Flexible busbars from AliExpress

Butcher

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Nov 14, 2021
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175
I'm surprised to find there is a no hole option. That way, you could put in the right size hole for you needs instead of using a one size fits many, approach. We all have drills and drill bits. A lot less to warehouse and make.
 

RCinFLA

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Jun 21, 2020
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These straps should be about 0.025 milliohms if they are truely copper and maintain good interconnection between laminations at the bolted down terminal ends.. Should probably use a stainless steel washer on top to ensure terminal area compression across full width of laminate layers.

At 300 amps that would be about 7.5 mV of voltage drop per strap.

Like China grade 'A' cells, you likely cannot trust they are pure copper. Brass is 95% the weight of copper so with dimensional measurement accuracy it hard to tell the difference by weight measurement.

Brass has 4.8 times the resistance of copper however.

Drilling holes in the laminate structure may not be so easy without possibility of snagging and twisting up individual layers. Would likely have to put external outside binding aluminum plates on ends and clamp it tight to keep drill bit from snagging on individual layers.
 

Butcher

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Drilling anything has issues but nothing that is too difficult to overcome. If I was a manufacturer, I certainly would sell them. A few less to stock and less machining. Sell them at the same price and you'll get more profit too.
 
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BMcL

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Sep 5, 2021
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836
These straps should be about 0.025 milliohms if they are truely copper and maintain good interconnection between laminations at the bolted down terminal ends.. Should probably use a stainless steel washer on top to ensure terminal area compression across full width of laminate layers.

At 300 amps that would be about 7.5 mV of voltage drop per strap.

Like China grade 'A' cells, you likely cannot trust they are pure copper. Brass is 95% the weight of copper so with dimensional measurement accuracy it hard to tell the difference by weight measurement.

Brass has 4.8 times the resistance of copper however.

Drilling holes in the laminate structure may not be so easy without possibility of snagging and twisting up individual layers. Would likely have to put external outside binding aluminum plates on ends and clamp it tight to keep drill bit from snagging on individual layers.
Selling something that's mis-represented to geeks will get you in trouble fast IMHO. Somebody will find out.
When it comes to drilling, I always use M42 cobalt drill bits and start with 3/32", then 3/16" and finally 1/4".
1/4" should give a tight fit over a 6mm post.
 

Nobodybusiness

Renewable energy user
Joined
Dec 19, 2021
Messages
1,115
Location
North Carolina
I bought some Weber Power Tech flexible busbars from Li-ion Battery Manufacturer Store on 12/16.

View attachment 77801
I figured they were coming from China since the original expected delivery date was in the end of January. I was pleasantly surprised to receive them today. It looks like they came from a US warehouse.
View attachment 77802
They seem to be high quality. You can order from them with confidence.


View attachment 77803
View attachment 77804
I bought the same ones.
Very happy with them.
 

MattiFin

Solar Addict
Joined
Dec 31, 2020
Messages
448
These straps should be about 0.025 milliohms if they are truely copper and maintain good interconnection between laminations at the bolted down terminal ends.. Should probably use a stainless steel washer on top to ensure terminal area compression across full width of laminate layers.

At 300 amps that would be about 7.5 mV of voltage drop per strap.

Like China grade 'A' cells, you likely cannot trust they are pure copper. Brass is 95% the weight of copper so with dimensional measurement accuracy it hard to tell the difference by weight measurement.

Brass has 4.8 times the resistance of copper however.

Drilling holes in the laminate structure may not be so easy without possibility of snagging and twisting up individual layers. Would likely have to put external outside binding aluminum plates on ends and clamp it tight to keep drill bit from snagging on individual layers.
Some of the flex busbars actually look like they have solid ends.
this one looks obvious https://image.made-in-china.com/2f0...ble-Bar-Copper-Connector-Flexible-Busbar.webp
 

jsmetalcraft

Solar Enthusiast
Joined
Jul 7, 2021
Messages
152
Selling something that's mis-represented to geeks will get you in trouble fast IMHO. Somebody will find out.
When it comes to drilling, I always use M42 cobalt drill bits and start with 3/32", then 3/16" and finally 1/4".
1/4" should give a tight fit over a 6mm post.
.250" is a sloppy fit in my book over 6mm (.236")
 

mdatot

New Member
Joined
Jan 18, 2022
Messages
11
These straps should be about 0.025 milliohms if they are truely copper and maintain good interconnection between laminations at the bolted down terminal ends.. Should probably use a stainless steel washer on top to ensure terminal area compression across full width of laminate layers.

At 300 amps that would be about 7.5 mV of voltage drop per strap.

Like China grade 'A' cells, you likely cannot trust they are pure copper. Brass is 95% the weight of copper so with dimensional measurement accuracy it hard to tell the difference by weight measurement.

Brass has 4.8 times the resistance of copper however.

Drilling holes in the laminate structure may not be so easy without possibility of snagging and twisting up individual layers. Would likely have to put external outside binding aluminum plates on ends and clamp it tight to keep drill bit from snagging on individual layers.
I bought the 71.5mm long ones and measured the resistance with a YR1035+ and got 0.1 mOhm (hole-to-hole measured at the inner edges of the holes). I'm mainly reporting this in the hopes of attracting more data points from other people though, because I have strong doubts about the accuracy of this measurement. The YR1035+ is a ~$50 Aliexpress thing really intended for measuring internal resistance in batteries, and while it is a real 4-wire precision resistance meter I have absolutely no way of calibrating it nor any real expectations of accuracy for values this small. It is reportedly quite accurate for measurements in the 10 mOhm range (which is really what it's intended for), but these values are two orders of magnitude smaller. The user manual for the device actually has a neat little FAQ section that cautions against trying to measure values below 0.3 mOhm, noting that "it is not impossible to measure, [but] the reading error is large", and "the measured value of 0.05 mOhm is sometimes very accurate, but the uncertainty will make the reference of little significance". FWIW the measurement is repeatable though and the same on all of the bars, and also the same regardless of whether I measure on the nickel plated top or bottom surface or the raw copper(?) sides of the bar.

I don't have any known copper busbars handy to compare against but once I get my cells I can report back.

(Addendum: they've improved the packaging etc quite a bit since that review I linked; my unit came in a neat little box with the manufacturer's logo on it that would be worthy of any mid-tier consumer electronics device, plus a user manual in decently readable English, and the UI on the device itself defaulted to English too.)
 
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