6MM wire for Fridge

Hi there,
I will check cig lighters for rating. I do run duel cig lighters there already.
Other than that, thankyou for your time and input.
I have enough here between all the replies to carry out the job properly.
Thansk again
Angelo

Hey Vince,
The way I see it mate is... if your fridge has been working fine for awhile then you are probably safe. I am just trying to do the best i can INCASE one day that 4mm wire lets go. Last thing i want is to be replacing wire while camping out bush.
Still well worth a look though. No need to panic mate, I would say its fine.
Regards Angelo

Hi Vince, if your power outlet is marked as 40 amps then it is pretty safe that it is that.
The wire might be another thing, most, if not all car makers over rate the amount of current you can put down a given wire. They all depend on the fuse to protect the given wire, which the fuse does and does safely.
What you may find is that the wire because of it’s size and length, can not actual deliver the correct current at the appropriate voltage.
So as you load up the wire, you drop the voltage. Some devices such as the motor in your fridge will increase the current required to operate them as the voltage decreases.
If you are planning to check the wire size, you will probably find that it is 4mm if your lucky. That’s the thickness of the wire as measured across the insulation not 4MM squared. At 4mm you will be lucky to get 15 amps max before you start to get a significant voltage drop. Further more as has been posted above, using the chassis as the earth return is not a good idea and you can bet that if it is a factory installed power socket that it will be earthed that way.
If you think you need to upgrade the power socket wiring, try running some thing like 8 B&S, this is 7.9 square and this will not only give you adequate power at the socket, you will have the bases for adding other outlets with having to run more wire.
Just an idea, Regards

Thank u Gerry, i have all i need now,
Regards Angelo

what gerry said.

When we (over)use the 6mm saying, we should be saying 6mm squared, not 6mm as measured across the wire. (that would be a pretty serious wire just to run a fridge off!)

Thanks for that Jeff.
Always interested i others opinions.
Regards Angelo

Angelo
As long as it is 6mm2 (pronounced "six-millimetre-squared") it should be fine... and there are two types of building wire... multi strand and single strand, although I am not sure if single is available in 6mm2... but get multi strand always!
Any electrical wholesaler will have the 6mm2 cable.. Haymens,John R Turk, Ideal etc etc....

Nah, that stuff 2.5 mm2 (square millimetres). Its ok at 240v for but not at 12v (from memory its rated to 28amps). I got my 6mm2 at Autopro, but Dick Smiths got it also, Sparky's 6mm2 is also hard drawn, meaning its not as flexible as you should have for the car, so forget about that too.

Current flows the same for 12v or 240v Rolande, as far as my elec theory schooling told me. That said I would always use proper flexible cable for vehicle wiring, and not the stuff you wire your house or shed with. Even multi strand house wire is too rigid for use in cars.

Knew there was a reason somewhere, must have got my wires crossed. :)
LOL
Rolande

hahahahahaha wires crossed hahahahahahaha oooops you're not serious are you? in that case excuse me hehehehe

pun definitely intended :)
Rolande

Jaycar Electronics will have everything you need - check this thread for the wire diagram: http://www1.jaycar.com.au/productResults.asp?FORM=CAT

Check out the on-line catalogue for connectors/ terminal/ fuses etc

It is not necessary to run a separate wire back to the bat. negative terminal, it is just necessary to have a soldered terminal fitted to the neg wire and that in turn secured under a solid body bolt/screw. If you look at the neg terminal wire at your battery you will see that it is attached to the vehicle engine or body, and the whole vehicle is therefore a negative attachment to that battery. Well made, solid connections are always a part of successful hook-ups.

I worry about ciggy lighters as permanent connectors as the plugs can vibrate and cause shorting and failed connections. The very best 2 pin connectors are the Anderson plugs - they really lock together and can carry up to 50 amps. I find them hard to come by but trailer manufacturers & some auto elects have them

Hi cocka, I’m sorry but the info about using the chassis and/or body work as the earth return is not good practice. 9 times out of 10 you will probably get away with it. But when it does not work properly, it’s a major time consuming problem to resolve. It’s industry standard practice to run both the positive and the negative wires at the same time. Also, the higher the current the more likely the chassis will turn in to a resistive path back to the battery and at 50 amps, I would lay money on someone using the chassis to carry the sort of load ending up having loads of problems.
And as a side line, to use the body or chassis you would need to remove the paint and in doing so remove any rust protection and if I was the owner of a new vehicle and some installer did that, well you can work that one out for your self.
As for soldering connectors, you will have a much better connection if you use crimp connectors and the correct tool to crimp them. If you want to solder after crimping, do so but after soldering a cable that is going to carry high currents, it’s a good idea to clean away any flux. Otherwise if the wire warms up, and with those sort of currents there is a good chance the wire will run warm. If it does then the heating of any flux may start some major corrosion problems.
When using Anderson plugs, unless you have the $400 dollar crimping tool then yes you will have to solder but just remember to clean up the solder connections after and coat the solder and beared copper with something like lanolin spray to water and rust proof the connection.
By the way, Anderson plugs are about the best battery wire connectors you can get and they are commonly available in 50 and 175 amp ratings.
I manufacture auxiliary battery charge control equipement and supply it to the trade. I also do the occasional install and where possible, if the batteries are permanently fitted, I always try NOT to put connectors of any form in the cable running between the batteries or from the battery to the device ( not always possible ) as every joint and connection is a potential resistance point.
Regards.

drivesafe,
try these sites for a few hours of pure enjoyment..........

http://www.dse.com.au/cgi-bin/dse.filereader?40680b850c9d08e6273fc0a87f9c070b+EN/catalogs/DTA0000010

http://www.the12volt.com/ohm/ohmslaw.asp#pie

http://www.powerstream.com/Wire_Size.htm

Drivesafe I guess by your trade you have had a look under a few engine lids but your not being very observant. In most vehicles the neg (-) pole of the battery will have one (large dia) short wire coming from it attached usually to the engine block. The whole vehicle therefore becomes the negative (earth) conductor to form the circuit back to the battery from every switched on device on the vehicle. It is common sense that any terminal that I might make to an earthing point is adequate in size, and is secured firmly under a bolt that is pulled up tight on its bear metal threads and the bolt has a much larger surface than the attached earth wire.
One would also choose a location that was preferably dry and the terminal sheathed.
I will concede that there is nothing wrong with running a return wire from an appliance but the Q is, is the wire thickness adequate enough to balance the slightly shorter distance that might be achieved in running a separate wire back to the battery. I don't think there is enough gain to worry about the effort. The vehicle is a great earth, use it.
As for using solder, remember it's mostly lead, the same as the battery terminals, so its an ideal conductor and I'd like to think my fuses would blow long before enough heat was generated in a cable that might melt my soldered joints.

First off, thanks Mainey, the first sites I have been to by the Powerstream is a site I have not seen before, thanks again and you demon straight what these forums are intended for, to learn from and to help others learn and once more thanks Mainey.

NOW as to the rocket scientist Cockup, I don’t know what your back ground is nor does it matter when it comes to replying to someone else’s posting. If you think I’m wrong AND I’M NOT then reply with some manors.
I have more than 25 years of automotive electronics under my belt, but having stated repeatedly in other postings, that I still find there is lots to be learnt both in the real world and in the cyber world, so if I’m wrong and someone wants to correct me, go for it as this is the best way for every body to learn.

To your sarcastic and UNOBSERVANT reply. The statement about MOST vehicles having a big earth wire going from the battery’s earth terminal the the engine is only partly right and for the very opposite reason you put forward. The next time you look at a vehicles engine, ANY and EVERY ( not most as you so put it ) engine has that big earth wire connected to it and thats because the earth returning to the battery via the chassis DOES NOT WORK for large current devices. Now Cockup, next time your under the bonnet ( and I would not recommend YOU do that to often ) have a look at the engine, any engine, and you will OBSERVE this big roundy thingy attached to the engine somewhere. This big roundy thingy is called a starter motor and it uses huge amounts of current that for many decades now, the motor companies have realised needs to have a decent positive and NEGATIVE to work properly. Thats why the big wire is there D’OH. It won’t work properly if you try to bring the earth back through the chassis.

So next time you have a remark about a posting try doing it civilly even if you can’t be right and that way, even though you are wrong someone else will most likely post an equally civil reply and point out your error. NO MORE NO LESS.

No professional installer would use the chassis as an earth return for high current applications ( not unless he was a tight A”” and was trying to save a few pennies ). As to how each individual does his own thing, thats your choice and all I’m doing is giving info that you can take or leave. I don’t set out to take the Mickey out of someone because I might not agree with there comments BUT if some no-brainer wants to have a go at me, “life’s short so I’m always ready for a laugh”

There were a couple of postings about soldering wire in vehicles.
If you are going to be joining low current wires then you can get away with just soldering. If you are going to be fixing wire intended to carry high currents then you should crimp terminal or screw terminal the connections where ever possible because high current joints have a resistance and this resistance can very very easily cause the wire joint or connection to heat up. The heat does not have to be that high for the solder only joint to let go. Note the heat does not have to get any where near the melting point of solder, solder’s strength reduces rapidly as the wires heat increases.
If you want to solder, use non sheathed crimp terminals and after crimping them to the wire then solder the crimp joint.

Regards all, you to Cockup

Hi Drivesafe,

I'm about to fit a dual battery system and will I have done a bit of electrical work will certainly take on board many of your suggestions and comments. One question I have is fusing between the main and aux battery. On the previous installation I did I used fusable wire but others have told me not to bother, yes there is a danger but you'd need to fuse each end to be safe and you can get to much resistance at the joints.

What's your view.

Thanks

Well good morning to all..............

Said nicely lmao

drivesafe,
I read your reply above and it appears you are having a go at me..
however I know you are NOT, it is just the way at appears in print.

Hope others will see it the way it was intended
two distinct messages placed within the same post
stating replies to two very different posters (people)

and not jump to the wrong conclusion. lol

No harm intended I believe.

drivesafe, me thinks you must have got out of bed on the wrong side the other day. Such aggression. I thought you might read my comments with a wry smile on your face and not take such effrontery nor be to thin skinned. If you feel insulted then I apologise for the tone in which I placed my comments, there was no malice intended.
However, I do not withdraw the point of my comments. My experience is based on close to 60 years under and in cars, many cars, and I have a wonderful workshop. I have just restored from ground up a Mini Cooper S, the battery for that car is in the boot earthed by a short wire to the body in the boot. Beats me how it works when the starters in the front but it does. My more modern computerised 4by is earthed in 2 places by one lead, bolted to the body below the battery and the same lead onto engine block. End of lead. No other attachments.
Now here is where you are right, I'm not a rocket scientist, and don't pretend to be one, but how can any electrical circuit be completed back to the battery unless, as in the two instances I have just honestly enunciated, it is either earthed to the bodywork/engine or, as you suggest a separate wire is run for special purposes. I did not disagree with your suggestions of a return earth wire but merely expressed my opinion, as you have, that a separate wire back to the battery was not necessary in this circumstance.
I also run a large boat winch from the back of my 4by and I installed appropriate sized wiring both + & - back to the backup battery as it appropriate to do so in that circumstance. See, I'm not a total mug after all. Just built a total wiring loom for the back of the 4by to improve the rear lighting system also.
I still disagree with the suggestion by you that it is OK to run a 25amp wire up to a cigy socket that's rated at 10-15 amps and for you to accept that that will make a suitable plug from which to run a fridge. I believe my suggestion of an Anderson plug is a much sounder option in both safety and performance.
As for your diatribe of insults about me personally and my name, you do yourself a great disservice and I and other members here on this forum do not need to be lectured to by you about about what is the purpose of this forum and how precisely it should be conducted. We usually tend to self moderate, have fun, and don't get involved in personal vindictiveness. So don't lecture me nor insult my name.

Hi Mainey, sorry for the confusion because I was genuine in my thanks to you as I always appreciate helpful info and don’t mind constructive criticism
Yes I think I should have separated the posting for clarity but I was a tad P###ed off with the idiotic reply from “cockup”.
Again I’m sorry for the mix up and was genuinely appreciative of the help
Best Regards.

Hi Austravel, if you are going to be fitting the second battery under the bonnet then putting some sort of protection on the positive running between the two batteries is really up to you but I would be putting circuit breaks at the battery terminals. You may have to spend up to $20 for two good quality circuit breakers but a fire will cost you a lot more.
If you are mounting the second battery some where else in the vehicle then there is no way I would not install circuit breakers at both battery positive terminals. If there is a small resistance because of the circuit breakers, it would be very small and a trade off I’m prepared to put up with for the protection they give.
Hope this is of some help to you.
Regards

Well cocka, what can I say.
I will apologise for the improper use of your name and I mean that genuinely. As for the rest, You are wrong can’t put that any simpler and if you think I’m wrong, find any other professional installer and see what they say.
Sorry to disappoint you but I was not offended but if you were TUFF.
If you read back through the threads of this posting you find that the first time any one tried to take the mickey out of someone else's posting was you. I NEVER stick it up someone unless they do it to me first, THEN I HAVE SOME FUN. You are obviously a bit thick, just try practising what you preach.
Regards all.

Thanks, thought as much. I've always used fuses etc on every wire I run (+ve that is) and didn't think much of this persons idea.

Hi Marty,
Thanks for the suggestion. I already have a proper setup from battery running 2 cig lighter sockest at rear. My only concern is that the wire was not the correct size and although i have had no problems offroadas far as running my 80 ltr waeco, I want to correct it for peace of mind.
But thanks for your input mate.
Cheers Angelo

I am about to do the same and will be running a seperate 6mm wire to the inverter from the aux battery via a 50 amp circuit breaker mounted at the battery end (mine is a 300w pure sine wave inverter with a 1000w surge), the breaker will allow te surge but not a continuous current higher than 50amps. Hope that helps

Clive/Bonz,

Just for some ideas:

I just put my inverter in permanently. To get it out of the water (just in case), it is in my new roof shelf. Used a twin wall socket with centre switch (gees they are a bugger to find in black!). Centre switch throws power to a relay which gives the 12v to the inverter. Means I can use the camera charger and something else at the same time from my cheapie inverter. But yours sounds like it has probrably got dual outlet anyway Bonz. Put my cd stacker up here as well so it is easy to get to and out of the water. Got 5 x 20 litre storage boxes up here as well for food and spares. Anyway, here are some pics:

http://www.geocities.com/cruiserpics/rearshelf

Mainey
I'm enjoying your comments and advice - very clear and succinct.

I have an issue with lighter sockets which we generally know as the ciggy hole etc. Some are of the design that click in others are held in position by the tension of side earthing springs of the male component, I fitted a couple of these (female) to the rear for light extensions, torch recharging etc (light stuff). My concern is in using this common push in type for refrigeration or anything with a decent current draw, whilst travelling. I believe there is a risk that with vibration the plugs move and with burning the connections will fail.

The terminals at the back of the female sector have to be well secured and protected as they are vulnerable also, as can be some pretty flimsy male plugs. This is all pretty much common sense I know, but I feel it needs emphasising.

To overcome this wobbly fridge connection I changed the plug on my fridge to an Anderson and ran separate heavier leads from the aux battery. There are other two pin plug systems that are, IMHO, much better considerations than the ciggy plug.

Would you agree with this scenario or do you think I'm being a bit paranoid ??

Cocka,
do it once and do it right
the amount of time and money you spend correctly setting up your power supply system from your battery(s) is minimal when compared to the hassles you get when you have a problem caused by initially taking short cuts.

I read posts of problems of batteries 'dieing' and people only expecting to get a few years from their battery systems, fridges using too much power to run at the correct temperature, and solar panels that don't supply power to run a fridge and I believe that they are generally caused because the system is not set up as it should be, simply because the owner tried to save a few $$ on a less expensive item or a thinner piece of wire because he read that some one else uses it, so it must be ok.

I don't believe you can be too paranoid about about your own safety, your health or your next hot meal and cold beer!