Installing cable for CT battery charging

Submitted: Sunday, Jul 17, 2005 at 10:58
ThreadID: 24794 Views:2291 Replies:6 FollowUps:11
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I'm about to install the cable to charge my aux batteries in the CT. I plan to use 4B&S cable. Should I run pos and neg cables all the way to the Anderson plug on the vehicle and the trailer? Or do I just run one cable and earth one side of plug?
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Reply By: GOB & denny vic member - Sunday, Jul 17, 2005 at 11:03

Sunday, Jul 17, 2005 at 11:03
goodday norm

just my opnion i ran both all the way from a fusible link / circuit breaker at battery to the anderson plug

steve
AnswerID: 120754

Reply By: Mad Dog (Australia) - Sunday, Jul 17, 2005 at 11:20

Sunday, Jul 17, 2005 at 11:20
Norm, for long term reliability it's best to run both neg and pos cables but if you can maintain a low resistance neg path via the chassis/body then that method is ok as well.
AnswerID: 120756

Reply By: Member - Norm C (QLD) - Sunday, Jul 17, 2005 at 11:21

Sunday, Jul 17, 2005 at 11:21
Just spoke to Bias boating. I can get 2 B&S for under $7.00 per metre. Even if I run 2 cables all the way, it will be under $100. Would be even better as it is about 32 sq mm conductor, but how thick is this stuff (about 12mm diameter??? does this sound right??) and how difficult to work with? Would I be able to get it into an Anderson plug. Is it difficult to bend around corners?
I'm going to try to get it inside the chassis rail and run it through there so it is out of the way. Just worried that it will be so heavy, I won't be able to get it through existing holes in the side of the chassis, bend it and pull it through.

I'll need to get an auto elec to crimp any connectors as I don't have the tools for this size cable.
AnswerID: 120757

Follow Up By: Member - Blue (VIC) - Sunday, Jul 17, 2005 at 14:18

Sunday, Jul 17, 2005 at 14:18
12 sq mm sees no discernable voltage drop between the batt and the rear of my Triton, sold as figure 8(12 sq mm pos & 12 sq mm neg), was only around $4/m from Carac Trailers here in Melbourne. Fits nicely into the Anderson plugs too, each side of the plug is about the size of a match box.
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Follow Up By: Member - Norm C (QLD) - Sunday, Jul 17, 2005 at 19:11

Sunday, Jul 17, 2005 at 19:11
Blue, that sounds like 6 B&S or equivelant. 6B&S is about 13mm sq I believe. Sounds like 2 B&S might be overkill.
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Follow Up By: Member - Blue (VIC) - Sunday, Jul 17, 2005 at 19:28

Sunday, Jul 17, 2005 at 19:28
Norm I had no idea what B&S was but thought I'd stick my 0.02 in anyway. It wouldn't do any harm to use bigger wire, comes down to manageability/performance... Just figured if you could go a little smaller diameter without losing performance, make life a bit easier with the install and buy some grog with the money you save... What could be better?
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Follow Up By: Member - Blue (VIC) - Sunday, Jul 17, 2005 at 19:33

Sunday, Jul 17, 2005 at 19:33
P.S. just finished reading ahead... The stuff I used is double insulated so I used that split corrugated conduit anywhere it came in contact with an edge. Other than that I used biga$$ cable ties to fix it flat on top of the chassis.
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Follow Up By: Mainey (WA) - Sunday, Jul 17, 2005 at 19:41

Sunday, Jul 17, 2005 at 19:41
Norm,
I would advise you to use the same cable as I use, simply because I believe it is suitable to the job you require of it, and you will get basically NILL voltage drop.

I would also advise you to run the cable ALL the way in both positive and negative cables and I would suggest you get the cable supplier to fit all the lugs to the ends of each of the cables for you as part of the deal.

Yes, my cable is 2 B&S, it's large by the standards of cheap & ineffective cables.
I seek battery efficiency, not to save money but only to save battery voltage!
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Follow Up By: Nick R - Sunday, Jul 17, 2005 at 21:45

Sunday, Jul 17, 2005 at 21:45
Norm,
What you are proposing is what I did, 25 sq mm (about 1/2 in diameter) through the chassis rail, I didn't run a neg core though, that would have been just too hard, took 2 of us quite a while to get the cable through as it was, maybe made harder because i cased it in poly pipe for added insulation. 1 end I joined to a very short section of 6 sq mm to the voltage sensitive relay (there was a fuse there somewhere too) and a short section of the same the other end to the Anderson plug with another piece of 6 sq mm into the plug with a loop soldered on and securely bolted to something (can't remember what I bolted it to) to act as the negative.
That size wire should be good, we pulled up to 120 amps @ 240Vac for 13 years through it!!!
NickR
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Follow Up By: Mainey (WA) - Sunday, Jul 17, 2005 at 22:50

Sunday, Jul 17, 2005 at 22:50
Nick, What were you using that would draw 120 Amps through 6 sq mm wire from a 12 volt battery ??

2 B&S ..is cross section 32.5 mm squared and 399 strands
6 B&S ..is cross section 15mm squared and 168 strands

2 B&S cable is $6 Mtr
http://www.solarvalley.com.au/dcfittings.htm
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Follow Up By: Nick R - Sunday, Jul 17, 2005 at 23:30

Sunday, Jul 17, 2005 at 23:30
Mainey,
The sentence read:
That size wire should be good, we pulled up to 120 amps @ 240Vac for 13 years through it!!!
You must have missed the "240 Vac" bit (240 volts AC) We didn't rely on anything 6 mm to do that!!!
Used JohnR's gu patrol to pull it out of the underground conduit, got about 70 metres of the stuff
It was one of 3 cores (2 active, 1 neutral) which ran our dairy, now 3 phase
it is about 20 really thick strands and the cable is really stiff. it is thicker than the starter cable on my LC80 although starter cable doesn't have to be as long.
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Follow Up By: Mainey (WA) - Monday, Jul 18, 2005 at 10:20

Monday, Jul 18, 2005 at 10:20
Nick,
I thought I was reading a post about 12v battery leads :-(
Admittedly both are copper wire, but that is the only similarity between them.

(QUOTE)1 end I joined to a very short section of 6 sq mm to the voltage sensitive relay (there was a fuse there somewhere too) and a short section of the same the other end to the Anderson plug with another piece of 6 sq mm into the plug with a loop soldered on and securely bolted to something (can't remember what I bolted it to) to act as the negative. (end quote)

Therefore the minium size of the battery “lead” is 6mm sq, and as you state the 240v wire you used was only 20 really thick strands of wire, and obviously without any known electrical specifications, not 399 strands of thin wire as used in 2 B&S cable and rated for a specific performance, you could have used a length of railway line :-) and join it to some 6mm sq wire each end and the capacity of the "cable" is still only 6mm sq, because the actual join or the 6mm sq wire is the weakest link in the length of the "cable" and therefore not recommended by any (qualified) Auto Sparky I have ever known.
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Reply By: Member - Geoff M (Newcastle) - Sunday, Jul 17, 2005 at 15:49

Sunday, Jul 17, 2005 at 15:49
Hello Norm,
Only thing to think of running cable through chassis rails and over metal is whether the cable is single or double insulated.
If single insulated, you may need to run it through some form of flexible sheathing to prevent chafing and shorts.

Geoff.
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Follow Up By: Member - Norm C (QLD) - Sunday, Jul 17, 2005 at 19:09

Sunday, Jul 17, 2005 at 19:09
Thanks Geoff. Thought I'd put it in flexible conduit where it enters and leave the chassis. Is that enough? I figured wher it is inside the chassis should be OK.
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Follow Up By: Member - Geoff M (Newcastle) - Monday, Jul 18, 2005 at 10:31

Monday, Jul 18, 2005 at 10:31
Hello Norm,
Only concern I'd have with single insulated in chassis rail are the bolts used to attach bash plates etc.
The cable may be laying over something that you cannot see. Have a look before you start and identify any areas that look like they might have sharp edges first then go on from there.

Geoff.
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Reply By: drivesafe - Monday, Jul 18, 2005 at 11:29

Monday, Jul 18, 2005 at 11:29
Hi Norm C, if you want to do a professional type fit that will give you the results you want always run both a pos and a neg cable, then for second battery installs in the vehicle, use nothing smaller than 8 B&S ( 8mm2 ).

To charge a battery in a trailer or caravan you should use nothing smaller that 10mm2 or 6 B&S ( 13.5mm2 ).

There is no reason why you can’t use smaller cable in either situation but you then have to allow a much longer charging time.

On the other hand, you can go to larger cable but there will not be that much of an advantage in either current requirements being met or quicker charge time. There will be improvements in both if you use larger cable but it will be very minimal and usually not worth the cost or inconvenience of having to fit the thicker cable.

To fit the cable, try to run the new cable next to the existing vehicle wires, this usually makes for a bigger installation job but the vehicles wires are usually located in safer places in the vehicle.

If you use the above size cable, you can then use SB50 Anderson plugs which, as the part number implies, are rated at 50 amps which is usually heaps big enough for most recreational applications.

For safety, you should fit a circuit breaker on either end of the pos cable as close as possible to the positive terminals on each battery.

A little trick I always tell people doing their own installations, is if you don’t already have a permanently powered cigarette light power socket in the rear of your vehicle then if you use the above cable, you can use the Anderson plug, that you are going to fit to the rear of the vehicle, as a junction and run twin 5mm Automotive cable to a new power socket in the rear, but don’t forget to fit an inline fuse near the socket.

Cheers.
AnswerID: 120903

Reply By: Member - Norm C (QLD) - Monday, Jul 18, 2005 at 14:50

Monday, Jul 18, 2005 at 14:50
Thanks for all the advice guys. I found an electrical wholesaler nearby. I got double insulated 'welding cable'. It is 25mm squared of conductor with what looks like hundreds of thin copper strands. It is very flexible given it's thickness and the double insulation.

I've fed it throught the chassis rail and will put the black split flexible conduit over it where it enters the chassis and where ever it is not inside the chassis.

Only cost $3.80 per metre, so I think I've done pretty well.

Haven't got the Anderson plug yet. May have to go bigger than 50 Amp due to the size of cable, but that's easy to work out.

Thanks again to all who responded. A great help.
AnswerID: 120930

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