6mm cable not enough for rear 12v sockets

Bit of a useless post but someone may find this one day on a Google search...lol

I recently set up the dual battery system with the Piranha management box and all that jazz but ran 6mm cable to the rear with some 12v outlets.

Everything works fine except for the fridge kept cutting out (on off, on off). Ran earth straight to chassis and tried earth to negative on battery too but still had same issue.

Ending up being just the cable with voltage drop so keep that in mind when running power. Don't cheap out, get quality 2 B&S RED "SINGLE CORE".

Thanks to Mudrunner for the advice.

Specifications
32.07 mm square nominal area
stranding 399/0.32
188 amp rated @ 30 degrees C

Yep the old voltage drop.
Bit overkill though, 32mm.sq is actually 255A rated.
6mm (4.58sq.mm) 50A rating, should have been fine for your fridge unless you were sharing that same cable with other accessories running at the same time.
Also if your fridge has a Danfoss compressor they can draw up to 20-25 amps on start up but only draw about 5A once running.
6mm cable over 6mts with a 25A draw you can expect about 0.55 volts drop which is too much in a 12V system. You want to keep it under 0.36V drop. Made worse too if your battery is low and other things running as well.
Cheers, Dave

Hi mate yeah I am sharing it with the camper lights, chargers and fridge, etc...

Question for Bordertech

I'm about to put in a 100w HF Codan NGT radio, with the aerial on the bull bar and will probably put in a 3rd battery in to run it, with that battery being located under the pod at the back.

Is 6mm strong enough to go the distance/length (it's not a loaded question for you sick people, either!!)?

Thanks.

Rossco

100 w at 12v = a current draw of 8.3A rosco

Quote:

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Originally Posted by DX grunt

Question for Bordertech

I'm about to put in a 100w HF Codan NGT radio, with the aerial on the bull bar and will probably put in a 3rd battery in to run it, with that battery being located under the pod at the back.

Is 6mm strong enough to go the distance/length (it's not a loaded question for you sick people, either!!)?

Thanks.
Rossco

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Dx grunt, depends on the length of the cable, the longer the length the thicker cable you will need. If you are going from front to back etc I would go atleast to an 8 B&S cable or even go up to the 6 B&S, run it into a fused distribution block and you could run other things off it as well as the HF, just a thought. You will obviously need to charge this 3rd battery as well and if in the back like you said I would use a minimum of 6 B&S. Are you going to join the batteries up into a triple battery setup or have one of the ARK battery boxes with the charger already in it.

Sorry if I have added to the confusion but it can cost a lot of money to fix a stuffup...I know as I have added more wires and taken wires out changed things around and it has cost me a few dollars.

cheers

Greg

Thanks guys.

I was going to run it off the 2nd battery, but seeings I'll be going to some pretty remote spots, I'll need it 'just in case' and want it to have an independent power source.

Charging in the middle of nowhere shouldn't be a problem because I have got 2 x 125w solar panels married up and hasn't let me down yet, but will need it wired into the 3rd battery.

I got told the best option is to turn it off when not in use, because leaving it on scan mode drains the battery pretty quick apparently.

I'd prefer to go the 6 B&S for 'peace of mind' because you rarely get a second chance in the outback.

Thanks again.

Rossco

Quote:

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Originally Posted by gregs

dx grunt, depends on the length of the cable, the longer the length the thicker cable you will need. If you are going from front to back etc i would go atleast to an 8 b&s cable or even go up to the 6 b&s, run it into a fused distribution block and you could run other things off it as well as the hf, just a thought. You will obviously need to charge this 3rd battery as well and if in the back like you said i would use a minimum of 6 b&s. Are you going to join the batteries up into a triple battery setup or have one of the ark battery boxes with the charger already in it.

Sorry if i have added to the confusion but it can cost a lot of money to fix a stuffup...i know as i have added more wires and taken wires out changed things around and it has cost me a few dollars.

Cheers

greg

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6b&s should do the job ,put in fuses and such and should be ok

dont forget you can top up the batteries with your panels as well

Your 100w Codan will draw around 20 amps

Very important lesson here

RF (Radio Frequency) watts and DC watts are two different wots

Is Big, Is Good! Better to over do it than suffer from voltage drop. Sudso does the mathes and I don't doubt the calculations at all. Just a big fan of going large to the back of the car to a distribution fuse box then work it out from there.

7 years ago I was fitting a Big Boss compressor for the back of the car and ran a decent wire but the thing just did not perform to expection. Re ran the wire 3 times bigger each time till I was running BIG stuff and the performance increased each time. Same thing happened to my 80lt weaco when I first got it, on off on off and not cold. Bloody voltage drop.

Go large. Do it once.

On the iPhone

I have run three separate 6mm dual core cables, one for the fridge, one for the HF and one for the 300w inverter, all using Anderson plugs and running off the aux battery, both + and -.

Runs fine for me, no problems so far, touch wood. Note, all cable have suitable fusing close to the 105ah battery.

Quote:

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Originally Posted by DX grunt

Question for Bordertech

I'm about to put in a 100w HF Codan NGT radio, with the aerial on the bull bar and will probably put in a 3rd battery in to run it, with that battery being located under the pod at the back.

Is 6mm strong enough to go the distance/length (it's not a loaded question for you sick people, either!!)

Thanks.

Rossco

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?Gday Rossco, not sure what pod in the back you mean for the battery but 6mm cable should be fine for the Codan from the radio to the rear as it isn't going be that long a run and as Yobbo said the HF draws more current than your average UHF, driving an auto tune antenna as well?
6mm is 4.58sq.mm and can handle 50A continuous but the longer the run the more the voltage drop. Say over a 4mt length in 6mm (depends where you mount your radio and battery) you'll only get 0.29V drop @ 20A draw which is perfectly acceptable, less than 3% drop. If it was 5-6mts long I'd say go to 8sq.mm (100A rated)
Sparkies use a max of 5% drop rule of thumb for 240V etc but for 12-24V etc it needs to be 3% or less.
Hope that helps,
Cheers, Dave

One thing to watch is some auto stores sell wire with the mm dia being total dia. including insulation not just the copper conductor- I have seen these so called 25A cables and they are more suited to wiring in a stereo than a high current draw item
Joe

I’ll either put the aerial next to the mobile phone aerial or take the phone aerial off and stick it there.
http://i1015.photobucket.com/albums/...Jun2010005.jpg

Was thinking about swapping the water tank over from the back left to the back right underneath the pod to make room for the 3rd batteryhttp://i1015.photobucket.com/albums/...Jun2010008.jpg

Quote:

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Originally Posted by JoeG

One thing to watch is some auto stores sell wire with the mm dia being total dia. including insulation not just the copper conductor- I have seen these so called 25A cables and they are more suited to wiring in a stereo than a high current draw item
Joe

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Thanks Joe.

I'm gunna take it to a proper HF radio installer and they can supply all the wiring ect and do it properly the first time.

Quote:

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Originally Posted by JoeG

One thing to watch is some auto stores sell wire with the mm dia being total dia. including insulation not just the copper conductor- I have seen these so called 25A cables and they are more suited to wiring in a stereo than a high current draw item
Joe

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Gday JoeG, all auto cable has always been identified and sold as the total diameter which doesn't really help as some of them have thicker insulation and dont relate to the actual copper conductor size, whereas all good quality auto cable does. Good auto cable states the actual conductor size in sq.mm on the packaging and there is a total diameter to conductor size standard with all good cable.
Cheers.

totaly agree here i hate running wires, just run one for over kill and fuse it all out the back makes fitting things later soo much easier
.

I normally shy away from recommending what size cable people should run down the rear of their vehicle for their accessories because there are just so many varying factors.

There are so many different options available for accessories (even just in the 3 main items people want to run from the back, fridge, lights and air compressor) and they all draw different amounts.

Then there is the confusion regarding wiring size, as stated above some of the cheaper wire has more insulation then wire.

I think MudRunners advice to AB is sound and will allow for any extras that AB might want to add later.

The downside is the extra cost in buying the larger battery cable.

The other thing to remember when using B&S cable is that the cable lugs/terminals require a special tool to fit them correctly to the cable.

A cable is only as good as the quality of it's connections.

whats wrong with brazing or soldering the connection ?

Quote:

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Originally Posted by beansathome

whats wrong with brazing or soldering the connection ?

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Nothing wrong with soldering the terminals on larger cabling but I would also crimp them as well, this way you have a better chance of the terminal and the cable staying together, but in saying that, soldering can also make the cable brittle and more susceptable to corrugations.

I have always crimped and soldered (and heatshrink) my connections on 8 B&S cable and bigger, regardless of whether they go into an anderson plug or a bolt on terminal. Anything else is usually just crimped and heatshrinked. And I also use an exorbanant amount of cable ties to hold my wiring in place so it doesn't move. I have done all my wiring this way for a while now and whether it be right or wrong I have never had an issue.

Oh and I always use split tubing on all my positve cabling, and on the chassis rails I run the positive inside 2 sizes of split tubing, for about $10-$20 it is great protection for the wires. Overkill?? yeah probably...but I know that they will not rub through and short out.

cheers

Greg

We'll, here's opening up a can of worms.

You will get a much better connection when the correct size lugs are crimped onto the battery cable using a good quality crimping tool.

Most people don't know how to solder correctly or have the correct equipment to do so. There is a little bit more to it then just heating up the lug with a blow torch and pouring the solder in.

As for crimping and soldering, yes it is a bit of an overkill, if the crimping is done correctly. If doing this I would recommend only allowing the solder to flow from the end of the lug/terminal to the end of the crimp. Don't allow the solder to flow past the crimp and down the cable.

My advice when planning something like this for your vehicle (if you are going to use B&S cable) is to work out the length of cable you require then drop into your local auto electrician and ask them to fit the lugs/terminals to the cable for you.

The above is based on the work practices I was taught and life experiences, my post is aimed at people who are not sure about the best way to approach this type of job.

I really don't want to get into a debate about soldering and crimping.

If you are happy soldering and have done so for years with no problems, then keep doing it.

After all, as long as the circuit works and you keep the smoke on the inside, then all's good.

There is too much valuable info in this thread which may get lost...lol....This is the mother load of hijacked threads!!!

Quote:

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Originally Posted by Yendor

We'll, here's opening up a can of worms.

You will get a much better connection when the correct size lugs are crimped onto the battery cable using a good quality crimping tool.

Most people don't know how to solder correctly or have the correct equipment to do so. There is a little bit more to it then just heating up the lug with a blow torch and pouring the solder in.

As for crimping and soldering, yes it is a bit of an overkill, if the crimping is done correctly. If doing this I would recommend only allowing the solder to flow from the end of the lug/terminal to the end of the crimp. Don't allow the solder to flow past the crimp and down the cable.

My advice when planning something like this for your vehicle (if you are going to use B&S cable) is to work out the length of cable you require then drop into your local auto electrician and ask them to fit the lugs/terminals to the cable for you.

The above is based on the work practices I was taught and life experiences, my post is aimed at people who are not sure about the best way to approach this type of job.

I really don't want to get into a debate about soldering and crimping.

If you are happy soldering and have done so for years with no problems, then keep doing it.

After all, as long as the circuit works and you keep the smoke on the inside, then all's good.

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Yendor, mate you won't get a debate out of me, I agree with your comments on this, especially taking it to an auto elecy to get the cables crimped as there are too many terminals/lugs out there that have been squashed using a screwdriver/chisel and hammer. This may work in an emergency but shouldn't be used as a permanent solution.

Greg

Crimping then soldering or vice versa is a big no-no. Do one or the other but soldering should really be left for only joining small size cabling. There is bugger all or virtually no soldered connectors from factory anymore they are all crimped for a good reason. Been this way for years. A connector crimped with good crimpers using good quality connectors should last longer than the life of the car.

When crimping larger cables... I bring it into work and use the hydraulic crimpers!
Have you ever cut in half something that's been hydraulic crimped? The cable and crimp fuse together into one solid piece of metal.

Quote:

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Originally Posted by KRISTOFFA

Have you ever cut in half something that's been hydraulic crimped? The cable and crimp fuse together into one solid piece of metal.

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yup ... that's what I was taught a looong time ago doing my trade. Hydraulic crimpers = higher pressure = heat = metal bonding = better joint. No need to solder. But if you do solder then "tin" the wire (heat the bare wire and apply a SMALL amount of solder) before solderng to the connector. Try not to let the solder "wick" past the insulation. Now that brings back memories ... that small 'puff' of flux smoke ... just the right amount of solder ... job well done.

Hydraulics are VERY expensive though. Most sparkies don't even have one. We hire ours out at work, have sparkies come in occasionally to have a lend of it.

Hydraulic crimpers have actually become much cheaper in recent times to the point of it being economic to buy one if you have a few cables to crimp. I recently bought one of these for $62 delivered. Comes with a range of dies to suit from 4mm to 70mm cables. 8 tonne pressure, others with higher pressure available for a bit more

By the time I have crimped all the battery & other connections in my vehicle I will have saved compared to the cost of ready made cables, or taking cut & prepared cables into town to get someone to crimp them for me ( & far more convenient too).

Cuppa

Quote:

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Originally Posted by Yobbo

Your 100w Codan will draw around 20 amps

Very important lesson here

RF (Radio Frequency) watts and DC watts are two different wots

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I'm to tired to think, can you please explain RF V's DC watts please.