How electrics work in a camper van - clarity requested!

[Dave46049]

Hi, I'm a newbee so please bear with - I have what I assume is a silly question!

I'm about to buy a motor home that has a leisure battery, I presume the leisure battery will power the electrical bits and bobs within the Camper such as lights, fridge etc when the camper is static.

When I have the camper attached to a power outlet - either at home or on a site - I presume the bits and bobs are powered from this.

I also have a solar panel that I presume "charges" the leisure battery.

Not the bits I'm confused on - When driving does the engine create charge for the battery ( bit like a car battery so it gets topped up ), also I have an LPG gas tank underslung - now I've heard that the fridge can be powered from this, but I don't understand how that would work. I also want to get a small microwave but I've read that using one would probably drain my leisure battery in seconds!

I also have have a whale gas / electric heating system which I presume is powered either by the mains hook-up or by the LPG depending on which one I want to use.

Sorry for all the presumptions - just want to get it clear in my head so I don't run out of juice to make my toast and watch the tv!

 

[denisejoe]

The only silly questions are the ones you don't ask for fear of feeling silly!

Can't help with all of your questions but can with some. You run your fridge off either gas if not on EHU and electric if on EHU. Lights are generally leisure battery powered although some motorhomes may have 240v lights which would run off EHU when on hook up and won't work on 12V (battery.

You will generally need to be on EHU to use a microwave although I believe it is possible to run from an inverter if it's big enough but not really know enough about inverters other than that they change 12V to 240V via the battery charged by the solar panel.

Someone with more knowledge will be along shortly.

Denise

 

[Lenny HB]

When you are on hook up everything that is normally power by 12v is still powered by 12v. The fridge & battery charger will run off mains and the 13 amp sockets will be live.

Yes the alternator will charge the leisure battery but unless you have a Battery 2 Battery charger fitted you will need to drive about 300 miles to charge a low battery.

Solar will charge the leisure battery but can also be setup to charge the engine battery.

If it is a 3 way fridge it will run from 12v when driving, mains when on hook up and gas the rest of the time.

IMO a microwave is a waste of time, if you are going to fit one you will need to fit an inverter and at least one more battery preferably more.
Of course you could fit a microwave and only use it when on mains hook up.

 

[Newt]

Hi,
Your elec hook up will run your fridge, heating, plug sockets and charge you battery. usually the lights, water pump are 12v.
Your engine will charge the batteries but quite slowly. As standard an inverter will be of no use, you need to upgrade batteries and charging systems. the fridge will run best on the gas but also 12v and EHU.
depending on its size don't expect too much from the solar but fine in the summer months.
You can use a microwave when on EHU but would need upgrades for the 12v to use without EHU.

 

[EzeeRider]

Hi, I'm a newbee so please bear with - I have what I assume is a silly question!

I'm about to buy a motor home that has a leisure battery, I presume the leisure battery will power the electrical bits and bobs within the Camper such as lights, fridge etc when the camper is static.

The leaisure battery will power all the 12v system in the van with the exception of the fridge. It is not usual for the leisure battery to power the fridge, it would drain the battery very quickly.

When I have the camper attached to a power outlet - either at home or on a site - I presume the bits and bobs are powered from this.

Correct but it may not charge your engine battery, it just depends on how the charging system for both the leisure and engine battery are configured.

I also have a solar panel that I presume "charges" the leisure battery.

I would think so but again it depends on how it is configured, it may also charge the engine battery if you have a dual charge regulator

Not the bits I'm confused on - When driving does the engine create charge for the battery ( bit like a car battery so it gets topped up ), also I have an LPG gas tank underslung - now I've heard that the fridge can be powered from this, but I don't understand how that would work. I also want to get a small microwave but I've read that using one would probably drain my leisure battery in seconds!

A microwave will indeed rapidly discharge your leisure battery. It is normal for the engine alternator to charge both the engine and leisure battery and run the fridge while the engine is running. It is normal for an absorbtion fridge to also be run from the LPG tank but I think I am right in saying that if it is a compressor type, it cannot. What make and model is your fridge? More help should be forthcoming if this is known.

I also have have a whale gas / electric heating system which I presume is powered either by the mains hook-up or by the LPG depending on which one I want to use.

It should be but I am not familiar with this system

Sorry for all the presumptions - just want to get it clear in my head so I don't run out of juice to make my toast and watch the tv!

Hope that helps.
Ezee

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[Dave46049]

If it is a 3 way fridge it will run from 12v when driving, mains when on hook up and gas the rest of the time.

IMO a microwave is a waste of time, if you are going to fit one you will need to fit an inverter and at least one more battery preferably more.
Of course you could fit a microwave and only use it when on mains hook up.

Thanks Lenny - The fridge is described as "220v / gas/ 12v fridge (85ltr)" - no mention of make or model...

 

[Odd-no-more]

Of course you could fit a microwave and only use it when on mains hook up.

We have a microwave and use it on hook up along with the electric kettle and the toaster we normally get EHU when it's cold enough to need some heating the rest of the time we use solar.

 

[Dave46049]

The leaisure battery will power all the 12v system in the van with the exception of the fridge. It is not usual for the leisure battery to power the fridge, it would drain the battery very quickly.

Correct but it may not charge your engine battery, it just depends on how they charging system for both the leisure and engine battery are configured.

I would think so but again it depends on how it is configured, it may also charge the engine battery if you have a dual charge regulator

A microwave will indeed rapidly discharge your leaisure battery. It is normal for the engine alternator to charge both the engine and leisure battery and run the fridge while the engine is running. It is normal for an absorbtion fridge to also be run from the LPG tank but I think I am right in saying that if it is a compressor type, it cannot. What make and model is your fridge? More help should be forthcoming if this is known.

It should be but I am not familiar with this system

Hiope that helps.
Ezee

Sorry don't know the make and model of the fridge yet - it's just described in the spec as "220v / gas/ 12v fridge (85ltr)"

 

[Kannon Fodda]

So lets break this down into a few bitesize pieces.

Electrics on a motorhome / camper have three parts. The 12V engine / cab. The 12V leisure / habitation. The 240V mains hook up (EHU).

The 12V engine has a small battery for the starter motor. It get's recharged from the engine's alternator, if the engine is running. This powers the engine systems, the headlights, tail lights, dashboard, cab air-con (if you have it), front windows, security alarms and similar.

The 12V leisure / habitation has it's own battery and is a separate system to the engine/cab. There may be more than one leisure battery, linked together. This system powers stuff such as your water pump and internal lighting. It will also do any of the base electrics for some appliances, for example a gas cooker hob may have electric ignition, or the gas heater needs electric to create a spark for the burner and power for any fan.

The 240V will power any mains outlets you have in the vehicle, it also serves a charger unit so the leisure battery can be recharged when you plug your vehicle in on a campsite. If you have appliances such as microwaves you will plug those into the mains power.

The engine alternator is usually connected to a relay which allows some of the charge, when driving, to be sent to the leisure battery to top that up. This can take some time, perhaps hours, if you have drained your battery.

If you have solar, this is usually connected to recharge the leisure battery. The size of your solar panel(s) and the amount of sun will determine if you have enough power to keep your leisure battery charged if you stay in one place for a few days. Very few vehicles have wiring allowing the solar to also be trickle charging the engine battery which can mean during winter or non use the engine battery is getting run down from alarm systems.

Many vehicles will combine all or parts of the connection systems into one unit. So your relay, EHU fuses, battery charger may be one device.

If you are off grid (not connected to mains) to run things like microwaves would need an inverter. That converts your 12V power to 240V. Microwaves need a lot of power so you'd need a good leisure battery system with lots of capacity and a big inverter.

Most motorhome fridges are 3 way, They can run off battery but only whilst the engine is running so when driving along. They can run on 240V, but only when you are on mains hook up (your batteries wouldn't last very long when you are parked up), or gas. You generally use the gas system when you are off grid.

Your heating system, for water and the inside will be gas and 240V. It uses a bit of 12V purely for the fans to push warm air around and to create spark for the gas burner flame. If you are on mains power, use the 240 setting. When off grid use the gas. Some systems will allow you to combine gas and electric, the gas boosting the electric when it's very cold, or perhaps the campsite only offers a low amperage mains power.

 

[Dave46049]

I guess what I'm trying to get as is that the van has some 13amp sockets - which if I plug the camper into a EHU then they will work like mains.

If I'm not on EHU and parked up, then they may work off the LPG if it's set up to do that? or if I had my engine running would that power the 13amp sockets - for microwave etc ( I guess the hob / grill powered by gas will supply my toast and tea ). The LPG will also keep the fridge running when not connected up to keep my milk and butter cool!

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[Eggs]

I guess what I'm trying to get as is that the van has some 13amp sockets - which if I plug the camper into a EHU then they will work like mains.

If I'm not on EHU and parked up, then they may work off the LPG if it's set up to do that? or if I had my engine running would that power the 13amp sockets - for microwave etc ( I guess the hob / grill powered by gas will supply my toast and tea ). The LPG will also keep the fridge running when not connected up to keep my milk and butter cool!

Forget about 230v/mains when you aren't hooked up, you can only do this through an inverter which, if used for any length of time will kill your leisure battery.

 

[Newt]

I guess what I'm trying to get as is that the van has some 13amp sockets - which if I plug the camper into a EHU then they will work like mains.

If I'm not on EHU and parked up, then they may work off the LPG if it's set up to do that? or if I had my engine running would that power the 13amp sockets - for microwave etc ( I guess the hob / grill powered by gas will supply my toast and tea ). The LPG will also keep the fridge running when not connected up to keep my milk and butter cool!

The 13amp sockets will only work on elec hook up.

 

[Dave46049]

Forget about 230v/mains when you aren't hooked up, you can only do this through an inverter which, if used for any length of time will kill your leisure battery.

Thanks - I'm getting the gist of it now!

Initially I plan on just doing some local day trips - so will be using EHU @ home, but when out and about I'll be "off grid" - so will use gas for the oven & hob, heating and fridge.

The spec of the van also refers to a "charger / transformer system".

 

[cmcardle75]

Hi, I'm a newbee so please bear with - I have what I assume is a silly question!

I'm about to buy a motor home that has a leisure battery, I presume the leisure battery will power the electrical bits and bobs within the Camper such as lights, fridge etc when the camper is static.

Yes, things will run off 12V, so they don't need mains electricity. There are some exceptions.

In particular, there are two main types of fridge. A "3 way" will run off the mains electricity when plugged in, but on gas when you don't have a mains hookup (but with a tiny 12V connection to run the light/electronics etc). They run on 12V when driving along, but only with the engine running, never when parked up. The other type of fridge is a compressor. This typically runs only on 12V and can be used from the leisure battery even with the engine off. Occasionally you'll find a 230V compressor fridge which runs off an inverter that can also be used from the leisure battery.

The space heating is similar, it that it won't run off 12V (but might use a small 12V connection to run the electronics). The main power will be supplied either by mains electricity, gas or diesel, depending on the model.

When I have the camper attached to a power outlet - either at home or on a site - I presume the bits and bobs are powered from this.

When connected, most of the 12V will still run off the battery. However, the battery will be being charged. An autoselect 3 way fridge will notice the mains power being attached and switch to electrical power and turn off the gas. The engine battery may or may not be charged depending on your install.

I also have a solar panel that I presume "charges" the leisure battery.

Yes, but it might also charge the engine battery, depending on the installation.

Not the bits I'm confused on - When driving does the engine create charge for the battery ( bit like a car battery so it gets topped up ), also I have an LPG gas tank underslung - now I've heard that the fridge can be powered from this, but I don't understand how that would work.

3 way fridges are absorbtion fridges that work differently from compressor fridges which you will be familiar with from houses. They are inefficient, but have the advantage of being able to work from any heat source, so can run from gas burners or electrical elements, which make them flexible. Their inefficiency means you need a large amount of energy input, which prevents them being run from a battery.

I also want to get a small microwave but I've read that using one would probably drain my leisure battery in seconds!

You can run a microwave from battery, but it will require a very large outlay in equipment. You'll need a very large pure sine wave inverter and considerable investment in batteries (preferably LiFePO4 to run such large loads), solar panels and chargers.

I also have have a whale gas / electric heating system which I presume is powered either by the mains hook-up or by the LPG depending on which one I want to use.

That is typical. However, these systems are also available to run on a single fuel, so you might find you have gas, but no electric capability, or vice versa (particularly on cheaper European vans).

 

[Stealaway]

I think you should look at fitting one of these. Almost all caravans and campers have something similar.

Power Systems | Shop | Sargent Electrical

To view each our systems click the relevant titles, to see all components relating to each system.

sargentltd.co.uk

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[Spriddler]

Hopefully you'll get manuals for the various bits of equipment which can be quite handy as a bloke's last resort .
It helps a lot to indicate your approx location in your Profile as there may be Funsters who'd be happy to drop by for half an hour if you need a bit of help.

 

[Dave46049]

Yes, things will run off 12V, so they don't need mains electricity. There are some exceptions.

In particular, there are two main types of fridge. A "3 way" will run off the mains electricity when plugged in, but on gas when you don't have a mains hookup (but with a tiny 12V connection to run the light/electronics etc). They run on 12V when driving along, but only with the engine running, never when parked up. The other type of fridge is a compressor. This typically runs only on 12V and can be used from the leisure battery even with the engine off. Occasionally you'll find a 230V compressor fridge which runs off an inverter that can also be used from the leisure battery. - The fridge is 220v / gas / 12v - which I guess is 3 way!

The space heating is similar, it that it won't run off 12V (but might use a small 12V connection to run the electronics). The main power will be supplied either by mains electricity, gas or diesel, depending on the model. Yes space heating is 4.7kw gas & electric / 220v

When connected, most of the 12V will still run off the battery. However, the battery will be being charged. An autoselect 3 way fridge will notice the mains power being attached and switch to electrical power and turn off the gas. The engine battery may or may not be charged depending on your install.



Yes, but it might also charge the engine battery, depending on the installation.


3 way fridges are absorbtion fridges that work differently from compressor fridges which you will be familiar with from houses. They are inefficient, but have the advantage of being able to work from any heat source, so can run from gas burners or electrical elements, which make them flexible. Their inefficiency means you need a large amount of energy input, which prevents them being run from a battery.


You can run a microwave from battery, but it will require a very large outlay in equipment. You'll need a very large pure sine wave inverter and considerable investment in batteries (preferably LiFePO4 to run such large loads), solar panels and chargers. Yes, I'll give up on the microwave unless hooked up!

That is typical. However, these systems are also available to run on a single fuel, so you might find you have gas, but no electric capability, or vice versa (particularly on cheaper European vans).

Thanks cmcardle75 - I've added some info above!

 

[Speve]

Nice looking van enjoy it

 

[Dave46049]

I think you should look at fitting one of these. Almost all caravans and campers have something similar.

Power Systems | Shop | Sargent Electrical

To view each our systems click the relevant titles, to see all components relating to each system.

sargentltd.co.uk

The van comes fully fitted with 12v management systems, and the heating and water also has it's own control panel so I'm hoping that covered.

 

[Dave46049]

Hopefully you'll get manuals for the various bits of equipment which can be quite handy as a bloke's last resort .
It helps a lot to indicate your approx location in your Profile as there may be Funsters who'd be happy to drop by for half an hour if you need a bit of help.

How do I do that - do I add it to the "profile banner"? - Found it!

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[Vipar]

Greetings peeps welcome from Bexley

Got your £15 back already

 

[Sugarnan]

Wow, thank you everyone who contributed to the above answers, I'm sorry that I missed this at the time it was being posted. Increased my knowledge immensely.

I sort of got the gist of this, but the part I did not have a clue about is just how long it takes the alternator to charge/top up the leisure battery when driving. It is not now surprising that on the 45-60 mins journeys, I was doing to keep the vehicle battery charged, that it did not support the leisure battery

Once I manage to find/install a new leisure battery and install BatteryMaster to balance power from using EHU either at home or occasionally at sites. There isn't space for a second battery (I could be wrong) so a solar panel may not be beneficial.

It is a simple van that suits me, all I need leisure 12v for is my fairy lights and the water pump - oh and probably hot water?

Charging of phone and gadgets I do while driving from one place to another.

If something crops up that you think I should know please say so

Thank you Dave46049 for asking your question in such a way that it has given me my answers too

 

[Vipar]

Greetings peeps welcome from Bexley

 

[pappajohn]

It is a simple van that suits me, all I need leisure 12v for is my fairy lights and the water pump - oh and probably hot water?

You won't be getting hot water from 12v.
Thats only possible on gas or hookup.
A second battery doesn't have to be next to the original but needs to be reasonably close.
If the original is under a seat of passenger floor a second could be fitted under habitation seating providing it isn't metres away.

 

[Sugarnan]

You won't be getting hot water from 12v.
Thats only possible on gas or hookup.
A second battery doesn't have to be next to the original but needs to be reasonably close.
If the original is under a seat of passenger floor a second could be fitted under habitation seating providing it isn't metres away.

I've managed hot water only once - at least I think I did! There is a separate switch above the hot water tank (10L) I didn't consider that it might be gas - interesting. But I haven't as yet used EHU. My leisure battery is currently under the single bench seat (next to the extending bed portion) sharing space with the water heater. the main bench houses the water tank.

I can only blame myself for not asking the right questions of the person I bought the van from. It looked like what I wanted and didn't consider the technicalities of running it - well as it is 17 year old, assumed it must work or the previous owners would have changed it.

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[Kannon Fodda]

Wow, thank you everyone who contributed to the above answers, I'm sorry that I missed this at the time it was being posted. Increased my knowledge immensely.

I sort of got the gist of this, but the part I did not have a clue about is just how long it takes the alternator to charge/top up the leisure battery when driving. It is not now surprising that on the 45-60 mins journeys, I was doing to keep the vehicle battery charged, that it did not support the leisure battery

Once I manage to find/install a new leisure battery and install BatteryMaster to balance power from using EHU either at home or occasionally at sites. There isn't space for a second battery (I could be wrong) so a solar panel may not be beneficial.

It is a simple van that suits me, all I need leisure 12v for is my fairy lights and the water pump - oh and probably hot water?

Charging of phone and gadgets I do while driving from one place to another.

If something crops up that you think I should know please say so

Thank you Dave46049 for asking your question in such a way that it has given me my answers too

Yes it is surprising how long it can take to recharge that leisure battery from the engine. My van had a manufacturer's all in one 12V relay / 230V charger thingy. But the relay (feeble thickness of wiring) and the device itself was limited to a max current of 12A (and you probably don't get all of that if other stuff in your van is still running whilst you drive). If you have taken your 100Ah battery down to 50% charge, it's going to take you driving across half of England to put that back.

I now have something installed called a B2B (battery to battery charger). This has dramatically thicker wiring linking the alternator and between the batteries, and the B2B in my case can operate at up to 60A. Obviously only when the engine is running.

In a 17 year old vehicle, with lack of the modern energy efficiency emissions stuff you might be able to sit somewhere idling the engine to recharge the batteries. Not that fuel economic. Modern engines, particularly with DPF systems will not like being idled for long periods (unless specially modified), and you can end up with visits to the local garage.

The Vanbitz Battery Master is great when on EHU (plugged in to power at campsite) or if you have solar. It keeps the engine battery topped up from the leisure battery. Leisure battery is usually charged whilst not driving from the EHU or solar. Some vans do have alternate systems where the Solar has dual battery outlet so can divert a small part of the charge direct to the engine battery, or that the relay/EHU charger can dual charge. Check what you actually have before forking out on the Battery Master.

Hot water will be heated using the onboard boiler system, perhaps integrated with the heating system - Alde, Truma, Whale are common brands. It may need 12V to operate some of the controls. But the heat input is either a 240V electric element when you are on EHU, or if off grid using your gas system. It's is rare but some vans have used diesel as the heat source. The 12v batteries do not do the heating. The 12V will pump the water out of your taps.

 

[TheBig1]

One fact of physics is producing heat or traction, as in motors, is always going to be power hungry. Burning LPG has a high calorific value so generates relatively high heat for the amount used. Using a 12v battery to provide either heat or traction is murderous for battery capacity

This is why the 12v element in fridges are very low wattage and only suited to keeping an already cold fridge cool in transit. Using EHU is much better and the element much higher wattage, but the best choice is always LPG

The absorption fridge uses physics to cool. This is not precise because that would serve no purpose here. But heat is applied in a column/chimney and the heat rising causes the liquid in the system to boil and gas inside the sealed system then cool and recycle. This passes over a heat exchanger that draws heat out of the fridge (cools the inside). By applying airflow over the fins at the top of the fridge, the gas/liquid cooling works more efficiently. This is why you see fans fitted in the vents of some fridges, not for the direct cooling effect, but to increase airflow, which in turn helps cool the fins on the fridge

 

[Sugarnan]

I've rummaged in previously unsought out cupboards and found a tatty ehu......wow battery now showing 11.84 before I go to bed tonight will switch on fridge to ehu to chill before disconnecting and setting off tomorrow

lol I also found the 'missing' big table to is to be used for making up the double bed.....hiding behind the spare forward facing seat (with 3 point belt) but there is large metal cone fitted to under table - to assemble as pedestal.....that metal cone would surely dig into the back of any such passenger should there be an accident......no extra passengers in my van!

I fear that letting the battery discharge to such an extent that display board not lit I may have damaged its capacity and/or performance?

Would I be wise in continuing to purchase a new battery tomorrow? (and keep as spare, trickle charged by small portable solar panel?) It is most unlikely to match the existing and therefore unable to be wired together?!

Kannon Fodda any suggestions on searching for charging relay/panel location, identification?

 

[Potty]

We only have one battery, 130 amps and a solar panel on the roof. we manage very well for several weeks touring with only occasionally using EHU. We do tend to travel 50 plus miles most days.

 

[Sugarnan]

Potty what size solar and which charging relay? I'm gathering information

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