What gauge wire for parallel setup?

[MagicMarty]

HI, I'm a new owner of a 1982 Excella 31'. My AS has 2 battery boxes separated by about 4 feet with the fuse box between them. Currently each positive and negative battery cable ties into the fuse box. I want to rewire the batteries to proper parallel setup.

This will require that I add 2 new cables about 4-6 feet long. One two bridge the positive terminals and one for the negative terminals. Maybe even longer in order to make it neat.

My question is what gauge battery cable should I get for this job? The writing I can see on the current wires is “G-9-R” on the red wire. Don't know what that means.

I have 2 AGM 27 92 amp hour batteries and a Boondocker 60 amp charger Converter.

Hope to get this done this week as our first outing in our new baby is this weekend. Any/all help is appreciated.

Thanks

[hotfoot88]

A good site for info on wire size would be Blue Sea, they have a chart available for length and current for correct wire size, along with other misc electrical ideas.
hotfoot

[Burnside Bob]

I was very surprised to see that the batteries in a friend's 2015 were cabled with what appeared to be #10 AWG from the factory.

I have a 2009 where the battery cabling was redone and routed thru a marine battery disconnect switch. Gauge is #6 AWG between batteries and between disconnect switch and 12 volt fuse panel.

You could have one battery removed, leaving the remaining battery to handle all loads. In my 2009 the 12 volt fuse panel is rated at 85 amps, so from a circuit design perspective #6, rated at 95 amps, would be specified.

If the trailer will always be powered by two batteries sharing the load, #10, rated at 52 amps, is adequate between batteries, but not between the batteries and fuse panel.

Personally, I'd go with #6 if I were to go new.

[MagicMarty]

Thanks,

Is there any problem with using the wire from a 4 or 6 AGW jumper cable to run between the batteries. Of course I would cut off the clamps and attach new connectors. Or is it better to get bulk wire, but that seems really expensive?

[CruizinDux]

Here are a couple of threads I have saved with posts from Lewster.

Posts 5 & 9
http://www.airforums.com/forums/f449...ed-154343.html

Post 23
http://www.airforums.com/forums/f449...-132157-2.html

As you can see in the image I opted for the 2/0 for the connectors. I'm not an electrician so I'm not sure if this is applicable to the 4-6' run. I also attached the before connection.

Maybe Lewster will check in?


Bob

[Zil]

If each battery's positive terminal connects to the positive terminal on the same fuse block, the same with the negative to negative. Your batteries are already connected in parallel. What do you want to accomplish with another set of cables?

[NY24]

A welding shop can fabricate heavy cables for you. Generally, the heavier, the better.

[MelGoddard]

Originally Posted by CruizinDux

Here are a couple of threads I have saved with posts from Lewster.

Posts 5 & 9
http://www.airforums.com/forums/f449...ed-154343.html

Post 23
http://www.airforums.com/forums/f449...-132157-2.html

As you can see in the image I opted for the 2/0 for the connectors. I'm not an electrician so I'm not sure if this is applicable to the 4-6' run. I also attached the before connection.

Maybe Lewster will check in?


Bob

I see that the orientation of your batteries is the same as what I received from the factory. Meaning, that You will have to remove a number of cables to gain access to the top fluid caps to check the water.

Following a previous post from 'someone', I turned that battery around, used the same jumpers to re-attach them, and now I can open the caps to check the fluids, no problem. before

after

[MagicMarty]

Originally Posted by Zil

If each battery's positive terminal connects to the positive terminal on the same fuse block, the same with the negative to negative. Your batteries are already connected in parallel. What do you want to accomplish with another set of cables?

Right now my circuit goes in and out of both bateries at the same time. Is it not better for the circuit to go in one battery and out the other?

[CruizinDux]

Originally Posted by MelGoddard

I see that the orientation of your batteries is the same as what I received from the factory. Meaning, that You will have to remove a number of cables to gain access to the top fluid caps to check the water.

Following a previous post from 'someone', I turned that battery around, used the same jumpers to re-attach them, and now I can open the caps to check the fluids, no problem.Attachment 289055 before

Attachment 289056after

Hey Mel, thanks for the reminder. I thought I had saved the above thread but could not locate it. Maybe they'll see this thread and jump in. This time I'll save the thread.

I agree, this is a great approach....duh, can't see the forest for the trees

I had thought about it but since I had already just converted to the 2/0, figured I'd wait till the grp 24 head south and maybe I'll convert to the 2X6's.

Also for us since we have no SP at storage, if I'm not using the TT in a few weeks I bring them home for a spot on my bench where I can kep a close eye on them and add a trickle charge and h20 top of as needed. My current setup is an easy disconnect/connect. Looking at this image (that I believe is from that thread) it's a bit of a birds nest.

Happy Trails

Bob

p.s I've read from lewster that it's best to have a the pos connect at one bat and the neg at the other batt

http://www.airforums.com/forums/f449...-154343-2.html Post 18

p.s.s I like the cable wraps. Great idea.

[uncle_bob]

Hi

If you want to have fun with wires, play away. 10/0 could be better than 6/0 you never know when 0.0001V at 2,000 A might matter.

Your converter / charger is likely putting < 50A into the batteries (25A each). A 1KW inverter will pull about 80A (40A each). On a typical setup, the inverter is more of a load than anything else. With 92 AH batteries, anything over about 90A per battery is a bit silly.

Unless you are doing something really weird, once you get to about number 6 (a very different thing than 6/0) you hit diminishing returns. A 12KW inverter would classify as "something weird". Forty feet of wire to the batteries would also be in the same category.

What are your goals here? If it's just "make it right", hooking both batteries to the same block is fine.

Bob

[waninae39]

here are the wire gauge charts

[Papou]

Originally Posted by MagicMarty

HI, I'm a new owner of a 1982 Excella 31'. My AS has 2 battery boxes separated by about 4 feet with the fuse box between them. Currently each positive and negative battery cable ties into the fuse box. I want to rewire the batteries to proper parallel setup.

This will require that I add 2 new cables about 4-6 feet long. One two bridge the positive terminals and one for the negative terminals. Maybe even longer in order to make it neat.

My question is what gauge battery cable should I get for this job? The writing I can see on the current wires is “G-9-R” on the red wire. Don't know what that means.

I have 2 AGM 27 92 amp hour batteries and a Boondocker 60 amp charger Converter.

Hope to get this done this week as our first outing in our new baby is this weekend. Any/all help is appreciated.

Thanks

I add a 100 Ah additional portable battery (in a case) with a 7 feet cable for occasional boondocking with AWG #2 cable with Anderson 175 Ah connectors. No electrical loss, flexible welding cable.
In a such case, I change the battery capacity "connected" in my Victron BMV-700 accordingly.
I install an additional portable 90 Watt solar panel (small 35 Amp. Anderson connector right hand side on the picture) over the existing 95 watt roof top of my 23 feet Flying Cloud.
With this set up, no generator needed, batteries are nearly always full.
The 600 watt inverter (with a 15 Amp. transfer switch) is used to enjoy watching TV, charge computers and I-Pad and even a hair dryer switched to 220 Volts (delivering 320 watt) for my wife...

See pictures of my cabling set up below.

Michel

[MagicMarty]

Originally Posted by uncle_bob

Hi

If you want to have fun with wires, play away. 10/0 could be better than 6/0 you never know when 0.0001V at 2,000 A might matter.

Your converter / charger is likely putting < 50A into the batteries (25A each). A 1KW inverter will pull about 80A (40A each). On a typical setup, the inverter is more of a load than anything else. With 92 AH batteries, anything over about 90A per battery is a bit silly.

Unless you are doing something really weird, once you get to about number 6 (a very different thing than 6/0) you hit diminishing returns. A 12KW inverter would classify as "something weird". Forty feet of wire to the batteries would also be in the same category.

What are your goals here? If it's just "make it right", hooking both batteries to the same block is fine.

Bob

Thanks Uncle Bob,

I surely don't want to add a ton of wire if I don't have to. I am trying to make this simple as possible.

One goal is to install a battery monitor to the system. In order to do this I need to install the shunt to the negative cable before the fuse box. Can I connect both negative cables to one side of the shunt and then just run one wire from the shunt to the fuse box?

This would eliminate having one 50 amp fuse on each battery and change it to both batteries being on one 50 amp fuse. Is that going to be a problem?

Is there any logic in splitting it up and running two wires from the shunt to the fuse box? That would bring a negative to both locations on the fuse block but seems to me that all that does is put 2 fuses the same circuit.

[uncle_bob]

Originally Posted by MagicMarty

Thanks Uncle Bob,

I surely don't want to add a ton of wire if I don't have to. I am trying to make this simple as possible.

One goal is to install a battery monitor to the system. In order to do this I need to install the shunt to the negative cable before the fuse box. Can I connect both negative cables to one side of the shunt and then just run one wire from the shunt to the fuse box?

This would eliminate having one 50 amp fuse on each battery and change it to both batteries being on one 50 amp fuse. Is that going to be a problem?

Is there any logic in splitting it up and running two wires from the shunt to the fuse box? That would bring a negative to both locations on the fuse block but seems to me that all that does is put 2 fuses the same circuit.

Hi

Run the two cables from the two negative posts to the shunt. Then tie the shunt to ground. That retains the wiring you have and it will work just as well as any other setup.

Fusing batteries independently is not normally how it is done. Most installations use a single fuse and size the wires accordingly. I have seen setups with no fuse on the battery at all.

The wire you use on a 12V system is normally a bit big to reduce the voltage drop. Fuses are sized to the wire's maximum current (catch fire) rating. The oversize you did to reduce the voltage drop is part of why a single fuse is probably going to work fine.

Fuse size is an independent issue. A 1KW inverter will pull 80 to 100A. If you have a water pump and other 12V loads, a 100A fuse might not be what you want. Sizing the wire and fuse for closer to 150 or 200A might be a good idea.

Bob