dual battery wiring and mounting help.

I've bought a dual battery system a while ago but havnt got it fitted up properly yet. I bought it just before xmas and as the power cable i got with the kit wouldnt reach the battery in the boot i just sat it on the backseat floor for the trip. I got back and bought a longer cord but without measuring how much i need and guessing the new cord i bough pulled up short as well.

So i was gona use the 2 cords to span the difference. But i still cant have the electronic battery controller mounted in the engine bay . Will it be alright if i mount it in the cabin probably within reach of the drivers seat at all? That way i can reach the battery in the boot plus i can reach the button on the electronic controller to jump start the car if i get a flat from in the car. Will this work. Was probably gona mount it on the side of the centre console or will it need to be higher. Biggest problem i can see having it there is if the car fills with water it will be swamped.

Question 2 is the other problem i got is the 2 cords i got are different sizes. One is a 14oammp power cord and the other is a 215amp power cord. Will this cause any problems and if not will it matter which way i run the cords. Like am i better having the 215amp or 140amp from battery to controller and then from controller to second battery.

I would be using the 215 amp for the longer distance run and the 140 for the shorter run. I can't see a problem having it mounted in the cab but I was seriously think about some sort of protection around it so no one gets zapped. Also make sure the battery is a sealed battery if going in the cab. Yendor will be the most knowledgeable with all this, if totally stuck pm him!
Scotty

I cover it with something yes but still gotta find the ideal spot.

This is the battery i'm using. Was going in the engine bay but wont fit and with how heavy this thing is could only imagine it would crack the wheel arch
http://www.ebay.com.au/itm/12-VOLT-1...ht_2077wt_1037

Battery is fine for inside the car... It will actually last longer in the troll instead of engine bay.
Scotty

Another member has just fitted a 3rd battery in the cargo area, might be worth searching to get some Ideas
very neat install as well. originally it was there was because no room under the bonnet, but heaps of Pics and step by step directions.
look in DIY section under 3rd battery install, or someone better than me may be able to post a link.
As for your cable start at the battery with your thickest and step it down, don't forget an inline fuse or thermal cut out close to
the pos on battery. run all cable in plastic convoluted tubing and cable tie cutting cable tie with stanley knife not side cutters.
No sharp edges that way, make sure battery is secure, dont want any missiles

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Originally Posted by threedogs

Another member has just fitted a 3rd battery in the cargo area, might be worth searching to get some Ideas
very neat install as well. originally it was there was because no room under the bonnet, but heaps of Pics and step by step directions.
look in DIY section under 3rd battery install, or someone better than me may be able to post a link.
As for your cable start at the battery with your thickest and step it down, don't forget an inline fuse or thermal cut out close to
the pos on battery. run all cable in plastic convoluted tubing and cable tie cutting cable tie with stanley knife not side cutters.
No sharp edges that way, make sure battery is secure, dont want any missiles

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Thanks mate do you mean the second battery or starter battery for the inline fuse? It will be bolted down in the back of the gq. Can you reccomend the best place to mount the dual battery controller in the cab?

I can't really help on that on but thought I would give you a reply, I have not fused any of my main battery cables and I have a triple battery system, everything I have coming off my batteries is fuses, I am interested to see if you get a response from yendor on this questions!
Scotty

In line fuse to both batteries mate

np99 what size?? and also considering the thickness of the cable i guess it would have to be a circuit breaker?
Scotty

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Originally Posted by BLKWDW

Thanks mate do you mean the second battery or starter battery for the inline fuse? It will be bolted down in the back of the gq. Can you reccomend the best place to mount the dual battery controller in the cab?

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What brand controller is it?

There's more room on the passenger side, either in the kick panel or even up behind the back of the glovebox.

For a rear battery installation I would recommend using circuits breakers, one mounted as close as possible to the positive post of each battery as well as conduit over the cables.

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Originally Posted by rottodiver

np99 what size?? and also considering the thickness of the cable i guess it would have to be a circuit breaker?
Scotty

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The circuit breakers are there just incase the main cable shorts to the body or chassis.

The size of the fuse or circuit breakers depends on the cable size used and to some degree what you plan on running from the rear battery.

If you have used 6B&S cable and are only running a fridge and some lights I would use 60amp circuit breakers.

You could easily go up to 80amp circuit breakers, the cable will handle this in normal operation.

The concern with going to high with the rating of the circuit breakers is if a partial short occurs it is possible that the current can slowly rise and the cable may overheat before the circuit break trips out.

mine is 25 mm squared cable!!!
to be honest i realise the importants of fuses and circuit breakers but have never thought to put one on these cables!!

Scotty

It's recommend to fuse due to the length of the cable and where you have to run it.

If you put the cable in conduit and have run it through the vehicle in a way that reduces the risk of it rubbing on any metal objects then you should be ok.

It's your call. The main battery cable that runs down to the starter motor is not fused.

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Originally Posted by Yendor

What brand controller is it?

There's more room on the passenger side, either in the kick panel or even up behind the back of the glovebox.

For a rear battery installation I would recommend using circuits breakers, one mounted as close as possible to the positive post of each battery as well as conduit over the cables.

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its a projecta electronic controller. Hmm so i will need breakers damn oh well better get searching for some was hoping to just put it together as is. The kit never supplied a fuse or breaker.

I also suggested having the controller on the drivers side as then if i was to get a flat battery on my own i could easily reach the button on the controller to jumpstart the car and be able to turn the key at the same time.

Would something like this do http://www.ebay.com.au/itm/12V-DC-CA...ht_2883wt_1271

I always had my dual battery in my .GQ under the bonnet so I am not sure why yours won't fit

I would think that it would be a real pain to have it in the back with all the other gear you have to fit

There are new style battery trays so you can mount them along the chassis underneath.....not my preffered option buy frees up space in the rear

Mic

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Originally Posted by BLKWDW

its a projecta electronic controller. Hmm so i will need breakers damn oh well better get searching for some was hoping to just put it together as is. The kit never supplied a fuse or breaker.

I also suggested having the controller on the drivers side as then if i was to get a flat battery on my own i could easily reach the button on the controller to jumpstart the car and be able to turn the key at the same time.

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I not familiar with Projecta. The quick google search I just did, states that you don't need to hold down the button on the controller to jump start, you just press it and the batteries will remain link as long as the starting battery is above 6 volts.

Did you get instructions with the unit? If the above is correct for your controller you are better off mounting the unit as close as possible to your main battery.

Doing this, they claim you don't need to fuse the cable coming from the main battery because their controller has current limiting protection.

They do advise to fuse the cable at the second battery. It looks like their kit supplies a fuse as part of the battery terminal for the second battery, did you get this in your kit?

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Originally Posted by happygtu

I always had my dual battery in my .GQ under the bonnet so I am not sure why yours won't fit

I would think that it would be a real pain to have it in the back with all the other gear you have to fit

There are new style battery trays so you can mount them along the chassis underneath.....not my preffered option buy frees up space in the rear

Mic

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the height of the battery is the issue as it fouls on the bonnet. Fitting in the rear wont be a problem. All i usually carry in the back is a fridge and tool box. once i get a few more parts for the install i'll make a false floor in the back having the fridge on a slide one side and the other a long draw for tools recovery equipment etc. Maybe some extra storage on the sides. Battery setup will fit behind the fridge in its own box out of the way. I dont need to fill the back of the car for trips as i have my camper trailer for that. All i need for day trips is fridge, tools and recovery gear.

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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Originally Posted by Yendor

I not familiar with Projecta. The quick google search I just did, states that you don't need to hold down the button on the controller to jump start, you just press it and the batteries will remain link as long as the starting battery is above 6 volts.

Did you get instructions with the unit? If the above is correct for your controller you are better off mounting the unit as close as possible to your main battery.

Doing this, they claim you don't need to fuse the cable coming from the main battery because their controller has current limiting protection.

They do advise to fuse the cable at the second battery. It looks like their kit supplies a fuse as part of the battery terminal for the second battery, did you get this in your kit?

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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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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

Cuppa, was any answer going to be correct. Lol

Also all cable I have ever bought has the voltage rating also

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Originally Posted by BLKWDW

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?

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Yep that setup sounds good and should give maximum protection against a short in the cable.

Quote:

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Originally Posted by 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. 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

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It's a standards test to ensure the quality of the cable.

You are correct is stating that the larger the diameter of cable (not including insulation) should carry more current.

What would happen say, if the cable manufacture started putting in less copper and started putting in some other cheaper mineral?

The current carrying capacity of that cable will be reduced.

Like most things automotive this test is a spinoff from other fields, so Ben-e-Boy might be able to answer this better then me.

From memory, the test parameters are

Set length of cable
Set voltage
Set ambient temperature
Set duty cycle

The cable temperature is only allowed to increase in temperature by x amount.

I hope that's correct it was a long time ago in TAFE we discussed that.

If you buy your cable from a reputable company for automotive use you normally don't need worry about this.

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Originally Posted by rottodiver

Cuppa, was any answer going to be correct. Lol

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Originally Posted by rottodiver

Also all cable I have ever bought has the voltage rating also

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Yeah OK, I went a bit over the top with my post. The several glasses of butterscotch schnapps around the camp fire a short time before may have had some influence! I guess if I had thought about it more, I might have just assumed you were referring to 12v cable,( but I have seen, on other forums, where someone has referred to an amperage rating of a cable they used in a 12v system, & it turned out they had used 240v cable & way too thin). I would still maintain that for charging purposes, if time to full charge is to be kept as short as possible, the heavier the cable the better within reason to minimise voltage drop.

My apologies, I guess I could have expessed myself a little better.

Cuppa

Hhaha cuppa...
Absolutely no apologies needed, I really enjoy reading your posts and no offence of any sort was taken.. Have a schnapps for me...lol
Scotty