Dual Battery Wiring Questions (Fuses, Wire Sizes, Battery Linking for dual start)

[Ryzz Advanced Member Find all posts View Profile Close Ryzz]

Just thought i might be able to get a few answers here. Ive been reading through heaps of DB threads and think i have my head around it.

I have just ordered a redarc SBI12D Isolator off eBay and acquired a 100ah Deep Cycle Battery + ARB Battery Cradle for it to fit in.

I understand the wiring between both batteries and the redarc, and if i have my facts straight, i need 100a breakers as close to the terminals on each battery as possible (for the run to the redarc). What size wiring do i need here? Im not 100% sure on the size as there seems to be some debate between 10mm2 & 16mm2.

Also im planning on running a power line to the rear cargo area to power a fridge and anything else i might need. Can someone confirm what size breakers would be suitable for this and also what size cable is relevant.

One last question, as the Redarc doesn't have a built-in override to link both batteries for starting incase of a dead cranking battery, so i was thinking of setting up my own remotely operated solenoid through a relay. Im not going to draw a wiring diagram for this, however if someone can confirm if this theory is possible by linking both positive terms through a remotely operated solenoid, would this be sufficient?

Thx in advance, i know some of these are bound to be answered in other threads, however after lots of reading and digging im a little confused and wanted some clarification.

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

I understand the wiring between both batteries and the redarc, and if i have my facts straight, i need 100a breakers as close to the terminals on each battery as possible (for the run to the redarc). What size wiring do i need here? Im not 100% sure on the size as there seems to be some debate between 10mm2 & 16mm2.

6B&S is rated for 140A loads, its a short run. It would be suitable for use with the 100A fuses.

Also im planning on running a power line to the rear cargo area to power a fridge and anything else i might need. Can someone confirm what size breakers would be suitable for this and also what size cable is relevant.

What does anything else you might need? Do you want one supply and a fuse block in the rear or multiple supplies and the connections in the engine bay?

One last question, as the Redarc doesn't have a built-in override to link both batteries for starting incase of a dead cranking battery, so i was thinking of setting up my own remotely operated solenoid through a relay. Im not going to draw a wiring diagram for this, however if someone can confirm if this theory is possible by linking both positive terms through a remotely operated solenoid, would this be sufficient?

Yes it is possible. but why would you want to have an additional unit? the Redarc has an override, its the blue wire.

[Pedro Advanced Member Find all posts View Profile Close Pedro]

I second the 6 B&S wiring.
Check out pages 3 and 4 of this thread for my wiring
http://www.pradopoint.com/showthread...allation/page3

[Ryzz Advanced Member Find all posts View Profile Close Ryzz]

What does anything else you might need? Do you want one supply and a fuse block in the rear or multiple supplies and the connections in the engine bay?

Probably a rear fuse block and multiple outlets in the back, maybe even an Anderson plug on the tow bar too incase I eventualy get a van. With this in mind should I run 6 B&S to the rear cargo and a second run for the Anderson plug? What sort of fuses would you put in the fuse block in the rear and in the engine bay? Sorry for the dumb questions :-)

yes it is possible. but why would you want to have an additional unit? the Redarc has an override, its the blue wire.

Haven't got the arc yet so didn't know about blue wire, will investigate, Thx!

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

Probably a rear fuse block and multiple outlets in the back, maybe even an Anderson plug on the tow bar too incase I eventualy get a van. With this in mind should I run 6 B&S to the rear cargo and a second run for the Anderson plug? What sort of fuses would you put in the fuse block in the rear and in the engine bay? Sorry for the dumb questions :-)

That is what I am doing, 6B&S to a rear 100A rated fuse block which i will purchase from www.springers.com.au, but any will do. And an additional 6B&S supply to a rear anderson plug - it is overkill, but leaves plenty of options for future upgrades without a wiring change. An alternative would be to run the 50A supply from the incoming connection on the fuse block.

Important to note that either way to adequately protect the circuit. If you run two supplies, use a 100A for the rear fuse block, and a 50A for the anderson under the bonnet. or if running the one supply a 100A in the engine bay and the 50A for the anderson at the rear where the tap off is.

Haven't got the arc yet so didn't know about blue wire, will investigate, Thx!

Lookup the technical pages on the redarc site, www.redarc.com.au. They show a variety of different installation methods. Additionally, the redarc has an instruction page in the box which details how to connect it and how to setup the override switch function.

Hope that made sense!

[footoo Member Find all posts View Profile Close footoo]

G'day Ryzz,
I used to work in the telecoms industry so work in sq mm, I think 16 sq mm is 6 B&S, am sure someone else will know this. 16 sq mm should be fine as others have said besides it about the biggest you can get into a 50amp anderson plug.

In the past I have run 35 sqmm cable between the main battery/isolator/aux battery. If you use 35/m8 lugs it works well, it is also handy to know someone with a hydraulic crimper. It can be a bit difficult to run but if you are winching you get minimum voltage drop between the batteries as the batteries will be linked with the engine running.

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

G'day Ryzz,
I used to work in the telecoms industry so work in sq mm, I think 16 sq mm is 6 B&S, am sure someone else will know this. 16 sq mm should be fine as others have said besides it about the biggest you can get into a 50amp anderson plug.

In the past I have run 35 sqmm cable between the main battery/isolator/aux battery. If you use 35/m8 lugs it works well, it is also handy to know someone with a hydraulic crimper. It can be a bit difficult to run but if you are winching you get minimum voltage drop between the batteries as the batteries will be linked with the engine running.

8B&S = 10mm sq. 6B&S = 16mm sq. 3B&S = 25mm sq.

Not much point going above the 6B&S with the redarc in it's not rated for those heavy loads and is the "weak point" in the system. Hydraulic crimpers are the best, picked up my set on eBay (6 tonne pressure on the crimp lug).

[wooley Avid PP Poster! Find all posts View Profile Close wooley]

8B&S = 10mm sq. 6B&S = 16mm sq. 3B&S = 25mm sq.

Not much point going above the 6B&S with the redarc in it's not rated for those heavy loads and is the "weak point" in the system. Hydraulic crimpers are the best, picked up my set on eBay (6 tonne pressure on the crimp lug).

what are these hydraulic crimpers like? I've only got a narva hex lug crimper, but it does do up to 120mm^2, not that i've ever gone that big.

[Prado BB Advanced Member Find all posts View Profile Close Prado BB]

Why is everyone recommending 6B&S cable? Even the Redarc installation guide on their website states 4B&S (for lengths up to 3m) if you are intending on using the override wire. I fitted 6B&S and when I had to use the override the cable got too hot for my liking, wish I had gone 4B&S.

[footoo Member Find all posts View Profile Close footoo]

PradoBB, hence my comment about 35 sq mm cable, which is better than 4B&S. We are essentially only talking short lengths so bigger is better, ie affordable.

Hydraulic crimpers will "crimp" the whole lug Where as the manual ones you need to do two crimps.

Hope this helps
Wooley these are manual crimpers, I think what you are referring are possibly these:-

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Regarding the 100A CB, It is preferable to use a fuse or better still a fuseable link than a CB.

Try to avoid placing additional contacts in the battery charge circuit as you don't want to
introduce any losses as even a very small resistance can have a large impact on recharge
times and hence the need for heavy cabling.

CB's in the load distribution side are ok but avoid on the battery charging side.

Cheers
LeighW

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

I can't find a picture of it in my files, so i've linked this to the ebay seller i initially bought it from. I was going to go all out with a heavy duty one, but i wasn't sure how much i'd actually use it... Turns out quite a lot! but it was worth the spend.

These are the same pics i recently added to my rig buildup page.


Perhaps, MLC should be encouraged to drop around my joint to get a few photos of the other crimp tools?

[wooley Avid PP Poster! Find all posts View Profile Close wooley]

I can't find a picture of it in my files, so i've linked this to the ebay seller i initially bought it from. I was going to go all out with a heavy duty one, but i wasn't sure how much i'd actually use it... Turns out quite a lot! but it was worth the spend.

Perhaps, MLC should be encouraged to drop around my joint to get a few photos for the crimp tool selection?

They look quite good for the price. Do they leave a nice crimp?

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

They look quite good for the price. Do they leave a nice crimp?

Yes, a very nice crimp in a uniform hex shape. Certainly do the job the same as the more expensive (aka heavy duty/trade) crimpers.
tidies up nicely after the addition of some heat shink.

Roo, some very good advise there, i also use springers for a lot of my parts!

[vk2ss55 Senior Member Find all posts View Profile Close vk2ss55]

Guys the protective device fuse etc is there to protect the CABLE , so rate it accordingly .

Cheers
Ross