Thread: camper trailer questions...

Originally Posted by Scary

out of interest I just spoke to Southern Landrover here in Perth and they have 12s to Anderson plug leads in stock for $30.

I will confirm once I pick up.

Scary, I just called them to ask what they are rated at but they said they only had the 12S sockets and that you can wire up anything you like to them including an anderson Plug. The only problem is that you must still be aware of the rating of the vehicle cabling. A 12S to 50A anderson plug doesnt mean you can run a 50A load off the vehicle. It might be best to pick a plug equal to or lower than the the vehicles 30A rated supply and then ensure that it is wored so as to connect only to the battery positive and not the ignition positive as this is only 15A (at least on LR4's)

Originally Posted by Muddy Diver

This is one of the most useful responses i have seen Weakestlink, so forgive me for probing a bit more. Many peopole here are talking about placing the loads onto the ignition pin of the 12S socket, was that the case for you? and what size fuse blew, was it the cars 15A or 30A or was it an in line fuse? Sorry for asking but I am trying hard to determine whether peo-le are wiring to the incorrect circuits for the size of their loads as this is not made clear within the stories. the 30A Battery Positive pin should be wred with 33A Cable to the socket and is fused at 30A obviously. I think that people are not connecteing to this supply for fear of deadening their cranking battery. The answer is a low volts isolator to switch off the load when the battery terminal volts drop to a level which will still allow a start to be made.

I had a 2 new heavy wire lines run and cut the white plug off and terminated the wires to my anderson plug. 40amp Inline fuse very close the the dual battery.

(The LED light bar blew/melted a 15 then a 20am fuse before I replaced the wire to it)

RE a comment "a four inch nail is not needed" where a tack would work - conversely long runs cause voltage drop and importantly having enough or over capacity which will not ever hurt except your wallet perhaps. How much is needed to run a fridge, charge a battery and possibly charge via an inverter bits like laptops, camera and similar while driving is not an equation best left for chance. My fridge works fine when I load it fully with cold stuff in low temperatures and it will not use a lot of power to stay cold. Fill it with warm meat, fish or perhaps a case of beer up north and I assume it will be drawing a lot more power for a fair while to get and keep the temperature down. What we use, where we are and where we are going all seem to have an impact on this issue. None of us need 4wd or a snorkel, bull bar or dual batteries all of the time. When we use or need the normally unused bit it is of course when we are having the most fun. Not sure if the existing wire could flatten a battery or worse cause a fire. Happily I will not find that out myself.

voltages and drop in mine at the anderson plug (with engine off)


At the dual deep cycle battery

On the main cranking battery (under a year old)


The cable to my camping trailer was not here to test today sorry.

Originally Posted by Muddy Diver

Scary, if your Camper has an inverter fitted, this is not going to be much use charging your camper battery as the inverter is supplied BY your CT battery and converts battery DC to AC so that you can run 240V domestic appliances (depending on inverter size and type). If you are saying that the inverter is supplied by the Cars 12V output and a 240V/ 12V battery charger is fitted on the CT to charge on the run then this may work but I am not sure of how long this will take to charge your CT Battery and it isnt the normal set up to my knowledge.

As regards the adaptor I cant even find a plug supplier in oz! According to an Auto Electrician I spoke to yesterday, the wiring has to be rated at a minimum of 10% above the fuse rating, so it looks as though the 12V battery +ve wiring in my LR4 is rated at 33A which should be more than enough to run my Redarc 1225 charger. Although it is rated at 25A my battery should draw nowhere near that.

I'm still waiting for a response from Landrover regarding the OEM wiring suitability, the (non OEM) auto electrician yesterday said that it should be fine but then went on to say that I should add Anderson plugs front and rear so could have been upselling?!

ok so I may be way off track her but my thought was to run power from the car via the 12s and anderson plug that connects to the battery in the trailer so while we are connected the fridge etc is essentially running off the car battery/alternator and I was going to go with the ignition only pin out on the 12s connection.

Am I wrong in thinking that essentially the alternator will provide charge down the line to the batteries in the camper trailer?

Yes the inverter is from the batteries in the camper to provide 240 out.

The whole point for me is to have the fridge running on the car power while travelling but not taking the fridge out of the camper. When onsite the camper and all the bits will run on batteries and solar.

Correct me if I'm wrong as I don't feel like blowing anything up this week

Originally Posted by Scary

ok so I may be way off track her but my thought was to run power from the car via the 12s and anderson plug that connects to the battery in the trailer so while we are connected the fridge etc is essentially running off the car battery/alternator and I was going to go with the ignition only pin out on the 12s connection.

Am I wrong in thinking that essentially the alternator will provide charge down the line to the batteries in the camper trailer?

Yes the inverter is from the batteries in the camper to provide 240 out.

The whole point for me is to have the fridge running on the car power while travelling but not taking the fridge out of the camper. When onsite the camper and all the bits will run on batteries and solar.

Correct me if I'm wrong as I don't feel like blowing anything up this week

Scary. Your idea is sound but a few checks of current draw will prevent overheating anything. Initially i'm thinking that a cold fridge and a discharged battery on your camper, could draw more than the 15A available on the ignition circuit. This, i believe, is the reason why many complain that the electrics of the 12s socket are inadequate. (Although I stand to be corrected when my own set up causes a melt down). The 12S pin has a permanent 12 V pin but using this while the alternator is not running could drain the cranking battery so an isolator could be used to switch off the trailer should the battery voltage fall to a certain level. It will then switch the power back through to the trailer when the alternator is running again. 30A should be more than enough for a fridge and some battery charging. Just as a cautionary check though,and again more expert people might correct me, but if your camper batteries are AGM Deep Cycle types which are poular for this type of use, then you may not want the two batteries in parallel (connected together) and charged by the same alternator as I believe that the AGM will not like the higher charging rates of the normal cranking battery types. If this is the case and you don't mind wrecking the AGM's fine but to prolong their life (and they aren't cheap) I would suggest a 12v/12v charger be considered. Hope this helps.

Originally Posted by weakestlink

I had a 2 new heavy wire lines run and cut the white plug off and terminated the wires to my anderson plug. 40amp Inline fuse very close the the dual battery.

(The LED light bar blew/melted a 15 then a 20am fuse before I replaced the wire to it)

RE a comment "a four inch nail is not needed" where a tack would work - conversely long runs cause voltage drop and importantly having enough or over capacity which will not ever hurt except your wallet perhaps. How much is needed to run a fridge, charge a battery and possibly charge via an inverter bits like laptops, camera and similar while driving is not an equation best left for chance. My fridge works fine when I load it fully with cold stuff in low temperatures and it will not use a lot of power to stay cold. Fill it with warm meat, fish or perhaps a case of beer up north and I assume it will be drawing a lot more power for a fair while to get and keep the temperature down. What we use, where we are and where we are going all seem to have an impact on this issue. None of us need 4wd or a snorkel, bull bar or dual batteries all of the time. When we use or need the normally unused bit it is of course when we are having the most fun. Not sure if the existing wire could flatten a battery or worse cause a fire. Happily I will not find that out myself.

voltages and drop in mine at the anderson plug (with engine off)


At the dual deep cycle battery

On the main cranking battery (under a year old)


The cable to my camping trailer was not here to test today sorry.

Thanks Weakest link.

Forgive me, my comment about replacing a fuse with a 6 inch nail because it keeps blowing was directed not at your led lights but at the owner of the vehicle who suffered socket damage after running his fridge.I don't want to become a bore or labour my point already made but when a socket, designed for the purpose, overheats then it is wise to check out why rather than beef up the wiring else a fire in the trailer could occur. Anyhooo.

Thanks for your information and wow did you go out especially to take the photos and do the tests. Thanks! you seem to show a 0.2V drop at the cranking battery then. I guess you are showing that nice big cable is better than thin which you wont find me disputing. Thicker the better. so long as the circuit is fused for the load. For example, you can have 50A cable to supply 12V at 7M distance but if it's to run a fridge of 12A then a 15A fuse should be fitted. I'm fine with this. Again, i dont wish to be correcting your thoughts on this but would like to share a thought with you regarding your led fault. Without "being there" I would bet a squillion that the cable size was not the problem. If you will allow me I'll explain.

Resistance in a circuit limits the flow of current. Higher resistance = less current. Thinner cable offers greater circuit resistance not less. You get higher current in lower resistance circuits (try placing a low resistance spanner across the terminals of your battery (no...don't) Fitting thinner wire would have resulted in dimmer lights as more of the available 12 volts would be dropped across the wire leaving less to light the led's. BUt even this over 2m would be minimal (the difference between 5 sqmm and say 2 sqmm is only 0.1 of a volt, hardly noticeable at the light output) But the effect of the increased circuit resistance of the thiner wire would be to "resist" current flow in the circuit, not increase it. I think that perhaps there was a short to earth on your thinner wire circuit which was cleared by rewiring.

I am wiring a camper trailer at this moment and have decided on 50A cable to go to a box to reduce volt drop but which will have a 15A circuit breaker installed as that's just more than my calculated current draw. Safe

Originally Posted by Muddy Diver

Thanks Weakest link.

Forgive me, my comment about replacing a fuse with a 6 inch nail because it keeps blowing was directed not at your led lights but at the owner of the vehicle who suffered socket damage after running his fridge.I don't want to become a bore or labour my point already made but when a socket, designed for the purpose, overheats then it is wise to check out why rather than beef up the wiring else a fire in the trailer could occur. Anyhooo.

Thanks for your information and wow did you go out especially to take the photos and do the tests. Thanks! you seem to show a 0.2V drop at the cranking battery then. I guess you are showing that nice big cable is better than thin which you wont find me disputing. Thicker the better. so long as the circuit is fused for the load. For example, you can have 50A cable to supply 12V at 7M distance but if it's to run a fridge of 12A then a 15A fuse should be fitted. I'm fine with this. Again, i dont wish to be correcting your thoughts on this but would like to share a thought with you regarding your led fault. Without "being there" I would bet a squillion that the cable size was not the problem. If you will allow me I'll explain.

Resistance in a circuit limits the flow of current. Higher resistance = less current. Thinner cable offers greater circuit resistance not less. You get higher current in lower resistance circuits (try placing a low resistance spanner across the terminals of your battery (no...don't) Fitting thinner wire would have resulted in dimmer lights as more of the available 12 volts would be dropped across the wire leaving less to light the led's. BUt even this over 2m would be minimal (the difference between 5 sqmm and say 2 sqmm is only 0.1 of a volt, hardly noticeable at the light output) But the effect of the increased circuit resistance of the thiner wire would be to "resist" current flow in the circuit, not increase it. I think that perhaps there was a short to earth on your thinner wire circuit which was cleared by rewiring.

I am wiring a camper trailer at this moment and have decided on 50A cable to go to a box to reduce volt drop but which will have a 15A circuit breaker installed as that's just more than my calculated current draw. Safe

crack at nails was off target sorry and no apology needed. The biggest nail I have is myself
The minor voltage difference is the battery types, newer cranking battery is the lower but that is to do with the deep cycle battery I assume.
I will put the voltage thingy on another D3 or D4 in the white plug to see and will post it. Several pull up in front of my business at times. I have fun chatting not meaning to offend and refuse to be offended by almost any comment. I am always right as are people who disagree with me Every question on the forum often puts me off tangent looking at a perspective which is not alway suitable for others. 4wd tv on C31 tonight had a little on power draw YOUR4X4 I was working when taking the voltages and while half looking at 4wd tv.

Look forward to seeing your project. Have fun and keep us in the loop where your trailer gets towed too.

Originally Posted by Muddy Diver

This is helpful PHL thanks. I see that you have connected to the 12V Battery Positive as I plan to. What is the maximum current draw of your CTEK charger? Have you used it yet and was all OK? Thanks again.

So far I've connected the CTEK (5A) and solar panels (Theoretical max 10A, but max I've seen is 8A). In theory it should be good to 25A, as that's what it's fused for.

I'm contemplating getting a CTEK to cig lighter socket attachment, so I can keep the doors closed, and still get external power.

Originally Posted by Muddy Diver

if your camper batteries are AGM Deep Cycle types which are poular for this type of use, then you may not want the two batteries in parallel (connected together) and charged by the same alternator as I believe that the AGM will not like the higher charging rates of the normal cranking battery types

FWIW, my D4 (current MY13) has an AGM cranking battery.

I gather from Tim that the AGM can take a higher charging rate via a higher voltage. The CTEK also has a higher voltage for AGM batteries, or normal wet cells in cold temperatures.