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| kljw Member Since: 23 Jan 2009 Location: Edinburgh Posts: 265   
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hi all
there are lots of post relating to the installation of a second battery within the vehicle, and the charging systems that are required. what i am trying to do, is add a battery in a small trailer we use to carry camping kit, and thus wire it up, so that it get charges as we drive. the battery will be used to power a cool box. so the question i have is this; how do i go about it? i am having some difficulty getting my head around what is needed and how it should be wired. if anyone can offer, a very simple, but effective answer, i would be greatfull. even better, would be a list of parts i need to. Cheers keith puer claudius |
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8th Jul 2009 3:25pm |
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| kljw Member Since: 23 Jan 2009 Location: Edinburgh Posts: 265
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Grockle
kind of thought hat, but it's the wirring to the battery, from the socket that is causing the headace, need to know what i need, and how it goes together. the socket at the back of the 90 is not an issue. Cheers keith puer claudius |
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8th Jul 2009 3:58pm |
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| niglyn Member Since: 12 Jun 2009 Location: Surrey Posts: 82  
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If you do not wish to fit the 12s socket (I assume u have the 12n for the trailer lights) which will include a switched 12V, then you can do the following.....
Get a automotive relay. Mount this in the battery box. There will be four teminals on it. 2 terminals operate the relay coil. One of these terminals must be connected to the negative of the battery. The other, run out of the battery box & connect to a supply that goes live when the ignition is on. The genuine LR one for Puma, is run under the front carpet & up behind the radio. Take the radio out & the button immediately to the left (can't remember what it is, heated rear window I think) has a white wire with green trace, this is where the wire is 'T'eed into. Of the other two terminals, these are the actual switch contacts, one end goes via a suitable fuse & connects to the positive battery terminal. The other is the wire you run to your seconary battery. Whilst you are running this wire, also run the negative from the battery as well. So now, when the ignition is turned on, the relay is energised, thus making the switch contacts close, which then connects the secondary battery to the main LR battery and they will charge in parallel. That is all there is to it. In olden days, one would take the relay power from the dynamo charging warning light, thus if 'no charge' light comes on, the secondary battery would be disconnected. These were called split charge relays, but are no longer needed with modern alternaters. They also used to have two relays, one for the secondary battery and one for the fridge. In a modern caravan, the fridge is actually connected as I describe above and the caravan battery is connected via a relay in the caravan to the non switched 12v feed from the 12s socket. The fride also has it's own negative return. It does give compatability problems, but I think we are getting far too deep.....(it is quite easy to have a 12s socket that will work on old and new 12s standards, which is actually what I do, but we are now getting deep deep deep) To try and put all of the above into one sentance...(deep breath) with the engine running, both batteries are connected together in parallel, with the engine off, the secondary battery must be disconnected from the main battery. Did it ! 
The way I describe is exactly how the genuine LR 12s is wired. The genuine LR one also has a connector which plugs into the 12n loom to pick up the fog lights. The best bet might be just to buy a universal 12s towing socket assembly. They are not expensive (genuine LR one is over eighty quid!!!) and then you will also be able to easily connect & disconnect the trailer battery using a suitable 12 plug. I have fitted towing electrics to my 300 & 2 Pumas, so can speak from experience. Hope the above helps, if not, feel free to re-post or pm. |
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8th Jul 2009 9:08pm |
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| kljw Member Since: 23 Jan 2009 Location: Edinburgh Posts: 265
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niglyn
thanks for tha help, and that is exactly what i need to know. i will be fitting a genuine lr 12s socket at the back. i assume this plugs into the same socket as the 12n plug. does the lr12s have all the switching gear in it, to connect and disconnect the battery when the ignition is switch on and off? also, if there is a alrge load on tha lternator, say when driving at night with lights on and the heater blowing, will the 12s setup detect this and stop charging the second battery? if the above makes no sense, tell me, i will try and word differently Cheers keith puer claudius |
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9th Jul 2009 8:21am |
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| niglyn Member Since: 12 Jun 2009 Location: Surrey Posts: 82
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Hi Keith, do not know which model LR you have, I have fitted a genuine 12s to a 300 & puma.
On the 300, might as well save the money and buy a generic 12s assembly. For the Puma, the 12s kit comes with everything needed. 12s is pre wired onto the loom, relay, relay holder etc. The loom is 'telescopic and adjusts fo 80, 110 or 130. You can hear the engine note change if you plug in the 12s with the engine running, as extra load is put on the alternator. The old 'split charge' relays did indeed disconnect the secondary battery when the dynamo was no longer charging (remember the glowing charge light when at idle?) but this is no longer a problem with modern alternators. Nowdays the secondary battery is connected whenever the ignition is on. The loom splits shortly after the 12s socket, one part you run up under the wheelarch and up to the rear lights (you need to remove the plastic splash guard that sits behind the rear lights) Assuming a genuine 12n has been fitted, there will be a connecter on the 12n loom into which the connector in the 12s fits. This connects the fog & reverse lights to the 12s. The longer part of the loom you now run along the chassis and up into the battery box. There is a spare hole in the rear of the battery box with a rubber bung in it. It is tough rubber so you will need to drill a hole in the bung to pass the 12s loom through. The relay can be mounted in the battery box (I secured it with a cable tie rather than drilling a fixing hole). One wire connects to the + of the battery. There is a spare drilled hole on the battery terminal, so I found a suitable bolt & used this to attacjh the + wire. The instructions say to bolt the - wire onto the chasisi, but I prefer to connect directly to the - battery terminal. The relay actually comes on its own loom and so has to be joined to the main loom. The connectors are already on the end of the loom, so it is a simple mattter of pushing them into the relay holder. The final bit is to route the ignition sense wire. LR want you to drill a hole in the seatbox, just next to the cubby box then route the wire under the carpet, remove the radio & run the wire behind the dash and to the switch to the left of the radio. My slight change to this, I found a rubber bung in the top of the battery box and used this rather than to drill a hole. I did need to extend the wire a little so it reaches the dashboard switch. The genuine LR kit does come with a destruction leaflet and pictures. Took me less than 1/2 hour to fit, although I had fitted another before thus knew how to do it. Hope the above helps, N. |
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9th Jul 2009 5:38pm |
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| kljw Member Since: 23 Jan 2009 Location: Edinburgh Posts: 265
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niglyn
thanks allot for that, justy what i neede to know, much ap[preciated. have ordered the kit from land rover. also, i have a svx puma Cheers keith puer claudius |
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9th Jul 2009 10:45pm |
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| Lionel Member Since: 12 Aug 2008 Location: Melbourne Posts: 59 
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If you are wanting to charge an auxiliary battery in your trailer, I would not recommend using the trailer plug as a voltage source. A substantial current may need to pass if your aux battery is in a discharged state, so I would suggest at least 6 mm cable using Anderson power connectors to your trailer. The grey 12V 50A ones would be ideal. This will ensure minimal voltage drop to your trailer, with good current carrying capacity. Cheers, Lionel |
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24th Sep 2009 2:31am |
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| foz.in.oz Member Since: 31 Jul 2008 Location: Gladstone, QLD Posts: 64 
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Also ensure that you have fuses at both ends of the connections to the battery in the trailer and the car battery. A short in the cable form say an accident could lead to high currents and possible a fire. Land Rovers are an addiction. Toyotas are for quitters.
WWW.CQLROC.ORG |
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24th Sep 2009 11:55pm |
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