230/110 Transformer power losses.. and costs.

[scotjimland]

As we are now on metered leccy I checked what the 230 - 110v transformer costs to run..

On no load it consumes 177watt = 4248 watts in 24 hrs,.. leccy is charged at 16p so that costs 68.5p per day or £4.80 per week .. £19.2 per month

The only appliance using 110v is the fridge .. so that makes it a very expensive fridge to run.. so I decided to switch the fridge to gas and switch the tranny off .. haven't costed the fridge on gas yet but my instincts tell me it's going to be cheaper than on leccy. ..
This may be a consideration if your RV is on the drive and connected to the leccy only to keep the batteries charged .. you may want to think about changing the 110v charger or using a stand alone 230v one

These figures are for a bog standard building site 3kva transformer.. a toroidal may be more efficient.

Jim

 

[Braunston]

Hi, Jim

Interesting subject, what type of fridge do you have is it absorption type and have you looked at the difference in consumption between absorption against the compressor type fridges

It appears they can be substantially different, from what little information i can find it seems that the absorption 2/3 way type fridges can consume between 10 and 25 amp @ 12volt and some of these are running 24/7 as it appears some of the smaller models may bypass the thermostat control, where from the earlier information the compressor type are nearer 1.5 to 4 amp @ 12volt

Be interested if you have found any information on the subject as if it is correct then it would seem the best solution has got to be running on gas, unless you have a compressor type fridge.

 

[scotjimland]

Hi, Jim

Interesting subject, what type of fridge do you have is it absorption type and have you looked at the difference in consumption between absorption against the compressor type fridges

It appears they can be substantially different, from what little information i can find it seems that the absorption 2/3 way type fridges can consume between 10 and 25 amp @ 12volt and some of these are running 24/7 as it appears some of the smaller models may bypass the thermostat control, where from the earlier information the compressor type are nearer 1.5 to 4 amp @ 12volt

Be interested if you have found any information on the subject as if it is correct then it would seem the best solution has got to be running on gas, unless you have a compressor type fridge.

Hi

It's a Norcold two way absorption fridge, ( no 12vdc ) rated at 300 watt , I've been looking into eventually changing to a compressor model, but quite haven't decided on whether a 12vdc or 230v domestic model.. I started thread on this idea a few days ago..

I came to the conclusion that a 12vdc compressor would probably be the way forward .. it could easily run on solar during the summer .. and be the most efficient during the winter on ehu .. downside is the size, the biggest 12vdc I've seen are about half the size of our current model but it may be a worthwhile compromise..

Jim

 

[Lampie]

Often leave my RV plugged into mains when I park up , must re think that.

Lampie

 

[scotjimland]

Often leave my RV plugged into mains when I park up , must re think that.

Lampie

Hi

I don't suppose many think about it, I knew there were TX losses but when your not being charged you don't really consider it.. or calculate the cost..
Fitting the Owl Wireless Power Monitor has been one of the most useful things I've bought.. it alerted me to the fact I was using leccy ... with nothing switched on.. it's like a dripping tap ..

Jim

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[Xoxoc]

.. downside is the size, the biggest 12vdc I've seen are about half the size of our current model but it may be a worthwhile compromise..

Jim

One of the things I like most about the American RV's we've had is the size of the fridge and freezer. I'd hate to have anything smaller and wonder how caravanners manage with the size of their fridges-they are tiny!

Here's a suggestion Jim, why don't you fill half of your fridge with empty containers so that you can only use the other half for your food. This will enable you to try a fridge with half the capacity and this way you will be able to see if you really can cope with a small fridge.

Regards

Bryan

 

[Geo]

On the basis of that previous post I bought an Owl off e bay now about £25 it may turn out to be the best thing ive bought in a while too:thumb:
Thanks for the heads up
Geo

 

[scotjimland]

One of the things I like most about the American RV's we've had is the size of the fridge and freezer. I'd hate to have anything smaller and wonder how caravanners manage with the size of their fridges-they are tiny!

Here's a suggestion Jim, why don't you fill half of your fridge with empty containers so that you can only use the other half for your food. This will enable you to try a fridge with half the capacity and this way you will be able to see if you really can cope with a small fridge.

Regards

Bryan

Hi Bryan

I agree about the size.. however we managed fine on a fridge half the size in the euro vans, it's like when you buy your first RV, you can't imagine filling all the lockers up then a few months later wonder how you managed without them .. sometimes you fill up because you can..

I remember camping with a Camping Gaz cool box ... but then again, we ate more tinned stuff ..

Another option is to have a combination 12vdc fridge and a freezer.. but double the cost..

Hi Geo

It doesn't sound much at first it's only when you do the sums you realise the full cost.. in a year it's enough pay the VED and some left over ..

 

[johnsandywhite]

I' ve just stated on your forum Jim. That when I tried it, it took 15.625KW for just having the transformer plugged in for one month. oh:

 

[scotjimland]

I' ve just stated on your forum Jim. That when I tried it, it took 15.625KW for just having the transformer plugged in for one month. oh:

Hi John .. that's quite a bit less than mine .. . maybe yours is a more efficient tranny .. ? either way, they cost money doing nothing .. and it all adds up ..

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[captmike]

Jim,
You'd probably have lower transformer losses if you bought a small autotransformer (rather than the large isolating transformer you are using), sized and wired purely to run the fridge. Losses should be less than a third of what you state and cost about It would certainly be much cheaper than buying a new fridge!

If you do go down the compressor route, look into putting new works into your existing fridge if you want to keep the big American one. We went though a similar exercise on our boat years ago and at the time there were no powerful 12v units available so threw that lovely GE double door fridge/freezer out. Some years later, Waeco, amongst others, brought out much more powerful compressors, evaporators and condensors which can be fitted to an existing "box". Talk to a marine refrigeration expert.

Mike