Making busbars (melting copper)

[BiduleOhm]

For Clamping I bought a pile of "straight edge" normally used with plastering walls.

They have flat surface and handle to make them strong enough for clamping.
Price was with 4 dollar per meter OK.

That looks perfect

It can be any profile you want as long as it's rigid and you can easily drill it for the threaded rods to go throught, it doesn't need to be U channel or square tube specifically.

I guess it's up to each one to figure out how much exactly "hand tight" is.

You really need a torque wrench if you want to torque something. Even someone really experienced with torquing bolts with a torque wrench can achieve something like a +/- 50 % accuracy by hand only, so not really precise... ^^

Probably have one set of the 280's total 560Ah
One set of 2* 152's, total 304Ah and
One set of the bad ones.

That would be acceptable too

 

[Frank in Thailand]

You really need a torque wrench if you want to torque something. Even someone really experienced with torquing bolts with a torque wrench can achieve something like a +/- 50 % accuracy by hand only, so not really precise... ^^

Absolutely right, yet the torque at this low force is highly depending on thickness of the rod, thread type, lubricant etc.

For a car wheel10 Nm more or less doesn't mean much.
I would not try this on a terminal.

With "Hand tight" 8 x 6mm rods , pressure will be between 200 and 400kgf.

Depending on own knowledge of force Working with tongue wrench does improve this a lot!

Switch to the relationship between terminal torque of max 8Nm and the 9Nm for the compression...

If one is unsure about their own strength, get a sensitive torque wrench and set it to 7Nm.
That gives it a little extra space before you pull out the thread...
The terminals are made of soft aluminium, you can scratch it with your nail..
(Or my terminals just are funny)

I think I'll be fine.
Quite a few years experience with tightening things.
I know the difference between not tight enough, tight, too tight and oepsie..

Fixed many different things, from excavators to cars to iPhones, and many, many computer related..

All fun in their own way.

 

[ToadHarbor]

It wasn't possible to release the copper from the mold, I ended up smasing it.

After this, I decided to stop using clay, and go to iron.

I have a few left over chunks.


Watching videos showed me that it's good to put some oil on the iron, and pre-heat.



View attachment 15102

After pouring


After cleaning:


The size is not correct for any of my cells, too big or too small.




But large enough to fit over every cell that is needed.

I just need to solder a few side by side.
Cut out the rest, and melt it again what can't be used.

One busbar is 6mm thick.

This should be sufficient to handle 300A

AMAZING ... just AMAZING you're wearing shorts. I'm glad it all ended well.

 

[Dhopewell]

Much less dramatic I purchased 1/4 x 1 inch tinned bar, 72 inches costs about $60 USD per foot delivered. There were a couple other items so individually sent delivery may be more. But it is hard to drill with hand tools - too soft and gummy.

 

[Zil]

lubricate the bit. There is a special wax stick, like a stiff grease. But I also used transmission fluid, motor oil, and wd-40.

 

[Frank in Thailand]

I have good drill,and yes I always use oil to lubricate when I drill into metal.

Also cutting thread goes a lot better with some oil

I'm confused about the $60 per foot delivery..
You pay $60 for 30cm of bus-bar?

I have total over 10 meters...

That make my bars relative cheap.
22kg for $375

How much Kg do you get for $60?
Exact dimensions don't seem to matter for the price.
1/2 inch, 1 or 1 1/2 Inch, all the same price per kg.

I payed about $17 per kg, include transport

 

[Dhopewell]

The price was $10 per foot delivered. A foot weighs about 460g so price is $22/kg. I think the price is a litttle high but it was already tinned.

 

[Frank in Thailand]

AMAZING ... just AMAZING you're wearing shorts. I'm glad it all ended well.

Yes.

And wearing shorts on purpose!!

Melted metal will burn directly in jeans or any clothing.
Why give yourself sense of falce safety?
Unless one would have the special thick leather clothing of a blacksmith..
You are screwed in case of problems.

When you get to the hospital, you'll be happy not to get the melted, fused with your flesh jeans pulled out of your wound.

Just clean melted metal is best for deep burns.
Anything else complicate the healing process.

As boy of 16 I was on fire, literally.
Ik know first hand how it feels... :-(

Most of my skin healed remarkably well.
My lungs not so lucky.

It might look scarry, but I know exactly what I'm playing with and what the results are if some goes wrong

 

[Frank in Thailand]

T

The price was $10 per foot delivered. A foot weighs about 460g so price is $22/kg. I think the price is a litttle high but it was already tinned.

Thanks!!

As I have no idea of normal market price, I was afraid I got ripped off.
Copper kilo price is 6-7 USD.

Then 17 per kg felt like a lot.

I got several quotes, some being almost double... So I guessed it was a good offer.

The bars are perfect, not dent, bended or twisted in any way. I choose to have them at 100 cm. length so I can cut the length I need.

After all the different possible setups that might happen as some of the cells are bloating/delaminating I needed the flexibility.

Thanks for sharing.
No I know I didn't got a ripoff price
(Or toerist price as they call it here.
Anyone who doesn't speak fluent Thai... Double pricing system)

 

[ToadHarbor]

Yes.

And wearing shorts on purpose!!

Melted metal will burn directly in jeans or any clothing.
Why give yourself sense of falce safety?
Unless one would have the special thick leather clothing of a blacksmith..
You are screwed in case of problems.

When you get to the hospital, you'll be happy not to get the melted, fused with your flesh jeans pulled out of your wound.

Just clean melted metal is best for deep burns.
Anything else complicate the healing process.

As boy of 16 I was on fire, literally.
Ik know first hand how it feels... :-(

Most of my skin healed remarkably well.
My lungs not so lucky.

It might look scarry, but I know exactly what I'm playing with and what the results are if some goes wrong

Okay, So I do blacksmithing and I have a thick leather Apron, steel toed shoes and fireman's gloves. That's why seeing your outfit amazed me. I've been burned plenty, have a few hole in my clothes, including one in my right boot.

 

[Frank in Thailand]

@ToadHarbor ,

Yes, on regular basis you have the proper equipment.
I'm sure your furnace didn't melt like mine

For a one time hobby project one should start with buying the property safety and when that is in place, the stuff needed to do the one time hobby project....

Totally agree and like many DIY totally ignored.

Not the safety.
The protective gear.

Then the choice, jeans or naked legs..
With any burns you better have naked skin.

Thrust me.
I know. The day before I was 16 I was lid up like torch..
Not my fault.
Goofy action of teenager friend pouring kerosene with 20% nitro on a fire...

That 5L jerrycan went off like a rocket and I was standing right in front of it.
My lungs got hit the hardest.

Bare skin is the best if you get burned.
Or good enough protective gear, special made for the job, that is better.

 

[Frank in Thailand]

Back on track of the bus-bar!!

I am working for weeks now to make bus-bar.

Cutting and drilling holes for total 80 cells, 160 Terminals, that took some time.

What took a lot longer time is tinning copper.

First making the acid mix, then tin rods, and 4 glasses and cleaning the bars .

It takes about 1 hour to tin all sides
(Electroplating)
I first tried my lab PSU, later I use my LiFePO4 cell, 3.2v is perfect voltage for electroplating.



My 4 glasses with half dipped in bus-bar.
More mass takes longer.

I have a few long, really long bars to connect 2 layers , they are dipping partly.


Not easy to do.

End result is quite professional



Why?
Several reasons.

Most importantly, prevent Galvanic corrosion.
The terminals are aluminium.
Bars are copper....
That will go bad in time.


I'm sure you all have seen this before.

A setup that is hopefully going to last 10 years is not something to build in 10 minutes.

Better take 10 weeks preparation, or in my situation, 20 weeks with all the Covid 19 delays.

Galvanic corrosion is real, and a problem over time.

Also reason to use 304 stainless steel headless bolts.
It's practically neutral to electric difference between the metals.

Why headless?
They give less stress on the weak aluminium thread in the terminal.



Next step is preparing the bus-bar to attach wires for BMS and others.

Keep you posted!