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TOPIC: Smart relays/ 12S wiring

Smart relays/ 12S wiring 9 years 7 months ago #179036

  • Netti_374307085
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RIGHT! Now I'm with you! I think.....I am such a girl when it comes to this stuff! I was getting a little confused about the Smart relay, I thought that was related to the more complex wiring system, which my car doesn't have but I understand now....Well, we'll soon see!



So, is this what I'll need - this cabling -http://www.towsure.com/product/565-S-Type_7_Core_Cable_-_Per_Metre Or more www.towsure.com/product/13912-21A_Single_Core_Cable_-_Per_Metre Or something else entirely. Can't seem to find the grade of cable my auto sparky was on about tho. No luck on Ebay. Maybe try motor factors?



One of these www.towsure.com/product/580-Inline_Blade_Fuse_Holder_-_30A



One of these cgi.ebay.co.uk/Smart-12s-Switching-Relay...QQrdZ1QQcmdZViewItem or this www.towsure.com/product/1828-Self-Switching_Combination_Relay



And a standard 12S socket for connecting everything to. I see you can buy just the sockets on their own, my auto sparky should be able to wire up the socket with the length of cable shouldn't he? And the fuse needs to be connected up at the battery end, the smart relay at the tow bar end and then to the socket on the towball?



Thank you so much for all your help Steve. I am taking my first trip with a van on the back on Wednesday, just with single electrics for the time being tho. I've put up a separate message about that tho. ;)
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Smart relays/ 12S wiring 9 years 7 months ago #179037

  • WatsonJohnG
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The only comment I would make to the above excellent advice is that I always run 2 seperate wires via 2 20amp fuses at the car battery to the relays at the rear as if one wire is used and the fuse at the car battery blows then the caravan battery can discharge into the fridge on tow

I have had this happen years ago before using 2 wires

I personally don't like the smartcom type of relay because of problems I have had with them not switching off in the past.

I have also seen(helped)other people on rallies where they have packed up or caused flat batteries so I use the 4 pin relays with a trigger from the car ignition circuit

That is just a personal preference and my friend who has an auto electrical business that includes towbar fitting assures me that they fit them and that the latest(now adjustable) version are OK


John
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Smart relays/ 12S wiring 9 years 7 months ago #179038

  • rosies
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As John says Netti there are several ways to skin a cat , all getting the same results . Naturally its your decision , or maybe your auto/elect, lol . split charge relay have been used for years and are well proven whereas smartcom relays are fairly new , but John has told me something I didn't know about the new adjustable types . So I can't advise you any further its your call . I will just leave you with more info on the smart relay I use .

type :- SMARTCOM (SC200) HEAVY DUTY 30 AMP

THE RELAYS SWITCH ON AT 13.5V AND OFF AT 13.2V

CABLE SPEC for battery to smartcom relay , single 44/o.33mm2 which is rated at 27.5 amps to minimise voltage drop . Inline fuse of 15/20 amp .



I have been trying to scan and copy and paste the instructions but I aint clever enough , it only scans into MY PICTURES as jpeg so can't copy , wish I was reasonable on these dam computers . Think they are for the young whiz kids rather than an aging single finger typer like MOI . BUT IT GIVES ME A LAUGH , Enjoy your time away and relax with hopefully some lovely sunsets , have a drink for me and please let us know how you went on with the break as well as the electrics installation . yours --- STEVE .
Yeti 170 4x4. Tourer and Trailer .
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Smart relays/ 12S wiring 9 years 7 months ago #179039

  • Netti_374307085
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John would the leisure battery discharging into the fridge damage the fridge? I know it's not good for the battery for it to go flat but I think those are easier to replace than a fridge.



Can 2 lengths of cabling be run into one single Smart relay? Or is the whole point that you only need one? If 2 cables, what does each connect to? Battery and ignition?



Finally, will a Smart relay normally come with wiring instructions? They're gobbledegook to me but my auto sparky needed the instructions for the bulb failure buzzer as he'd never fitted one before.
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Smart relays/ 12S wiring 9 years 7 months ago #179040

  • WatsonJohnG
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Hi Netti

It would not harm the fridge or any other appliances in any wa

The 2 wires would come from the car battery terminal each via an individual fuse and go either to 2 relays (smartcom or otherwise)or one combination relay which is just like 2 joined together

With the smartcom type as engine revs increase it senses the rise in current/volts and switches on automatically so it needs no feed from the ignition.The 4 pin relay needs a trigger from a car ignition source as well to switch on

The relays come with wiring insructions

Hope that helps

John
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Smart relays/ 12S wiring 9 years 7 months ago #179041

  • WatsonJohnG
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If using a dual smartcom it would not need 2 wires from the car battery as if the car battery fuse blew them no current would flow at all to the relay so the caravan battery drain would not happen as the relay would not switch on

stores.channeladvisor.com/towbar/Items/sc200

John
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Smart relays/ 12S wiring 9 years 7 months ago #179042

  • colin-yorkshire
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hi netti

I can not add much to the top class information you have had already from steve and john both spot on regarding relays



there are only 2 points I can think of that might help you

first the wire/wires that come from the car battery to the relays can be fitted underneath the car and cable tyed into position before entering the boot (relays in boot for protection) I say this because some cars mine included do not have any accsess into the engine bay from the inside of the car

without drilling a new hole(not recomended)



second the bulb failure buzzer only works on the indicaters not the side or brake lights and should come with its own wiring diaghram but if not basicly it will have 5 wires comming out of it one green,one green/white one yellow one yellow/white and one white

it is spliced into the 12N wire like this:- green to green from lights. yellow to yellow from lights .green/white to green wire to plug. yellow/white to yellow wire to plug. white wire to earth.the buzzer will sound only if all the lights are working.



hope this is not too confusing

colin
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Smart relays/ 12S wiring 9 years 7 months ago #179043

  • WatsonJohnG
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Colin that is so true of my new type Nissan X trail(no problem with the older type XT)

I tried for ages to find a way through for the wiring from the engine compartment and in the end used caravan black waste piping as trunking under the car with lots of nylon ties and avoiding the exhaust

John
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Smart relays/ 12S wiring 9 years 7 months ago #179044

  • rosies
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Hi Netti , You already have your 12n socket and wiring fitted so dont think about the bulb failure circiut as that should already have been taken care of by your auto electrician . The 12s socket is a completely differnt circiut apart from rear fog lights/ reversing lights . Again all excellent advice from John and Collin on underside cabling , its just that some vehicles have large rubber grommets ( seals between bodywork holes and items passing through the said holes in the bodywork ) which you can make a small hole in to pass a cable/wire through between engine compartment and interior . Such as around the steering column and main wiring harness .

Yes same as most things these days ( apart for ikea ,lol ) you get simple instructions with a smartcom relay , thats what I was trying to copy for you after I scanned it , but I am a dumbo in that department . I Know you said you where going away Wednesday so you will probably read these remarks when you get back . So please tell us how the first outing went , suspect you will have so so many question for everyone ,I am sure other vanners on here will love to help as well as tom , dick and harry , sorry Steve , John and Collin .

IF YOU LAUGH EVERYDAY THEN LIFE MUST BE WORTH LIVING , STEVE .
Yeti 170 4x4. Tourer and Trailer .
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