Yet another wiring question!!

[donh54]

Setting up a battery on the camper. I've got Tims' wiring diagram to follow (great work, mate!), only difference is that I'll want to have a solar panel hookup for whilst we're in camp.

Car has one of Tims' controllers (S 40 I think, without running out to the shed to check)

Solar panel has a regulator, etc built in, so that's all good.

Just wondering, if I put in a junction box on the line just before the trailer battery, will that feed the aux car battery as well (if it's hooked up, obviously), and, subsequently, the cranking battery, too?

Thanks in advance

[Homestar]

As in the line before the battery controller? Yes, that would charge the cranking battery and the controller would stay connected to the auxiliary battery while the sun was out and the voltage was high enough.

Where's the solar panel going? If you want to leave it connected to the auxiliary battery while you drive around for the day, then it would be better connected after the controller to the aux battery only. After all, the controller is there to make sure your cranking battery doesn't go flat. :)

So it will depend a bit on how you plan to use the panel and the vehicle a bit to what would be considered optimal.

[donh54]

No. After the battery controller.
I am looking at booking the solar up to the trailer.
While the trailer is sitting in one place, the solar system is charging the battery on the trailer.
What I am asking is, if the trailer battery is being charged from the solar panels, but s the car Aix, and main, going to be charged as well

[donh54]

I don't want you to over-read this, nor do I want to over-react to some fairly obvious points.
The car has a working dual battery system.
I am wiring up a trailer battery system as per Tim's system.
The only thing different from Tim's' system, is that I want to add a solar input to the system.
The solar input will only be used when stationary
I just want to know if a straight out junction box fitting will work or not.
Hopefully that's sorted out any misunderstanding

[Homestar]

Ah - all good, Yep, just whack a junction box in anywhere it's easy to get to the battery wiring. :)

[alien]

Ah - all good, Yep, just whack a junction box in anywhere it's easy to get to the battery wiring. :)
X2 or if you want to save on the work just use a double adaptor and use the Andersom plug
https://www.autoelec.com.au/ssl/public_autoelec/store_v4/product_detail.asp?id=1449&cat=28
I use one of these so the solar panel can charge just the trailer, just the cars 2nd battery or both.

You may have to check the specification or ring Tim to ask if your isolator will also charge the crank battery.
Usually it's not required as the car should be turned off and fridges etc. running from the isolated aux battery at camp.

[loneranger]

Something to consider if you are running the solar panel to the trailer battery and then using a junction box to charge your car is the voltage drop back to your car battery. You might be better with a double Anderson plug.

[drivesafe]

Hi folks and first off, alien, just be careful, that junction could potentially be quite dangerous, and it's not the first unit of this type I have come across.

The problem is that they have used 6mm AUTO "WIRE" ( 4.5mm2 ) to make the junction and then claim it has a 50 amp carrying capacity.

6mm AUTO cable has a maximum continuos current carrying capacity of just 38 amps and should be protected with no grater than a 30 amp fuse.

Now most dual battery systems, if done properly, will have at least 6B&S cabling ( 13.5mm2 ) and be protected with as high as a 60 amp fuse or circuit breaker.

I personally set up these systems using a 50 amp auto resetting circuit breaker, just for the added bit of extra safety.

By now you all get the picture. That setup is just not safe.

I make a STAR PLUG setup, to do what is being discussed here.

This is something anyone with the ability to be able to work thick cables can do but I also supply these on request, for $25 when bought with one of my kits.

I use three short lengths of black 8B&S ( 7.9mm2 ) and three short lengths of red 8B&S ( 7.9mm2 ) and wiring each colour in a triangle shape, placing two 8B&S cables in each of three Anderson 50 amp terminals.

This setup gives you an effective 16mm2 cable connection between the vehicle batteries and the camper trailer or caravan house batteries, so the whole cable run is not compromised by placing thin cable in the setup, like that 6mm plug setup would do.

Here is a photo of the STAR PLUG I make up to fit with the AL-KO system.

With a similar STAR PLUG made up using three GREY Anderson plugs, you could then safely plug your solar into the third Anderson plug.

https://www.aulro.com/afvb/images/imported/2016/10/256.jpg

[donh54]

Thanks for that info Tim.
The wiring is to be all 6BS. Trying to find a junction box with decent terminals is proving a bit tough, at least here in Warwick. May have to wait until I go to Toowoomba next time.
That plug system is intriguing. If I can't find a suitable jb I might try that.
Thanks again.

[DiscoMick]

We have a similar setup with a Traxide unit in the Defender linking two batteries, and a trailer battery with an Anderson plug directly off the trailer battery for the solar.
As Tim says the link between the two vehicle batteries and the Traxide has to be pretty hefty - ours is wired for a 60 Amp fuse.
If I want to use the solar to charge the vehicle I plug it into an Anderson plug in the vehicle.
As for the trailer, check the maximum output of your solar through the regulator and then size the wire and Anderson plug on the trailer accordingly, I suggest. Better to oversize than to undersize.
I doubt if plugging the solar into the trailer and leaving the trailer plugged into the vehicle would result in much solar power flowing back up from the trailer battery to the vehicle - too long a length of wire.
I'm planning to add a solar panel to the roof rack of the Defender to keep it charged when running our second fridge, a 35 litre Evakool, in the back of the Defender.
If you want faster solar battery charging in the trailer, you could put a DC-DC charger in the trailer, which could bump the current up to 20-30 Amps depending on the model. Make sure it is one which can accept solar input.
Hope that helps.

[donh54]

Thanks for the input, Discomick.

I'm leaning towards making a star plug like Tim's one above for the solar hookup, and using it at the connection between trailer and tow car. Saves adding extra plugs, joins, junctions etc, with the resulting voltage drops. There to the trailer battery is less than a 3 metre cable run, and about 4 metres to the aux battery in the car , all with 6BS cable.

I'll give the dc to dc charger a miss. Seen a lot of people waste a lot of money on them. For the amount of power we use, even without the solar panel, we get quite a few days before we need to top up batteries. Biggest load we have on it is a 35 litre Weaco fridge, which gets opened once a day, and a 14 litre one for drinks.

My power saving methods have been described as crude, but effective. For example, taking beer out of the fridge a six pack at a time, and drinking the last one before it gets too hot. :p :p

Thanks again to all for their input

[DiscoMick]

Thanks for the input, Discomick.

I'm leaning towards making a star plug like Tim's one above for the solar hookup, and using it at the connection between trailer and tow car. Saves adding extra plugs, joins, junctions etc, with the resulting voltage drops. There to the trailer battery is less than a 3 metre cable run, and about 4 metres to the aux battery in the car , all with 6BS cable.

I'll give the dc to dc charger a miss. Seen a lot of people waste a lot of money on them. For the amount of power we use, even without the solar panel, we get quite a few days before we need to top up batteries. Biggest load we have on it is a 35 litre Weaco fridge, which gets opened once a day, and a 14 litre one for drinks.

My power saving methods have been described as crude, but effective. For example, taking beer out of the fridge a six pack at a time, and drinking the last one before it gets too hot. :p :p

Thanks again to all for their input
How big is your solar? If you are going to try to charge two or even three batteries simultaneously you would need some big panels, at least 200 watts I'd think, to achieve a decent recharge.
Re. beer, I just put one or two in the fridge and replace them each time, so I'm only cooling 1-2 at a time. Or drink red wine, which doesn't need cooling.

[donh54]

195 watts (3 x 65 Watt panels)

When I was a lad, we used to drink our beer "Kimberley Cool" which meant it was cool enough not to burn your hand! :o

[DiscoMick]

Solar sounds good.


When I lived in Thailand beer came with a glass of ice. This had two benefits:
1. Didn't need a fridge to cool the beer
2. Beer got so watered down you could drink lots of the stuff and still walk a straight line.