Running 3-way fridge in 220v mode off inverter while driving?

Check out the caravanner forums and some recent caravan magazines.
This is common practice, and makes the 3 way fridges work better...have not yet tried to myself.
Don't know if it's legal or not.
BW.

Hi Graham
The simple reason WHY your fridge runs better on 240v than 12v [especially over such a short distance] is undersized 12V cables giving excessive lost voltage @ the fridge
The same problem you have found with the lighter sockets
UNDERSIZED for the current [Amps ] involved

Yes, many do use inverters to bodgy overcome the problem, instead of FIXING the problem with the correct cables
It also makes for good sales for the inverter sellers who will tell you that is the answer

AS far as 240v is concerned ,it can be just as deadly from an inverter as from the mains power
Deaths have occurred using inverters

USE with GREAT care
One point that should be considered is the safety RECOMMENDATION:-

" ONLY HAVE ONE CLASS 1 DEVICE[has a 3pin plug] connected @ any time"

You can with reasonable safety connect multiple Class 2 devices[2pin plug] @ the same time


Peter

Some good comments above Kevin but I wouldn't unessasarily run 240v - I have seen more than the odd car go down both with shorts , and even shallow water crossings on flooded highways lead to engine stalls and people getting out of the car and this isn't good with 240v.

I like to approach problems from an engineering point of view and this means get data first.

Why not do a test with your fridge with a direct 12v connection and 240v connection and see how it performs - then its probably just a matter of using good cabling as suggested above.

If you do do this measure the (12v) voltage actually at the fridge just to be sure.

G'day Graham, I have run my 25 yr old 3way Finch on 240v via a 1200watt inverter
in the back of the Jackaroo for several years, & it works like a dream. It runs off my
starter battery & is only used when car is running. I have been taken to task on this site for running such a big inverter...very inneficient & so on. I reckon my fridge draws less than 150w..the inverter barely gets warm & the inbuilt cooling fan doesnt
run. I am aware of the safety issues but dont consider this setup to pose any higher risk than 240v in any other domestic situation. I had the inverter checked by a leco
& it has inbuilt safety switches on input & output sides as well as low voltage cutout.
I run it direct off the battery with 6AWG wire, earth & live. Got it off ebay for about
$150...so that makes it rubbish to some..I prefer experience to be my guide. I'm not
recomending this to anyone, but it works for me.cheers....oldbaz.

People continue to be in denial and willfully ignorant over the dangers of portable inverters.

The unavoidable fact is that people have been killed in Australia by portable inverters.

We have become accustomed to the very safe way that our domestic electrics are installed......most people will have no idea how strictly electrical installations are specified and the multiple levels of protection provided in a modern domestic or industrial installation.
We have a level of "plug in confidence" with 240V mains that borders on recklessness, becasue of the regulated safety of the system.

BUT, the majority of those levels of protection are simply not there or can simply not be relied upon to work where a permanent earthing system properly tested and properly bonded bonded to the greater mass of earth exists.

You can not rely on any of the fuses, circuit breakers or safety switches doing a damn thing to save your life where a portable inverter is involved.

There are plenty of people out there that say they have been doing this or that dangerous thing, but have not been hurt......that is down to either luck or statistics, depending on your view.

An live source of 240volts in a moving vehicle can be a very dangerous thing.......should that vehicle be involved in a serious acceident or a rollover that 240V supply could end up anywhere.

As for all those things that need charging.....I do not believe there is a single one that can not be charged directly from 12 volts with no 240V involved.



Now to the fridge.
the problem with 3 way fridges is they cool the internals by applying heat to the works.....not the most efficient process at the best of times......these fridges are designed primarily for gass and will always work better on gas, because gas can deliver more heat than is convienient or practical from electricity...especially from 12 volts.

3 way fridges draw quite large amounts of current from 12 volts, even then the amount of energy available is low compared to gas.....so just to keep up many simply don't bother with a thermostat.

Remember, "ya Cana change the laws of physics, Jim".....to get the same amount of cooling requires the same amount of enregy regardless of the source.

Wired corretly, the fridge should draw the same ammout of 12 Volt current on either 12 or 240V via the inverter...probably more on the inverter

As has been mentioned many 3 way fridges have the same heater wattage on bothe 240v and 12 volts.

It is Oh so common for perple to grossely underestimate the size of the wiring required to deliver adequate power to 3 way fridges...thus they commonly work poorly on 12 volts.

Likewise people frequently underestimate what is required to run an inverter.

many of these fridges have 120 to 150 watt heating elements, bigger ones may be more........that puts things 10 to 15 amp area.

Ciggy lighters where never designed to deliver continuous high currents, a good one will deliver 15 amps, but the contact quality is inherantly poor and to expect 15 amps contunous is unreasonable.
I would not rely on more than 5 to 7.5 amps continuous out of a ciggy lighter..even a good one.
Most of the ciggy lighter plugs are even poorer propositions.

A ciggy plug on any more than a 120 watt inverter is a joke, even on a 120 watt inverter run continuously expect reliability problems.

There are any number of better plugs to use, the most pratcical for 15 amps is the T plug...like a mains plug but with 2 pins arranged in a "T"

I do not like to se a 50 amp anderson that is not wired capable of delivering its full 50 amps continuous.

Now to the wiring.
If you are running the length of the vehicle say 7 meters as the wire flies.....for 15 amps the absilute minimum to run is 6mm automotive ( 4.5mm2) twin.
A better choice would be 6mm2 solar twin.
Don't expect any sort of sucess on less, and that is for exclusive use of the fridge.
AND if you are smart only while the engine is running.

cheers