Dry camping battery bank expectations

[janstey58]

Hi All, Our 2015 Discovery 40E has 6- 6V AGM batteries with a 2800 watt inverter. We have a Whirlpool side by side fridge running off the inverter when not plugged in. Can I hear from owners with similar setups on expectations of battery life running the fridge and little else while boon docking? I am just wondering do I have 4hrs, 8hrs or more battery life before kicking in the generator? Thx, Jeff

[janstey58]

Thanks for all of the real world experience, that is what I was looking for! It sounds like I have more off the grid capability that I guessed, and I do have a nice sized solar panel as well. Jeff

[et2]

You should be able to program your genset to come on automatically when batteries get to your programmed discharge. Never have to worry about it. Read up on it, it's not hard to program.

[Bill_Satellite]

traveylin wrote:
I have only 2 12 volt batteries for my Lower end class A and get maybe 3 3.5 days of normal usage. An energy hog not mentioned in above comments is the circulating fan for the room heater. While the heater itself is propane the air circulation is battery driven electric. I will get about 18 hours before having to run the gen set

Do you also have a residential fridge in this coach as the OP was asking about?

[Ivylog]

My ice maker heater draws 300W for almost a minute... not the end of the world but 8-10 times a day adds up when trying to conserve power. Turning it off made the difference between my power management system shutting down because of low voltage at a rally using their generator power.

[Dale_Traveling]

Bill.Satellite wrote:
It uses 96 total watts for what time period? Does the ice maker draw any noticeable power at all? My guess is no. Fill the tray with water. Sit there for an hour or so. Turn the gear that spits out the cubes. Repeat. Opening the door will likely cause a larger draw than an ice maker in any fridge.

Actually the ice maker will spike a power demand due to the heating element that will come on during end of a cycle to free the cubes from the mold. Not sure what the wattage might be but suspect a couple of hundred per cycle. Over riding the cycle will save energy.

Another high power consumer associated with a fridge is the frost free feature. Another heating element that comes on from time to time to warm the freezer slightly to knock down any frost that might form.

If possible disabling both for the time periods when exclusively operating off stored energy will help along with limiting how often and how long you have a door open. Personally unless I was on the edge of not being able to get thru a night running off batteries I wouldn't worry about either.

[MrWizard]

You have 600+ amp hrs total should be able to go overnight and then some if needed
We 675 amp Hrs of AGM batteries and a residential fridge
DW goes to bed 10~10:30 pm, I tun in later
If we are full at 8 pm
We will be about 80% in the morning
We use approx 130+ amp hrs overnight, tv, pc, fridge, electric blanket on the bed
If I pushed it we could go 24 hours and reach the 50% charge level
If we did nothing but the fridge, we could go longer

You should be good for the night, but you want a full recharge the next day, with a top up before quiet hours and shut down
Guessing at a minimum 4 hour generator run then start it again for supper and run till approx 8pm

Start the evening with a full charge, should be no problem,
Skimping on the recharge causes problems

[traveylin]

I have only 2 12 volt batteries for my Lower end class A and get maybe 3 3.5 days of normal usage. An energy hog not mentioned in above comments is the circulating fan for the room heater. While the heater itself is propane the air circulation is battery driven electric. I will get about 18 hours before having to run the gen set

[time2roll]

From the posts I read you should be able to go one to three nights depending on other usage.
Assumes battery starts tip top 100 percent charged and good condition.
I would plan to run the generator 2 to 4 hours per day.

If you park in the sun 500 to 800 watts solar would about do the trick.

[Bill_Satellite]

Ivylog wrote:

DrewE wrote:
A modern residential fridge uses somewhere in the general vicinity of 1 kWh per day, perhaps a little more. A single 6V golf cart battery store around 1.3 kWh of energy, of which around half is usable. A little rough arithmetic suggests that around three days would be a not unreasonable rough expectation. Anything more precise would require measuring the power requirements of your particular setup.

An accurate reply for just the refer but you cannot turn everything else off that uses 12v power. My 21cuft refer uses 96 total watts when running on a PSW inverter if I turn the ice maker off and it runs a little less than half the time... 1.0 kWH as estimated above. You will have 2-4 amps of parasitic load 24/7 in a big MH that you cannot get rid of. Add some lights, water pump, TV and charging phones you are better off running the generator any time you use the microwave or coffee maker... one hour per day should be enough to keep the batteries up assuming a 100 amp charger.

It uses 96 total watts for what time period? Does the ice maker draw any noticeable power at all? My guess is no. Fill the tray with water. Sit there for an hour or so. Turn the gear that spits out the cubes. Repeat.
Opening the door will likely cause a larger draw than an ice maker in any fridge.

[Dale_Traveling]

DrewE wrote:
A modern residential fridge uses somewhere in the general vicinity of 1 kWh per day, perhaps a little more. A single 6V golf cart battery store around 1.3 kWh of energy, of which around half is usable. A little rough arithmetic suggests that around three days would be a not unreasonable rough expectation. Anything more precise would require measuring the power requirements of your particular setup.

I'm with Drew but I also think three days will be really pushing it before the inverter shuts down due to low volts. Just remember the longer you go without recharging the long you'll need to run the generator to recharge to full capacity. Throw a solar panel or two or three,,, on the roof and if the sun light is favorable you might be able to go indefinitely.

[Ivylog]

DrewE wrote:
A modern residential fridge uses somewhere in the general vicinity of 1 kWh per day, perhaps a little more. A single 6V golf cart battery store around 1.3 kWh of energy, of which around half is usable. A little rough arithmetic suggests that around three days would be a not unreasonable rough expectation. Anything more precise would require measuring the power requirements of your particular setup.

An accurate reply for just the refer but you cannot turn everything else off that uses 12v power. My 21cuft refer uses 96 total watts when running on a PSW inverter if I turn the ice maker off and it runs a little less than half the time... 1.0 kWH as estimated above. You will have 2-4 amps of parasitic load 24/7 in a big MH that you cannot get rid of. Add some lights, water pump, TV and charging phones you are better off running the generator any time you use the microwave or coffee maker... one hour per day should be enough to keep the batteries up assuming a 100 amp charger.

[Bill_Satellite]

You can easily go an entire night while you sleep as you really won't be using anything else (minimal anyway). If you truly run little or nothing else you can go much longer. How often you open the fridge will also make a difference in the length of time of batteries will last.

[DrewE]

A modern residential fridge uses somewhere in the general vicinity of 1 kWh per day, perhaps a little more. A single 6V golf cart battery store around 1.3 kWh of energy, of which around half is usable. A little rough arithmetic suggests that around three days would be a not unreasonable rough expectation. Anything more precise would require measuring the power requirements of your particular setup.

[CA_Traveler]

No one can answer that question because it's totally dependent upon your total battery draw and other factors like amount of battery recharge, temperature, etc.

Hopefully at least overnight would be OK.

Adding a battery monitor would be a major step in determining your loads and battery charge.