Battery charging cable size.

[wonderdust]

Hi, i am about to rip out the charging cables to replace with new so i am after some advice on what size to use. I already have 40mm2 link cables to the 4 cabin and starter batteries.

 

The cables being changed are the main negative, the main B+ from the 70 amp alternator, the Albright relay cables and the starter cable, i can get some 120mm2 cable for free do you think this is over the top?

 

At the moment the B+ cable goes straight to the battery bank with no fuse, when replaced should this pass through the battery cut off switch and an inline fuse added. If it does require a fuse, what type of fuse and cable termination do others use as 120mm2 seems to be massive for the available inline fuse blocks that are sale.

 

Thanks in advance.

 

Wonderdust

[DHutch]

120mm^2 sounds a little large, although if its free its worth having even if you dont use it.

 

- Presumably they alternator, batterys, relay etc are all together and in the stern. No big cable runs?

 

 

 

Daniel

[Guest]

Hi, i am about to rip out the charging cables to replace with new so i am after some advice on what size to use. I already have 40mm2 link cables to the 4 cabin and starter batteries.

 

The cables being changed are the main negative, the main B+ from the 70 amp alternator, the Albright relay cables and the starter cable, i can get some 120mm2 cable for free do you think this is over the top?

 

At the moment the B+ cable goes straight to the battery bank with no fuse, when replaced should this pass through the battery cut off switch and an inline fuse added. If it does require a fuse, what type of fuse and cable termination do others use as 120mm2 seems to be massive for the available inline fuse blocks that are sale.

 

Thanks in advance.

 

Wonderdust

Bigger than needed under normal cicrcumstances, but if you can make it fit physically, then why not?

[WotEver]

Go for it! 120mm for free sounds better than 90mm for £50 (or whatever).

 

T

[Gibbo]

Also.......

 

Technically, in order to comply with the regs, the alternator should go through the isolator switch.

 

But that introduces its own problems. Firstly, not all isolator switches are man enough. Those little black plastic ones with the red pull out key are a joke. Also, it means if someone switches the isolator off whilst the engine is running your alternator could fry.

 

But that's what the regs say. It doesn't need to be fused to comply with the regs but it does to agree with good practice.

 

Gibbo

 

PS: 120mm is great!

Edited September 4, 2009 by Gibbo

[churchward]

Wow 120mm2 huh? I got raised eyebrows at a motor factors when I asked for some ends to be crimped on some 70mm2 cable! They thought I might be wiring a power station.

 

Still, apart from practical considerations of fitting large cable I guess there is no such thing as a cable being too big. So why not use it if it's free.

[Sir Nibble]

Also.......

 

Also, it means if someone switches the isolator off whilst the engine is running your alternator could fry.

 

 

Gibbo

Also also, it means that if you have a major overload with melting insulation and smoke, when you isolate the battery if the engine is running the alternator will continue to pour current into the overload.

Edited September 4, 2009 by Sir Nibble