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[ElectricRebel]

Hello,
Since I've tinkered with replacing the busbars in my bike with ones made from copper, I decided to actually go for it and I did it.
I've thought about using copper for it's better conductivity and mechanical resistance, since the original Energica Busbars seem to suffer from creeping of the Aluminum.
Energica originally used six 30mm² cross sectional area made from Aluminium in the 21,5 kWh battery packs to connect the 9 battery modules.
The first ones suffered pretty severely from them deforming under the pressure from the bolts alone under elevated temperatures. Basically the Busbars were straight bolted into the battery only with some washers to clap them down. The high clamping force on a small area meant those batteries were more prone to have the busbars deforming.
The latter 21,5 kWh batteries had some stainless steel shims in between the bus bars and the bolts.
Which did spread the clamping force more evenly, but these batteries are also showing signs of the busbars failing. There are even batteries that were "repaired" after the first set of busbars failed with a repair kit issued by Energica themselves, including a new set of busbars with steel shims.
And even those are failing too after some time.
This affects bikes more that are used frequently, get a lot of DCFC etc.
The deformed busbars will also lead to arcing, which could damage the cell tabs as well as the busbars.
And the DCFC charge will fluctuate quite a bit and the temperatures inside the battery will get elevated quicker.

Aluminum is prone to creeping at somewhat low temperatures (seen from a metals perspective), temperatures seen in our batteries (between 35 and 50°C)

Copper does creep to, but it begins at was more elevated temperatures. If we ever get to temps that high where copper could creep, we have a whole set of other problems, like fire   

I designed and manufactured two sets of copper busbars with a cross section of 40mm² + steel shims, as well as nickel plating all that.
One set was given away to another guy who currently upgrades his battery too...

Yesterday finally finished the battery of my bike and installed it, so today I could test it for the first time...
And boy was it a success.
It worked flawlessly.
The bike is running very well and I spooled down the first 400 kilometers...
It's like a complete different bike 😁

If someone is interested too...
I might produce more of these Busbars if there are enough people who want a set to...
Problem is it's quite expensive. It's around 275€ per set + shipping 😬😬...
Maybe some here are as crazy as I am🤣🤣

Best regards from Germany...

[Grauteufel]

Another important improvement in such a high vibration environment, I believe copper has a much higher fatigue limit than aluminium. I would also think that the aluminium would be more prone to corrosion that the copper too.

[Specter]

it depends on the environment, and copper can crud up very quickly indeed.
Aluminum interestingly will very quickly form a thin oxide layer over a 'raw cut' or however you want to state it, to help prevent further degradation.

inside the battery case should be a pretty sealed up environment, hopefully a clean one too, so there shouldn't be a ton of crap to interact and corrode with.

copper wont flow as easily as aluminum, so the loosening issues that causes can be avoided.  on those lines, I've used cuni before for bus bars and it has worked very well.   overall though copper is just a much wiser choice for a bus material over aluminum, especially in that environment with the heat flux and vibration / jarring it can take.

interesting project here, and the end result is much better with copper than aluminum, however the labor involved is quite a bit.

aaron

[jotjotde]

@ERebel: Again congratulations!

I've seen ERebel's new busbars, they look so sleek  Battery casing should be made of glass to admire them 

[ElectricRebel]

it depends on the environment, and copper can crud up very quickly indeed.
Aluminum interestingly will very quickly form a thin oxide layer over a 'raw cut' or however you want to state it, to help prevent further degradation.

inside the battery case should be a pretty sealed up environment, hopefully a clean one too, so there shouldn't be a ton of crap to interact and corrode with.

copper wont flow as easily as aluminum, so the loosening issues that causes can be avoided.  on those lines, I've used cuni before for bus bars and it has worked very well.   overall though copper is just a much wiser choice for a bus material over aluminum, especially in that environment with the heat flux and vibration / jarring it can take.

interesting project here, and the end result is much better with copper than aluminum, however the labor involved is quite a bit.

aaron

The corrosion resistance of copper is lower than that of aluminum, because of that I've given them away for nickel plating to a company. The oxide layer on the aluminum also increases resistance, so the original busbars are also coated with some form of metal ...probably tin or nickel too.

I also had Arcing at the normal cell clamps too, so I replaced all the bolts there too....(See pic down below)

[Specter]

i forget the name of the company but way back when i was doing a solar project and used copper/nickle bus bars.  very corrosion resistant, very durable and won't creep on you.  cuni alloys are fairly common and you should be able to even get some sheet and brake it to what you need then punch it / drill it out as you need.  in the switchboards they use tin a lot to coat the copper bus to help keep it cleaner.

aaron