Leaving caravan for 6 weeks should battery be left on charge or not

[Javert]

We will be leaving our caravan on our seasonal for about 6 weeks in October/November. We have electric hookup but should we leave the caravan on charge continuously or not?

Over the summer I did not leave it on when we were not there and it seemed to stay full all the time presumably due to solar. I have also been running off battery for a couple of days each weekend we were there and just charging it up for a day or two each time.

Recently when it’s been left for a couple of weeks, the gauge on the control panel has been at the bottom of the green section verging on “fair” instead of “good” when I got back to the van, so the battery is now running down when we are not there, presumably due to lack of solar (we are under trees so the solar panel doesn’t work to full capability). The only things running when we are not there are the alarm and whatever the fridge consumes to keep it running on the hook up.

I am not sure if it’s worse to leave it on charging for 6 weeks, or to risk running it down to empty. How many weeks should it normally last if we are not there and everything is powered off except the alarm, with fridge running on electric hookup?

 

[Martin_E]

It would be extremely useful to say what make, model and year van was to help you give a educated reply to your question 🤔

 

[otherclive]

Running a lead acid cell down to empty is likely to do it permanent damage.

 

[rich0805]

It would be extremely useful to say what make, model and year van was to help you give a educated reply to your question 🤔

I'm struggling to understand how that information would make a difference to the answer.

 

[Jcloughie]

If all is working as it should, your solar should keep your battery topped up without any help. Today I just left my van on its seasonal pitch, not only did I turn off the master switch, but I removed the plug from the post. However, if there are weaknesses in the circuitry these should be what is addressed, eg. Poor battery.

John

 

[Javert]

It would be extremely useful to say what make, model and year van was to help you give a educated reply to your question 🤔

It’s a Swift Sprite that was bought brand new in March this year with a new battery.

Generally we leave the power hooked up so that the fridge keeps running.

From what I can tell, the battery charger in the caravan is somewhat intelligent in that it applies a high number of amps charge if the battery is a bit run down, but then the amps reduces to very low after some hours.

Confusion for me is that I have read that you should not leave the battery continuously charging as it might damage it, but if you leave it and it runs down to zero that will also damage it.

 

[otherclive]

It’s a Swift Sprite that was bought brand new in March this year with a new battery.

Generally we leave the power hooked up so that the fridge keeps running.

From what I can tell, the battery charger in the caravan is somewhat intelligent in that it applies a high number of amps charge if the battery is a bit run down, but then the amps reduces to very low after some hours.

Confusion for me is that I have read that you should not leave the battery continuously charging as it might damage it, but if you leave it and it runs down to zero that will also damage it.

In modern vans the charger does vary its output to meet the battery needs. But even in autumn and winter conditions the solar should keep the battery charged. As the trees loose leaves the access to winter light will improve. Need to make sure that everything is switched off that’s not essential.

 

[Martin_E]

I'm struggling to understand how that information would make a difference to the answer.

I can’t see why you are struggling to something so simple 🙄
Some vans you can isolate the 12v via a shut down button to preserve the 12v , other vans just disconnect the negative on the battery.

 

[Javert]

In modern vans the charger does vary its output to meet the battery needs. But even in autumn and winter conditions the solar should keep the battery charged. As the trees loose leaves the access to winter light will improve. Need to make sure that everything is switched off that’s not essential.

When we leave the van, the control panel at the door is powered off, so I would assume that the only things that could draw power from the battery are the alarm and any power that the fridge needs for it’s control circuitry?

 

[rich0805]

I can’t see why you are struggling to something so simple 🙄
Some vans you can isolate the 12v via a short down button to preserve the 22v , other vans just disconnect the negative on the battery.

Whether you isolate the battery or nor doesn't make much difference to " if it’s worse to leave it on charging for 6 weeks, or to risk running it down to empty". If the battery is just left it will go flat whether or not it is isolated.

 

[otherclive]

Whether you isolate the battery or nor doesn't make much difference to " if it’s worse to leave it on charging for 6 weeks, or to risk running it down to empty". If the battery is just left it will go flat whether or not it is isolated.

A fully charged battery that is properly isolated should be okay for six weeks. I’d bring mine home when putting the van into storage and leave it in the garage. I’d periodically then give it a charge using a CTEK.

 

[Martin_E]

It’s a Swift Sprite that was bought brand new in March this year with a new battery.

Use the 12v shut down button. This will help preserve your battery

 

[Martin_E]

Whether you isolate the battery or nor doesn't make much difference to " if it’s worse to leave it on charging for 6 weeks, or to risk running it down to empty". If the battery is just left it will go flat whether or not it is isolated.

Perhaps you should go round all the battery suppliers and inform them that their batteries will go flat while sat on their shelves and they will need to charge them……..good luck with that 🙄😉 a batter will hold most of its charge while on a shelf or in a van when not connected

 

[rich0805]

Perhaps you should go round all the battery suppliers and inform them that their batteries will go flat while sat on their shelves and they will need to charge them……..good luck with that 🙄😉 a batter will hold most of its charge while on a shelf or in a van when not connected

There's a difference between a new, unused battery and one that has been in service for some time.

 

[Beardy]

Perhaps you should go round all the battery suppliers and inform them that their batteries will go flat while sat on their shelves and they will need to charge them.

There's no need to inform them, they already know!

Battery information guide, all you need to know about batteries

Information guide to automotive and motorcycle batteries by Yuasa, including storage, maintenance, charging and performance.

www.yuasa.co.uk

a batter will hold most of its charge while on a shelf or in a van when not connected

Leave any lead acid battery long enough and it will reach a state where it cannot be recharged. How long depends on the battery condition and storage temperature.

https://texford.com/2022/02/everything-you-should-know-about-storing-and-charging-agm-batteries/#:~:text=As%20a%20general%20rule%20of,last%20about%20half%20that%20long.

 

[Beardy]

I am not sure if it’s worse to leave it on charging for 6 weeks, or to risk running it down to empty. How many weeks should it normally last if we are not there and everything is powered off except the alarm, with fridge running on electric hookup?

If your battery completely drains at best it will be damaged and will lose capacity, at worst it will be destroyed.

Martin_E's question regarding your caravan was very relevant (or at least the year of manufacture was IMHO). You have a modern caravan that is almost certainly fitted with a charging system designed to maintain the battery at around 13.7v, there shouldn't be any problem leaving it on charge for extended periods. Would you be concerned about overcharging your battery if you were staying in your caravan for 6 weeks?

However, as others have suggested, if your solar panel is factory fitted it should be capable of maintaining the battery with the alarm system running (assuming that your caravan isn't located in constant shade). It would be worth getting a ladder and giving the panel a clean. You may find that it's covered in leaves, green algae and bird droppings. It doesn't take much to reduce the output of a solar panel.

 

[Buckman]

Over the winter our caravan sat for 3 - 4 months not being used and no issue with battery. We had a 100w solar panel. The caravan also had an active tracker and alarm operating 24/7 365.

 

[Beardy]

Over the winter our caravan sat for 3 - m4 months not being used and no issue with battery. We had a 100w solar panel. The caravan also had an active tracker and alarm operating 24/7 365.

I have a 25w solar panel that I leave inside a south facing (tinted) caravan window. Even through winter it keeps the battery fully charged - some days it provides very little but it's enough to overcome the self discharge (I don't have an alarm).
I also have a bluetooth battery monitor that logs the voltage every couple of minutes so I can easily keep an eye on it via my phone.

 

[ProfJohnL]

(we are under trees so the solar panel doesn’t work to full capability).

The OP has clearly stated he is parked under trees so his solar is compromised.

You tell us you keep your fridge operating on mains power, so that must mean you have your EHU connected whilst you are away. This obviously means you could also keep your caravan battery charger (technically a power supply these days) working, and as others have said, the more modern power supplies are intelligent enough to monitor their charge output to protect the battery from over charging, thus it should be perfectly safe to keep the battery on this charger 24/7 indefinitely.

Why you want to keep the fridge running for 6 weeks of non use, i'm not sure? Please don't tell me you are keeping perishables in the fridge? I presume you take chilled or frozen items with you when you intend to use the caravan, so just make sure you pack your items with some cool blocks or cleaned old plastic milk bottles filled with water and frozen. Turn on the fridge when you get there, and transfer the cool blocks with the food into the fridge to keep things chilled whilst the fridge cools down.

 

[Javert]

Use the 12v shut down button. This will help preserve your battery

Sorry I’m a beginner to caravans. Is that the button on the big electric box under the seat ? (There are 2 buttons to control the charging and the electric heating circuits, and another button at the back which shuts down the entire box - is that what you mean?)

If I use the 12V shut down button does that also mean the fridge won’t work, whether or not I’m on EHU?

To the question on the fridge - you are right there is not much point leaving the fridge on for 6 weeks (it does have a freezer compartment so in theory you could leave something frozen in it but it will cost about a pound a day to run when we could just take that stuff home).

The other thing that I am wondering about - I am at the caravan now. I charged the battery for about 24 hours. I then switched off the charger, and about 15 hours later, the voltage is showing 11.9 volts with 0.9A load. (This is on the caravan display I am not measuring it at the battery with the battery disconnected). I can’t swear to this but I’m sure it was reading more like 12.5 volts for a couple of days earlier in the summer when not under charge.

Because we are under trees the solar panel seems to be generating less than 1A or 0 most of the time (I have seen it generate a lot more when we took the caravan to other places and it was sunny). I have cleaned the solar panel of leaves recently but not washed it so I will also do that. I ave to admit that sometimes I’m not clear whether the solar panel is only generating next to nothing because it already thinks the battery is full or because it’s not getting enough light.

 

[Martin_E]

Sorry I’m a beginner to caravans. Is that the button on the big electric box under the seat ? (There are 2 buttons to control the charging and the electric heating circuits, and another button at the back which shuts down the entire box - is that what you mean?)

If I use the 12V shut down button does that also mean the fridge won’t work, whether or not I’m on EHU?

Yes, there is a black button that I think says 12v shutdown. Yes this will kill all the 12v in the van other than the alarm. As for the fridge, some vans with the shutdown button off the fridge will still work, some other vans it will turn the fridge off as well.

In summer there is generally enough sun to keep the battery topped up even with the 12v shutdown still on, however as daylight hours dwindle there is less charge being produced, often this will mean more power is being used than is being replaced by solar, even with nothing on in the van as there is a constant draw from the electronics. The shutdown button makes a big difference as it’s a tiny amount lost with it off and solar can generally keep up with topping the battery up.

 

[Buckman]

Easy to forget to shut down the 12v as that causes the biggest drain on any battery.