12v and 240v switch over

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Roy748
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12v and 240v switch over

Post by Roy748 » Sun Mar 17, 2019 5:28 pm

Hi all. I am seeking some advice on behalf of my nephew. He has recently bought a bongo with a conversion which also came with a 100w solar panel fitted on the roof. The conversion has two twin power sockets for electric appliances but these only work when on electric hook up. He would like to have them running on either the lesiure battery or mains when necessary. So my question is how do we wire it up so that he can switch between either power source. I assume some switch is required so as to protect each circuit.
Thanks in advance.
Bob
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Re: 12v and 240v switch over

Post by Bob » Sun Mar 17, 2019 6:38 pm

When you say 'two twin power sockets' I'm guessing you mean 13 amp/3 pin rather than 12v 'lighter' sockets.

If so you would require an inverter to run 240v off the leisure battery, not just a couple of switches, and battery life would be very limited, there's only so much 'juice' in that black box under the bonnet. :wink:

Geoff will (hopefully) give a much better answer, but I'd just run 12v equipment if not on hook up and mains gear when plugged in. 8)

Hope that helps. :wink:
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g8dhe
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Re: 12v and 240v switch over

Post by g8dhe » Sun Mar 17, 2019 7:11 pm

Indeed, very few people bother with inverters there not that efficient and battery capacity is a lot less than people realise.
These days most items have 12 volt options available if you take a look for them.
The only thing that doesn't work is any form of heating, again battery capacity just does not permit sensible levels or duration.
If you do have only 230v mains items for say medical equipment or similar then inverters may be your only option, but you will need to make sure what sort of power waveform the equipment requires some devices will need a good sinewave others can get away with cheaper versions which only simulate a sinewave.
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Roy748
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Re: 12v and 240v switch over

Post by Roy748 » Sun Mar 17, 2019 11:47 pm

Hello.
Thanks for your time and information. I think from what you say the best way to give him power off grid would be to wire in an inverter which offers 2. 240v 3 pin sockets incorporated. I think most of his items are 12v, only he hoped to have switch that he could flick to power the 3 pin sockets with either 12 or 240v. He has a 100w Sloane panel fitted to the roof which will help with battery drain.
ade33
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Re: 12v and 240v switch over

Post by ade33 » Mon Mar 18, 2019 2:07 pm

You'd need a solar panel the size of Hampshire to power a mains inverter. :)

The problem is that to deliver 240V mains at a reasonable current, an inverter will consume even a large (110Ah) leisure battery in very short order, and the biggest solar panel would not even get close to keeping up with the current demand.

For every kW your inverter is rated at, you're looking at a current draw at 12V of more than 80 Amps.

This is also why electric cars don't have roofs made of solar panels; it just isn't worth the expense, as solar panels generate so little current.

What are you hoping to power?
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Re: 12v and 240v switch over

Post by mikeonb4c » Mon Mar 18, 2019 4:29 pm

ade33 wrote: Mon Mar 18, 2019 2:07 pm You'd need a solar panel the size of Hampshire to power a mains inverter. :)

The problem is that to deliver 240V mains at a reasonable current, an inverter will consume even a large (110Ah) leisure battery in very short order, and the biggest solar panel would not even get close to keeping up with the current demand.

For every kW your inverter is rated at, you're looking at a current draw at 12V of more than 80 Amps.

This is also why electric cars don't have roofs made of solar panels; it just isn't worth the expense, as solar panels generate so little current.

What are you hoping to power?
Things are changing out there:

https://youtu.be/rJD-ezbC5QU

But you're right, inverters are not really the solution. In practice, it boils down i think to:

If you need any kind of space heating, kettle heating, cooking heating etc you need either gas or 240v hookup. You can, for good money, get a compressor type coolbox that will chill and freeze stuff whilst needing only leisure battery and decent solar power output. For the rest the (electric) challenge is to use low power LED lighting and other types of volltage changing transformers if needed for devices.
Roy748
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Re: 12v and 240v switch over

Post by Roy748 » Mon Mar 18, 2019 5:54 pm

Thanks for all the advice, I will pass on your thoughts to my nephew.
Bob
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Re: 12v and 240v switch over

Post by Bob » Mon Mar 18, 2019 7:40 pm

If you Google something like 'Camping stove heater' it will bring up gadgets which sit on the gas ring and heat your living space. :wink:
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