12v/240v

[engelside]

So, I'm just trying to get my head around how various MH related stuff works.

Fridge is 12v/240v/gas - does that mean it has 2/3 separate compressors?

240v sockets obviously work direct from hook up.

Heating on our van is gas only, although the air is obviously blown around. Lighting is 12v. Water pump works on 12v/240v? Electric water heating (does have gas also) works on 12v/240v?

So question is really I suppose does lighting, blown air fan, water pump and heater work off 12v all the time (even on hook up) or will there be a transformer for some/all of them?

 

[Landy Andy]

Your fridge won’t be a compressor fridge, it will by an absorbstion fridge. So has two heating elements. 12v and 240v. Basically one heatsink with three options to heat it (240v, 12v, or flame from gas)

Heating is powered by 12v and can use two different heating sources. A pair of 240v heating elements, or gas.

Most things in the MoHo are 12v, and the power coming from the batteries, which are then charged by the 240v charger. The fridge and heating are the only two items I can think of that also use the 240v, and both can be used on alternative power sources (12v, or gas)

 

[kevenh]

Fridge Power
Our fridge is 12v/240v/Gas, and looking for info to assist, I just discovered that the 12v is ONLY from the vehicle battery when the engine is running

I'll have to remember that. We normally use gas or EHU on site but there's a brief 12v usage while we prepare to drive away from home where knowing that the habitat 12v is not used could be useful.
Luckily a fridge will stay cool for the <5min gap between finishing departure prep & drive off

Water Heater
Our Truma water heater is Gas or 240v for the heater. 12v for controls only.
Gas mode on our's has adjustable temps but like an immersion heater, on 240v it's fixed at 70deg

EHU
In our MH, mains from a EHU is only for a few 3 pin plugs, and an alternative power source for water heater & fridge. AND BATTERY CHARGING!!!
iirc our Truma heater is only Gas.

EDIT: Add a forgotten EHU usage

 

[autorouter]

Fridge is 12v/240v/gas - does that mean it has 2/3 separate compressors?

It's not a compressor fridge, it's an absorption fridge. It works on a different principle.

The cooling pipe circuit contains a complex mixture of liquids and gases. When heat is applied near the bottom of the pipes, the mixture circulates, and magically produces cooling near the top.

The heat source can be a 12V element, a 240V element, or a small gas flame. In motorhomes they usually have all three. You can switch between the heat sources, either manually, sometimes automatically.

Automatic Energy Selection (AES) fridges have a small control board powered by 12V, that controls the switching of the heat sources.

As others have said, the 12V element is often only powered when the engine is running. That's because it takes quite a bit of power, and would flatten a big battery in a few hours, and it's the kind of thing that's easy to leave on accidentally.

Absorption fridges are also often used in hotel rooms, because they have no compressor and are very quiet.

 

[autorouter]

So question is really I suppose does lighting, blown air fan, water pump and heater work off 12v all the time (even on hook up) or will there be a transformer for some/all of them?

Yes, they will all be 12 volt devices. There will be an inbuilt mains battery charger that keeps the battery topped up while on mains hookup.

The heating will have a 12v control circuit, and the blower fan will be 12V. It might have an electric heating element as well as gas heating (some do, some don't). The heating element will be 240V not 12V.

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[engelside]

Thanks for all the replies, really helps to start to understand the ins and outs of MH electrickery!

The fridge 12v does indeed only work whilst the engine is running, and we haven't used it with gas yet as there is an issue with the fixed gas tank that is being looked at tomorrow. What is better when not on hook up gas or 12v? I am assuming gas if, as mentioned above, 12v is draining on the leisure battery.

As far as water heating is concerned, I would the same is true, use gas where possible to conserve LB.

Space heating is gas only but of course is blown air, what sort of power is used by this system, should it be used sparingly when off-grid? We do have a solar panel but haven't had time to assess how efficient it is yet.

So many questions!

 

[HandyAndy]

If you are paying for a pitch with hookup, why would you want to use your own gas at cost to you when the 240v is essentially free??
Because my heating is gas only I've only just realised I should be utilising the hookup electric more and using an electric heater instead, otherwise what's the point in having 240v in the van just to charge the batteries

 

[pappajohn]

Thanks for all the replies, really helps to start to understand the ins and outs of MH electrickery!

The fridge 12v does indeed only work whilst the engine is running, and we haven't used it with gas yet as there is an issue with the fixed gas tank that is being looked at tomorrow. What is better when not on hook up gas or 12v? I am assuming gas if, as mentioned above, 12v is draining on the leisure battery.

As far as water heating is concerned, I would the same is true, use gas where possible to conserve LB.

Space heating is gas only but of course is blown air, what sort of power is used by this system, should it be used sparingly when off-grid? We do have a solar panel but haven't had time to assess how efficient it is yet.

So many questions!

You don't seem to have grasped any of the replies....
The fridge 12v system DOESN'T use the leisure battery to cool the fridge, only to run the control board which has minimal current draw.
As above with the water heater, 12v leisure battery only runs the blown air fan for room heating and the control board/thermostat.

12v power consumption used by the control boards is minimal but the blown air 12v fan is a reasonably heavy load and will drain your battery for sure in far less than 24 hours but will run indefinately on hookup as the battery is constantly being charged.

 

[engelside]

If you are paying for a pitch with hookup, why would you want to use your own gas at cost to you when the 240v is essentially free??
Because my heating is gas only I've only just realised I should be utilising the hookup electric more and using an electric heater instead, otherwise what's the point in having 240v in the van just to charge the batteries

No, I realise that on hook up that I would utilise the 240v setting on the fridge. We are however planning on "wild camping" and I want to understand how best to do this.

 

[engelside]

You don't seem to have grasped any of the replies....
The fridge 12v system DOESN'T use the leisure battery to cool the fridge, only to run the control board which has minimal current draw.
As above with the water heater, 12v leisure battery only runs the blown air fan for room heating and the control board/thermostat.

12v power consumption used by the control boards is minimal but the blown air 12v fan is a reasonably heavy load and will drain your battery for sure in far less than 24 hours but will run indefinately on hookup as the battery is constantly being charged.

Sorry, a lot going on at the moment so perhaps not paying enough attention to replies.

Of course, if not on hook up the only alternative is to use the gas setting.

As regards the water heating, again, sorry, my confusion. This can only be used with 240V and gas, correct?

Will need to be circumspect using the heating then when not on hookup.

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[pappajohn]

Sorry, a lot going on at the moment so perhaps not paying enough attention to replies.

Of course, if not on hook up the only alternative is to use the gas setting.

As regards the water heating, again, sorry, my confusion. This can only be used with 240V and gas, correct?

Will need to be circumspect using the heating then when not on hookup.

Yes, got it.

The blown air heating should be thermostatically controlled so once to pre-set temp the fan will slow or stop altogether until the room cools slightly then restart so not using it at all is false economy.
All you need to do is know when your battery/ies need charging...... And if wild camping, a method of charging it/them.

50% discharge is the accepted limit to prevent battery damage and the easiest, if not the most accurate, way to check is voltage with a multimeter.
The chart below shows you the various voltages and relative percentages... Ignore volts per cell.

 

[autorouter]

What is better when not on hook up gas or 12v? I am assuming gas if, as mentioned above, 12v is draining on the leisure battery.

Best to use gas when not on hookup. Many MHs won't use 12V power to cool the fridge unless the engine is running.

If yours allows you to do this, be careful, it's easy to forget and drain the batteries. However it is useful for situations where you can't use gas, like on a ferry or the Channel Tunnel.

The 12V power to the fridge heating element is an entirely separate from the 12V for the fridge control circuit. The control circuit usually stays on all the time.

.

 

[Richard n Ann]

The above voltag/percentage chart is only any use if the battery has been unloaded, unused or disconnected for at least an hour, some say 2 hours, ?

 

[Reallyretired]

Fridge and freezer once cold will stay cold for a long time if the doors arent opened so no need to try to run on 12v in the tunnel. Most wont anyway unless the engine is running. Ours was off for 3-4 hours in high 20s temperature without excessive warming.

 

[rosalan]

!2v Fridge, can drain your leisure battery if for some reason there is no gas, no hook-up and the engine is not running BUT normally I believe the 12v is supplied by the alternator when driving.
Wild camping:- We have a solar panel to keep the batteries full, although in the UK you could sometimes struggle to get enough sunlight.
Gas for the fridge etc, we use autogas re-fillable bottles (GasLow, Gasit, Alugas etc) because every country use different bottles which are not exchangeable. Autogas stations supply cheaper gas which you can get anywhere.
Wild camping problems tend to be associated with liquids. Where to get water, where to get rid of it and more importantly where to empty your toilet cassette.

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[Camping Gaza]

If you want to wild camp its best to fit as many batteries as posssible I have 3 120 Ah and that's not enough!, also 3 100 watt solar panels and a 40 amp B2B charger, still not enough for UK wilding IMHO

Swap out any light bulbs in the hab area for LEDs Get a 12v to 19v power adapter for a laptop if you have one rather than charge things using an inverter.

Your blown air heating will use the most from your batteries, to turn the fan, not for heating of course.

In winter, and autumn I dont power my fridge at all, it all goes outside in a box on the roof or on the bike rack, stays fresh as a daisy if you buy fresh foods every day or two. Buying frozen rather than fresh and sticking in your fridge to thaw saves on power too, the supermarket has already provided the energy for you. Example, a 1KG frozen lasagna took 2 days to thaw completely with no power going to the fridge (this was 4 days ago, its chilly here!) that's how good the insulation is and with the fridge back exposed to the outside via the outside vents

My advice, much to the annoyance of most is to buy a suitcase generator for emergencies, when you run out of gas and need heat or to cook, or you can't start your van to get back home. (just dont use it if you are camped with others)

Water and waste, most garages have taps or water points, so carry a water container. Some churches have graveyards with taps too. If you have to public loos also have a water supply but need a smaller container to fit under the taps, to fill your larger.

To empty grey water, get a collapsable bucket and find a roadside drain, easy.

Buy a second toilet cassette, so you have a changeover system you can empty down public loos.