Connector recommendation - external, for solar

[Northwards]

Hi folks, 

Hard on the heels of my questions in the 'Fridges' thread I've found that my preferred connector solution won't work so am now at a bit of a loss to identify a suitable connector. Rather than take a thread on fridges off on a tangent I thought I'd ask here. I did search 'connectors' - but didn't find anything relevant in the first couple of pages. 

The idea is to carry a portable 100 or 120W solar panel to help run a fridge when camping in off-grid locations, or simply campsites with no hook-up. Roughly a 10A current.

Because we want the car in the shade (we are pale blue Scottish types) and the solar panel in the sun(!) I am looking at decently heavy cables something between 4-6mm² which would allow for a 10-12m cable run between panels and car without too much voltage drop.

I'd also wanted there to be an 'external' connection between the panel and the car - something mounted to the outside of the vehicle, rather than a cable coming in through a door or window. This would allow the solar panel to stay connected if you needed to go away and lock the doors for a short spell.  

My initial thought was 'magcode' connectors - a male and female magnet activated pair which would allow for frequent plug/unplug/plug cycles. They have 15 and 25A versions, so OK there. I really like the look and principle of these, but today I've investigated further and the datasheets say the plug side will only take 2mm² cable max.

I had thought of mounting the socket end at the top of the B pillar - a little bit sheltered by the rain gutter, and roughly half way along the car which means the solar panels could just as easily go to the front or the back depending on the site.  

So now I'm looking for a similar sort of "through panel" socket solution. I've looked at marine fittings, but nothing jumped out immediately.

As an alternative I've also wondered about using towing plugs/sockets - I guess I could mount one front and back, allowing the solar panel to be plugged in either end. The other option I've looked at are the smaller end of the Anderson connector range. Maybe I could mount one of these front and back...? Quite small and discreet.

I'll admit I'm a compete solar newbie, so there may be some basic reason this won't work, and I'd be happy to learn this sooner rather than later. On the other hand, if anyone has any experience or knowledge of a particular connector that might suit this requirement I'd be glad to hear it. 

At the moment, the Anderson connectors, fitted front & rear, strike me as being the front runner but maybe there's something else out there which would do the job? 

Thanks as always.

 

[muddy]

I would vote for Andersons but 175A so you can use them as jump start points.

[L19MUD]

27 minutes ago, muddy said:

I would vote for Andersons but 175A so you can use them as jump start points.

I would second that and have a set of jump leads that plug into mine. The rear one also runs the tipping trailer and a winch on the front of a trailer if needed

[Northwards]

Thanks very much to both. At the moment those options are probably a step too far for me.

I had originally written, and then deleted because I thought my post was already too long, that the wiring from whatever connector I use will run to an MPPT solar controller, and only then to the battery. 

[landroversforever]

5 hours ago, Northwards said:

Thanks very much to both. At the moment those options are probably a step too far for me.

I had originally written, and then deleted because I thought my post was already too long, that the wiring from whatever connector I use will run to an MPPT solar controller, and only then to the battery. 

I was going to say it would need to do that so no good for jump starts. 

I’d go for something like a Neutrik Powercon connector. Used in the AV industry for power upto about 20a so perfect for something plugged in and out regularly. You can get the sockets with a cover which makes them IP54 from memory. Or just make a little flap/connector box etc to keep the worst off. The connector and socket together are reasonably well sealed/mechanically protected. 

[Bowie69]

For solar, go big on the connectors and cable, voltage drop is a real efficiency killer.

For your ~100W panel you need at least a 20A connector,  but that is only half the story ... most 20A connectors won't take the previously mentioned 4mm2 wire. 

I'd just go anderson ~50A, or whichever takes 4mm2 comfortably, well proven connector for this sort of thing. 

[muddy]

I forgot about the controller! is there a way to have the controller with the panel? im not sure where you want the most cable run to minimise losses.

[Northwards]

Thanks again.

Andersons are still the front runner, though I’ll take a look at those Neutrik ones. Though I’ve never used Andersons myself I do know they are well-regarded. I know you can get covers etc, but how well do they cope with moisture? Pretty well I’d have thought given they’re often used for winches etc?

On the question of controller location, some of the suitcase kits you can get have the controller stuck on the back of the panel, but I was told that this isn’t a great place to put it as it gets hot, which reduces efficiency. I think Victron (I’ve bought one of these) recommend having the controller as close to the battery as possible, and that does make sense when it’s being integrated with other stuff.

I have also wondered if I’m over-thinking this, and that putting the charge cable in through a window and then locking the door would be fine for the sorts of locations I’m most likely to be in. This would mean one connection, probably still an Anderson, but with no concerns at all about moisture.

[Ed Poore]

2 hours ago, muddy said:

im not sure where you want the most cable run to minimise losses.

The run with the highest voltage on it. There's a reason that the UK power distribution is done at 400kV .

The technical reason is power lost in a cable is due to it's internal resistance and is calculated by P=I²R (P is power, I is current and R is resistance). So to reduce power loss in the cables the quickest way is to reduce the current. Given that V=IR as well (Ohm's law) then in order to transmit the same amount of power down a cable you have to up the voltage.

It also allows you to use lower quality conductors (just as CCA - copper clad aluminium) which may make the transmission line cheaper overall whilst maintaining the same design criteria.

Note this works for all kinds of cabling not just power transmission and AC as well except you use the RMS value rather than peak.

As an aside the resistance of a cable is given by R=pl/A where p is the resistivity constant of the material, l is the length and A is the conductor surface area. So you can see why larger diameter cables are better for reducing power loss as they decrease the overall resistance.

One would assume that a solid cable would be better but that's not strictly true, p changes with temperature (sometimes quite drastically). Lots of fine strands within the cable are not only a more flexible cable but also provide greater surface area for heat to dissipate thus keeping the resistivity of the cable down.

[Snagger]

Small Anderson sockets would work well enough.  You’re worried about moisture - don’t be, just give the contacts a dollop of Vaseline and they will be well protected but won’t get the grease on anything else because of the shrouds around each contact protecting them from wiping the grease on other items.

As Ed says, keep the high voltage from the panels for as much of the run as possible and site the controller/chargers close to the battery.  In a typical Defender, I’d mount the controller inside the battery box under the passenger seat and the Anderson socket on the top of the seat base in the void under the front edge of the seat or on the front of the seat base, trailing the cable to the panel out of the bottom rear corner of the door - it will prevent water running into the cab through the breached door seal and will also give the weakest pinch on the cable.  I don’t like the idea of easily accessible sockets outside the car unless they are on a switch and fuse, as too many thugs like to sort them out to burn the car.

If you are determined to have a permanent external socket, I’d look at fitting hinges and strong magnetic catches to the dummy heater intake grille on the driver’s side wing top, with the socket hidden underneath, or simply mounted to the bulkhead under the bonnet so the wire can run through the bonnet edge gap to whichever side has the best sunlight.  Simple is good.

Bigger Anderson sockets on the front and rear ends for jump starting are a nice idea, but those lengths of cable need to be heavy gauge to avoid losses and again need to be on an isolator inside the cab to ensure they are dead at all times not in use in order to prevent them being abused.

[landroversforever]

I’d probably avoid the Anderson’s if you’re going to put any lube etc on them… they’ll just attract dust and dirt as they’re not very well sealed even with the caps. 

[fmmv]

You might find something suitable in the Bulgin Buccaneer range, and they are well sealed

[hurbie]

2 hours ago, landroversforever said:

I’d probably avoid the Anderson’s if you’re going to put any lube etc on them… they’ll just attract dust and dirt as they’re not very well sealed even with the caps. 

that's very easy to fix , mount your anderson connector the normal way , and get the sikaflex out , fill the back of the connector around the cable with the sticky stuff ... put on some grease on the contact's and a dustcap to finish ...

works for years on HGV .... so may be usefull on our hobby vehicles 🙂 

[Snagger]

21 hours ago, landroversforever said:

I’d probably avoid the Anderson’s if you’re going to put any lube etc on them… they’ll just attract dust and dirt as they’re not very well sealed even with the caps. 

Only if fitted externally, which I wouldn’t recommend for vandalism reasons, as I said.

[Northwards]

Thanks all for your replies.

I have to say that vandalism as described above just hadn’t even occurred to me. I guess that’s to do with where I am.

When I was initially thinking of mounting plugs externally, my thought was the black Anderson SB50s, and located as discreetly as possible so as not to attract attention. Given the replies I think I’ll now row back on that and fit one inside somewhere that’s easy to get to.

The controller will be inside/to the back of the battery box so somewhere close to there. Front of the seatbox as suggested, or maybe to the rear. 

[Peaklander]

My controller is at the back of the seat box as there's more room behind the batteries. If you mount at the front, you might still have a spider in the way (splits the immobilise signal from the 10AS to the starter, IP etc) and anyway doing that pushes the batteries towards the back. This makes it harder to get to and protect the terminals. There's a decreasing amount of verticalness  as you move to the back of the battery box. I have two batteries side-by-side across the box.

There is also room on the outboard end of the battery box (alongside the door) but I have a distribution fuse box there.

[Snagger]

34 minutes ago, Northwards said:

Thanks all for your replies.

I have to say that vandalism as described above just hadn’t even occurred to me. I guess that’s to do with where I am.

 

I have become very concerned about such things ever since the reports of the rash of vandals in Australia shorting out winch control ports after running the winch rope over the roof of the car and attaching it to the tow hook to cut the car in half with its own winch around 20 years ago.  With the rise in the aggression and self-righteousness of modern environmentalists, I usually expect the worst.

Internal connection would prevent the above, keep the contacts clean and avoids drilling any holes in the body that may leak.

[Bowie69]

So would an isolator.

[Snagger]

Isolators prevent shorting, but not the dirt and corrosion.

[Bowie69]

But the cap, petroleum jelly and sealant sort those out.

[Northwards]

3 hours ago, Peaklander said:

My controller is at the back of the seat box as there's more room behind the batteries. If you mount at the front, you might still have a spider in the way (splits the immobilise signal from the 10AS to the starter, IP etc) and anyway doing that pushes the batteries towards the back. This makes it harder to get to and protect the terminals. There's a decreasing amount of verticalness  as you move to the back of the battery box. I have two batteries side-by-side across the box.

There is also room on the outboard end of the battery box (alongside the door) but I have a distribution fuse box there.

Though my car is too old to have the 10AS and spider unit, my set-up is already non-standard. 

On the front of the box is the VSR and an isolating switch. The highlighted boxes show where I'm planning to put another fuse box and an overall charge controller. 

Then this one shows where I'm planning to put the MPPT controller - on the back wall of the battery box.

I didn't do the accessory/split charge thing shown here. To be honest, rather than going for the middle of the available spaces, it could have been installed a bit more thoughtfully, allowing for future options, but hey ho. I could move stuff a little, but then need to take more time to seal up screw holes etc. Having made up cardboard templates for the units to go in, there's just enough room for installation plus getting the wiring connected.

Anyway, this is the plan. I just need to sit and have a think now about where's best/easiest for the solar panel plug to go. I think I'm comfortable now that Andersons are the things to use -  it will just be a compromise now between ease of fitting/wiring access as well as ease of access/flexibility when plugging in the panels. 

There will be a new, dedicated plug for the fridge going in, probably fixed to the cubby box, on the passenger's side. If I'm putting in an additional connection there, it might make sense to put the solar in there too..... still thinking... 

[Peaklander]

I realised that my fridge cable was dropping a volt between the battery box and fridge (behind the driver). I upped the cable size and reduced the length of 'slack' plus I swapped the (high quality) cigarette joint and now use a small Anderson. It has made a big difference as the fridge now sees the full battery. It was cutting out on low volts, when my previous battery was down on charge but not at the cut-off voltage as shown at the dash voltmeter.

For interest, what are all the relays for? You haven't used standard LR wire colours so it isn't obvious Edit although they are perhaps not for standard circuits 😊

 

[Northwards]

Thanks Peaklander - that's useful information/context on the fridge wiring. I had thought to use a better-than-average cigarette socket, but based on this I might as well go straight to the Andersons.

The relays are for the accessories wired/switched through the cubby box. The switches run: roof lights; A bar spotlights; heated seats; heated screen.

That's still what I have in place, except that the dodgy home-made cushion has gone. Once I'd put a subwoofer speaker in an enclosure under the cubby, it lifted the whole thing too high. 

Like I said, I didn't do this initial wiring job, but I was given a file/document with all the colours itemised, including 'spare' wires run during the installation for future use - and I have used a couple. I guess there must be standard LR wiring colours for some of these things - heated seats for example. I don't really know whey they wouldn't have been used. 

Having owned the car 20-odd years I have done little bits and pieces of electrical work over time, and eventually realised the huge benefit of sticking to standard loom colours, so when I rejigged some of the dash wiring to fit a Raptor console, I bought a few lengths of relevant standard colour cable and used that where needed.

If you're intererested (or bored!) when I joined Lr4x4 I think I posted a link to a build thread on Defender2.net, where I've been a member longer. It's not quite up to date, but near enough.

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