Advice For 240v To 12v Output

[Lexlee]

Hi,
First post on this forum so please excuse my lack of knowledge.

I have a 12v 300watt water heater /hand wash with fold down bowl (type fitted to some work vans etc) that I thought about fitting to my caravan.
Here comes the lack of knowledge,
1. If I connected it to the 12v in the caravan would it draw 20 odd amps?
a) cables in van look too thin compared to the rather heavier duty ones on
The handwash.
2. As most sites seem to limit to either 10 or 16 amps max , would a solution
Be to run it off a transformer 240 to 12v, would I still be drawing too much
Or would it change due to introduction of the transformer, guess what I should
Ask is what amps what I draw from the supply to transformer?

Any help greatly appreciated and thank you in advance.

 

[telectrix]

your current @ 12V would be 25A. however, running from a 240V/12V transformer, the current @ 240V is only 1.25A ( actually be nearer 1.5A due to losses ), so it would pose no problems for the caravan's 240V supply.the cables from the transformer need to be able to carry >25A, i.e. 4mm or 6mm.

 

[Lexlee]

Thank you Teletrix, great help. Guess there's so such thing as a stupid question.
Think I'll trawl the net for a transformer , any advice on whether I should have slightly higher wattage transformer or just 300 fo match the heater?

Thanks again your a star.

 

[simpson93]

1.25amps I believe upto transformer

ahh too late

 

[telectrix]

Thank you Teletrix, great help. Guess there's so such thing as a stupid question.
Think I'll trawl the net for a transformer , any advice on whether I should have slightly higher wattage transformer or just 300 fo match the heater?

Thanks again your a star.

go for a transformer with a rated output of 30A or greater @ 12V. better to be a bit over than running it full whack. check that the heater will run on a.c. some may have controls that require D.C.

 

[Noworkin]

go for a transformer with a rated output of 30A or greater @ 12V. better to be a bit over than running it full whack. check that the heater will run on a.c. some may have controls that require D.C.

You'll need a pretty hefty transformer for a 30 A output and they don't come cheap .

 

[DPG]

Agree with the above - this will be a big expensive transformer. How long will it be running for? If you can run it from a battery and keep the battery topped up I would say it might well be a better option. Daz

 

[ruston]

I don't understand this to be honest . Unless it is a very old caravan , most have a perfectly adequate 240v water heater already fitted as standard. For the occasions that you have no mains supply it would be easier to use the gas to heat water.
Gas is usually fitted as standard too.
If you are thinking of heating water only from the 12v battery , frankly you are wasting your time regards efficiency.

 

[Lexlee]

The van I have is dry and not confident enough to drill holes in it risking onset of damp. No water heater either as its a dry van. So was trying to think of different way of having the option of hot water if needed without blogging up cooker with pots of hot water for cleaning.

 

[amlu]

small boiler + a gas bottle stashed somewhere. may be tricky running off instant hot water system off vehicle electrics.

or a small tank with immersion element hooked up to some solar panels/vehicle electrics. may need an inverter in the middle.