

0.5 A for 1 hour = (0.5A * 1h) = 0.5 Ah

Energy, measured in watt-hours in this case, can be found by multiplying charge by voltage, and this is a more appropriate unit to use when comparing systems with differing voltages, as you mention.

1 A at 12V for 1 hour = 1 A * 12 V * 1 h = 12 W * 1 h = 12 Wh

0.5A at 24V for 1 hour = 0.5A * 24V * 1 h = 12 W * 1 h = 12 Wh

[MEXICOWANDERER]

I TRIED using watts and watt hours on this forum once, and got blasted for it.

[Bumpyroad]

2oldman wrote:
. What is night mode... it has a clock?

.

???????

bumpy

[2oldman]

wolfe10 wrote:
Double the voltage and amps are halved to produce the same watts.

Yes, but he said "amp hours"

12v at 1 amp for one hour= 12 ah
24v at .5 amp for one hour= 12 ah

A more appropriate unit would be watt-hours if you want to get technical. Please tell me if I am wrong.

[wolfe10]

2oldman wrote:

MEXICOWANDERER wrote:
Keep in mind 24 volts uses half the amp hours of 12 volts

huh?

Correct.

It uses the same amount of energy (WATTS)

VOLTS times AMPS= WATTS

Double the voltage and amps are halved to produce the same watts.

[2oldman]

MEXICOWANDERER wrote:
Keep in mind 24 volts uses half the amp hours of 12 volts

huh?

[MEXICOWANDERER]

From actual data my 24 volt 18 CF refrigerator uses 48-53 amp hours in 90F ambient with an average interior temp of around 35F

Its twin, the freezer uses 85 -92 amp hours to keep -5F

Keep in mind 24 volts uses half the amp hours of 12 volts