Do I need a leisure battery?

[benbo66!]

A commonly posted generic question but I've not found one that matches the lower ones detailed here so hopefully of use to others who have these if answers can be found...



I must stress that my only concern is for my caravan’s fridge operation but hopefully this will become clear.


I regularly (only) take my caravan to sites with 240v hookups so didn't/don't see why I would need a leisure battery for any purpose at all?


I don't know whether this is correct - my caravan servicer last week advised that if I don't have a leisure battery when it is hooked up to 240v the caravan's charger would be supplying the 12v to the fridge which would be abusing it...he advised I should have a leisure battery because the 240v supply should be supplying power the charger which would in turn supply/top up the 12v leisure battery to make sure it had sufficient power to provide 12v to the fridge because, long term, the caravan charger is not designed to supply 12v to the fridge or any 12v devices in the van.

This sounds reasonable but is it correct?

The real reason which prompted my posting here is that when he serviced my van last week he tested and verified, so he tells me and I strongly believe to be correct, that the caravan power supply lead (by the A frame of the van) which connects to any towbar power socket does enable the fridge to work whilst towing (and the car engine on of course!) i.e. it was not a broken lead but when I connected my car to the van, the fridge does not work.




I don’t know how he did this nor do I challenge this but I know he did not connect my car’s towbar socket to the van and he has today stood by his test and I trust him.



Very interestingly however when he learnt that I do not have a leisure battery he advised that I need a leisure battery for the fridge to work whilst towing.



So…I now have these 2 questions which despite tons on googling I cant resolve so can anyone help please?...



1. If you only attend caravan sites where you hook up to 240v power and wish to use all caravan electrical appliances, do you need really a leisure battery so that the caravan charger is not damaged over time or is that incorrect?



2. Can the fridge only work when towing providing you have a leisure battery?



If 1 is ‘yes’ you might wisely chose to /must install leisure battery but if 1 is ‘no’ but 2 is ‘yes’ you might only decide to install a leisure battery if your journey time is so long that the drop in the fridge temp is unacceptably low?



Thanks sincerely in advance.



Ben

 

[RogerL]

Some modern fridges do indeed need 12v from an independent supply when towing - a small, cheap, 12v car battery will suffice if you always use a mains hook-up.

 

[Jcloughie]

Two points here.

The caravan will work without a battery on hook up. But it will strain the charger/power supply. A battery is required for smoothing out the supply. But it does not need to be a specific leisure battery. A small battery will suffice. It need not be expensive or heavy. But will not be much good if you ever need to use a mover.

The fridge, so far as I am aware, works completely of the car supply, so cannot see if a van battery is needed. But if it is, the small one will do.

John

 

[benbo66!]

Hi John,

Thanks ..when you advise "A small battery will suffice" please can you qualify that e.g. an example on Amazon?

thanks
Ben

 

[Jcloughie]

Hi John,

Thanks ..when you advise "A small battery will suffice" please can you qualify that e.g. an example on Amazon?

thanks
Ben

You can get one like this,


But It would be sensible to check with someone more expert in electronics.

That is 5 amper hour. Perhaps a bit bigger might be safer. Not sure where you could look for better advice. No doubt more will come along on here.

That one would need new terminals to be fitted. So maybe, a car battery, with standard terminals might be easiest.


John

 

[Hutch]

Benbo, which caravan do you have, this will help .
My caravan has a power unit which has a separate 12 volts battery charger, and also a 20 amp 12 volt power supply to the caravan when on EHU. Just a small car battery from Halfords I'll probably be suitable for what you require.
Things like the fridge controls and the caravan 12 volt lights and possibly the fan on your heater all require 12 volts to operate.

 

[benbo66!]

You can get one like this,


But It would be sensible to check with someone more expert in electronics.

That is 5 amper hour. Perhaps a bit bigger might be safer. Not sure where you could look for better advice. No doubt more will come along on here.

That one would need new terminals to be fitted. So maybe, a car battery, with standard terminals might be easiest.


John

Two points here.

The caravan will work without a battery on hook up. But it will strain the charger/power supply. A battery is required for smoothing out the supply. But it does not need to be a specific leisure battery. A small battery will suffice. It need not be expensive or heavy. But will not be much good if you ever need to use a mover.

The fridge, so far as I am aware, works completely of the car supply, so cannot see if a van battery is needed. But if it is, the small one will do.

John

Benbo, which caravan do you have, this will help .
My caravan has a power unit which has a separate 12 volts battery charger, and also a 20 amp 12 volt power supply to the caravan when on EHU. Just a small car battery from Halfords I'll probably be suitable for what you require.
Things like the fridge controls and the caravan 12 volt lights and possibly the fan on your heater all require 12 volts to operate.

Hi Hutch,
Thanks for your attention.
My van is a swift challenger sport 513

 

[benbo66!]

Hi Hutch,
Thanks for your attention.
My van is a swift challenger sport 513

514 even!

 

[ProfJohnL]

Hello Benbo,

What you may need will depend on the make model and age of the car and caravan and fridge you have, as the way power is supplied to trailers auxiliary circuits has changed over recent years, and this can affect operation of the fridge, and the charging of the caravan battery.

Many modern cars now have wht are called "smart alternators" and these now don't produce power for the trailers auxiliary circuits all the time. Some car manufacturers will allow the cars computers to be reprogrammed for towing, check with your car supplier

In terms of what happens inside caravans and the availability and need for 12V power has also changed over time. Most caravans will have a "habitation relay" which is designed to disconnect the the caravans habitation equipment form the caravans 12V battery when towing. This prevents untoward operation of some appliances whilst towing. The relay automatically looks for power from the tow vehicle and when it sees it it isolates the habitation equipment.

However some items of equipment may need a constant 12V supply to maintain their control circuits (such as some modern fridges and radio's) and these may have a separate low current 12V feed just to do this.

Whether you need to have a battery in the caravan also depends on how old the caravan is and what you want the power for.

When using mains converters/chargers/power supplies to produce a "12V" dc supply they always have a maximum current they can deliver. Older caravans with simple battery charger's may only have a 2 or 3 Amps current capacity,

Because these chargers were very basic they produce only a half wave rectified output with no peak voltage regulation or smoothing with peaks in excess of 20V and dips of 0V. at mains input frequency. Slightly better quality chargers might have a full wave output, but still with the same range of output voltage but the pulses will be at twice mains frequency. This type of out put is not suited to powering electronic control systems. To improve them, and to enable higher current items like water pumps to operate correctly, a 12V lead acid battery would be connected to provide smoothing and as a current reservoir to take over from the charger when it cannot provide enough direct power.

More modern caravans have proper "power supplies" with smoothed and regulated outputs with improved current capability, as distinct from the early battery chargers. These newer devices are better suited to to powering modern electronics, but they will only produce power when mains power is available, and whilst they generally a 12 to 16A out put capability, they still aren't able to power caravan movers which is why a lead acid battery is still often needed. and also it allows limited operation of 12V systems when off grid.

If in any doubt fit a 12V battery.

 

[Beachball]

We look at the same make as yours and that had a 85ah battery on but it had a motor mover and12v lights, fridge and battery charger ,

 

[benbo66!]

Hello Benbo,

What you may need will depend on the make model and age of the car and caravan and fridge you have, as the way power is supplied to trailers auxiliary circuits has changed over recent years, and this can affect operation of the fridge, and the charging of the caravan battery.

Many modern cars now have wht are called "smart alternators" and these now don't produce power for the trailers auxiliary circuits all the time. Some car manufacturers will allow the cars computers to be reprogrammed for towing, check with your car supplier

In terms of what happens inside caravans and the availability and need for 12V power has also changed over time. Most caravans will have a "habitation relay" which is designed to disconnect the the caravans habitation equipment form the caravans 12V battery when towing. This prevents untoward operation of some appliances whilst towing. The relay automatically looks for power from the tow vehicle and when it sees it it isolates the habitation equipment.

However some items of equipment may need a constant 12V supply to maintain their control circuits (such as some modern fridges and radio's) and these may have a separate low current 12V feed just to do this.

Whether you need to have a battery in the caravan also depends on how old the caravan is and what you want the power for.

When using mains converters/chargers/power supplies to produce a "12V" dc supply they always have a maximum current they can deliver. Older caravans with simple battery charger's may only have a 2 or 3 Amps current capacity,

Because these chargers were very basic they produce only a half wave rectified output with no peak voltage regulation or smoothing with peaks in excess of 20V and dips of 0V. at mains input frequency. Slightly better quality chargers might have a full wave output, but still with the same range of output voltage but the pulses will be at twice mains frequency. This type of out put is not suited to powering electronic control systems. To improve them, and to enable higher current items like water pumps to operate correctly, a 12V lead acid battery would be connected to provide smoothing and as a current reservoir to take over from the charger when it cannot provide enough direct power.

More modern caravans have proper "power supplies" with smoothed and regulated outputs with improved current capability, as distinct from the early battery chargers. These newer devices are better suited to to powering modern electronics, but they will only produce power when mains power is available, and whilst they generally a 12 to 16A out put capability, they still aren't able to power caravan movers which is why a lead acid battery is still often needed. and also it allows limited operation of 12V systems when off grid.

If in any doubt fit a 12V battery.

wow, wow, wow...thanks John and al very precise and (mostly!) understood.

I could add that I have a 2011 Honda 2.2 CRV and that the van is from 2013 but unless there is some expert who knows about this specific combination no one is going to be able to assuredly advise me so let me pose a different question...

I am now going to buy a leisure battery which I was resisting because of the weight so what type/size/model/brand would you recommend which could also accommodate me being off grid for 2/3 days where I would use gas to power fridge/heating/stove?
thanks
Ben (not Benbo but Ben was already taken haha)

 

[otherclive]

How long is a piece of string? My approach would be minimum of 100 ah preferably 125ah, but you would still need to carefully manage your power consumption. Are lights LED, do you have a mover, do you have a solar panel?? Is your heating blown air or Alde. If blown air can you have the gas heater on without the fan running? A larger battery will give you more flexibility.

 

[Buckman]

wow, wow, wow...thanks John and al very precise and (mostly!) understood.

I could add that I have a 2011 Honda 2.2 CRV and that the van is from 2013 but unless there is some expert who knows about this specific combination no one is going to be able to assuredly advise me so let me pose a different question...

I am now going to buy a leisure battery which I was resisting because of the weight so what type/size/model/brand would you recommend which could also accommodate me being off grid for 2/3 days where I would use gas to power fridge/heating/stove?
thanks
Ben (not Benbo but Ben was already taken haha)

I would suggest buying a 85ah battery to future proof yourself in case at some point you decide you need a motor mover. Secondly if you ever go off grid i.e. a rally, the battery could last a few days operating lights, water pump and fridge. Regarding the fridge the caravan battery will only activate the controls on the fridge and will not cool down the fridge.

Regarding cooling the fridge while towing the caravan, I consider it a waste whether or not the car has a Smart alternator. It may help keep a fridge cool, but will not cool it down. On a hot day the temperature in the fridge will probably rise.

When we used to go to France on the ferry, we would stop overnight at a site near to the ferry port, cool fridge down to maximum and this with some ice blocks would keep the fridge cool for at least 24 hours. Worked better keeping fridge cool that way than when the fridge when connected to the car,

 

[Jcloughie]

wow, wow, wow...thanks John and al very precise and (mostly!) understood.

I could add that I have a 2011 Honda 2.2 CRV and that the van is from 2013 but unless there is some expert who knows about this specific combination no one is going to be able to assuredly advise me so let me pose a different question...

I am now going to buy a leisure battery which I was resisting because of the weight so what type/size/model/brand would you recommend which could also accommodate me being off grid for 2/3 days where I would use gas to power fridge/heating/stove?
thanks
Ben (not Benbo but Ben was already taken haha)

That’s a rethink then. I would think a 75 or 85 amp/hour leisure battery would do you nicely as you don’t have a mover.

 

[ProfJohnL]

I will not recommend any specific brand of battery, as I don't have enough relevant experience with each battery make to know.

As to the size of battery you will need for 3 days off grid, very much depends on what equipment it will power, how much current each applaince consumes when its on (or off in some cases) and how long you will be using each appliance. armed with that information you can work out the amount of power you will need and thus the size of battery to support that life style.

Don't forget to include the lights and phone chargers et. Its surprising how much power using lights for a couple of hours uses.

It makes sense to review what appliances you really need and choosing energy efficient ones, especially lights, Consider changing bulbs to LED's which will make an immediate boost to energy efficiency. Modern LCD TV's use considerably less power than models from only 10 years ago.

Use gas for fridge, water and space heating and cooking.

Consider fitting a 100 to 150W solar panel to keep the battery topped up.

 

[Mr Plodd]

Rather than buying new, an old car battery that is past it sell by date for car starting would still fulfill the needs you are looking for, as the current draw would be absolutely minimal, and save you a few quid.

 

[ProfJohnL]

Rather than buying new, an old car battery that is past it sell by date for car starting would still fulfill the needs you are looking for, as the current draw would be absolutely minimal, and save you a few quid.

Without knowing what you are running on a battery you have no way determining how much current will be needed and whether it will be "minimal" or not.

 

[benbo66!]

thanks...all great advice...lights are LED and no motor mover and we can run the heating on gas without blowers

One final question...can you power a motor mover via a 240v hookup providing of course you can get the van to a place close enough to hook it up?

 

[audiorob]

No the motor mover should be run off 12v battery and not when mains is connected. My van has the cut-off switch for the mover located to specifically exclude its use when the mains plug is present.

 

[otherclive]

thanks...all great advice...lights are LED and no motor mover and we can run the heating on gas without blowers

One final question...can you power a motor mover via a 240v hookup providing of course you can get the van to a place close enough to hook it up?

Motor movers are wired to a separate 12v circuit within the caravan which draws from the battery. If it came off 240v the initial current draw would probably trip the EHU supply.

 

[JTQ]

One final question...can you power a motor mover via a 240v hookup providing of course you can get the van to a place close enough to hook it up?

In the day of our Powrtouch [2008] that was a definite no no, to the extent as "audiorob" has commented, the installations usually physically inhibited you doing so.
I have never tried it to discover if Powrtouch knew what they were doing, just assumed that the warning was there for some good reason.

 

[benbo66!]

thanks all...i'm good

 

[Lutz]

Just out of interest I wonder how the Continentals manage. Relatively few of their caravans have batteries at all.

 

[Hutch]

Just out of interest I wonder how the Continentals manage. Relatively few of their caravans have batteries at all.

Probably have a 12 volt power supply when on EHU, rather than a battery charger and battery. As I mentioned on my Coachman the Power supply unit , when on EHU gives a 240 volts supply, a 12 volt smart charger for the battery and a 12 volt 20 amp supply for the caravan internals.

 

[RogerL]

Just out of interest I wonder how the Continentals manage. Relatively few of their caravans have batteries at all.

They have electrical systems designed not to need a battery - as I suspect you well know.