Aluminum alloy busbars conductivity
- Thread starter yabert
- Start date
RussNM
Solar Wizard
$75 bucks for a 2 troy oz bussbar. Im all over that like a duck on a junebug! NOT! I bet Martha Stewart uses those and cant understand why everyone else doesn't. Im actually wondering if ANYONE could actually see any difference in that vs copper?I'm over it. Going to use silver bars in the future.
I'll just say they are aluminum....
robbob2112
Doing more research, mosty harmless
Raw copper bar stock cheap... they also have the 4" wide on sale.... or regular price for any of it.
Cut them out or have them cut the right width or length and trim yourself.
Speedy Metals 1/4" x 4" 110 Copper Flat
Buy 110 Copper Flat from Speedy Metals, America's favorite online metal store with unsurpassed service, highest quality and best selection.
www.speedymetals.com
Cut them out or have them cut the right width or length and trim yourself.
Yes, conductivity is 75% compared to electrical grade copper. IACS = International Annealed Copper Standard.
Could be even worse depending on manufacturer, I didn’t go digging exact standards.
Zwy
Emperor Of Solar
RussNM
Solar Wizard
So do you think you would see any difference if you went with c110 ? Im just trying to wrap my head around this to see if anyone could tell that they have more or less "power" depending on their choice of bussbar. Is this whole thing like "my production car Bugatti Veyron will do 267mph compared to your Bugatti Mistral will only do 261mph?
......And if we go with the prettiest most electrically conductive copper bussbars and then thru a standard service panel which has ALUMINUM bussbars does it really make that much of a difference?
robbob2112
Doing more research, mosty harmless
The power is the same in all cases if the bar is sized property.
Lower conductivity means higher resistance at the same size, so you oversize for different materials. The reason you use known alloys is to be able to do sizing.
Brass is also used a lot, copper and zinc. The cheap bars have low quality alloys with more cheap zinc. Real electrical alloys of brass have a lot of copper so are more expensive. The trick is there is no way to test outside of a lab. They claim the are thick copper plated the nickle. To get a good finish you have to plate with copper first. But DC doesn't use a skin effect so the bar needs to be very conductive or a good alloy. The thick plating would need to be 4mm to do the job properly. When the bar is 20mm that is a large percentage so I don't trust it. This is why I don't use brass bars for anything. They will work but waste energy as heat.
I have read a few things that suggest the less conductive materials limit the ability to pull surge currents through when they are needed, but I would need to do more research to be sure.
Lower conductivity means higher resistance at the same size, so you oversize for different materials. The reason you use known alloys is to be able to do sizing.
Brass is also used a lot, copper and zinc. The cheap bars have low quality alloys with more cheap zinc. Real electrical alloys of brass have a lot of copper so are more expensive. The trick is there is no way to test outside of a lab. They claim the are thick copper plated the nickle. To get a good finish you have to plate with copper first. But DC doesn't use a skin effect so the bar needs to be very conductive or a good alloy. The thick plating would need to be 4mm to do the job properly. When the bar is 20mm that is a large percentage so I don't trust it. This is why I don't use brass bars for anything. They will work but waste energy as heat.
I have read a few things that suggest the less conductive materials limit the ability to pull surge currents through when they are needed, but I would need to do more research to be sure.
No clue!
With bussbars this is only a matter of needed size and maximum temperature rise. You can compensate the worse material by selecting larger cross-section.
Power-wise the differences are neglible unless you have 100 feet of busbars. Limiting factor is in 99% cases the busbar temperature.
RussNM
Solar Wizard
Exactly what I was thinking. Resistivity is measured in meters. Who has 39in long bussbars? Im sure someone does.
I looked up SparkyJJO's aluminum bars and the resistance was something ridiculously small like .000000032 ohms per meter!
So also I've come to the conclusion that unless you're running hundreds and hundreds of amps thru your bussbars the difference in the top "cost-wise" materials are pretty negligible .
robbob2112
Doing more research, mosty harmless
HEY,
I have a pair of 45" copper pieces... of course I intend cutting them down to make other things... 45 being the longest I could get without jumping to the next higher price for shipping.
But those with the cabinets for server rack batteries may indeed have 40" bus bars if they run the height of the cabinet.... Seems like there was a scandal when EG4 shipped some of their 5 tall cabinets with aluminum bars in it for a while and the description said it was supposed to be pure copper.
+60" of busbar on each leg and 120kwh of battery. To some extent, it probably affects how each bank charges/discharges, but most days it stays in float long enough that everybody gets what they want.
RussNM
Solar Wizard
Even so I doubt it would make very little difference even if you switched to aluminum and say doubled the thickness? Who knows unless you have a sophisticated lab or even the desire to experiment...
Considered al but IIRC, it was going to be as expensive as cu. It wasn't the difference in ampacity that worried me as it would be MacDonalds supersized, it was all those cu lugs bolting up to an al bar creating lots of places for oxidation, or whatever that krap is that likes to grow in those spaces. Noalox works, but hey, why push the luck.
sunshine_eggo
Victron's little biatch
21P14S with 644 inches in total bus bars joining cells.
What I did.
Copper was just too expensive.
LOTS of Al alloys and conductivity:
Yes, aluminum has a lower conductivity than copper and the different aluminum alloys have varying conductivity values. Before I bought any of my aluminum flat bar I did the research, so I wasn't surprised. As @robbob2112 said above, as long you you keep the conductivity differences in mind and select the correct size it's not a problem. I've used both copper and aluminum.
Aluminum can be easier to work with. I can TIG weld (most) aluminum in my garage. Welding copper is possible but it is uncommon. Aluminum is lighter than copper and less expensive. Aluminum is more readily available and in a wider variety of sizes. There are aluminum alloys that cannot be welded (7000 series alloy I think). I have not looked into welding any of the higher conducting aluminum alloys (1000 series).
I'm not in a humid environment so I haven't plated any of my copper. I leave it bare and be sure to coat the contact surfaces with NO-OX-ID.
Aluminum can be easier to work with. I can TIG weld (most) aluminum in my garage. Welding copper is possible but it is uncommon. Aluminum is lighter than copper and less expensive. Aluminum is more readily available and in a wider variety of sizes. There are aluminum alloys that cannot be welded (7000 series alloy I think). I have not looked into welding any of the higher conducting aluminum alloys (1000 series).
I'm not in a humid environment so I haven't plated any of my copper. I leave it bare and be sure to coat the contact surfaces with NO-OX-ID.
robbob2112
Doing more research, mosty harmless
One thing not talked about yet is the thermal conductivity... the idea shape of copper for DC conduction is square, but the ideal for shedding heat is a thin rectangle. Some materials like aluminum conduct heat many times faster than others like brass.
Zwy
Emperor Of Solar
I do, in both the shop system and the house system. All shown in my build thread photos and videos.
It actually is quite surprising the voltage difference between each pack attached to a central busbar as indicated on each BMS screen. I have all 8 lit up now. All cable lengths are the exact same length, that is explained in a video too.
As for using aluminum busbars, as long as it is sized properly for the same resistance as a length of copper, then go for it. You will need to know what aluminum alloy you are using and size appropriately which was the purpose of this thread. For 110 copper, those specs are easy to find.
Don't forget to ensure any aluminum oxide is cleaned off the connection and to use an antioxidant. With copper, I just nickel plate it and can wipe the surface clean with a solvent.
Square D offers both the Homeline and QO lines. Homeline uses aluminum busbars, QO is copper. Can you guess which Square D line I use?
yabert
Solar Addict
Here another good and simple reference who compare Copper, Alu, Brass, Iron : https://www.ihiconnectors.com/IACS-conductivity-electrical-alloys.htm
Brass is terrible!
Brass is terrible!
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Zwy
Emperor Of Solar
All JK's. No I didn't calibrate the BMS but one can see the differences in current draw too. With cables coming from each side of the box to the central busbar, the cables had to be mounted on the positive busbar with different spacing between holes.
Even at different current draw (which you can also calibrate by the way), the voltage should be pretty much the same. If there are big differences, calibrate the voltage: otherwise the individual cell voltage readings are also incorrect and this can cause issues with the protection limits.
