14S9P Samsung 50E battery pack build

A previous topic I had covering my build went walkies so this is a new topic to check my thinking during my build. I have already had some super useful discussion in the aforementioned topic as well as doing plenty of reading on cell life and life cycling by the members here doing that testing.

I have settled on the battery I am using - The Samsung 50E, which I will be using at 70-80% of capacity to extend cycle life.

The pack is part of a swappable battery system powering a portable computer station, not a bike.

Wherever possible I will be looking to implement safety features in the design of the battery. The chances of failure are low, but the outcome of failure can be extremely damaging.

I am fusing each cell to internal bus bars, the layout I have in mind is shown here:


Each series cell is capable of 88A continuous, but the max load the system I am making would put on the cells is about 51A, and usually significantly lower than this. I would like to build in overheads however so I was think to spec the busbars to carry the full 88A.

I just wanted to check however that I was correct to think that each busbar between each series group needed to be able to carry the full 88A?

Assuming they do, I then used the following table:
https://www.powerstream.com/Wire_Size.htm

To get a cross sectional area required. So for a 10mm width and 1mm thick bar the "amps for chassis wiring" would be a bit under 89A.

So would a 10x1mm busbar with each cell individually fused be correct for this?

So I'm just bumping this as I think I may have got my thinking wrong on how much current each connection between P groups needs to carry.

Or rather, I haven't got the total wrong, but the cals on the 'busbar' wrong.

In the pic I posted, each bar that the cells are fused to needs to carry 80a+

I therefore did the calculations on the bar as width x height to get the conductor area, then compared this to standard copper AWG wire capacity.

Problem being I did this for these bars as if the current were flowing from one end to another - but it is actually flowing widthways across the bar to the next group (correct me if my understanding is wrong here). So I specced my bars, which are 220x13x1.5mm as carrying over 135amps.

However I now realise the maths should probably have been 220x1.5 - which is... well... thousands of amps.

Am I right in my thinking here - that my 'busbars' between P groups are way over specced?

pretty much yes probably only an amp goes sideways but copper seems like a good heat sink for when a fuse wire blows, anyone look at using aluminum?

just re-read, 89amps from 9p basically 10 amps but typically 6amps continuous, you could almost just use the nickelstrip everyone uses or nickelplated copper

That's true, although OTOH a large heat sink may actually increase the burn temperature of the fuse. Not sure how easy Alu is to weld or solder. I know it's harder than steel to weld with an arc.

Re your second paragraph:
That's correct on a per individual cell basis, and as the P group is the full 9 cells wide the amperage is essentially flowing cell to cell you are likely right that any nickel that would ordinarily carry 10A from a single cell would be fine when spread across the P group in this manner.

I actually decided to use 15A fuse wire.
(nickel plated copper) It's well above the spec I need and its burn temp is probably 30-40A+, but for what it protects against it should be good, as any short will result in hundreds (even thousands) of amps.