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Re: Which Solar panel?

Posted: Thu Jun 13, 2019 8:53 am
by RMS
Shouldn't really need to wire it to the starter battery - unless you are using that battery for something while you are camping (lights, phone charger etc.). If you have a voltage sensing split charge relay, then it will top up the starter battery before starting to charge the leisure one, but depending on the state of the starter battery and how much sunlight there is, that might mean it never reaches the voltage required to start charging the leisure battery.
If it's a simple relay split charger which switches on when the alternator is running, wiring the solar panel to the starter battery won't charge the leisure battery unless the engine is running.

So, really, no - connect it to the leisure battery.

When I used to park mine outside for weeks/months without using it, I made up a fused lead with a cig lighter plug on each end and used it to link the starter battery to the leisure battery - that made sure both batteries were kept topped up whenever the sun shone.
You could wire in a switch to connect the two, though that could get left on if you forget - I used to loop my wire through the steering wheel to remind me to unplug it before driving.

Now it is parked in the barn, I just trickle charge them both every month or so, depending on use.


Re: Which Solar panel?

Posted: Wed Jul 24, 2019 10:32 am
by smokey2a
Thanks all, been given a 100 w 12v rigid panel and Control box,(donation to charity) the control box is a basic from with very little information as to whats happening (no read out screen) Recommendations please for a good cost effective box as this ones like Zebedee it goes up and down so much. 12.4 to 17 volts . On the volt meter.

Re: Which Solar panel?

Posted: Mon Jul 29, 2019 6:32 pm
by Jonny72
I’ve found this a really interesting and helpful thread. It seems there’s quite a lot of science to consider before selecting the controller if the leisure battery is something other than a regular lead-acid battery, i.e. differing in type from the starter battery. In the rebuild of my Carawagon, I’m looking at installing a deep-cycle Lead Crystal leisure battery, matched to CTEK controllers ... 2149130179 to receive charge from a 120W solar panel mounted flat, but hinged on the roof-rack.

A lot of upgrades going into the Carawagon rebuild, and I think the solar panel will really increase utility, without having to rely on a powered campsite for running a fridge or charging phones/cameras etc.

Re: Which Solar panel?

Posted: Tue Jul 30, 2019 3:08 pm
by Peaceand
I've got a similar setup with a deep cycle battery as a leisure battery, and standard lead acid as the starter. The 80W solar panel on the front rack (mounted flat) rarely puts in more than 6 amps in the UK, if that helps any estimations for amperage.

I've used a standard 20A solar controller for the last couple of years and it has worked wonderfully. I can't find the exact model, but it looks like this is a very similar version: ... SwZbRdKWvX

Combine that with a solid state split charge relay to get the engine charging the leisure battery while driving: ... 0005.m1851
and you'll have an excellent setup that should keep the leisure battery topped up when driving and when parked.

The CTEK kit looks like it combines those two things into one system?

Best regards,

Re: Which Solar panel?

Posted: Tue Jul 30, 2019 9:02 pm
by Jonny72
Thanks Patrick, that’s really helpful. Could u ask a little more about the type of deep-cycle leisure battery that you’re using? Is it also a lead acid battery? The controller that I was planning to get to charge the lead crystal battery has to be a bit different than the type you linked to, but is quite a lot more expensive. I’m thinking if your experience with that type of split-charge relay works well, as it should when the starter and leisure batteries are of the same nature, e.g. lead acid, whether there’s a need to get the more expensive lead crystal battery as the more expensive control / split charge relay system. In fact, my Carawagon still has the original split-charge relay fitted next to the battery in the engine bay, so might see whether it’s still working after all these years before buying / fitting new products.

The link for the solar panel is really helpful, thank you. I think the CTEK might be the gold standard, and again, not sure whether it’s really required.



Re: Which Solar panel?

Posted: Mon Aug 05, 2019 9:44 pm
by Peaceand
Hi John,
My setup is an Absorbed Glass Mat type lead acid battery under the passenger seat (this style: ... attery/d34 ) - linked up to the solar charger, and the alternator when the engine's running. It's done well considering it's age now, and the fact I have accidentally flattened it a couple of times.

I must admit I've not encountered lead crystal before, but they look to be an improvement over lead acid especially in terms of long term battery life.

If you have all the old charging wiring there though, adding a traditional lead acid type would be very easy...
You could even test it with an old car battery and a volt meter. Running a fridge may be a bit much, but charging things and running LED lights would probably be fine on any old battery.

Let us know what you end up doing though, lead crystal may be the future!

Re: Which Solar panel?

Posted: Sat Aug 10, 2019 1:38 pm
by Jabbawocky
Hi all

Just back from Corsica. To help the 50 watt solar panel on the roof box, I bought this folding 80 watt panel. ... 2749.l2649. I fitted a Hella type DIN plug to match the din sockets I have fitted to the outside of the Dormobile.

Having used the 50 watt set up before setting off, I wasn't expecting any issues, but when we got to the south of France problems started. The fridge was tripping out and when I tested the leisure battery, it was nearly flat after only a few hours parked up. It was about 40 C in the truck and the fridge was having to work hard in the brilliant sunshine. What could be wrong?

It turned out, because I had wired the roof panel to the leisure battery, the voltage from the panel was raising the voltage on the leisure battery and the Split charge relay was not cutting. The high volt/low amp supply from the panel was enough to stop the Alternator charging the battery, but not enough to charge the battery itself. To solve this, I disconnected the roof panel every time we set off and re-connected the roof panel every time we parked up.

The two panels worked great and we had no further issues. I now need to research split charge systems to find one that will not have this issue. So far, I only know of the CTEK unit.

When it stops raining, I will test if this was a problem here in the UK and I missed it.

Re: Which Solar panel?

Posted: Mon Sep 16, 2019 5:33 pm
by woollen797
I have 2 x 25 watt panels on my roof rack which do OK for my use. I recently discovered that my alternator wasn't charging after I dislodged the fuse out off of the solar side of the split charge. I've been charging both batteries via solar only.