Trailer Lights Logic Circuit & Step Down Voltage Converter

[ntsqd]

Stumbled onto this while looking for something totally unrelated. I love the internet!

Seems to me that using the circuit below (I came up with it to solve a different problem) with 12VDC applied to the 30A breaker would do the trick.
Can one not just tap between the batteries of a 24VDC vehicle for 12VDC? If not, rather than polluting here could it be linked as I'm sure if that's the case that it's been discussed.

 

[KOOTENAY KRUZER]

Yes you can tap between the batteries but the one you are drawing from will have about half the lifespan of the other one. My experience.

 

[Ron R]

Never tap between the batteries!!!
It looks like a cheap solution to get 12 V but in reality it's very expensive.
How much will a good 30A converter 24V to 12V cost you? 150 Dollars? What will two batteries cost you?
Because you'll have to replace both, the one because it's constantly 'cooked' and the other one being constantly on low voltage. Replacing every year and a half or so.

No, THE solution is to use a DC/DC converter, nothing else. Put a relay in front of it and have it switched by the ignition key.

 

[KOOTENAY KRUZER]

I have used a tap between batteries since forever, one battery seems to last a few years, the other is good for about a year and a half like Ron R says. I am sure the one that lasts longer would last even longer if I wasn't doing this. Tried a converter but couldn't get one at the time that had enough power for my new stereo (well, it was new in 1983). Also tried adding a 12V electrical system but always had trouble with the alternator mount bracket. I hope to eventually resolve that problem when I go to put the truck back on the road.

 

[cavecan]

found many different 24-12 converters from Australia REDARC supply power conversion products to the global trucking and automotive markets around $100 us for 4 circuit unit 10amp they have a EB24A thing allows you to use 12 vilt electric brakes on 24 volt tow vehicle. I have orderd 1 of each tired of changing bulbs and lights to tow trailers.

 

[CruisingNaturalist]

Trailer wiring

Hi everyone. This is my first post.

I bought an 87 HJ60 a couple of years ago and put a trailer hitch on it almost immediately not knowing about the difficulty in the wiring. The guy just refused to do the wiring. I've been wanting lights since forever, and just haven't figured out how to do it yet so finding this thread is great.

What is the simplest way of dealing with this: I could get my brother to figure out the diagram and make me one, since I'm a little challenged in this area, or should I just buy one of those systems from Redarc in Australia?

Thanks,

Tim

 

[webbz47]

I built this 4 relay cct for my BJ70's trailer wiring and it seems to work well. You might be able to get away with 5A 24V relays but I used 10A. The outputs are switched at 12V so your 24-12V conversion is done with the relays not heat dissipating resistors.

 

[Stone]

<EDIT> Just noticed that Bruce still has the diagram in post #3.

Basic idea was to use the 24V relays as a logic circuit to turn the separate stop and signal lamps on the LC to the combined one in the trailer. The switched voltage coming into the relays was 12V from the Solar Converter or other step down converter...so no need for resistors. It worked well in my BJ74 when I had it...cheers.

 

[markthemenace]

Hello folks...my cruiser's finally been registered and insured! Got rid of the sealed beam on one side and dropped in an spare Autopal that I had lying around to complement the Bosch H4 on the other side. But I digress...

The NEXT order of business for me is to wire up trailer lights. The POseemed to have a trailer setup but I couldn't find wires anywhere. There's a hitch and all, but no wires that I can see. So...just a quick question, does the diagramme in Post #03 still the best one to follow? I can swing by NAPA on the way home to get the relays.

What about this little gem from princess auto. Does it help any?

 

[Estancio]

That Princess Auto unit does not have info on 24 to 12 volt conversion. It appears to be simply a connection box without actual voltage conversion. Just a hunch, based partly on that price.

 

[markthemenace]

OK...so that one's out. What about the relay option on post #03. That works good for most people?

 

[markthemenace]

OK, did some digging just now. I knew there must've been some trailer wiring done before...I mean who puts a hitch and not do the wiring? I opened up the rear washer-bag panel and pulled out a whole mess of wires.

Well, he's got wires tapped for running lights, turn signals and brake lights. Weird thing is, he's got TWO brake light wires. I guess i'll just seal one away. Everything is 24V.

So tomorrow, I'm off to Lordco for the 4 relays! A couple of questions first though:

1. Where do I get the 12V that's in the diagramme? Is this like headlights where the 12v is switched? Or is this a dedicated 12V that I've got to run from the front (my converter maybe?)
2. Why does the LEFT turn signal to three relays and the RIGHT one only to the RIGHT turn signal relay? I can understand the BRAKE signal going to all three, but why the LEFT turn signal?

Stone, your post with the pictures...do you still have those pictures? Would love to see your setup and how you store it all away. Thanks for all the help!

 

[chet]

the 12v should come from your converter.

2. the logic in post 3 will also make a 4 wire trailer plug that suits most trailers. The power for the turn signals comes from the brake light relay. when the brakes are applied it will send power to both turn signal lights. When the brakes are not on and power is applied to a turn signal power will flow from the normally closed terminal on the brake relay(87a) to the turn signal relay and out to the turn signal.

Clear as mud?

 

[markthemenace]

Hahahah, yes, it was totally mud for a few minutes, then a lightbulb moment. Understood, thanks Chet!

 

[HiQPen]

I am looking to convert the 24V to 12V with the redarc VRM:

http://www.redarc.com.au/products/product/compact-trailer-lighting-reducer_10a-4/

and then use a converter, just as you would any 12V cruiser:

http://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Curt/C56175.html

Probably not the cheapest solution. Does anybody see any other issues?

 

[lisponger]

Digging up an old thread as I work on a teardrop project that is 12v for a 24v truck...

Is the general consensus on this post is that the #3 wiring loom/logic box post will work? Or has there been anything new since that time (10 years ago!)


OR

Do I just purchase 24v LED bulbs and be done with it...

PS What seller do you all purchase your 24v LED lights from?

 

[Freewheel]

Yes, the #3 diagram will work. I built it in 2008 and still use it.

 

[Malahki]

Yup works great plus its simple and cheap!! Here is mine

 

[TLC Norway]

Family, I need a 7pole version. I don't like the clutter of all the relays.
I'm gonna ask a gifted friend to solder up some magic for me.

 

[Quat]

Has anyone used this in conjunction with a brake controller?
Looking to set up an HJ61 with a controller and 7 pin connector. I was going to order a redarc but then I'd still have to do something for the turn signals it looks like, so I am wondering if I could run a system like diagram #3 into a brake controller, and then have a converter to power turn signals and charging into the 7pin connector, along with a second relay system for the turn signals.

Thanks!