What Busbar size for 600A in 3P4S 816AH 12V, different sources different sizes and different ratings…

[captainrivet]

Hi all,
What size of busbar do I really need for 600A in a 3P4S bank?
I have 99% Cooper tinned in 20mm x 5mm which I can double up or tripple (then I need to order more)

Depending on the source I get different rating for busbars, see below:
If I go with Victrons rating then i need 600/4,17 =143sqmm
20mm x 5mm= 100sqm = 417A, so if I double them up I get 20mmx10mm = 200sqmm means 834A

If I look for specs I find the following:

Copper Busbar Rating

View Copper Busbar Rating - Approx D.C rating (1). Approx A.C rating. Moment of Inertia. Modulus of Section Z. By Austral Wright Metals.

www.australwright.com.au

This source tells me: 1sqmm is 2,925A
20mm x 10mm or 200sqmm is 585A,
25mm x 10mm or 250sqmm is 695A

If I go to an amperage calculator it tells me:

Busbar Current Calculator Online | Electrical4u

Enter the breadth and thickness of the busbar; do not enter the length of the busbar. Then press the calculate button, you get the aluminium or copper busbar

www.electrical4u.net

Putting into calculator: 1sqmm is 1.2A
20 mm x 10mm or 200sqmm =240A
35mm x 15mm or 475sqmm =630A
20mm x 2mm =48A or 32a Alu (factory delivered busbars), really ???, Will Prowse pulled 1C= 272A when testing the cells with these busbars

Victron Lynx 1000 is rated for 1000A cont and has
a 30mm x 8mm= 240sqmm = 1000A (Cooper tinned busbar)
Victron rates 1sqmm= 4,17A

The flexible busbars by Webertech with 600A rating are
25mm x5mm = 125sqm = 600A
Webertech rates 1sqmm= 4,8A

10.68US $ 2% OFF|Flexible Busbars 17525b5 600a 500a 400a 300a - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I am building a 3P4S 816AH bank with 12x Lishen 272AH. I or most likely the wife will occasionally pull around 450A kinda continue during cooking (3 burner stove plus convection oven) for around 10-15min, normal average cooking operation is more like 150-250A.
To have some headroom and keep everything as cool as possible I like to spec for 600A. Please no discussion and upgrade to 24V, I have my reasons to stay 12V and the „extreme use“ is seldom but I need to spec for this plus some headroom to be safe.

 

[HRTKD]

Where are these bus bars going? It sounds like you're using them for between the cell terminals, but you don't explicitly come out and say that.

If you built 4s3p you wouldn't have to worry about the terminal-to-terminal bus bar amps as much.

Stacking bus bars isn't as simple as it sounds. If you look at the ampacity charts, the amp rating for 1 bus bar doesn't follow a linear increase when you go to 2 bus bars. 100 amp rating of 1 doesn't equate to 200 amp rating for 2. Also, there is usually a footnote that says that stacked bus bars require an air gap, which is necessary for heat dissipation.

Below is the ampacity chart that I reference most often. To get a 600 amp rating you would need either 3/8"x1.5" or 1/2"x1" (thickness x width).

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.

www.copper.org

 

[captainrivet]

Where are these bus bars going? It sounds like you're using them for between the cell terminals, but you don't explicitly come out and say that.

If you built 4s3p you wouldn't have to worry about the terminal-to-terminal bus bar amps as much.

Stacking bus bars isn't as simple as it sounds. If you look at the ampacity charts, the amp rating for 1 bus bar doesn't follow a linear increase when you go to 2 bus bars. 100 amp rating of 1 doesn't equate to 200 amp rating for 2. Also, there is usually a footnote that says that stacked bus bars require an air gap, which is necessary for heat dissipation.

Below is the ampacity chart that I reference most often. To get a 600 amp rating you would need either 3/8"x1.5" or 1/2"x1" (thickness x width).

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.

www.copper.org

I use them for cell connection and as main busbar which is directly connected to the battery busbar where the 4 main fuses for the 2 inverters and main load+charge busbar connects. The +/- busbars are going through the compression board and 90 degrees directly attached to + the 1000A AC/bat shunt for the Electrodacus is connected and from shunt then 15cm long busbar 10mmx20mm where the 4 main fuses and the PV shunt connects.

The Cooper.org charts and stuff is fo commercial high voltage busbars which heat up and are run in parallel.
I double up the busbar and have full contact (the grub screw and the separate sensor wire screws push it together) on the whole length supported by good conductivity of the tin. This acts like one 10mmx20mm piece of busbar I was told by Material specialist of Swiss Empa which certifies all Metall material in Switzerland.
So this chart is not fitting to our installation case here and I mentioned this on top in my comparison.
How could Victron give a 1000A rating on a 240sqmm=8mmx30mm busbar. They are highly professional and due to copper.org charts this would be good for around 384A continuous….

 

[Eric-S80]

I use them for cell connection and as main busbar which is directly connected to the battery busbar where the 4 main fuses for the 2 inverters and main load+charge busbar connects. The +/- busbars are going through the compression board and 90 degrees directly attached to + the 1000A AC/bat shunt for the Electrodacus is connected and from shunt then 15cm long busbar 10mmx20mm where the 4 main fuses and the PV shunt connects.

The Cooper.org charts and stuff is fo commercial high voltage busbars which heat up and are run in parallel.
I double up the busbar and have full contact (the grub screw and the separate sensor wire screws push it together) on the whole length supported by good conductivity of the tin. This acts like one 10mmx20mm piece of busbar I was told by Material specialist of Swiss Empa which certifies all Metall material in Switzerland.
So this chart is not fitting to our installation case here and I mentioned this on top in my comparison.
How could Victron give a 1000A rating on a 240sqmm=8mmx30mm busbar. They are highly professional and due to copper.org charts this would be good for around 384A continuous….

Hi, I am on the same page. I have the same Lynx distributer and measuring the large bushbar inside made me wonder how that is possible? Did you made any steps in you project?

 

[captainrivet]

Hi, I am on the same page. I have the same Lynx distributer and measuring the large bushbar inside made me wonder how that is possible? Did you made any steps in you project?

Hi, will just use 5x20 tin plated cooper bar doubled up so 10x20=200sqmm. Thats whats available in France and a friend is bringing to Canary islands today. Should be good for my max 600A if Victron quotes 240sqmm is good for 1000A...
Will do a stress test with all fired up and see if it heats up or not...if well then i add a 3rd on top