Club 80-90 Forums

I have the original standard 3-way fridge (RM-122B or something like that).
Also now have a 350W inverter (only £20 from Argos! bargain!!!)
Question: when driving, is it better to power it on 240Vac from the inverter, or directly using the standard 12V setup?

This is becoming a very popular mod and it is far more efficient to run of an invertor as the power losses are lower resulting in improved cooling for the fridge. The major benefit is that the fridge is thermostatically controlled on 240V and yje 240V element isn't on permanently as with the 12V option. Thats how I run mine, from the invertor when the 3 way fridge is installed. Do a google search, lots of info on this and worth doing IMO.

that's great, thanks!

AngeloEvs.....quote 'it is far more efficient to run of an invertor as the power losses are lower resulting in improved cooling for the fridge' I was just wondering where you got this information from...is it fact or your experience....I'm just interested as invertors themselves are regarded as being very inefficient but if you are basing this statement on fact so I would be interested to read up on it.
Martin

We both know that power is best transmitted at high voltages and low currents (e.g. The National Grid) to minimise power losses. The 12V 100W element requires just over 8 amps, the 240 volts 100W element requires less than 500ma. This is the basis of the power efficiency argument - less loss in the cable more energy transferred to the element itself. There will be losses in the Invertor and no argument about that but the 240V element is thermostatically controlled and this balances the argument in favour of the 240v operation since it will only be on as and when required.

No need to quote furmula as I am pretty sure you use them every day as I do. Problem with many conversions is the 12V feed is long and gauge barely adequate. Good Invertors are cheap and far more efficient these days compared to say 20 years ago.

I'd be interested in some real world examples.
The losses in 12V wiring should not be that high maybe 10 or 15W equivalent to losses in converting 12V dc to 230V ac.
Most fridges I've seen sit pretty close to the Battery box. except in diesel engined vans.

I assume you still need to switch the inverter via the ignition? so losses there would be the same.

The main advantage would be the thermostat in the 230V fridge circuit.

T

Fair comment regarding real measurements Tony, like you point out, every van and its' wiring are different. The point about losses in the invertor is correct but these are in the invertor primary not en-route to the element. The total power consumed is higher (depending on the efficiency of the invertor used), eg 108 Watts on the primary side but the low current output at 240V results in low power loss in the secondary circuit and the remaining 100W is delivered with neglible power loss to the element. It's an interesting idea and a popular mod. Lots of articles to be found if you do a search on Google. Even if you are sceptical its worth pointing out to members that if the 12V element becomes defunct and your fridge is connected to a 13A socket as Autohomes are, then a simple quick fix is to connect it to an invertor and run it off 240V until a replacement is fitted. Thanks for the interest and your comments...........

Angelo