HOUSE FRIDGES & INVERTERS

[Gilligan004]

How long can you run the fridge on 1000 watt inverter?
Does the fridge have to be on inverter all the time?
When on shore power, does it still run on inverter?
I know nothing about inverters so any info would be great!  Gil

 

[Rene T]

How long can you run the fridge on 1000 watt inverter?
Does the fridge have to be on inverter all the time?
When on shore power, does it still run on inverter?
I know nothing about inverters so any info would be great!  Gil

I run my fridge while we're on the road. When we stop for the night and there's no shore power, I just shut off the inverter and unplug from my truck.  I don't want to take a chance of draining the battery in the truck. When we do connect to shore power, I have a auto transfer switch which automatically switches the source of power from the inverter to shore power.

https://www.amazon.com/Xantrex-8080915-PROwatt-Transfer-Switch/dp/B004S5Y158

 

[Gary RV_Wizard]

There are multiple options for that.  The ideal way is to utilize an inverter with a built-in transfer switch that senses when shore power is active and uses it, and actually inverting only when needed.  The inverter is wired to both a shore power circuit and the batteries and it uses whichever is available.  An example would be this model from AIMS:
https://www.aimscorp.net/1200-Watt-Pure-Sine-Inverter-with-Built-In-Transfer.html

It's also OK to just wire the fridge to the inverter and always run that way, relying on the separate converter/charger to simultaneously charge the batteries when shore power is active.  It's a little more wear & tear on the batteries and the electronics of the inverter and charger, but that's not a big concern if the RV is used only occasionally.  Probably not a good choice if you camp off-grid often or for extended periods, though.

The "how long" question is a tough one, since it depends on a number of variables. The biggest one is the size (in amp-hours) of your battery(s). The battery bank is the inverter's fuel tank, so it's impossible to estimate without knowing how much fuel you have for that inverter. The next big variable is a personal one, mostly how often the fridge door is opened and how long. The fridge compressor has to run to re-chill every time, so the power consumption increases dramatically every tie the door is opened. Related to that is the room temperature around the fridge and also the exterior sidewall temperature, both of which heat up the fridge somewhat and cause it to run more.  With reasonable answers to those questions, you could expect to operate a fridge for 12-24 hours without battery charging. 16 hours is a commonly reported figure.

 

[John From Detroit]

How long can you run the fridge on a 1000 watt inverter: FOrever. but that is teh wrong question
Does the fridge have to be on the inverter all the time or can you switch it over to Shore power
Depending on the inverter. YES and No/Yes.
When on shore power does it still run on the inverter No/YES

Now some better explanations.

An inverter just makes 120vac out of battery voltage.  It is designed to do that... forever (years on end) and so long as it has battery power... So the "How long" depends not on the inverter but the batteries.

A single pair of GC2 will run a 100 Watt Fridge for about 10 hours assumign a 50% duty cycle. and no other loads... Wattage of Fridge/10  divide that by 2 for 50% duty cycle.. and divide the result of that calculation into the battery's C/20 Rating (GC-2 are 220 amp hours per pair). THen divide that by 2 again (50 % state of charge minimum on battery for GC2 For Group # you can only safely use about 1/4 the stored power)

To the second "Can you switch to shore power"  YES you can.. But you ask two questions at the same time. and the third question applies to the "Or should you run it via the inverter"

Inverters come in 2 types. or 2.2 types  One is a "Stand ALone" this device has 12 volt IN and 120 out and that's all folks...

For running your fridge you likely want one of the two INLINE types
These have 12 volt in. 120 volt in 120 volt out and automatically switch to shore power (or generator) if present.. You need do nothing the box does it automatically.

The .2 on this is many of the INLINE are also battery chargers. and usually very very good ones.  So the 12 volt is bi-directional.. IN if you have no shore power.. OUT if you do.

I know this sounds confusing but it gets worse the more you get into it

Figure about 2 hours for a 200 watt fridge 50% duty on a single pair of GC-2.

Have a group 27.. Even shorter run time.

So how long depends entierly on the batteries
and the rest on the type of inverter.  But most liklely answers are

Leave it plugged in to the inverter and let the inverter choose shore power if it can.
If it can not then I'd move it to a Shore outlet.

 

[grashley]

Good information above!

Part of Gary's comments included how often it was opened.  If you are traveling and the fridge was cold when you started, it requires very little power to keep it cold (assuming the door stays closed  ;D ).  Further, the tow vehicle should provide some recharging power to the battery.  In other words, when traveling, the fridge should stay cold indefinitely.  The question of how long the fridge stays cold on an inverter only comes into play when you are stopped or camping without shore power or generator..

 

[Larry N.]

The question of how long the fridge stays cold on an inverter only comes into play when you are stopped or camping without shore power or generator..

Actually, as Gary and John have indicated, it's not a matter of the inverter, per se, but it's dependent on battery capacity when not on shore power or generator/alternator.

 

[Gilligan004]

Thank y'all for your info. It gives me a much better idea now!  Gil