Battery bank to inverter...cable size?

[Trop Cher]

Hi,

What size cable would I need for a two metre run from the battery bank to an inverter 1500w nominal power / 3000w maximum power?

Many thanks

 

[[2574]]

This: http://www.the12voltshop.co.uk/Shop/about-cable-sizes.html says 35mm^2

I don't have access to the Calder reference manual at the moment but that would be the place to look for confirmation.

 

[VicS]

Hi,

What size cable would I need for a two metre run from the battery bank to an inverter 1500w nominal power / 3000w maximum power?

Many thanks

Yiou dont say what voltage the system is but assuming 12 volts

Allowing 3% volts drop ( ie 0.36volts)

Taking the total cable length as 4m ( ie 2m positive and 2 m negative)


For 3000watts
I calculate that the cable should have a resistance of no more than 0.36 ohms/1000m ie somewhere between AWG 1 and AWG 0, say about 50mm²

 

[nigelmercier]

If sizing for the maximum power, I would suggest you need 70mm²

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

Such a load will deplete the average 400aH battery bank in less than half an hour.

 

[pvb]

It's not a great length of cable, so go for the biggest you can reasonably fit. Certainly 70-90mm2.

 

[VicS]

It's not a great length of cable, so go for the biggest you can reasonably fit. Certainly 70-90mm2.

On reflection safe current carrying capability is probably the deciding factor rather than volts drop is this case.

If the cables are in free air AWG 00 will be adequate but if bundled together with other wiring AWG 000 would be more appropriate

AWG 00 is a little less than 70mm² AWG 000 is 85mm²

 

[Richard10002]

This: http://www.the12voltshop.co.uk/Shop/about-cable-sizes.html says 35mm^2

I don't have access to the Calder reference manual at the moment but that would be the place to look for confirmation.

I read it as a 2 metre run from inverter to battery, so 4 metres of cable there and back:

Thus 70mm2 cable. I may be misunderstanding?

 

[philip_stevens]

Hi,

What size cable would I need for a two metre run from the battery bank to an inverter 1500w nominal power / 3000w maximum power?

Many thanks

Just about all you need to know here http://www.tlc-direct.co.uk/Technical/DataSheets/Skytronic/Guide_to_Inverters.pdf Guide to Power inverters.

 

[Trop Cher]

Many thanks for the replies

It is indeed a 12 volt system and four metres total run, therefore I've decided to go for 70mm cables. Thanks also for the links to sites which I've read and saved.

 

[JumbleDuck]

It is indeed a 12 volt system and four metres total run, therefore I've decided to go for 70mm cables. Thanks also for the links to sites which I've read and saved.

It might be worth remembering that 2 x 35mm^2 is (a) a lot bendier than 70mm^2 and (b) dissipates the heat better. Takes up a wee bit more room, though.

 

[prv]

For 12.5 volts in a healthy system, but taking the worst-case 3000W draw, my volt-drop spreadsheet comes up with an acceptable 2.8% loss using 50mm^2 cable.

Pete