Solar Battery Top Up?

[aamcle]

Sorry about posting this I'm confident it's been asked but the search engine has strained what little patience I have.

I have a Lunar Venus and I would like to use the mover to bring it out of it's storage location and that requires a charged battery.

What solar options just for battery top up can your recommend?

Ideally I'd like a panel that that sits inside the window if it's posible.

I have a solar panel controller from a previous project, would I need to use it with a small panel?
How are panels connected, to the vans electrics or directly to the battery or to the movers connections?

Many Thanks aamcle

 

[Grey13]

Hi, Without any detailed research I am sure you cannot just connect the solar cell directly to the battery. You need a regulator to ensure correct charging power is applied and that the battery is not overcharged. Typical of this http://www.qis-uk.co.uk/Pics/Solar%20charger.JPG Rgds

 

[ProfJohnL]

Hello aamcle

Solar top up is definite option, but it does depend on what equipment you may have in your caravan that draws current when the caravan is stored (e.g. tracker, radio, etc). It will also depend on which way the solar panel points to get its daylight.

Even tough you may think a caravan mover uses a lot of power, when you actually look at how they are used it may surprise you how little power they actually use;-

It is a characteristic of all electric motors to have maximum torque (and current demand) at zero RPM, and as the motor speeds up the torque and current drop quite significantly, This is certainly true of caravan movers. So whilst they may have a high maximum current rating, the used average current is typically about 25% of the peak (Stalled) value. Some movers may have a peak current value of 80A (for both motors combined) which will drop to probably less than 20A once its moving.

If it ran at 20A for 1 hour, then that would be 20Ah, but in reality most movers are only used for less than 5 Min (1 twelfth of an hour) so that reduces the battery capacity used to 20/12 =1.7 Ah.

Not so much when you look at it like that. It also means that a relatively small 5W solar panel will be enough to replenish the battery over a day - even on a dull day.

However if you are have any other items I mentioned above , then you may need to consider a bigger say 12a 12W panel

Just for information, we have worked out that a 50W panel is just about enough to keep a battery topped up when the caravan is being used whilst on holiday (excluding things like computers, and tv for more than about 2 hours) so you may want think about investing a little more for a more capable system of use whilst away.

 

[Raywood]

To see if it is feasible it would help if you could say how far the mover would need to move the caravan and which model of Venus you have. The mover is designed for only moving very short distances, and even if it has a fully charged battery then I do wonder if it will last the course.
My advice would be to ask the mover manufacturer to see what they say, but I would think you will need at least a 110 amp battery and given the speed (or lack of it) these things move at will the site operator allow this.

 

[aamcle]

Lunar Venus 550/4.

I need to move the van about it's own length then turn it 90 degrees on a nearly flat surface so it's not far or difficult.

My nearly new 80 amp/hr battery is well able to do the job multiple times IF it's reasonably well charged.

When I store the van I isolate all the power so the only loss should be the batteries self discharged, just the loss caused by standing.

I was hoping somebody would be using a panel for this purpose and would share their experience.

ATB. AAMCLE

 

[Grey13]

The picture shown in my first post is used with my solar cell sitting on top of my van and easily charges the battery. I have a Power Touch mover and use it up a steep driveway and have never had a problem. I have looked from time to time and noticed the LED lamps on the regulator indicating a fully charged battery. https://www.kemo-electronic.de/en/Transformer-Dimmer/Controller/Modules/M083-Battery-charging-regulator-12-V-DC.php https://www.rapidonline.com/kemo-m149-6a-solar-charge-controller-regulator-12v-60wp-55-2231 https://www.rapidonline.com/pdf/110527_an_ml_01.pdf

 

[Kevin2306]

if the solar panel isnt an option, how about keeping a spare batter at home on trickle charge and swap over when you need to move the van?

Kevin

 

[ProfJohnL]

Hello Ray.

When Carver first demonstrated the first caravan mover they had a weighted chassis to represent a caravan, and a single 110Ah battery lasted a whole day of demonstrations.

As I have explained on several occasions and again in this thread, Just becasue a mover has a high current rating it only pulls that current when starting to move. After that the current drops to a much lower level which depleats the battery much less quickly than you might think. A 5min use of a mover will typically use no more than 2Ah of battery capacity or less. That is the equivalent of a 20W halogen reading light for 1 hour.

In reality most smaller 85Ah leisure batteries will run a mover, the possible limiting factor may be initial start up current capacity of the design of the battery. Larger batteries are recommended to ensure the user still has plenty of 12V power for other caravanning purposes.

 

[VicMallows]

aamice,
I am wondering how long you are leaving your caravan in storage at a time, and also how you are ensuring that your battery is FULLY charged BEFORE you leave it in storage?

If, as you say, the battery is FULLY isolated whilst in storage, it should retain ample capacity after several months if it is in decent condition. (As already mentioned, it is constant small loads over a long period which really deplete the battery: are you QUITE certain that there is NOTHING drawing power whilst in storage?).

Even if your battery is indeed fully isolated, a small PV panel will certainly ensure the battery is always fully charged, and is especially useful if your batteries are getting a bit 'tired'. On my boat I use a 12"x12" 15W rigid panel directly connected (no regulator) to maintain 160Ah of domestic battery for many months over winter. (My boat batteries are nearly 15 years old and came from the local caravan dealer).

Alternatively, if you are interested in using the 'van 'off-grid' you could of course consider a much larger panel (perhaps 100-150W) which WOULD then need a regulator ......and we get into a whole deeper subject!

Finally, I just repeat that the most vital factor is ensuring your battery REALLY IS fully charged when you leave the van .....this is not necessarily easy.

 

[Craigyoung]

We use ours quite regularly , and our battery was a Brand Spanking New 11o amp fitted only just in July when we got the mover fitted. We have used it quite a few times since, been to Holland been away in the last few months too but when I went to pull it out of the storage on Sunday, flat as a pancake and without the mover it took four of us to manoeuvre it onto my drive it looked like it had been abandoned !
so I've taken it back and got a new one under warranty at 12o amps!
Like someone has said in recent post or thread, I am also not happy as when I plug it into the house and hook it up the radio come straight on! So even if you think your battery is fully charged.......

Craig

 

[Dodger524]

Possibly part of the problem is that it is difficult to be sure that your caravan battery is fully charged when returned to storage. This will be a greater problem if you are using a car with a Euro 6 engine.

 

[Lappy]

Why would it be a problem if your car is a Euro 6 engine? My car is Euro 6 and I am confident it charges the battery, as I know it maintains the fridge temperature whilst connected (with engine running).
Regards,

 

[ProfJohnL]

Hello Lappy,

There have been some reports of vehicles particularly with Start Stop economy systems failing to properly charge the auxiliary batteries in trailers. Apparently the strat stop system should be disabled when towing. Different manufacturers deal with this in different ways, some require manual intervention others detect a trailer on the wiring system and automatically manage the process.

 

[otherclive]

My previous Forester and this Skoda have stop start, but I normally turn it off as part of the pre take off checks. But when I had Towbars fitted to the cars I had the model specific electrics and checked both. When coupled to the caravan the stop start was inhibited as were the rear sensors. The fridge worked fine and on arrival at site the battery display showed it to be fully charged. Ah but not sure the cars were Euro 6. Might have be Euro 5.

 

[VicMallows]

I think the point that has been lost in the last few posts (Euro6 etc) is that if your caravan battery is at all depleted when you start your journey home, it is very unlikely that it will be fully charged by the car by the time you arrive home. This is because the charging voltage will at best be around 14.4v, and there will be further voltage loss between the car and caravan. At this voltage it may take many hours or even days to FULLY recharge the caravan battery. (There are ways to mitigate this problem if it is really an issue, but that is a different topic).

(Any Euro5/6 issues may certainly exacerbate the problem, but the fundamental is basic to all cars)

 

[Lappy]

Hi ProfJohnL,
Thanks for the explanation with regards to the car's electrics and how they are wired to operate. As I do not have the Stop/Start function, this should ensure the battery and fridge will not be affected.
Regards,

 

[Craigyoung]

I hate the stop-start system even when I am not towing that is the first thing I switch off.!!

 

[otherclive]

I hate the stop-start system even when I am not towing that is the first thing I switch off.!!

I’m with you on this one. My current car and the last one would stop the engine as you halted and had your foot on the brake. But put it in neutral before applying the handbrake and the engine restarts. Fundamentally I don’t like sitting in Drive with the foot on the brake except for transient halts.

 

[chrisn7]

The issue is that to save fuel, some cars have smart alternators that do not charge all the time. This is because there is also a brake energy regeneration system that charges during times of deceleration, but can also kick in to prevent excessive discharge. The battery is therefore unlikely to be fully charged much of the time

This process inevitably affects the caravan battery too, so you may arrive at your destination with the leisure not as charged as you might have thought.

This is not new - my BMW towcar was built late 2009 with a Euro5 engine, and has this set up that far back, so it not just a Euro 6 on issue

 

[Dodger524]

I think the point that has been lost in the last few posts (Euro6 etc) is that if your caravan battery is at all depleted when you start your journey home, it is very unlikely that it will be fully charged by the car by the time you arrive home. This is because the charging voltage will at best be around 14.4v, and there will be further voltage loss between the car and caravan. At this voltage it may take many hours or even days to FULLY recharge the caravan battery. (There are ways to mitigate this problem if it is really an issue, but that is a different topic).

(Any Euro5/6 issues may certainly exacerbate the problem, but the fundamental is basic to all cars)

A better explanation and the remedy can be found at the Caravan Chronicles site.

 

[VicMallows]

A better explanation and the remedy can be found at the Caravan Chronicles site.

Yes, Charles (Sterling) does indeed offer one solution and markets decent products. I do not always agree with some of his claims.