leisure batteries and towball electrics wiring

[Lonesome-Whizkid]

:cheer: I have no idea how long a leisure battery will last if its as big as 120 amp hrs, I used to have a 60 amp hr leisure battery but still had no idea how often it should be charged and only used it once to operate a drill as I was connected to a 240 volt pure sign wave inverter to fix a fence. Lets say your using it for the travel kettle and laptop and led lighting that comes as standard with caravans and small travel tv. will it last for weeks without being recharged or are we talking days? An example would help.

And also, If I'm going to be buying a caravan that's a 2008 model with the 12N - 12S connection if I chose to sell it later to upgrade to something more upmarket that has the newer 13 pin connection can I keep the old 12N - 12S on my towing vehicle and get a connection adapter that modifies the connections?

 

[Parksy]

In terms of the battery charge, if you use sites with ehu (electric hook up) you shouldn't have to worry because the on board battery charger will keep your battery charge topped up under normal circumstances.
If you go 'off grid' regularly, say on club rallies where no ehu is available a 120 a/h leisure battery in good condition should hold enough charge to power 12v lights, the water pump, the electric toilet flush if fitted and the ignition for the fridge, water heater and the caravan heating system.
There are other options such as solar power used by regular ralliers but I won't overload you with information at this stage.
Leisure batteries are not always fitted to used caravans from dealerships so check if the one that you eventually buy has one first.
If you need to buy a new leisure battery go for the highest amp/ hour capacity.

 

[WoodlandsCamper]

If you need to buy a new leisure battery go for the highest amp/ hour capacity.

.... but only if it physically fits into the battery compartment. Older caravans may have smaller lockers.

Yes - you can get adapters for 12N/12S to 13 pin connections.

 

[Damian]

As far as towing electrics are concerned, you would be better off having 13 pin plug and socket from the start.
It is a much better system and there is no need for adaptors, which almost always cause problems.

 

[Lonesome-Whizkid]

I read in the caravan manual that 120 amp hours is exactly what it says it means, that if its fully charged it should power a one amp appliance for 120 hours with the exception of 25% for allowance of condition of battery, temperature and age. So If I run a 7inch travel television at 0.2 amps it should last for at least a 3 or 4 weeks without needing charged? B) Or should I say charging mobile phone would be as little as 0.2 amps, a travel tv might be higher, like 1.5 amps.

 

[colin-yorkshire]

hi Lonesome-Whizkid,
this afternoon I wrote a long detailed post about caravan batteries, the different types, uses discharge rates, and applications. However for some reason all the text got deleted as I tried to submit it!!!! :evil: :woohoo: .
as I almost lost the will to live, and a laptop as it flew across the room (they are really robust aren't they) I have no intention of trying to re do it, :cheer: :cheer: :cheer: .
so here is a quick-ish answer.
1. before deciding on which battery to use ask yourself one question where am I going to use the van!! if like most of us you intend to go on sites with a EHU (electric hook up) you dont need a big leisure battery at all because it will never go flat the battery is only basically a buffer between the power unit and the 12v supply, in which case a simple cheap car type starter battery would be fine, in fact better because they are designed to be constantly charged (as in a car) the occasional usage before going back on charge will do no harm.
2. if however you decide to go the off grid route like Parksy who enjoys rallies and CL's with only a tap and Elsan point you would need the biggest leisure battery you can get (providing it fits into the battery box) to sustain the 12v system for as long as possible, extended stays would however require some form of recharging though possibly with the aid of a solar panel, or a spare battery,
3. dispite what you may think the discharge rate could be quit high you quote 120 hrs at one amp this is basically correct however with the water pump, lights and other electrical drains this could be down to 12hrs, or 4 hours per day for 3 days not much good if your on site for 2 weeks. I once did a drain test on my van turned on all the 12v equipment inc tv ect the power drain was 15 amps,and would have flatten the battery in a couple of hrs.

as for the choice of plugs I am with Damian on this the 13pin is far better as you progress to a newer van this will have the 13pin plug anyway so you might as well have it from the start,

 

[JTQ]

I read in the caravan manual that 120 amp hours is exactly what it says it means, that if its fully charged it should power a one amp appliance for 120 hours with the exception of 25% for allowance of condition of battery, temperature and age.

Sadly reality is very different.
Firstly the AH rating depends on the drain rate, so if you just take a little current you will get a much higher apparent Ah rating than if taking a higher current. Responsible makers/branders/resellers of our Leisure batteries use a European standard that depletes the battery in 20 hours. The standard is EN50342 C20.
There are many selling anything but EN compliant batteries.

Secondly whilst batteries can give their "all", doing so wrecks them very quickly, and how quickly depends on build standard and depth of depletion.
As a guide a "starter" battery is designed with depletions of only 20%, a reasonable quality Leisure battery at best 50%.
So that so called 120Ah battery could yield a consistent workable 24 Ah, or 60Ah.
It all depends on really the suitability for purpose of the battery, and that inevitably reflects in the price, weight and bulk.
If buying a genuine EN50342 C20 compliant 120Ah battery you will get towards that usable 60Ah figure. If buying cheaply a non compliant one you stand near zero chance of getting it for long.

 

[Lonesome-Whizkid]

Can you get a gauge that monitors a leisure battery to let you know that its needing recharged?

And also, am I correct in assuming that whilst the van is hitched up and in tow, that the towing vehicles electrical supply charges the leisure battery in the van? :blink:

 

[Sproket]

If you have a 12v cigarette point you could use one of these to monitor the battery voltage.

 

[colin-yorkshire]

And also, am I correct in assuming that whilst the van is hitched up and in tow, that the towing vehicles electrical supply charges the leisure battery in the van? :blink:

yes it does!

 

[Lonesome-Whizkid]

So, Is the van's Leisure battery getting its charge from the towing vehicles alternator or is there an independent charger on the van that does that? And If I had a solar panel would that be switched off with the solar panel control unit whilst in tow? and switched on when sited in a park? This is all new to me? But fortunately i am understanding! Even if i post silly questions lol.

 

[Damian]

When you connect the car to the van, and the engine is running,it triggers a habitation relay inside the van which isolates the van 12v system and only supplies power from the alternator to the van battery and fridge.
The solar panel control unit takes care of the panel,which will come back into its own when on site.