Trailer Plugs - Round versus Flat

Submitted: Friday, Feb 05, 2016 at 18:11
ThreadID: 131553 Views:6644 Replies:14 FollowUps:28
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Greetings all.

About to get ourselves a brand new off road van to replace our camper trailer that has served us well for many years. Time for a bit more comfort.

Old camper connects to the car via a 7 pin round plug. New caravan I think comes with a 7 pin flat plug although I am sure I could get a round plug fitted if necessary as I'm paying.

Is there any major advantage of one over the other? I still need to have access to a round plug system as I borrow a mates old trailer now and then.

So my options are:-

1) Have the van manufacturer fit a round pin plug to the van.

2) Have a flat pin on the van, keep my car round pin and use a round to flat adaptor for the new van. Problem with this option is if the adaptor was taken by someone who wanted it more than me, I would be left with no van brakes.

3) Permanently fix a flat pin under my round pin on the car. Wiring from one to the other is a little difficult but could be done. Would then have outlets on the car for both van and the mates trailer.

4) Replace my round pin on the car with a flat and then make up an adaptor flat to round for when I borrow the mates trailer. Trailer has no brakes so no adaptor would not be too dangerous apart from no lights if it got knocked off. Probably no chance that an adaptor would disappear however on the few occasions I borrow the trailer.

Over to the forum for merits of flat plugs versus round plugs.
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Reply By: Roachie Silverado - Friday, Feb 05, 2016 at 18:35

Friday, Feb 05, 2016 at 18:35
The large 7 pin round plug (there are large and small sizes in the round shape) has larger pins and in my opinion is more robust and desirable.
I just went through the exercise of changing my camper trailer and box trailer over to the large 7 pin round type. Previously, my camper trailer had a 12 pin flat plug (7 "standard" pins over 5 larger pins) and 2 of the larger pins were used for charging the batteries in the camper. I changed it around so the battery charging is now done via a Anderson plug and the 7 pin round plug does everything else.
It is not a difficult job.....the kind of job anybody with a rudimentary screw driver set could undertake in about 30 minutes. There are very good wiring diagrams on the internet and the Narva plugs have the diagram on the back of the pack too.
Good luck,
Roachie
AnswerID: 595963

Follow Up By: Notso - Friday, Feb 05, 2016 at 18:57

Friday, Feb 05, 2016 at 18:57
Yep, I did the same on my caravan. 7 Pin Round and Anderson Plug,
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FollowupID: 864731

Follow Up By: TomH - Friday, Feb 05, 2016 at 19:13

Friday, Feb 05, 2016 at 19:13
Larger contacts transfer more current better. However an even heavier cable for Fridge and batteries is advisable Something like 6 B & S via Andseron plugs
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FollowupID: 864733

Follow Up By: Kenell - Friday, Feb 05, 2016 at 19:44

Friday, Feb 05, 2016 at 19:44
My camper had large 7 pin round and an anderson but my car came wired to 7 pin flat and anderson. The converters (I had 3 ultimately) caused me so much grief I changed my car fitting to the 7 pin round and no more grief. In the end converters are just another place for a fault or loose earth. On corrugations they shake loose sometimes too. Simpler the better for mine.
I am going thru the same process i.e. changing my soft floor for a hybrid. Interested in the choice you have made.
Ken
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FollowupID: 864735

Follow Up By: Member - Rosco from way back - Friday, Feb 05, 2016 at 20:21

Friday, Feb 05, 2016 at 20:21
Yep ....
Count me in on the 7 pin large round, for all the reasons stated above.
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FollowupID: 864737

Follow Up By: TerraFirma - Monday, Feb 08, 2016 at 14:03

Monday, Feb 08, 2016 at 14:03
In my case I had multiple trailers, boats etc all with 7 pin round so it was easy to stay that way. Also agree on the robustness, albeit I see many 7 pin plugs mounted so low on 4WD's that could easily be damaged.
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Reply By: pop2jocem - Friday, Feb 05, 2016 at 20:47

Friday, Feb 05, 2016 at 20:47
Personally I would go with option 3)

Maybe a bit more work initially, but once done no more worries about adaptors.

Also as has been mentioned, fit a 50 amp Anderson plug to charge any house batteries in your new van.

Cheers
Pop
AnswerID: 595970

Reply By: Member - Phil G (SA) - Friday, Feb 05, 2016 at 21:27

Friday, Feb 05, 2016 at 21:27
"New caravan I think comes with a 7 pin flat plug "
New caravans these days often come with 12 pin flat plugs and more, so you better ask the question.

Mine came with 12 pin flat (with extra pins required for fridge power, plus Breaksafe system plus fridge power sensing lead, plus Breaksafe battery monitor of you live in NSW),
plus grey anderson plug for house battery charging
plus a red anderson plug for the van's ALKO ESC
Plus a 4 pin connector for the reversing camera!
Phew!!
AnswerID: 595971

Follow Up By: Roachie Silverado - Friday, Feb 05, 2016 at 21:48

Friday, Feb 05, 2016 at 21:48
Crikey Phil,

By the time you get that lot all plugged in and ready to head off, it'd be time for morning smoko break!!! hahaha

Cheers,

Roachie
1
FollowupID: 864739

Follow Up By: Member - Phil G (SA) - Friday, Feb 05, 2016 at 23:04

Friday, Feb 05, 2016 at 23:04
Haha yes exactly the way I feel about it too - lots of gadgets but they are all boring!
1
FollowupID: 864742

Follow Up By: Member - johntoyo - Friday, Feb 05, 2016 at 23:44

Friday, Feb 05, 2016 at 23:44
Yes for me it had to be 12 pin flat, with a 50 amp minimum Anderson to the tug batteries through 6b&s cable. 30amp breakers at the tug battery.

Current drop and poor earths if you use the tug body etc. can be an issue.

Works for me, but we all have our preferences.
2
FollowupID: 864743

Follow Up By: gbc - Saturday, Feb 06, 2016 at 10:53

Saturday, Feb 06, 2016 at 10:53
12 flat seems to be the new 'standard' in plugs. All our new utes and trailers go that way. I don't see any reason to change and then use adapters.
1
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Follow Up By: Member - Phil G (SA) - Saturday, Feb 06, 2016 at 17:29

Saturday, Feb 06, 2016 at 17:29
At least with a 12pin flat socket you can plug a 7pin flat plug into it.
And the extra 5 pins are upsized to 35A so you can slip in a decent 8B&S cables (pair up the pos if you like) and you'll be adding an extra earth.
1
FollowupID: 864760

Reply By: Member - mepvic - Saturday, Feb 06, 2016 at 07:23

Saturday, Feb 06, 2016 at 07:23
Thanks all. Round pin and Anderson plug seems to be the way to go if possible. Will need to check with the van supplier on what they offer. I think they take power supply for the break away from the Anderson plug. Already have an Anderson plug for charging the camper batteries so will insist on this combination for the caravan if I can. My round pin has the usual trailer lights plus I've wired in a Tekonsha brake controller for the van brakes. Not used a brake controller before so it will be an interesting learning curve.

Going for an AOR Quantum Ken. Expensive but where we go and for our lifestyle will be well worth the extra $. Had a Kimberley Kamper for the last 11 years and have done over 120,000K with it. Fantastic unit but a little more comfort on the cold return to Victoria after 3-4 months north will make the life of a Nomad even more enjoyable for my lady and me.

Think option 1 the best. Simple, don't have to worry about piggybacking cables into my existing round pin and don't have the concern of losing an adaptor.

Thanks to all
AnswerID: 595973

Follow Up By: Member - John - Saturday, Feb 06, 2016 at 09:51

Saturday, Feb 06, 2016 at 09:51
G'day, just trying to clear up in my mind the following statement, "Not used a brake controller before so it will be an interesting learning curve." all Kimberley Kampers have brakes that need a brake controller to work and you have had one for the past 11 years, just doesn't make sense to me................
Cheers, John
John and Jan

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Follow Up By: Hewy54 - Saturday, Feb 06, 2016 at 11:54

Saturday, Feb 06, 2016 at 11:54
Brake controllers are only if you have electric brakes. Many KK's have hydraulic discs, so no controller needed.
3
FollowupID: 864749

Follow Up By: Member - John - Saturday, Feb 06, 2016 at 12:01

Saturday, Feb 06, 2016 at 12:01
Hewy, I thought they all KK came with electric brakes, either disc or mechanical.......... Cheers, John
John and Jan

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Follow Up By: Member - mepvic - Saturday, Feb 06, 2016 at 12:14

Saturday, Feb 06, 2016 at 12:14
Hi John. Is that why the Kimberley is hard to stop.

Just kidding. Ours is 11 years old and has hydraulic discs operated manually via an over-ride cylinder. Electric wasn't an option back then. Can get either electric or over-ride on the new Kimberley
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Follow Up By: Hewy54 - Saturday, Feb 06, 2016 at 13:01

Saturday, Feb 06, 2016 at 13:01
Bought ours in 2011 and had a choice of over ride or electric. Nowdays I think most people opt for electric.
2
FollowupID: 864756

Follow Up By: Kenell - Saturday, Feb 06, 2016 at 17:40

Saturday, Feb 06, 2016 at 17:40
The AOR Quantum is indeed a nice unit. We have ordered a Lifestyle Reconn after 5 bloody years of relentless searching. Reckon I could have moved to the Quantum with the money I have spent on caravan and camping shows. Think we'll be happy though (at least I will). Might go up a spec next time. Enjoy your new rig.
Ken
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FollowupID: 864761

Reply By: Member - John T (Tamworth NSW) - Saturday, Feb 06, 2016 at 07:50

Saturday, Feb 06, 2016 at 07:50
Hi Mepvic

The good folk at AOR will be happy to wire up the round 7 pin for you. Steve (owner) and Daryl ( service manager) and the team are more than helpful.

I bought a secondhand Quantum middle of last year and while in Qld had AOR give it a checkup. Cost to me - $0.00.

I use a 7 pin flat and an Anderson myself and have never had any problems such as plug coming out or the like. When the plug was fitted I sprayed t
All of the internal connections with varnish - stops the possibility of corrosion.

Cheers
John T (Lifetime Member)
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Selcall 2619
"Argue for your limitations and sure enough they're yours" - Richard Bach in "Illusions"

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AnswerID: 595974

Follow Up By: Malcom M - Monday, Feb 08, 2016 at 07:16

Monday, Feb 08, 2016 at 07:16
Spraying "All of the internal connections with varnish" would certainly stop any corrosion. Wouldn't do much for electrical connectivity either.
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Follow Up By: Member - John T (Tamworth NSW) - Monday, Feb 08, 2016 at 12:26

Monday, Feb 08, 2016 at 12:26
Malcolm

Once all the screws are tight the varnish will have no effect on electrical connectivity. The ADF ( RAAF in my case used a similar product on aircraft wiring to stop moisture problems on connections)

Cheers
John T (Lifetime Member)
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Follow Up By: Malcom M - Monday, Feb 08, 2016 at 12:45

Monday, Feb 08, 2016 at 12:45
Apologies, missed the fact that you have already assembled the connector before drowning it.
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Reply By: Sand Man (SA) - Saturday, Feb 06, 2016 at 07:58

Saturday, Feb 06, 2016 at 07:58
Request the manufacturer to provide a 7 pin flat trailer connector with a separate Anderson connector for the van battery circuit and 12 volt supply via the vehicle alternator.

Then, use a 7 pin flat to 7 pin round adapter to connect to your existing round vehicle socket.
The adapters are readily available from motoring retail stores, like Supercheap, Repco, Autobarn, etc.

There is no real preference for round over flat, but the flat plug/socket arrangement is much easier to wire and repair and is the pseudo standard.

If you "standardised" and changed your vehicle over to a flat 7 pin socket, the adapter can still be used when you borrow your mates trailer.
Bill


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AnswerID: 595975

Reply By: 9900Eagle - Saturday, Feb 06, 2016 at 07:59

Saturday, Feb 06, 2016 at 07:59
The biggest problem flat plugs suffer is when the plug is pulled out, people wiggle them sideways causing the pins to loose tension.

AnswerID: 595976

Reply By: Sigmund - Saturday, Feb 06, 2016 at 11:18

Saturday, Feb 06, 2016 at 11:18
Whatever you choose, for ask for alloy. Long gravel roads are rough on plastic.

And Anderson plugs can rattle loose and spoil your day. You can get mounts with a hinged cover that will clip around a lug that can be fitted to the trailer side plug - just the same way that a cover on a flat trailer socket will clip behind the lugs on the plug.
AnswerID: 595978

Follow Up By: Member - mepvic - Saturday, Feb 06, 2016 at 12:20

Saturday, Feb 06, 2016 at 12:20
Thanks Sigmund. I know all about Anderson plugs rattling loose. Destroyed many before I fitted the hinged cover maybe 4 years back. Used to carry 10 or so Anderson plugs as spares to replace the damaged ones until I discovered the hinged covers. They work well and have not had any problems since installed.
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FollowupID: 864752

Follow Up By: Sigmund - Saturday, Feb 06, 2016 at 12:37

Saturday, Feb 06, 2016 at 12:37
Goodo.

Many folk aren't aware of the problem and it happens commonly on rough roads.

One plug cost me $30 at Yulara!
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FollowupID: 864755

Reply By: noggins - Saturday, Feb 06, 2016 at 11:49

Saturday, Feb 06, 2016 at 11:49
Being a bit different I have an array of the 3 main plugs across the back of my ute.
The Small 7 pin the Big 7 pin and a 12pin Flat ( will take a 7 into it) as well as a 75A blue andersen plug for the van's battery power.
I do have a 75 to 50A converter plug if ever needed

I can plug just about any trailer into it, thank gawd they all use a std 50ml tow ball


zz
AnswerID: 595979

Follow Up By: Member - johntoyo - Saturday, Feb 06, 2016 at 17:19

Saturday, Feb 06, 2016 at 17:19
Noggins, I have the McHitch towing unit. Far superior imho than the 50mm ball.
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FollowupID: 864759

Reply By: Member - Julio C (VIC) - Saturday, Feb 06, 2016 at 15:00

Saturday, Feb 06, 2016 at 15:00
Take a look at " EZ Connector " not cheap but the best plug on the market.
AnswerID: 595984

Follow Up By: Allan B (Member, SunCoast) - Saturday, Feb 06, 2016 at 15:21

Saturday, Feb 06, 2016 at 15:21
'
And a steal @ $200.
Cheers
Allan

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Follow Up By: Member - mepvic - Saturday, Feb 06, 2016 at 16:08

Saturday, Feb 06, 2016 at 16:08
Now that's what you call a plug. Probably could do away with the Treg coupling as well and just use the plug for towing. Thanks Julio but I think I will stick with my standard 7 pin round. Can't see my mate putting one on the trailer I borrow from him either.
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FollowupID: 864758

Follow Up By: Allan B (Member, SunCoast) - Saturday, Feb 06, 2016 at 18:20

Saturday, Feb 06, 2016 at 18:20
'
I am not so sure that the "EZ Connector" is as good as it sounds.

The plug contacts engage by direct 'butt-connecting', i.e. simply face-to-face with no wiping action.
If there should be any significant debris (dust or sand) adhering to a contact face then there may be no electrical contact made. In industry, plug connections are arranged to have a 'wiping' action which dislodges surface debris. Heavy duty contactors (big relays or motor starters) are arranged so that their contacts incorporate some wiping action as they close. EZ's criticism of standard plugs with wiping contacts "abrading" or "arcing" does not stand up to industry experience.

The EZ website makes much of "Lab test results" (whose lab?) but quote only "Salt water spray","Submersion" and "Mechanical shock" with no reference to dirt, dust or sand....... the stuff that Australia is made of. They display a video of an EZ plug being cycled in-and-out of connection under electrical load but in a very clean environment. It proves nothing.
They make much of the feature that the magnetically retained plug will disengage should the vehicles move apart with the plug engaged. A good feature so long as they will remain engaged on our severe tracks!

The most odd feature offered is a range of adaptors to allow EZ to be used with existing standard connectors, which seems to rather nullify the benefits that they extol.
Cheers
Allan

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Follow Up By: Member - ACD 1 - Saturday, Feb 06, 2016 at 21:43

Saturday, Feb 06, 2016 at 21:43
Hi Allan

I am running an EZ Connector (as standard equipment) on my camper trailer.

So far I have had no issues with the connector not connecting properly, working loose or collecting excess dirt. Infact, I was so impressed with it I did not have a conventional one fitted to the new bumper when I replaced it. I am also replacing all the fittings on my trailers to match. In the interim, I am using an adapter to bridge the gap.

I have given it a fairly good run as we went around Australia with, like I have already said, no issues. This included muddy water, sand and high iron content sands (this is the only time I had to wipe it clean before inserting it into the socket). We also did a fair few kilometres on some severely corrugated roads including a trip to the Cape, Odnadatta Track, Gunbarrel Highway.

I have just licensed a new boat trailer fitted with an EZ Connector and the vehicle inspecton agent (a local trailer maker) was quite impressed with it. He liked the simplicity of how it joined together and separated (magnet) rather than having to wriggle them apart as usual. But, he was sceptical about its ability to maintain contact on rough roads until he tried to pull the plug off the draw bar to fit into the socket, the magnet is pretty strong.

So long as you remember to put the plug into the little holder, insert the plug into the socket to keep the dirt off when not in use and put some white grease on the two "O-rings" I don't think there would be any issues.

Cheers

Anthony
VKS 3539
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Follow Up By: Allan B (Member, SunCoast) - Saturday, Feb 06, 2016 at 23:00

Saturday, Feb 06, 2016 at 23:00
That's good Anthony and I'm pleased your happy with it.

I have no issue with the design whilst they remain connected but as you say "I had to wipe it clean before inserting it into the socket" and "So long as you remember....etc".

Regular pinned connectors can be reliable too if cared for in the same way.
Cheers
Allan

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Follow Up By: Member - John - Sunday, Feb 07, 2016 at 10:48

Sunday, Feb 07, 2016 at 10:48
Good morning, wonder how the EZ Plug would go in the Pilbara, oops dropped it, now can't get all the iron ore sand off the plug's magnet................................. Just a thought.
John and Jan

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Reply By: Member - Phil G (SA) - Saturday, Feb 06, 2016 at 18:01

Saturday, Feb 06, 2016 at 18:01
If you've bought a new AOR Quantum, I'd be very surprised if they had anything except a 12 pin plug, and most likely will have an additional anderson plug just for the battery charging. If so, I don't think you'll have any choice in the matter. They will require you to have the correct wiring on your tow vehicle before they will let you leave with the van. That was the case when I bought my van last year. I asked for a wiring diagram which they happily sent, and did my own wiring.

You need to phone them up, find out and just do what they say. But 12 pin plugs are great. The 5 extra pins are 35A which is more than your large 7pin round plug, and big terminals are a waste when all the lights these days are LED and draw very little current.

There's a lot of extra wires these days on a modern van - Brakesafe, ESC, reversing camera, anderson plug, extra earthing, and maybe an IGN source for a 3-way fridge but I expect the Quantum will be compressor. Its all good, and all serves a purpose, so go with the flow.
AnswerID: 595985

Reply By: Member - Leigh (Vic) - Sunday, Feb 07, 2016 at 11:14

Sunday, Feb 07, 2016 at 11:14
Having got tired of miss matching plugs I have fitted a female base plug to the draw bars of my trailers/ caravan and now use different leads with male ends to connect. Mates who use them make up and carry their own lead. Problem solved for me.
AnswerID: 595992

Reply By: swampy - Sunday, Feb 07, 2016 at 20:51

Sunday, Feb 07, 2016 at 20:51
hi
12 pin standard current features plus mid level current draw capable ,lights brakes etc

50 amp Anderson at least 6b&s cable battery charge

convert your existing car to 12 pin

use an adapter for round plug

swampy
AnswerID: 595999

Reply By: Malcom M - Monday, Feb 08, 2016 at 07:12

Monday, Feb 08, 2016 at 07:12
Make it fit your gear!
Use an adapter for any other peoples gear.
Your mate may not have a trailer for ever and blacktop use is not too likely to dislodge the adapter.
Rather silly building compromises right from the start.

I've always had flat connectors as they fit my trucks and trailers easier. Having said that the round plug does have a higher amperage rating but this has never caused me an issue. My serious power is via an Anderson which again is flat and fits my towbars better.
AnswerID: 596004

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