Aux battery cables
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Elder User
Joined: Jan 2008
Posts: 825
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From: SW Washington coast
Aux battery cables
I want to run auxillary batteries for lights and sound when I am camping ... What size wire should I run? They will be located slung under the bed as that is the only space big enough for 4D batteries which I might get for free ... As I might relocate the fuel tank , a pair of these should do me ... Gotta plan for all contingencies ...
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Joined: Jan 2001
Posts: 56,979
Likes: 2,734
From: Virginia
Just go buy a isolator, and mount it under the hood, it splices into the alternator wiring. Then run two 10 gauge wires side by side from the other connection on the isolator, down along the frame and hook them to the batteries. These are your charge wires.
For your load connections on the batteries, I would take the equipment you will be running and add up the loads. For the lights, add up the watts of all the lamps you will be running at the same time, and divide that number by 12. This will give you the approx amps they will be pulling.
Also do the same for the sound equipment, and any other loads you may have. If you have any loads that will be over 30 amps, I would consider splitting those loads up.
Once you have all this figuring done, I would buy a aux or add-on fuse box. You will have a idea how many circuits you need, and you can buy one or two fuse boxes, or even a single inline fuse will work if your loads are not very large.
Just to keep everything simple, you can keep using the 10 gauge wire. It's good for 30 amps. So if your total aux fuse box load is going to be 60 amps, you can run two parallel 10 gauge wires, which would be good for 60, 3 for 90amps, etc. If you prefer not to run parallel conductors, you can buy larger wire.
So you feed the aux fuse box with the proper size wire from both batteries(you can jump the + of one battery to the other bat + and then run this wire to the fuse box ) You then size the fuses in the fuse box just above the load that circuit will be pulling, and come out of each individual fuse with the proper size wire for that fuse. So if you have a circuit with approx 25 amp load, I would put a 30 amp fuse on the circuit, and 10 gauge wire.
20amp =12 gauge wire
15 amp = 14 gauge wire
10 amp = 16 gauge wire
They also make circuit breakers you can buy instead of fuses. It doesn't matter, just so you get the idea that coming off the batteries, you need some sort of protection for your circuits.
For your load connections on the batteries, I would take the equipment you will be running and add up the loads. For the lights, add up the watts of all the lamps you will be running at the same time, and divide that number by 12. This will give you the approx amps they will be pulling.
Also do the same for the sound equipment, and any other loads you may have. If you have any loads that will be over 30 amps, I would consider splitting those loads up.
Once you have all this figuring done, I would buy a aux or add-on fuse box. You will have a idea how many circuits you need, and you can buy one or two fuse boxes, or even a single inline fuse will work if your loads are not very large.
Just to keep everything simple, you can keep using the 10 gauge wire. It's good for 30 amps. So if your total aux fuse box load is going to be 60 amps, you can run two parallel 10 gauge wires, which would be good for 60, 3 for 90amps, etc. If you prefer not to run parallel conductors, you can buy larger wire.
So you feed the aux fuse box with the proper size wire from both batteries(you can jump the + of one battery to the other bat + and then run this wire to the fuse box ) You then size the fuses in the fuse box just above the load that circuit will be pulling, and come out of each individual fuse with the proper size wire for that fuse. So if you have a circuit with approx 25 amp load, I would put a 30 amp fuse on the circuit, and 10 gauge wire.
20amp =12 gauge wire
15 amp = 14 gauge wire
10 amp = 16 gauge wire
They also make circuit breakers you can buy instead of fuses. It doesn't matter, just so you get the idea that coming off the batteries, you need some sort of protection for your circuits.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
West Marine has a chart for amp load vs. wire size vs. length.
Myself, I would probably run a min. of 6 gauge for the charging wires, front to back. Make sure you put the batteries in a box to protect them from road debris, a drain hole, that the top if is vented, and mount the batteries on top of wood when you clamp them down. The wood provides a barrier to shock and insulation.
Myself, I would probably run a min. of 6 gauge for the charging wires, front to back. Make sure you put the batteries in a box to protect them from road debris, a drain hole, that the top if is vented, and mount the batteries on top of wood when you clamp them down. The wood provides a barrier to shock and insulation.
Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Just go buy a isolator, and mount it under the hood, it splices into the alternator wiring. Then run two 10 gauge wires side by side from the other connection on the isolator, down along the frame and hook them to the batteries. These are your charge wires.
For your load connections on the batteries, I would take the equipment you will be running and add up the loads. For the lights, add up the watts of all the lamps you will be running at the same time, and divide that number by 12. This will give you the approx amps they will be pulling.
Also do the same for the sound equipment, and any other loads you may have. If you have any loads that will be over 30 amps, I would consider splitting those loads up.
Once you have all this figuring done, I would buy a aux or add-on fuse box. You will have a idea how many circuits you need, and you can buy one or two fuse boxes, or even a single inline fuse will work if your loads are not very large.
Just to keep everything simple, you can keep using the 10 gauge wire. It's good for 30 amps. So if your total aux fuse box load is going to be 60 amps, you can run two parallel 10 gauge wires, which would be good for 60, 3 for 90amps, etc. If you prefer not to run parallel conductors, you can buy larger wire.
So you feed the aux fuse box with the proper size wire from both batteries(you can jump the + of one battery to the other bat + and then run this wire to the fuse box ) You then size the fuses in the fuse box just above the load that circuit will be pulling, and come out of each individual fuse with the proper size wire for that fuse. So if you have a circuit with approx 25 amp load, I would put a 30 amp fuse on the circuit, and 10 gauge wire.
20amp =12 gauge wire
15 amp = 14 gauge wire
10 amp = 16 gauge wire
They also make circuit breakers you can buy instead of fuses. It doesn't matter, just so you get the idea that coming off the batteries, you need some sort of protection for your circuits.
For your load connections on the batteries, I would take the equipment you will be running and add up the loads. For the lights, add up the watts of all the lamps you will be running at the same time, and divide that number by 12. This will give you the approx amps they will be pulling.
Also do the same for the sound equipment, and any other loads you may have. If you have any loads that will be over 30 amps, I would consider splitting those loads up.
Once you have all this figuring done, I would buy a aux or add-on fuse box. You will have a idea how many circuits you need, and you can buy one or two fuse boxes, or even a single inline fuse will work if your loads are not very large.
Just to keep everything simple, you can keep using the 10 gauge wire. It's good for 30 amps. So if your total aux fuse box load is going to be 60 amps, you can run two parallel 10 gauge wires, which would be good for 60, 3 for 90amps, etc. If you prefer not to run parallel conductors, you can buy larger wire.
So you feed the aux fuse box with the proper size wire from both batteries(you can jump the + of one battery to the other bat + and then run this wire to the fuse box ) You then size the fuses in the fuse box just above the load that circuit will be pulling, and come out of each individual fuse with the proper size wire for that fuse. So if you have a circuit with approx 25 amp load, I would put a 30 amp fuse on the circuit, and 10 gauge wire.
20amp =12 gauge wire
15 amp = 14 gauge wire
10 amp = 16 gauge wire
They also make circuit breakers you can buy instead of fuses. It doesn't matter, just so you get the idea that coming off the batteries, you need some sort of protection for your circuits.
Steve
Moderator
Joined: Jan 2001
Posts: 56,979
Likes: 2,734
From: Virginia
West Marine has a chart for amp load vs. wire size vs. length.
Myself, I would probably run a min. of 6 gauge for the charging wires, front to back. Make sure you put the batteries in a box to protect them from road debris, a drain hole, that the top if is vented, and mount the batteries on top of wood when you clamp them down. The wood provides a barrier to shock and insulation.
Myself, I would probably run a min. of 6 gauge for the charging wires, front to back. Make sure you put the batteries in a box to protect them from road debris, a drain hole, that the top if is vented, and mount the batteries on top of wood when you clamp them down. The wood provides a barrier to shock and insulation.
Thread Starter
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Elder User
Joined: Jan 2008
Posts: 825
Likes: 2
From: SW Washington coast
Thanks for the good words ... Didn't think of an aux fuse block ... Was just gonna have a junction strip with inline fuses ... I wonder if since I have no air any more I could mount an alternator in the place of the compressor and run the aux batts off that? ... That would totally isolate the aux system ... Just a thought ...
Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Thanks for the good words ... Didn't think of an aux fuse block ... Was just gonna have a junction strip with inline fuses ... I wonder if since I have no air any more I could mount an alternator in the place of the compressor and run the aux batts off that? ... That would totally isolate the aux system ... Just a thought ...
Steve
