Setec ST35-II with a 7 pin plug

[Peter D]

Hi All,
Our big trip is coming up, and I still haven't figured out how the power system works in our van (17.56-2), or whether I should attempt to improve it for the trip. We bought second hand, so I missed out on hearing an explanation of how the system works from Jayco (and the Jayco paperwork is too vague, while the Setec paperwork is too detailed!:dizzy. We share the van amongst our family, and while I've done a few modifications to it and have towed it from place to place, I haven't actually spent a night in it yet. Consequently I have a few basic questions about it all...



I have a 7 pin plug - am I correct in thinking that the "Aux in +ve" wire leads to the reverse pin on the trailer plug? And if so, would you then have to have your tow car wired differently to standard to make it all work properly (i.e. have something other than the reverse light hooked up to the reverse pin)?

We're going to be covering lots of kilometres each day on our trip, and stopping in powered caravan parks most nights, so the main objective of any mods to the electric system would be to keep the fridge cold (we have the smaller 104 litre fridge). If I run a wire from the car battery (6 b&s, with circuit breaker and a VSR, via anderson plug) to the van, should I hook it up to the battery or the fridge itself?

Any tips or advice would be much appreciated!

 

[Big Gee]

Hey Peterd,

I suspect from what your saying the best way for you would be with a VSR, Anderson plug & go straight to the fridge. If you plan on powered overnight stops then you will probably not have to worry at all about the house battery.

A couple of the auto elec's may shed some more light on the subject.

 

[Peter D]

To the fridge? Thanks Big Gee, I'm new to the world of auto electrics, but keen to do it myself, especially since I've got myself some decent crimping tools for the first time ever. I've nearly done my head in trying to figure things out doing searches on the net. If it all blows up on me, we've always got the highly efficient esky I just got on sale!

 

[boots33]

using pin 2 on 7pin plugs for power has been the "standard" for many years and you will find lots of vehicles wired that way.

As you are going to be wiring the tug from scratch I think 6 b&s and anderson plugs will be the way to go. Even though you plan to stay at powered sites you should run the cable to your battery and leave the fridge connected as it is, this will give you the ability to both run the fridge and charge your van battery at the same time while on the move.

You can use a vsr or a heavy duty relay that is switched from the ignition circuit. I like to run both a negative and positive so that means two runs of cable through your vehicle.
As your van is already wired you have a couple choices, I would use the existing wire that is connected to the trailer plug now. remove it from the 7pin plug and connect it to an anderson plug. all you need to run then is an additional 6mm wire back to your van battery for the negative connection. I would leave the positive wire connected to the aux in of your setec as it is now.
you could run 6b&s in your van also but i think for your purpose it would be overkill.

you should note.

the setec 35 requires you fit a fuse/circuit breaker no larger than 30a in the vehicle.
the fuse should be fitted as close as practical to the vehicle battery.
if you decide to bypass the setec and connect directly to the van battery you will need to fit a fuse at the van battery end as well.
if your fridge is not connected through the setec you should fit a low voltage cutout to it as well.
Take care when running your cables, watch for hot areas,sharp edges,areas where the cable will be exposed to damage. fit extra insulation where needed and secure it well.

 

[Peter D]

Thanks Boots.

My 15 amp projecta battery charger arrived today (IC1500). Would the projecta be any better than the setec for overnight charging? If so I'll take it with us on the coming trip.

I think I've got my head around the anderson plug in the tug, I'll get started on it, and give my poor old brain a bit more time to decide how to wire up the van.

 

[boots33]

Thanks Boots.

My 15 amp projecta battery charger arrived today (IC1500). Would the projecta be any better than the setec for overnight charging? If so I'll take it with us on the coming trip.

The series 2 setecs are 4 stage smart chargers and the st35 can deliver up to 15a to charge the battery, so i can see little reason for carrying another 15a charger. save the weight and use it to carry important stuff like more beer.

 

[Peter D]

The series 2 setecs are 4 stage smart chargers and the st35 can deliver up to 15a to charge the battery, so i can see little reason for carrying another 15a charger. save the weight and use it to carry important stuff like more beer.

I've seen so many people bagging the setec on the net, I was left wondering...

I'll concentrate on giving it a nice healthy 12v supply and hopefully that'll keep us happy - thanks again Boots.

I'm pleased with the projecta - my 100ah gel has gone from just under 10v to over 14v in around 5 hours.

 

[boots33]

Much of the negative comment is in regard to the series 1 version. They were not smart chargers and had a very high standby draw when not plugged in to 240v. When you consider the many many thousands of these units that are installed I'm sure you would be seeing more than a few bad comments if they were that bad. I have certainly never had any problems with mine.

 

[Peter D]

Well I've installed cable from car battery via anderson plug to the van battery and setec (6 b&s in car, 8 b&s in van, like Boots suggested) and it all appears to be working well, except the 12v light on the fridge power selector switch doesn't go on like it should. I didn't want to wait around with the car idling for hours to see if the fridge gets cold, so I slid the fridge forward and I could get battery voltage from the purple wire in the pic here:


Does that mean the fridge is working on 12v? Maybe just the led has gone kaput for some reason?

I still can't figure out how the wires on the fridge correspond to the wires over at the Setec and the battery. The fridge isn't connected directly to the battery, and the setec isn't connected to any of the slightly thicker wires which I can see feeding the purple and red wires on the fridge. And the setec fuse panel doesn't mention the fridge...


Is there some standard way these things are wired? Again, any tips/advice would be appreciated.

 

[Peter D]

A correction to above - the purple wire is fed by 2 skinny black wires, and they appear to be the wires plugged into "aux" on the setec, if I'm using my multimeter correctly. So fridge = Aux. Now maybe I just need to confirm that the only thing not working properly is the led on the fridge power selector switch...

 

[Burnsy]

G'day Peter D, in our 16' the setec and van battery had nothing to do with the fridge so I'm assuming yours would be the same. The 12V supply to fridge is only from your tow vehicle. hope this helps!

Cheers.

 

[Peter D]

I think I'm going to have to bite the bullet and pay an expert to sort it all out :eek: I plugged the mains in and turned the fridge on with a hot bottle of water inside the fridge, and 3 hours later, if it was beer it'd be cold enough to drink. Very pleased with that! Then I decide to check that the gas option is working, and I can't even get the hot plates to work, so I'm under the van looking for a tap that I may not have known about (other people use the van so I'm never sure what has changed since the last time I saw it). And I touch the chassis of the van at a particular point, and I'm recieving an uncomfortable zap of electricity through the frame :mmph:

I turned the 240v off and it was gone. It certainly wasn't a 240v zap - it must be 12v coming from somewhere (and I was touching the frame on the other side of the van and felt nothing). Times like this I wish my electrical engineer brother lived in the same town as me!

 

[ElectricGuru]

I think I'm going to have to bite the bullet and pay an expert to sort it all out :eek: I plugged the mains in and turned the fridge on with a hot bottle of water inside the fridge, and 3 hours later, if it was beer it'd be cold enough to drink. Very pleased with that! Then I decide to check that the gas option is working, and I can't even get the hot plates to work, so I'm under the van looking for a tap that I may not have known about (other people use the van so I'm never sure what has changed since the last time I saw it). And I touch the chassis of the van at a particular point, and I'm recieving an uncomfortable zap of electricity through the frame :mmph:

I turned the 240v off and it was gone. It certainly wasn't a 240v zap - it must be 12v coming from somewhere (and I was touching the frame on the other side of the van and felt nothing). Times like this I wish my electrical engineer brother lived in the same town as me!

Hey Peter

That is very scary that you are feeling a tingle and that it is removed when the 240 Vac is turned off.

If you want you can PM me your details and depending on where you live, I might be able to provide some assistance over a cold one...

It is possible for some leakage to be occuring but usually only on things like hot water elements. If you can feel it, then it may be something on the way out or some 240 Vac insulation on a lead or wiring wearing through. Not good either way...

Could also be that the van frame is not earthed properly when you plug the lead in. Without the proper frame connection, you become the earth return path when you touch it.

Let me know what you want to do as I would not advise you go looking for it yourself, especially with the 240 Vac stuff.

Cheers

Gil

 

[Peter D]

Hi Gil,

Yes, it's slowly been dawning on me the dangerousness of the situation. This after plugging the van back in a few times this afternoon and wandering around touching anything underneath made of metal! Even the brake drums give a tingle. Unfortunately I'm on the northside, may not be convenient for us to meet up, but thanks a lot for the offer. I'll send you a PM.

 

[Peter D]

Made some good progress today. Turns out the earth on the 40 year old power cord I had attached to the van was faulty - when I eliminated it the zap from the chassis disappeared.

Gil dropped around and checked that the wiring of the van itself was safe, and pointed me in the right direction for hooking up the anderson plug wire. Thanks heaps Gil! He even went easy on me when I had to confess to grinding down the pin on my 15 amp lead. What a guy! Will be checking out the Amp-Fibian/other legit alternatives this evening.

I rigged up a quick connector to test things out and have had the 12v led on the fridge switch lighting up, and now I've got a choice between 2 alternative ways of powering the fridge - either connecting straight to the battery, or via the setec

 

[cruza driver]

Good to hear its all sorted Peter, and a relatively easy fix that could have been dangerous if left unattended.:thumb:

 

[ElectricGuru]

Hey Peter

No problems, glad that you are sorting this out ready for the big trip.

Link to the diagram for my van wiring as discussed HERE. Just ignore the connection details for the solar at this stage.

Did you check the "birds nest" under the van by taking the cover off? I am guessing that there will be a join there with the big cables that come in from the plug and then go off to the fridge as well.

Take it easy on the road and enjoy!

Cheers

 

[Peter D]

Link to the diagram for my van wiring as discussed HERE. Just ignore the connection details for the solar at this stage.

Did you check the "birds nest" under the van by taking the cover off? I am guessing that there will be a join there with the big cables that come in from the plug and then go off to the fridge as well.

Yep, a few more answers to the puzzle were contained in the birds nest. That wire running from the birds nest to the back of the van, then across and forward to the fridge seems to be the weakest link as far as transmission losses go - the voltage drops .9v over that run.

I was thinking of plugging the anderson line into the setec, not the battery, and thus avoid having to buy a cut out switch for the fridge, but a guy I was talking to today was telling me the merits of having the fridge connected to the constant 12v of the battery, and not the fluctuating power of the alternator, [edit to add: though that said, a fridge is never hooked up directly to the alternator - there's always at least one battery between the alternator and the fridge, so I think the beers we were drinking may have been hindering the thinking] so I think I might bite the bullet and get the switch. And while I'm at it I can run a new shorter thicker line from battery to fridge.

In case the info is useful to anyone, the wire from pin 2 on my 7 pin plug runs down one side of the van, branches off and goes to the "aux in +ve" slot on the setec, and the other branch does a long loop around the back of the van and forward again to the fridge where it connects to the red "12VDC heating element" wire seen in this pic: