Battery voltage & solar pannel

[starlightdj]

Hi all, hope you can help with any information.
First time away for a weekend without electric hook up, we have a solar panel and regulator which I connected direct to the battery terminals.
The voltage on the inboard power unit stated 12.5v rising to 12.7 after a full day then dropping to 12.4 overnight before rising again during the second day.
My questions, does this type of range sound right or is it too low?
I know when I am on electric the volts reading seams more around 13.5.
If that does sound right, next question, which is the best way to couple up to the battery, is it direct to the terminals or is there other ways.
Sorry for being vague but looking to try rallying so want to try and get things right.

The van is a 2009 sterling Europa. The solar panel is a freestanding unit

Thanks
John

E

Eme

 

[Sproket]

What size is your solar panel ( amps ) ?

 

[Parksy]

The voltage reading on the caravan power unit can sometimes be misleading or inaccurate and a lot depends on how much sunlight you get and the wattage of the solar panel but the reading shows that the panel is re-charging the battery and the reading looks mid range / normal.
If your solar panel is freestanding it's probably more convenient to couple to the battery via the regulator, take care to place the panel with the solar cells facing the ground or cover them up when connecting just in case of an inadvertent short circuit which would damage the panel if it is generating power when you connect.
I used my 80 watt solar panel as a free standing unit when we first tried rallying but I mounted it on the roof of the caravan and hard wired it directly to the charging circuit after we decided that we enjoy rallying.
Click Here to see how I did it.

 

[starlightdj]

Hi thanks for the reply, the panel was bought a couple of years ago from maplins, it's quiet large in size about 30 inches tall by 12 inches wide and I think from memory 12v 18w.
It seamed to charge however we were probably over cautious as we wouldn't turn anything on in the van, except taps and the electric toilet flush.
Tried led replacement lamps but they just seam to flicker on and off so might have to look further into that.
Thanks
John

 

[Damian]

An 18w panel is not a lot and will struggle to keep the battery charged.
That size is only useful to keep a battery topped up in storage, not in use.

You need a decent sized unit to power a van on a rally or off hookup,around 80w minimum.
12.4v is an almost flat battery, it needs to be around 12.8v minimum to supply everything correctly

 

[Parksy]

Damian beat me to it!
Bear in mind that a rally normally lasts from Friday afternoon (ish) until Sunday so your leisure battery if fully charged before you go should last over the weekend anyway. The Maplins solar panel will trickle charge your battery when the caravan is not being used but it might be less expensive to pick up a cheap 110amp/ hour leisure battery as a back up for rallying.
An 80 - 100 watt solar panel with the correct voltage regulator will set you back around £200 from e-bay, (there are some silly mega-bucks £400+ rip-off prices quoted with lots of nonsense about 'cheap solar panels not being any good') which is a significant investment unless you know that rallying is for you.

 

[ProfJohnL]

It occurs to me that it is possible the battery may be past its best, which would limit its ability to accept the charge. Arrange to get it checked at a bettery specialist - you may need a new one.

 

[starlightdj]

Thanks for all your advice, now actually checked the battery with a multi meter, it gives a reading of 13.2 without any load.
re the solar panel also checked that whilst facing the sun and it gave a reading of 8.1v.

So although the thought was there I dont think it will be much use on a rally.

Re panels themselves, I think im going to splash out and get a decent freestanding one as we might change the van in 18 months or so.
Any idea on a brand or supplier or any recommendations if its allowed.

I have checked the net and seam to be able to get an 80w from towsure for around £240 however noticed on flee bay you can get higher wattage ie 110-120w for circa £140. Is there any real difference?

Any help & advice would be gratefully received.
Thanks again
John

 

[Parksy]

Hi John
The only real difference is the price.
I bought mine on the reccomendation of fellow rally goers from a Bromsgrove company called
Greener Electric
I collected my monochrystaline panel (avoid polychrystaline for caravan use) but they also do mail order, they are reputable and not too expensive, they usually supply the solar regulator and cable as part of the deal.
The panel is not 'freestanding' in the sense that it's in a plastic case, I made a stand using left over pieces of 32mm plastic drainage pipe with cable ties securing the pipe to the aluminium panel frame and used it successfully for 12 months before I decided to fit the panel to a Z section frame on the caravan roof and hard wire it to the charging circuit.
I can easily remove it if I decided to change the caravan because the external cables can be separated via external cable plug / sockets and the panel is bolted to the Z section with 8mm stainless steel nyloc nuts / bolts.
The higher the wattage on Monochrystaline panel for your budget the better so a 120watt panel for £140 looks to be a good investent. Factor in around £60 extra for a decent solar regulator and automotive cable if these are not included.

 

[starlightdj]

hi Parksy
many thanks for your help, will contact them for a price. Always like to use someone whom has been reccomended.
Until i started looking into matters just didnt realise how many different types & makes there are. with so much conflicting information!

We have our first rally booked for 3rd to 5th of Aug. so would like to try and get ready for that as its a type of vanning we have always fancied trying, I know its a pricey way to start but dread the thought of the battery packing up half way through as I know my daughters will use lights and power without a second thought. I think i need to train them more lol.

Thanks again, will let you know how I get on.
Cheers
John

 

[Parksy]

Hi John
If you need any help or advice let me know.
Your battery should last over the weekend but regulars on the rally field almost always use solar power to re-charge the battery. Bear in mind though that a solar panel can't perform miracles, you will still need to try not to waste battery power.
12v Led light bulbs use significantly less pwer than the old radiant type, use a portable led lantern instead of the awning light and you should be fine.
Who are you rallying with?

 

[starlightdj]

Hi Parksy
Its with the Sterling owners club, at Belmon Hall, Cheshire

joined the club at the nec show last year, but its the first chance weve had to actually make one of their weekends due to work.

We like the idea of going somewhere different from the normal run of sites, but apart from that havent got much of a clue about how involved you have to get as yet, or wheather you are just left to your own devices.

But if we dont try, we will never know.

Thanks again and I might just take you up on the offer of extra advice re the pannel later.
Cheers
John

 

[starlightdj]

Hi Parksy
Thanks for the recomendation to greener electric, Placed the order online on saturday, on tuesday tried to go on their web site and it kept sending me to google chrome search page, so I phoned them up.
It turns out i picked the week when they have changed names and took the web site down, They are now called Bromsgrove Solar the new web site is only basic but they are working on it). The lady was very apologetic stating the order hadnt been processed due to the web site being taken ofline, she then took all my details and said the panel would be despatched that day, It arrived by mid day today, cant beat that for a swift delivery.
Now the proud owner of a 80w panel plus controller and 5meters of cable for £159 which i thought was a great price.
The panel itself is bigger than i thought and is square rather than rectangular, I have it wired up to the controller and the battery in the living room and just with a small halogen bulb pointing towards it is giving of a 11.5 v output.
Im just trying to figure out a way of making a stand for it so it can be freestanding and hopefully no one will walk into it lol.

Cheers
John

 

[Parksy]

Hi John, thanks for letting me know about the name change, I will be able to recommend them under their new name now.
The reason that I hold this firm in such high regard is that when I bought my solar panel from them I made a mistake the very first time that I tried it and I short circuited it

Not surprisingly the panel wasn't charging after that but the company exchanged it there and then with no awkward questions being asked.
I used my panel as a freestanding unit for the first 12 months, there were two reasons why I decided to roof mount it permanently.
The first was because I was worried that if an excited child was running around the campsite or rally field too close to my caravan they could run into it and get badly hurt.
The second and main reason though was that when we were going home after each trip I'd wipe down the panel, cover it up with the two halves of it's box secured by bungees and lay it on the fixed bed for safety when under tow.
Herself was always moaning about this and worrying that creepy crawlies which may have hidden somewhere on the panel would invade the bed

I used a length of 32mm plastic waste pipe cut to size, two push on 90° elbow joints and a couple of pipe support brackets round the pipe which I secured to the back of the panel via the holes that were in the frame using cable clamps. Here's a couple of pictures.........

The plastic piping is lightweight and gives good stability, you can vary the angle of the panel to keep it fully into the sun and it folded away under the panel when it was time to go.

 

[starlightdj]

Hi Parksy
Many thanks for the help and advice.

We have now survived our first rally and come back with a fully charged battery to boot.

The solar panel worked a treat and prooved its worth after the friday night when my daughter left the lights on inside whilst we were in the marquee.

Used your idea re the pvc piping to make a frame to stand in on, it was a very simple and quick resolution which worked perfectly.

As for the rally itself, we are so glad we tried it, everyone was very welcomming, the kids made new freinds, and we had a great time.
Will now have to plan our shifts better so we can go on more.

Cheers
John

 

[Parksy]

You're welcome John and I'm glad that you enjoyed your first rally and the solar panel did it's thing.
Rallying doesn't suit everybody and of course different associations and organisations do different things so you have to find the one that you like best. For families with yongsters though it's a great way of maximising the use of your caravan to it's full potential without breaking the bank and you don't normally have to book in advance.

 

[TD42]

Hi Starlight, you state that the van meter reads 13+vdc when you are on hook up. This is correct (13.8 is what it should read) this is because the battery is actually being charged from the power suppy unit in the van,if you disconnect the EHU the reading should drop to 12.8 for a fully charged battery. However a battery has to stand for approxamatly 6hrs after being charged before a true reading can be obtained with a multi meter due to what is known as "float charge" on a freshly charged battery
from the reading you give it would appear your battery is only half charged @12.5vdc I would remove the battery from the van & fully charge it using a car battey charger,preferably a "smart" one that has leisure battery settings
PS most caravan chargers will only charge to approx 80% as they operate at 13.8v but a battery needs over 14+ volts to fully charge
a smart charger does this & then drops to a lower voltage to maintain the battery.as said by others anything less than a 40watt solar panel is only suitable for maintaining the battery when the van is not in use