Residential fridge in motorhome is draining my batteries

[twinboat]

Be very carefull about disabling the defrost cycle. I did this on a fridge and it stopped working, due to internal frost buildup, in 3 or 4 days.

We found that the frost was building up and blocking the passages between the fridge and freezer, to a point, where the plastic was getting deformed.

My unit has a simple 24 hour clock that goes into defrost for 20 minutes or so a day. It draws about 20 amps DC, double the amps while running normally, so not a significant impact on battery life.

Many fridges have anti- condensation heat strips around the door seal. They can be turned off to conserve energy. The defrost cycle is not user controlable.

I am curious if others have tried disabling the defrost cycle and what were the results.

[carl.swoyer]

I had a cedar Creek 34sats with the amanna residential. Using four 6 volt golf cart batteries wired in series and parallel with a 800 watt inverter. I purchased a quality remote thermometer and placed it inside the fridge. By using the remote thermometer I was able to turn off the fridge at night while dry camping. If we woke up at night we could monitor the interior temperature and if needed turn the inverter on again. This process allows you to conserve battery life and we did the same mid day.
I have a four door no cold. It is junk. My replacement is already failing , only 6 weeks old.

[carl.swoyer]

Also keep the water level up with distilled water. And a sign of overcharging is bulging batteries and excessive amount of acid mist about the battery box.

[Waiter21]

Jim J nailed it.

Your inverter is converting 12 volts DC to 110 volts AC. Its almost a 10 to 1 ratio for current draw.

So, for every amp you need at 110 volts, your inverter is going to consume 10 amps at 12 volts to create it..

On of the unintended side effects of RVing, a lot of people learn about energy management and the cost of generating electricity.

[Scottybdivin]

There is also the efficiency rating of the inverter. Most high-end inverters are only 90% efficient at best. Therefore the ratio is more like 11.1 to 1. For every 1 watt AC it takes 11.1 Watts DC. I found out the hard way that cheap inverters have a far less efficiency rating.

[twinboat]

Originally Posted by carl.swoyer

I had a cedar Creek 34sats with the amanna residential. Using four 6 volt golf cart batteries wired in series and parallel with a 800 watt inverter. I purchased a quality remote thermometer and placed it inside the fridge. By using the remote thermometer I was able to turn off the fridge at night while dry camping. If we woke up at night we could monitor the interior temperature and if needed turn the inverter on again. This process allows you to conserve battery life and we did the same mid day.
I have a four door no cold. It is junk. My replacement is already failing , only 6 weeks old.

Isn't turning off the fridge at night, creating a longer run time and more energy use in the morning, to cool it back down ?

Has anyone tracked and recorded the difference ?

[Pexring]

I tested the batteries. Pictured is my best test. Most are in the middle of the white (fair) section, so it appears the life of my batteries are getting close to the end?

Each battery is 232AH and I have 4 batteries.

I just got done with dryland camping for 10 days at our county fair. Generators cannot be run from 11pm to 7am. To get thru the night, I put a timer on my fridge so it would shut off for 4 hours during the night and that got me through the night without the inverter going on a beeping fit.

[Gary RVRoamer]

The inverter is connected directly to my batteries. With the fridge running off of the inverter, I put my clamp around the wire coming from the battery and it pulls 8.2 DC amps with flickers (sometimes) up to 15 DC amps. When I shut the fridge off, the inverter pulls just 0.8 DC amps from the batteries. When the inverter is shut off my batteries last forever.

As others have already said, the 12vDC amps for the inverter will be 10x-11x the 120vAC amps, so 12.5-15 DC amps is about right. And that will indeed run your batteries down if it is continuous, but the fridge should not be running more than maybe 15 minutes per hour. Of course, the amount of run time depends on the temperature in the RV, how often you open the door, ventilation around the fridge, etc.

You didn't mention the age and condition of the batteries, so it's hard to guess how long they should last. 4x 6v bats would be about 450 amp-hours when new, but lack of maintenance (e.g. water in the cells) or other problems could severely curtail that.

[mel s]

Originally Posted by

When my Dometic fridge died, I replaced it with a Frigidaire FFTR1022QB. I've successfully used residential fridges in other campers but this one is kicking my butt.

I have four 6-volt batteries and a 2000 watt pure sine wave inverter. When I run the fridge off of my inverter, it drains the batteries down in about a half a day.

I bought an amp meter with a clamp that reads both AC and DC amps.

When the fridge is running off of shore power, it reads 1.25 AC amps. Perfect. See picture.

The inverter is connected directly to my batteries. With the fridge running off of the inverter, I put my clamp around the wire coming from the battery and it pulls 8.2 DC amps with flickers (sometimes) up to 15 DC amps. When I shut the fridge off, the inverter pulls just 0.8 DC amps from the batteries. When the inverter is shut off my batteries last forever.

What am I missing?

Pexring
Apparently you don't have enough power in your four 6-volt batteries rb to provide a continuous 8.2 DC amps, which sometimes "flickers to 15 DC amps", for longer than about a half a day.
Mel
'96 Safari

[computerguy]

Originally Posted by Pexring

I tested the batteries. Pictured is my best test. Most are in the middle of the white (fair) section, so it appears the life of my batteries are getting close to the end?

Each battery is 232AH and I have 4 batteries.

I just got done with dryland camping for 10 days at our county fair. Generators cannot be run from 11pm to 7am. To get thru the night, I put a timer on my fridge so it would shut off for 4 hours during the night and that got me through the night without the inverter going on a beeping fit.

Attachment 136964

Good info on this thread.
A couple things to note:
The age of a battery is not as critical as how the battery has been maintained over it's life. Flooded lead acid batteries can and will last 8+ years if maintained properly.
Flooded lead acid batteries like to be fully charged.
They do not like to be run below 50% state of charge.
Voltage is not a good indicator of the current state of a battery. If interested in the "real" state of the battery get a battery monitor like a Trimetric 2030 or a Magnum BMK.
It's good practice to equalize flooded lead acid batteries to remove lead sulfate from the plates.

[vsheetz]

Originally Posted by Pexring

I tested the batteries. Pictured is my best test. Most are in the middle of the white (fair) section, so it appears the life of my batteries are getting close to the end?

Each battery is 232AH and I have 4 batteries.

I just got done with dryland camping for 10 days at our county fair. Generators cannot be run from 11pm to 7am. To get thru the night, I put a timer on my fridge so it would shut off for 4 hours during the night and that got me through the night without the inverter going on a beeping fit.

Attachment 136964

Did the batteries have a good charge on them when you checked the specific gravity? I also do a breakdown test as well as checking specific gravity. Double checked the charger is providing a good and full charge?

From the test results and discussions in this thread, I think the batteries are marginal with little life remaining. How old are they?

[carl.swoyer]

I successfully used that process for 4 1/2 years. Realize that the fridge is off and no one is opening the doors during the off time, it becomes an ice chest. NOTHING ever thawed or spoiled. Using the wireless thermometer you can fire it back on and recovery time is less than running 24/7

[carl.swoyer]

Sorry for not remembering everything at once, But.... do make sure your on board converter is not running off your inverter. In other words if the Inverter for the fridge happens to be on the same circuit as the converter, the converter is changing off the fridge batteries. This was the case in my cedar Creek. I had to separate them.

[Dr4Film]

Originally Posted by carl.swoyer

But.... do make sure your on board converter is not running off your inverter. In other words if the Inverter for the fridge happens to be on the same circuit as the converter, the converter is changing off the fridge batteries. This was the case in my cedar Creek. I had to separate them.

totally with your post.

My Inverter/Charger/Converter are all in one unit and it has been running my Samsung fridge fine for well over 4 years now.

Please explain in more detail what you are stating and why it is important?

Dr4Film ----- Richard