I’m getting one of those foldy-suitcase-style solar panels for the campervan, a 120W job. It comes with the charge controller already connected to the back, and a pair of cables with crocodile/alligator/whatever clamps for attaching to the battery to be charged.

Now, the leisure battery is buried rather inaccessibly under the drivers seat, and is currently charged via a split charge diode from the main battery under the bonnet, or via a 240v battery charger that kicks in if we’re on hook-up. I’ve been mulling over various connector/wiring options for connecting the solar panels, but then I thought “am I making life difficult for myself, can’t I just connect the panels to the main battery using the clamps they come with, and let the split charge diode take care of everything?”.

So, can I?

There will be far better qualified people along in a minute but as somebody who has converted at van (T6) would be interested in knowing the van model?

I put the electrics in mine and used a Ctek 250SE as the later ones use the start stop tech so needed a more sophisticated unit to charge the leisure battery and they do come with inputs for a solar panel.

i guess its down to how your split charge works.

i think my split charge only works if the voltage is above 12 point something volts – this basically means when teh alternator is running.

i would run a connector cable from the buried leisure batt to somewhere convenient.

on and do you recon you’d be able to charge an eeb off the leisure with the added solar? this is what i am really interested in doing! cheers

Following.
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Going to attempt similar on my Mk7 Transit, alternator to charge engine batteries, in that order, and then leisure batteries and solar to do the same.
Apparently mine is easier as it’s a Euro6 without the stop/start…

Dependant on your split charge.

You have every chance it’ll work in bright sun and your generating +13.5v thus triggering split charge

In indirect/poor sunlight it’s arguable that you’ll get anything to your leisure batteries at all as it’ll not reach threshold volts to trigger split charge

For all the hour it’ll take to run a pair of correctly rated cables to an accessable point I think it would be a worth while addition to get the most out your panels.

on and do you recon you’d be able to charge an eeb off the leisure with the added solar? this is what i am really interested in doing! cheers

If you ride over night…..possibly over the course of a sunny day with about 3 times the ops solar it’ll charge eventually.

There will be far better qualified people along in a minute but as somebody who has converted at van (T6) would be interested in knowing the van model?

T5, 54 plate, not a fancy conversion

i think my split charge only works if the voltage is above 12 point something volts – this basically means when teh alternator is running

Same here. 13 point something actually IIRC

In indirect/poor sunlight it’s arguable that you’ll get anything to your leisure batteries at all as it’ll not reach threshold volts to trigger split charge

A-hah, of course, I hadn’t considered that.

For all the hour it’ll take to run a pair of correctly rated cables to an accessable point I think it would be a worth while addition to get the most out your panels.

Aye, I think you’re right.

For all the hour it’ll take to run a pair of correctly rated cables to an accessible point I think it would be a worth while addition to get the most out your panels

Definitely this. It’ll make life easier in the long run.

Our solar panel shows little generation if the leisure battery is full. Its fully wired in to the leisure battery. I therefore wonder if it thinks the vehicle battery is full, it wouldn’t put enough over to the leisure?

https://www.t6forum.com/threads/guide-mobile-solar-panels-how-i-did-it.13225/

Choose a suitable connector to replace the crocodile clips

Run another cable and connector from the leisure battery to a convenient spot. Fuse this cable close to the battery to protect against shorting. Use the lowest fuse you can get away with, perhaps 5 amps? (Your connector and cable must always be rated higher than the fuse)

Run another cable and connector from the leisure battery to a convenient spot. Fuse this cable close to the battery to protect against shorting. Use the lowest fuse you can get away with, perhaps 5 amps? (Your connector and cable must always be rated higher than the fuse)

This would be what I would do in your case, only I’d use a battery circuit breaker with a 10a trip setting, rather than a fuse – that way you can isolate connector when no solar connected. Treat it as a solar shore power connector.

think my split charge only works if the voltage is above 12 point something volts

On the T6 (and no doubt others) its more complex than that due to the start stop thing. Hence the need for a more complex regulator and not the older version.

T5, 54 plate, not a fancy conversion

Then it may work although I would run the wires also. You could present both poles in a fused bar somewhere and you could add other items later if you need to.

Spooky has it. Deffo the neatest solution. Incidentally I have a T6 so with smart alternator, but the convertors put a crappy split charge regulator in it, rather than the CTEK it should really have. It does charge the leisure ok but it’s not ideal. I generally keep the fan on pos 2, as bizarrely that keeps the alternator charging. Have to say I thoroughly detest smart alternators !

Thread revival time. I now have the solar panels, after hilariously getting them delivered to our old house, 150 miles away…

Anyhoo, they’re the folding briefcase type, 2*60W, with the charge regulator attached to the back of the panels. I’m wondering whether I should disconnect it from there and mount it in the van, so it’s a) better protected from weather and b) I can read the output etc more easily.

So I’m thinking:

Solar panels – Fuse – 5m(ish) cable – Connector (in van) – 10cm(ish) cable – Charge Controller – 2m(ish) cable – Fuse – Leisure battery

For the connector in the van I’m thinking of something like this

For the cable I was going to use 42A/4.5sq.mm rated stuff, to keep losses to a minimum on a longish run.

Fuse sizes TBC, I need to double check the panel/controller output.

That all sound sensible?

Seems like alot of work for a very low wattage suitcase

Why did you go suitcase over fixed?

Because

a) we don’t need any massive wattage, it’s predominantly to run a 40w compressor fridge so a 120W panel is fine
b)the wiring work is not much (in fact fairly trivial; cutting to length, stripping ends, connecting, bit of routing behind furniture in the van, that’s it), in fact less than I’d have to do for a fixed panel because then I’m probably looking at drilling holes to route the cable back in
c) a fixed panel needs, well, fixing, a folding one doesn’t.

we don’t need any massive wattage, it’s predominantly to run a 40w compressor fridge so a 120W panel is fine

I’m kinda with trail_rat on this one.

It’s only 120W in full sun, on the roof it might get that for most of the day, but on the dash (assuming that’s where it’s going if you’re not drilling holes) even if you park facing the sun it’s only going to get that for a few hours.

I’ve got something similar for keeping the infrequently used car battery topped up. I just cut the ends off and put a cigarette lighter plug on the end. Check what the van has, there’s a slightly narrower “12V accessory” plug that looks similar that’s replaced cigarette lighters in some cars some plugs fit both (the contacts are just more springy), some off eBay are too big.

Works both ways.

Suitcases work best when you want to park van in the shade on say the continental sunny days.

Which is why I asked.

In the UK I’d take fixed on the roof over a suitcase all day long -the work to secure and feed cables is pretty minimal once you done the wiring.

Suitcase are fine as an alternative to fixed. You can park in the shade and put the panel in the sun, moving it to maximise sunlight.
Do it properly and get some connector cables hard wired in – probably available pre-made from eBay/amazon. Keep the crocs for if you ever want to charge the starter battery from solar. Leave the PWM controller on the panel and buy a £20 BM2 battery monitor, which will give loads of charge data via a bluetooth phone app.

What type of controller is it? (PWM, MPPT, …?)

You don’t need a fuse between the panels and the controller (but you do between the controller and the battery).

If you were going to the trouble of doing it, try to get the controller close to the battery (i.e. <1m).

4mm^2 sounds like overkill from panels to controller, particularly if it’s an MPPT controller.

I think there’s some confusion as to the panels I have. They’re not the little dashboard jobs, they’re like this (not these, but like this):

https://www.sunstore.co.uk/product/12v-lightweight-solar-battery-charger-120w-briefcase/

They’re over a metre squared unfolded. They’ll be outside, on the floor, tilted/aimed towards the sun, hence the 5m cable to allow them to be put in the sunniest spot/direction. Or maybe flat on top of the van, depending on position/pitch.

And I’ve done the maths, 120W is fine for a fridge that runs at 40W when it runs (it doesn’t run all the time), is switched off at night, and assuming the 110ah leisure battery is fully charged at the start of the trip.

Anyway, back to the wiring question…

Ah, while i was typing the previous reply I see some people answered the wiring question.

It’s a PWM controller.

The cables will be hardwired to the battery and to the panels, with a connector on the end of the ‘long’ cable from the panels, to connect to the ‘in van’ cable. This kind of thing:

If you were going to the trouble of doing it, try to get the controller close to the battery (i.e. <1m).

Yeah, thought about that, the easiest place to put the controller is in the boot, but the battery is under the driver’s seat. I’ll see if I can find somewhere closer.

I had a similar suitcase panel, but wasn’t happy with the on board controller, so wired the panel ( bypassing the onboard controller) using M14 solar connectors to a PWM ( maplins 10A ) controller with a readout for amps, the controller was connectorised using these connectors and protested using an inline fuse in the same M14 connector connected to the leisure battery.

You then get to maximise your charging current by moving the panel to follow the sun, I got 10A on a good day.

A MPPT controller would be better.

https://uk.rs-online.com/web/p/solar-connectors/1931798/?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Power_Supplies_%26_Transformers_Whoop-_-Solar+Connectors_Whoop-_-1931798&matchtype=&aud-828361747427:pla-303106401315&gclid=CjwKCAjwoZWHBhBgEiwAiMN66YaqBIKRSeSDHd7TxcSaty3s2CESPjLjY62hEMwyvJ8ZK1q6TG3QZxoCs2AQAvD_BwE&gclsrc=aw.ds

I’ve got a 120w solar panel mounted flat on on my roof and MPPT controller. No split charger so mains or solar charging only. My thinking being charge via mains before a trip away and the solar will just keep the battery topped up (I’ve set the parameters to avoid overcharging). I’m not convinced it’s actually doing anything despite what the controller is saying. I need to get ammeter stuck in series and see if it’s actually charging 😐 as even after weeks of not using it, the battery is never anywhere near full. I guess the ‘120w’ assumes angled towards the sun whilst on the equator and clear sky. Be interesting to see what it’s actual churning out. I hope you have more luck OP.

It’s a PWM controller

A MPPT controller would be better.

+1

Going by the specs of the panels you linked to as an example, a PWM controller would top out at about ~80W (6 amps into ~14V). An MPPT controller could give the full 120W (~8.5A into ~14V).

ETA: 160W of solar flat on the roof of our camper easily keeps the fridge running 24/7 from April to September, except if there is a few days of hot, sultry, overcast weather – this is with an MPPT controller.

A MPPT controller would be better.

Ah, okay. Are the ones from eBay that are around £25 any good?

as even after weeks of not using it, the battery is never anywhere near full.

That doesn’t sound right at all.

Should be fully charged unless A. Your parking it in a cupboard or.B your batteries are banjoed C you’ve left something on

You can’t buy a MPPT controller for £25. It may say it is but it won’t be, it will be PWM.

Victron or Epever kit starts at £75, they are also much larger due to the components inside the box.

That doesn’t sound right at all.

Should be fully charged unless A. Your parking it in a cupboard or.B your batteries are banjoed C you’ve left something on

Or D the cheap controller that came with the panel is rubbish. Van gets daylight most of the afternoon (so not A), battery lasts a weekend running lights, charging devices and running a compressor fridge when fully charged (so prob not B) and I’ve installed a master switch which is left off (the control panel displays voltage/approx % if left on so it’s really obvious, so not C).

That’s my thinking too. My battery should be 100% pretty much all the time. I need to test the current to see if it’s actually outputting anything at all. If not I’ll swap the controller. If it is then I’m wrong about the battery.

Edit: it’s a PWM controller. My bad. Just looked and similar ones are £10 on Amazon… That might be the issue😂

Those Anderson connectors you linked to are great, but they are very bulky and you’d have to flood the terminal with solder and a gas torch to put your wires in. I’d go with a lower amp connector.

I have plug in panels as I normally have canoe on the roof. Although that comes off to put the roof up its easier to orientate the panel towards the sun than to move the van. And van can go in the shade and panel in the sun. Having the panel really facing the sun makes a big difference.

Victron controller in the van permanently wired to leisure battery. Anderson connector in engine bay and another connector on the panel. Then two leads one short if panel is just being hung on side of van or bonnet and one long if I want to park in the shade but have the panel further away. Don’t often do this as paranoid someone drives over the panel!

Might sound like a lot of hassle but its just part of the setting up camp routine.