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I've just got myself a lunar Delta rs and it's going in storage, but I'm curious at how big a solar panel (in watts, amps) I would need to keep the leisure battery trickling over,

I'm Intending on sitting it on the shutter in the sky light as my windows have that tint on it.
 

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I've just got myself a lunar Delta rs and it's going in storage, but I'm curious at how big a solar panel (in watts, amps) I would need to keep the leisure battery trickling over,

I'm Intending on sitting it on the shutter in the sky light as my windows have that tint on it.


So the panel will only be used to charge the battery, not to run any loads? And for long periods at a time? Really the question is what amp rating your charger will need, and that will drive what size panel you want.

Obviously you will need a regulated/multi-stage charger to avoid overcharging your battery but you could get away with a very small one if I understand your requirements correctly.
 

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It's just really for keeping the leisure battery charged up over the winter months, I put a new 110amp leisure battery in it to try and hold a decent charge. As for amps etc, I'm clueless about those things ?
 

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It's just really for keeping the leisure battery charged up over the winter months, I put a new 110amp leisure battery in it to try and hold a decent charge. As for amps etc, I'm clueless about those things ?


Working backwards:

Your battery will need a certain voltage supplied to it to keep it in tip-top shape. How much that is depends on the type of battery (AGM, gel, etc). It's usually between 13-15V.

A good charger will actually vary this voltage regularly and let the battery discharge and recharge slightly. This is what is meant by chargers that say they are "three stage" or "smart".

In order to supply that voltage, a 12V trickle charger is usually rated in amps. For example, I have a 12V 20A charger for my trailer battery (which is 110Ah like yours). 20A is enough to charge the battery even when it is supplying power to my fridge. It is way more than you need to keep it maintained in storage: the point is 12V DC chargers are usually described in terms of amps.

Solar panels, however, are usually described in watts. This is because both the voltage and current vary according to how much sun the panel is getting. This figure is a maximum - obviously the panel can produce no power at all if it's dark.

In theory watts=amps*volts, so if you picked a 1A charger you'd need at least a 12W solar panel (12W=1A*12V). In the real world the equation is a bit messier than that and there are some efficiency losses involved.

However, I'm massively over complicating things. The panel you need is very small (something in the order of 10W would do) and if you buy one designed for this purpose the electronics you need to control charge voltage will be built in. Just buy it and plug in.

Something like this would do fine:
http://www.sunstore.co.uk/10w-12v-Solar-Battery-Charger-Vehicle-Kit.html

Note I am assuming you are putting the battery into storage fully charged and it will not power anything while stored. If you want to charge it after use, not just keep it topped up, you will need something much more substantial.
 

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Wow, thank you for explaining that to me. It's very much appreciated ????

The only thing that'll be running off the battery while the caravan is in storage is the factory fitted alarm system.
 

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Wow, thank you for explaining that to me. It's very much appreciated ????

The only thing that'll be running off the battery while the caravan is in storage is the factory fitted alarm system.
The main issue you will have is a leisure battery is not designed to be constantly on charge . They are designed to be fully discharged and then charged . The new battery wont last long if left on a solar panel . We have several batteries on solar panels but always use a standard automotive battery.
 

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I have a 160AH one on ours it also has a on board alarm however in winter storage I remove the terminals and just leave it, longest was 6 Months and it was fine still almost a full charge, I figured the alarm was a bit pointless in storage anyway as the storage people check them daily, of more value is a cover and mouse proofing one got into ours last year and made a proper mess of the cushions had to be reupholstered, actually chewed its way through one of the plastic floor vent grills.
 

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The main issue you will have is a leisure battery is not designed to be constantly on charge . They are designed to be fully discharged and then charged . The new battery wont last long if left on a solar panel . We have several batteries on solar panels but always use a standard automotive battery.


A proper DC charger will vary the charge current and voltage and periodically allow the battery a small discharge to avoid exactly this issue.
 

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Leisure batteries don't need to be discharged, but they do need a "profiled charging cycle" as described above, to make them last a decent time.
 

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Leisure batteries don't need to be discharged, but they do need a "profiled charging cycle" as described above, to make them last a decent time.
Maybe that does work however that wasnt what the OP was asking about.
From many years experience using solar panels (35-40 watt) with batteries attached ,Deep cycle leisure batteries dont last but automotive do on the same job.
 

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Maybe that does work however that wasnt what the OP was asking about.
From many years experience using solar panels (35-40 watt) with batteries attached ,Deep cycle leisure batteries dont last but automotive do on the same job.
Indeed, as I recommended privately....! :)
 
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