dual battery wiring and mounting help.

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Originally Posted by rottodiver

G,day Yendor,
Did you look at the link blkwdw posted for the fuse, after reading what you wrote I think I will install something that and being that I would not need to get terminals crimped on the cable it looks like it will be a matter of just cutting the battery cable and installing it in line!!
Scotty

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Hi Scotty,

I did have a look at the link. I'm not sure what size cable blkwdw has. Going by the amperage rating he stated, I guessed he has 6 & 8 B&S.....the cable won't fit into the circuit breaker and I think he may already have a fuse.

Have you look at the Navra range?

http://www.narva.com.au/products/bro...rcuit-breakers

I know getting terminals put on the cable will be a PITA but it will give a better connection.

You can also get fused battery terminals, this might make it a bit easier at the rear battery.

Cheers Rodney

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Originally Posted by BLKWDW

This is the kit i have. http://www.ebay.com.au/itm/PROJECTA-...ht_7992wt_1037

I realise getting it as close to the main battery as possible is best but there wire they supplied and the wire i bought doesnt reach the battery properly in the rear from the controller in the engine bay it get just behind the rear seat. If i have to bite the bullet i will buy longer wire but i was hoping to see if i could get away with using the 2 wires i already have. If i was to mount in the cab the closest place to the battery would be i the drivers side somewhere.

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Yeah you can do that. I would recommend using two circuit breakers one at each batteries.

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Originally Posted by Yendor

Yeah you can do that. I would recommend using two circuit breakers one at each batteries.

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SO something line this at each end http://www.ebay.com.au/itm/CIRCUIT-B...ht_1689wt_1271

Can i use the fused terminals at each end instead or are the breakers a better option
http://www.ebay.com.au/itm/PROJECTA-...ht_4465wt_1037
http://www.ebay.com.au/itm/DUAL-BATT...#ht_771wt_1271

Also the larger cable i have is 3b&s 26mmsq 215amp rated and smaller one is 6b&s 14mmsq 140amp rated

Quote:

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Originally Posted by BLKWDW

SO something line this at each end http://www.ebay.com.au/itm/CIRCUIT-B...ht_1689wt_1271

Can i use the fused terminals at each end instead or are the breakers a better option
http://www.ebay.com.au/itm/PROJECTA-...ht_4465wt_1037
http://www.ebay.com.au/itm/DUAL-BATT...#ht_771wt_1271

Also the larger cable i have is 3b&s 26mmsq 215amp rated and smaller one is 6b&s 14mmsq 140amp rated

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I personally prefer circuit breakers for this type of installation.

Yes you can use fuses. Sometimes finding replacement fuses can be a pain and expensive.

Also if using a ANL type fuse you will probably need to go up to a 100amp fuse.

Either one will be fine.

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One is a 14oammp power cord and the other is a 215amp power cord.

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At risk of appearing to be picky (although I don't think I am) can anyone tell me what is actually meant by xxxamp power cable? I have seen this used several times on the forum & seem to be the only one who has questioned it, which makes me wonder if everyone else think they know what it means. All it tells me is that one is likely a heavier gauge than the other.

Cuppa

Alright so if i use the 70amp breaker i posted up at the starter battery then use the smaller cable to make the shorter run to the electronic battery controller on the drivers side dash somewhere then use the larger cable to make the longer run to the rear of the car to the same breaker then to the second battery in the rear. sound right?

Ok cuppa I will give this a go.... Basically if collectively you are running say 50 amps you need cable that has a 50 amp or higher rating( up to about 15 ft I believe, and if you were running 50 amps you would use higher) . The cable would overheat and melt if too much draw is used on smaller amp cable( no real difference to a fuse blowing accept cable would melt and short)
I am no auto electrician but this is my understanding of it....
Scotty

Good work Rotto, the cable will be rated at a certain amperage which it should be able to carry in ideal circumstances ( i.e Free Air )

Cable will automatically be de-rated by the way it is installed ( i.e is it bunched up with a whole heap of the cables, is it installed where it is subject to high ambient temperatures, length of cable, etc )

I hope this helps

Mic

Ok, I know what you are both saying, but stating that a cable of any size has a current carrying capacity of xyz amps, without stating the voltage at which it can carry those amps is meaningless. Also when it comes to solar &/or battery charging in a
low voltage system such as 12 volt, any percentage of the output of either the solar panels or the battery charger lost to heating the cable because of resistance caused by cables being too thin are greater significance than in higher voltage systems. Generally the stated current carrying capacity of a cable is the amount of current it an carry without getting so hot that it starts to melt the insulation. When charging batteries at 12v we need our cables to be more efficient than that to ensure that we get as much of what is being produced to the battery, rather than warming the cable. For this reason it makes more sense to talk about the physical size of the copper conductor inside the insulation rather than the cable's rated current carrying capacity. For my 300w of portable solar panels I have a lead of just under 10 metres to connect them to my regulator. This cable is 6B&S size , which has a copper core of 13.2mm. A cable of 13.2mm has a far greater current carrying capacity than 300w of solar panel can generate, but this size is needed to avoid too much loss through voltage drop/resistance. It's like a hose pipe, the larger the diameter of the hose the less resistance, the greater the flow rate. As a general rule the same can be applied to connecting in car chargers, as correctly sizing ('oversizing') the cables will ensure that the maximum current can flow, & the batteries will charge more quickly. Unless planning to always drive for long hours we want the batteries to be charged as quickly as possible. I raise this not to be picky, but in the hope that it might help someone avoid disappointment that the charger they fit doesn't quite live up to their expectations, because they thought that choosing their cables on the basis of it's current carrying capacity was the right thing to do.

I,m not suggesting that the cables chosen in this instance are incorrect, they may or may not be, because without knowing how thick they are & at what voltage that amperage rating is at I have no way of knowing.

I,m sure that Yendor, whom you will note has referred to cable in B&S size, might be able to better explain what I've tried to say.

Cuppa

Ok, I know what you are both saying, but stating that a cable of any size has a current carrying capacity of xyz amps, without stating the voltage at which it can carry those amps is meaningless. Cable rated for 100amps @240v will be much thinner than cable rated for 100amps at 12v.
Also when it comes to solar &/or battery charging in a low voltage system such as 12 volt, any of the output of either the solar panels or the battery charger lost to heating the cable because of resistance caused by cables being too thin will be a greater percentage of what is being generated than in higher voltage systems. Generally the stated current carrying capacity of a cable is the amount of current it can carry without getting so hot that it starts to melt the insulation (as you have explained). When charging batteries at 12v we need our cables to be more efficient than that to ensure that we get as much of what is being produced to the battery, rather than warming the cable. For this reason it makes more sense to talk about the physical size of the copper conductor inside the insulation rather than the cable's rated current carrying capacity. For my 300w of portable solar panels I have a lead of just under 10 metres to connect them to my regulator. This cable is 6B&S size , which has a copper core of 13.2mm. A cable of 13.2mm has a far greater current carrying capacity than 300w of solar panel @ 12v can generate, but this size is needed to avoid too much loss through voltage drop/resistance. It's like a hose pipe, the larger the diameter of the hose the less resistance, the greater the flow rate. As a general rule the same can be applied to connecting in car chargers, as correctly sizing ('oversizing') the cables will ensure that the maximum current can flow, & the batteries will charge more quickly. Unless planning to always drive for long hours we want the batteries to be charged as quickly as possible. I raise this not to be picky, but in the hope that it might help someone avoid disappointment that the charger they fit doesn't live up to their expectations, because they thought that choosing their cables on the basis of it's current carrying capacity was the right thing to do.

I,m not suggesting that the cables chosen in this instance are incorrect, they may or may not be, because without knowing how thick they are & at what voltage that amperage rating is at I have no way of knowing.

I,m sure that Yendor, whom you will note has referred to cable in B&S size, might be able to better explain what I've tried to say.

Cuppa