HI
Now that looks like the same set up that was proposed, by PeterD & others in the now closed thread. that was claimed would destroy every thing [electronics, Alternater ETC}
It is still simply picking up an ignition switched line to supply the coil with the fridge connected by the contacts to the tug battery!

But as I posted on the now closed thread IT does have one big disadvantage
The fridge is turned on immmediately you turn the key to 'RUN",even before you start the starter.
If the battery is sick or low on capacity ,the fridge load [15 <25A] could be the straw that breaks the camel's back & all that is needed to prevent the starter from turningthe motor over

This can be an even bigger problem with deisels & the preheaters

It also does not act as a low voltage cut out ,while the ignition switch is "ON" the fridge will draw power,the engine does not have to be running.
I pointed that out in the closed thread & gave my preference to a VSR.[Voltage sensitive relay]
Does not cut the fridge in until the tug battery reaches around 13<13.2 V , turns fridge OFF if the voltage drops below around 12.5>12.6V depending on brand & model.
.
But the model # of the 3way  fridge is equally important as many do have an inbuilt voltage sensor which shall be connected to the D+ terminal of the tug [or a similar point]
The correct operation & safety features depend on that connection with those models.

Depending on fridge model, MOST WILL COOL, not just hold while on 12v,IF,they are correctly installed

That means physically& electrically AND MOST ARE NOT

Very, very,few are wired with heavy enough cables from crank battery to fridge, resulting in excesive voltage drop & the fridge not getting its 'rated voltage['Min 12V]

even if only 1V is lost the fridge is only getting 84% of it's rated power

But Thanks for showing how to connect a common ignition controlled relay


ps
Using exactly the same set up ,with a higher rated [current] relay is commonly used for direct charging of VAN /auxilary batterries.but with the same disadvantages as posted above
Again A VSR is preferable

PeterQ

Blue wrote:

---

Hi oldtrack..

this IS NOT the same circuit as in the closed thread that I warned of..

peter dee's circuit was jacking directly into the "ignition" circuit of a 1968 Datus 1200 special.. or something like that..

mostly.. they don't exist anymore nor should that circuit that he put forward that would destroy a modern day electronic ignition system...

this system that I have put forward, is 100% accurate, to todays electrical systems.. there is no question... 100%

This is the Forums first Sticky,

 

if they want to grow up and become part of the modern world and not seen as silly old farts in Caravans as we are today..

Cindy needs to recognise this and join forces with other nomad forums to become a greater power.. to push for more free camping.. to push for our rights as Nomads, to travel this land without the hindrances of capitalists trying to force us into there worthless caravan parks!!!

---

IF this is typical of the Stickys, then GOD help all the readers

 THere is nothing wrong with the pics you have posted & yes the wiper line is ONE of the good points to pick up a line that is switched by the ignition switch

I have,from time to time used that point myself, purely because it was more convenient!!

But it is the verbal claims you make that are the problem.

IT is NO different to making ANY conection to the load side of the run position of an ignition switch

That is basically what PeterD showed 

A line from the load side of the ignition switch to the coil.

t

RE "mostly.. they don't exist anymore nor should that circuit that he put forward that would destroy a modern day electronic ignition system"

Please explain HOW it could destroy modern electronic ignition systems???

AND quote"peter dee's circuit was jacking directly into the "ignition" circuit of a 1968 Datus 1200 special.. or something like that.."

 What makes you think it is only relevent to that model vehicle??

It is typical of all coil/distributer type systems,. but that makes no difference in the end it is doing EXACTLY the same as your wiper connection

He is Still connecting to Run side of the ignition switch.

That is where the wipers/relays are connected.

He has connected NOTHING to the ignition system 

He has simply used that terminal as being a convenient point to get a direct connection to the load side of the ignition switch when it is in the run position, in the engine compartment

Anyone with an ounce of electrical knowledge would see that

Would you have been happier if he simply moved that connection to the back of the ignition switch? 

Even Google can lead those with only a little knowledge astray.

then another old saying

"A liitle knowledge can be dangerous" 

I do hope that Cindy does have the stickys vetted by QUALIFIED persons before they are allowed on the forum otherwise many many people will be led up the garden path.

PeterQ

-- Edited by oldtrack123 on Friday 31st of October 2014 11:01:44 PM

oldtrack123 wrote:

---

aussie_paul wrote:

---

On modern day cars does the ignition load side of the switch also power the ECU?

Aussie Paul. 

-- Edited by aussie_paul on Friday 31st of October 2014 10:58:04 PM

---

 

Paul

It does not matter what it powers .

If that  common point can run the wipers, radio, ,.some lights  window winders etc, or THEIR operating relays, all those things that only come "on" with the ignition switch in the run position, it can certainly run an additional  small relay coil.WITHOUT interfering with the"electronic" ignition sysyem or any other system.

 

PeterQ

---

Understood Peter, that is how I imagined it would work. Just checking that there can be no interference with sensitive electronics from that point. Playing devils advocate here..Thanks.

Aussie Paul. 

Blue  

and so it should be something we can pass on to our fellow nomads to save our viewers a few bucks... !!

 

 

---

 NO, NO

If such a sticky exists it should show all the options with their advantages & disadvantages & errors/ incorrect info  removed 

NOT just a one eyed" this is what I have or done so it must be best!!!

Or something found on" Face Book", or some other" I did it this way"

PeterQ

Well that's a bit rich. Blue canes me for wrong information in one thread and then posts the same solution on another thread. Be warned folks, this shows the value of Blue's advice. He does not seem to know what he is talking about.

The information in that diagram is what I presented to the auto electrician that did my work. I have two relays like both in the Dometic diagram and Blue's recommendation. One relay is energised by the accessories circuit for the battery charging line. The other is operated when the ignition switch is in the run position and is for the fridge feed. These relays have been operating for 6 years without blowing any of the logic circuitry under the bonnet

A word of warning regarding connecting things up in the engine bay of your tug, it is easy to cook something if you are not familiar with auto electrics. If you get an auto electrician to do the work then it is his responsibility to cover any damage. That is why they charge a lot more than a tradesmans wages to do the work. As well as the overheads he has to cover for his workshop he has to cover the insurance part of his work.

Redarc SB112 voltage sensitive relay is available for $106. Why would you stuff around trying to wire into the vehicle system, when you can fit a 100 amp "smart" relay, that doesn't require any tapping into the vehicle system. You have the advantage of battery power not being drawn by accessories until engine is running & charge voltage is  above 13.2 volts. (as previously stated)

I don't know if the 12 pin plug has a heavier pin & socket for auxiliaries. I certainly wouldn't advise anyone to wire a fridge through a 7 pin flat plug. Just not good enough.

Cheers Pete

dorian wrote:

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I agree that the VSR is probably the best solution, but at $106 I'd be very tempted to make my own. Surely it can't consist of much more than a comparator with hysteresis, plus a transistor driver.

---

 Woo Dorian, you're talking way above my head there. $106, (a good bottle of scotch, tank of fuel !!!!) I've been a heavy equipment maintenance fitter most of my working life & done a fair bit of auto electrical work. If we wired something, we would go into the store & select a wire that looked big enough for the job & never thought any more about it.

It's only since I've been doing a bit of work on rv's that I've started looking at wire size required for current draw & distance. Life's always a learning curve.

Cheers Pete

wasn_me wrote:

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1. Redarc SB112 voltage sensitive relay is available for $106. Why would you stuff around trying to wire into the vehicle system, when you can fit a 100 amp "smart" relay, that doesn't require any tapping into the vehicle system.

2. You have the advantage of battery power not being drawn by accessories until engine is running & charge voltage is  above 13.2 volts. (as previously stated)

3. I don't know if the 12 pin plug has a heavier pin & socket for auxiliaries. I certainly wouldn't advise anyone to wire a fridge through a 7 pin flat plug. Just not good enough.

---

 1. With a difference or $106 Vs $6 I will take the relay every time.

2. If you use the accessories circuit in stead of the run circuit, it is disabled while the starter motor is in operation. Problem solved. Also you have the option of getting a little extra power into your battery late at night if you have flattened thebattery. I had a battery that dropped its guts whilst in WA. If I put the ignition switch on the accessories position for 20 minutes before going to bed I would get enough battery if we needed to get up in the night. It would have been too much trouble to achieve the same result with a VSR.

3. The switched on vanners know that the the small round 7 pin and flat 7 pin plugs will not carry fridge power if your wiring is heavy enough to poser the fridge efficiently. We just need to convince the van manufacturers an auto electricians of this (I educated another auto sparkie only last week.)

Phil C wrote:

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Once again our "friendly" forum is descending into chaos, name calling and downright bullying. OH and look.. the same protagonists.

Im off to do some research and see just how many threads have been closed due to you lot, then I will raise a formal complaint with Cindy, as your attitudes are NOT what this forum is about or needs.

OMG cant you people get a dose of NICE!!!!!!

A very pissed off Phil C

-- Edited by Phil C on Saturday 1st of November 2014 09:55:23 AM

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 Phil from an " A " Grade Electrician..  I 'm not about to jump down your Throat.. But It does cause me to wonder WHY  A DIESEL MECHANIC is talking anything about Electrical of any form..

I'm not happy...

Juergen

This is the kind of circuit that comes to mind. The component values need refinement to achieve the desired cutin and cutout voltages.

                            Acc
                             +
                             |
                            .-.
                            | |                           Acc
                            | |                            +
                            '-'                            |
                             |                             |
       Acc                   +----+                     ___|__
        +                    |    |                     |     )||  |
        |             Zener  z    |                 D1  -     )||  |  relay
        |              6V8   A    |                     ^     )||   \
       .-.                   |    |                     |_____)||  |
       | |   +---------+    ===   |   IC1b                 |
       | |   |         |    GND   |                        |
       '-'   |         |          |  |\|                   |
        |    |   |\|   |          +--|-\         ___     |/
        |    +---|-\   |     ___     |  >--+----|___|----|  Q1
        |        |  >--+----|___|-+--|+/   |             |>
        +--------|+/              |  |/|   |               |
        |        |/|         22K  |        |               |
        |                         |   ___  |              ===
       .-.      IC1a              +--|___|-+              GND
       | |
       | |                            1M
       '-'
        |
        |
       ===
       GND

wasn_me wrote:

---

2.   I never considered the difference between accessory circuit & ignition circuit. A good point. A mate has his fridge wired through a relay powered from the wiper motor (ignition on). I must point out the difference to him.

I'm a bit paranoid about using start battery for any other purpose, if I stop in a remote location for a leak I'll leave the car running. I've had  a couple of start batteries fail after a long run & stopping (both had some age on them) ?????

3.  Is the 12 pin plug any different. ( I've only ever used andersen plugs)

Cheers Pete

---

 2.  There have been many threads on this and other forums asking where the best place to pick connect to a circuit controlled by the ignition switch. A favourite answer id the wiper motor power input, particularly on Toyotas.

If you have relay switched power feeds you don't have to worry about failing to start after a rest stop.

3.  Have a look at the OP. You will see the different sized pins on the 12 pin connectors. Pins 1 - 7 are good for 7- 12 A depending on the manufacturer. Pins 8 - 12 will carry 30 - 35 A. The small round 7 pin connectors commonly used in WA have the same size pins as the flat 7 pin connectors.