8B&S cable to cig lighter socket. Suggestions?

John,

I may have misunderstood your post. My recommendation for merit type plugs and sockets was based on an understanding that you were trying to upgrade wiring in your car. If so, I stand by my recommendation to use merits.

If your intention is to have flying leads from a power source, then I agree with other posters - use Andersons.

Cheers

Ditto Dude
I run a dual battery system in the Troopy with a third N70 in the camper linked by Anderson plug adjacent to the trailer conection, Anderson extensions off both the second, (isolated by smart relay) in the Troopy and Camper to run 2 solar panels into the system for fridges etc. 3mm cable on the lot. Seems to work pretty well.
Cig plugs are strictly metropolitan IMHO.
Cheers
Tor

Just a Post Script,

Make it a dedicated frig circuit as Frank suggested. Forget the cig circuit.

John,
The merit socket I have here in my hand has standard spade connectors.
These spade connectors do not fair well with heavy prolonged current draw.
I have not seen any other type of connections fitted to merit plugs. If using the merit plugs I would suggest soldering the wires to the connections on the back of the plug. As you will do with the anderson plugs if you use them.

Anderson plugs are way cheaper and carry far more current than do merit plugs. Admittedly they are not as pretty nor do they have the discrete fitting of the merit plugs. But they are a better plug for a frig. in my opinion.

If you buy a pack of 10 Anderson plugs from Derrick at ABR Sidewinder they are as cheap as they come. Around $3 each for a quality product.
I use them on all sorts of things. Remote 12v pumps. extension leads for the 12 volt compressor etc etc. I even fitted them to my CTEK charger so that all I have to do is plug into the anderson AUX plug on the back of the car to charge the Aux battery in the car or the van. So.. any extra plugs you buy won't go astray.

Note that I have no connection with ABR Sidewinder other than being a very satisfied frequent customer as are many people here on Exploroz.

Cheers, Bruce.

John,

When I did mine I used a merit socket with flat (male) slide-on terminals. For the 8B&S wire I used yellow female slide on terminals. They are the largest I could find but they won't take all the copper in 8 B&S. To overcome this I removed the yellow insulation, opened up the tube that takes the wire into a U shape and soldered the cable in, and then restored the insulation with heat-shrink. Put the heat-shrink on the cable before attaching the terminal!

Putting skinny wire into the Andersons - just strip enough insulation to allow you to fold the copper twice or three times to fill or nearly fill the Anderson terminal and solder it. Tidy up with heat-shrink.

There are pros and cons about soldering vs crimping. I don't have a decent crimper and I can solder, so that's what I do. I use a pencil-type gas blowtorch to heat up larger things like lugs, Anderson terminals and large cable, otherwise a largish electric soldering iron. When the solder runs just quickly run it into the joint. Tidy up with heat-shrink.

Cheers

As Bruce said, the flat spade connectors do not fare well with heavy prolonged current draw. But if all you're doing is using big cable to keep voltage drop down for your fridge, then I imagine the max current will be about 5 amps, which those spade terminals will handle easily. Also, I pinch them up a bit with pliers before assembling to get a firmer contact.

If you choose to solder directly to the terminals of a plastic socket, do it quickly so you don't melt the plastic around the terminal and ruin the socket.

A bigger iron quickly applied is much better than a too-small iron applied for a long time.

Cheers

Thanks Bruce and Frank very much - exactly the sort of information I was after.

John.

I meant to add that if you use the cigarette lighter socket system and buy something new then its just plain old "plug and play". Like a replacement DC/AC converter to replace the one that just blew up. Or you get a new laptop and want to run it off 12V. No need to try and get the plugs changed to an anderson one. Yes stick to the anderson for trailer to car stuff and charging but for accessories (fridge, DVD player and radio and kids games) use the cig lighter.

Phil

Good site. They carry a great range of fittings and cables.

John.

I think it's worth paying a bit more. Also if you use them then mount then in a protected corner etc.

And they can look heaps better when mounted as we have.

Phil

We actually used the double wall mount similar to these ones: I didn't see this one in my original post.

Thanks for your reply but the frig is a Waeco.

John.

"The other thing 8B&S is way over kill for a fridge...... 6mm auto cable if the ideal size."

6mm auto, the diameter nof the cable including insulation. How much of that is plastic and how much copper, Olcoolone? It varies from brand to brand and according to the conscience and desired profit margin of both the manufacturer and reseller.

Gauge is a better spec.

Yes, 8 gauge is probably over specced for a fridge, but it really depends on the length of the cable run (which we don't know and anyway the OP specced 8 B&S in his question, so that's what was addressed) and whether or not it will be a multi-purpose outlet with possible bigger loads. In which case an Anderson might be better.

Cheers

Would be very interested as to why the cable I have suggested may be overkill. My information mainly comes from these forums and I read repeatedly about the problem of voltage drop but have not understood, as an amateur, why some loss of voltage would be critical to running the frig. From my readings I came to the conclusion that 8B&S was the cable I should choose. I do not intend to run any bigger load from this outlet and the run distance is about 4 metres. It certainly would be simpler and cheaper to use the 6mm auto as suggested.

Ready to be enlightened, John.

Thinking about what I wrote about the problem of voltage drop. I guess the issue may be that the frig compressor is set to not respond unless a certain voltage is sensed. This voltage would be sensed earlier by the frig if some of the drop in voltage was due to cable losses.

John,

Don't forget that in electrical terms your cable run is twice the length of your cable - 4 metres positive plus 4 metres negative, 8 metres all-up. That will help you determine the gauge you need.

Repco sell one that is described as sheathed twin core, 50 amp. It's pretty heavy, but lighter than 8 B&S. I've use that over 3 metres for a 5 amp load (my fridge/freezer on Hi) and it's fine in regard to voltage drop. I suspect it would be ok for your fridge over about 4 metres, and it fits into yellow terminals so you can satisfactorily crimp them with a cheap crimper rather than soldering.

I can't relate it to automotive cable sizing (eg 4mm) because the influx of cheap cabling with excessive plastic vs copper has been largely discredited as an indicator of current carrying capacity (sorry Olecoolone, but that's the way the cheap and nasty bu**ers have caused us to go.)

If you think you might use your cable for heavier duty, then if I were you I'd go for your 8B&S. You can get that as sheathed twin core (for neatness) from an auto sparky.

Cheers

Crossed posts here, John.

"Thinking about what I wrote about the problem of voltage drop. I guess the issue may be that the frig compressor is set to not respond unless a certain voltage is sensed. This voltage would be sensed earlier by the frig if some of the drop in voltage was due to cable losses."

Most definitely. Over-specced cable is far preferable to under-specced.

Cheers

Gday John,

You are right in wanting to minimise voltage drop with your Waeco for 2 reasons. The Waeco draws a beefy 5 amps when cycling, and secondly it has built-in low voltage cutout, so you don't want it cutting out prematurely.

So if you ran your Waeco from a factory cig socket, the wiring is very skinny - rated to carry 10 amps.
If you followed olcoolone's suggestion of 6mm sq (say 12Ga cable), it's stacks thicker - rated to take about 35 amps. Will do the job nicely with little measurable voltage drop when the fridge is cycling.
If you ran 8B&S cable, it is rated to take about 80 amps. That is overkill for a fridge that draws 5 amps. The wiring becomes heavy, bulky and a PITA to solder and connect.
I agree with the others - Anderson plugs are really cheap and probably the most reliable connection in a vehicle that is used offroad. They are also overkill (rated at 50A) but work really well at $3 a piece.

Cheers
Phil

Olecoolone posted

"6mm auto cable if [is?] the ideal size." That's 6mm diameter, including insulation - what will fit thru a 6mm hole.

He did not have a "suggestion of 6mm sq (say 12Ga cable)".

The difference is chalk and cheese and it's significant for John (and everyone else working with 12V).

6 mm sq is somewhere between 8 and 10 gauge. 12 gauge is 3.3 sq mm and is only just adequate for 5 amps over 4 metres (8m for 2 wires, = 25 feet) with a 2% voltage drop - see a calculator at here). You will get a voltage drop from 12 to 11.8 which is fine if your battery is at 12V. When it is at 11.5, then the current will increase above 5 amps (your fridge will try to draw the same power, 60 watts. 60/11.5 = 5.2amps) Increased current will cause increased voltage drop and so it will go as the battery voltage drops the current increases until the low voltage cutout on your Waeco cuts in and turns the fridge off as a measure of self-protection.

If just adequate is good enough, John, if you're happy with that go for it. Phil's right - smaller cable is easier to manage.

Knowing now that your application is restricted to a fridge, personally I would go for the larger 50amp twin-core sheathed. It's Narva cable, which as I said, I got from Repco. It works fine over 3m for my fridge with the same compressor as yours - a Danfoss BD-35, drawing 5 amps at 12V.

Cheers

8BS is not overkill if you are trying to minimise losses through voltage drop. No point in wasting AH heating up wire.

I have actually just replaced the 6mm install I had previously due to a voltage drop under load of 1.2v front (battery) to rear (Waeco CF60 fridge). The old install used Andersons. There was also a large drop in the factory Waeco fly lead - another .8v!

I now have 8BS from the aux battery through a large inline fuse (have seen the resettable breakers nuisance trip from vibrations) to the rear and terminates in an anderson plug. Given the drop in the thin Waeco cable I took the covers off the fridge and installed an Anderson on it in parallel with the factory inlet and made up an anderson to anderson fly lead from 8BS. I prefer a removable fly lead so that when I take the fridge out I dont have a cable lying around.

Result - less than 0.2v drop front to rear measured at fridge under full load (turbo button on).

Pat

000 to 8 B&S is often refereed to battery and starter cable (BTW B&S does not stand for battery and starter) from there on it goes into general automotive accessory cable that is refereed to as in the diameter size from 6mm to 1.5mm.

You made a comment about not being guaranteed the amount of copper wire in side the cable...... all leading brands are nearly spot on to each other...... teachers you for buying cheap Chinese stuff of ebay!

The reason we use terms like this is because it is what it is reconsigned as.......

If you want to be precise how does 4.58mm cross section with 57 X 0.32 strands sound.

Maybe it's referred to as auto cable and in mm's for a reason..... in industrial applications most cable this size is hard strands and the insulation is harder making it not as flexible.

If it's so wrong why are all automotive connectors specified to take specific mm sized wire?

Do a Google search for automotive wire sizes and you will not see anything under 8B&S referred to as a cross section size or gauge.

WHY.....When replying to a simple question that had been asked by someone with little knowledge on the matter who want to get it right when they do it ;there always has to be some who come back and reply in over the top technical jargon that only confuses the matter.

B&S and mm is what is used these days in automotive ....... gauge sizes is a very old term.

Like many industries....... they all have there own terms for something even that it exactly the same.

Frank...... you are talking miniscule voltage differences...... do you use $100 gold plated connectors, plugs and sockets....... do you test the resistance of the join before proceeding?

We are talking non critical levels here....... BTW does any one know where I can get a tyre gauge that reads 0.1psi increments..... I want to get my tyre pressures right....... seriously if you have any more then .2 - .3v drop when under load in cabling that is getting to a point of concern.

And Frank I am sure you are aware of the term (mV / amp / metre) to calculation voltage drop........6m of 6mm auto cable at 12v drawing 5 amps you should never see a voltage drop exceeding .1 of a volt........ if you were drawing 50 amps the story would be much different.

The only time the .2 -.3v may be a problem is if it's a signal from a transducer, variable voltage controlled circuit or multiplexed and maybe PWM

Olcoolone,

Thanks for the background on why automotive cable is described in mm of diameter. I accept that it's entrenched and I'm not going to change it.

However, none of the on-line wire size calculators that I have found use the automotive mm spec (which includes insulation) in their tables or interactive calculators. They all use conductor size, be it diameter, B&S, AWG, sq mm, etc.

I apologise if I used "over the top technical jargon", but I cannot see the point of offering an unsubstantiated opinion. Without something to back it up, how can the OP evaluate one opinion against another? I will try to include less detail in future.

Mate, I did not intend to have a shot at you and start a slanging match. Yes, I did point out an inconsistency in your use of 6mm, 6mm sq and 12Ga and tried to clarify the significance of that for John.

I don't think I was talking miniscule voltage drops but I did try to point out, with some supporting discussion, that according to the calculator I linked to the 12Ga cable that you mentioned was on the limit of suitability in John's situation.

That is why I suggested Narva's 50amp sheathed twin-core, which coincidentally :-) is exactly the "4.58mm cross section with 57 X 0.32 strands" you mentioned (bottom of this link).

Cheers

Frank I haven't taken you post as an attack or used it for a slinging match.

The cable you are talking about is classed and referred to as 6mm and yes that is the size I would suggest.

If you walked into any auto electrical business; whether retail or whole sale and asked for cable as you have described it you would be met with a stunned look....... whoever if you walked in and asked for 2,3,4,5 or 6mm cable they would know what you want.

For over 25 years that I have been involved in auto electrical 2,3,4,5 or 6mm cable is 2,3,4,5 or 6mm cable and battery and starter cable has always be referred to as 0000, 000, 00, 0, 1, 2, 3, 4, 6 and 8B&S.

If you were to look at the specs of the cable then the cable would be all the same for all industries (conductor area), the number of strands, size of each strand, insulation and material the stands are made from can vary as per the industry it is used in and application.....

Other industries use different terms....... you can gauge what industrie someone comes from by the terminology they use...... most call nuts, bolt and screws...... nuts, bolts and screws, in aviation they are called fasteners.

If we are doing a rewire from start from the front of the vehicle to the rear we will always use 3B&S cable and then distribute it to individual fused circuits made up of smaller cables....... the reason we do this is you never know what some one will want to add at a later date.... like an air compressor, camper trailer, battery in the back....... it's easier and cheaper to do it once that twice.

The only thing I disagree with is rating cable in amps, as a rule of thumb we will not use 6mm cable for runs over 3m that require over 25 amps constant.

Did you know cable by it's self is rated different to cable in a loom.

In a earlier post you made mention about resistance...... the biggest problem with resistant is the higher the resistance the lower the voltage, the lower the voltage the more amps needed and more heat is generated.... this in theory is true but the biggest problem is when the cable can not disperse the heat getting generated....... as more heat is generated the resistance increases and it keeps on increasing to the point where the wire becomes a heating element melting everything around it....... think of it as an electric fan heater, as long as the fan is running the element can disperse the heat.... stop the fan and the element overheats and fails, wire is the same...... it's a controlled heating element, keep the power down for a given size cable and less heat is generated.

Olcoolone,

Thanks for that.

You make a good point about different industries having different naming conventions for the same things, so I will bear that in mind.

I wish every auto electrician was as conscientious as yourself. At almost every one of our club camps across the country that I have attended over the last 6 years or so a couple of us have ended up involved in correcting shoddy or non-functional electrical work that other members have paid significant money for. Doesn't do much to instill confidence.

Yep, I was aware that loomed and isolated cables are rated differently, and why.

Anyway mate, I don't think there's much more to say. I've enjoyed the discussion and learned a bit. Time maybe to give readers a break.

Cheers and have a good one.

Thanks, Peter, for that info. Many of the other posts directed me away from the cig plug and your post confirms that I should use the Merit plug for the frig (which is a Waeco) connection.
John.