Flexible bus bar question

[K8MEJ]

I have some EVE 280Ah cells slowly making their way across the ocean. I've been thinking about how to make the bus bars for the terminals and I think I'd prefer something more flexible than solid bar stock. I've seen some threads with homemade copper lugs attached to tinned copper braid. Is there an economical source of these ready-made? Thank you

 

[Supervstech]

I have some EVE 280Ah cells slowly making their way across the ocean. I've been thinking about how to make the bus bars for the terminals and I think I'd prefer something more flexible than solid bar stock. I've seen some threads with homemade copper lugs attached to tinned copper braid. Is there an economical source of these ready-made? Thank you

Economical? Not really, flexible readymade are usually pricy... think $5 each.
A roll of braid, and some copper pipe in a vice, then plate, or solder them... or both. And boom, high end custom flexible busbars.

Tin Plating, Nickle Plating or Solder plating Bus bars - History

diysolarforum.com

 

[Johncfii]

K8MEJ:
Like you, I wanted flexible cell interconnects. I wanted them to allow for spring-compressed cell expansion. i prefer to only use tinned copper, so the rather costly, and only slightly flexible, non-tinned CALB bus bars don’t interest me. Looking at tinned copper braid, I found that high ampacity braid is pretty expensive.

I ended up making my own out of 5-inches of #1 AWG TEMCO welding cable ($1 for 5” from Amazon in the form of a 15-foot length) and tinned copper SELTERM terminal lugs ($1 each from Amazon in qty 25.) I already owned a hydraulic crimper (a cheap Chinese version that works quite well), so the cost was $3 per interconnect. And I know the ampacity for sure.

If you are going to make your own out of flexible copper braid, be sure you know the ampacity of the braid. If the ampacity of the braid isn’t listed, you can be sure that it is pretty low. Even then, try to verify by asking how many strands of what gauge wire are used to construct it, and confirm the calculation.

Here is a photo of one of my DIY flexible interconnects. (The photo was taken before adding a bit of shrink tubing to cover the crimped end of each lug.) The ampacity of this #1 AWG wire is almost exactly the same as the rigid bus bars that came with my 280:amp cells, although they are obviously a bit longer.

I found that bending the cable after stripping the ends, and before crimping the lugs, produces an interconnect that pretty well holds that shape, while being pretty flexible over a limited range of motion.

Kind regards,
John, K7KEY

 

[K8MEJ]

Economical? Not really, flexible readymade are usually pricy... think $5 each.
A roll of braid, and some copper pipe in a vice, then plate, or solder them... or both. And boom, high end custom flexible busbars.

Tin Plating, Nickle Plating or Solder plating Bus bars - History

diysolarforum.com

Yes, that does sound pretty easy actually. Thank you. If you happen to know of a good source of high current braid please let me know. I'll google around and see what I can find.

 

[K8MEJ]

John, that's a good idea, too. Thanks.

 

[K8MEJ]

Yes, that does sound pretty easy actually. Thank you. If you happen to know of a good source of high current braid please let me know. I'll google around and see what I can find.

McMaster-Carr has it. That didn't take long

 

[Gazoo]

Yes, that does sound pretty easy actually. Thank you. If you happen to know of a good source of high current braid please let me know. I'll google around and see what I can find.

I haven't ordered these yet and I don't know anything about the quality. But these might be an option.

Ground Straps - Grounding - Connectors, Cordsets & Terminals - Products

www.galco.com

 

[Supervstech]

McMaster-Carr has it. That didn't take long

You can also get braided battery cables at tractor supply, or northern tool, and cut it up for use...

 

[Capt Bill]

I haven't ordered these yet and I don't know anything about the quality. But these might be an option.

Ground Straps - Grounding - Connectors, Cordsets & Terminals - Products

www.galco.com

Specs say braided wire has just a 50 amp rating. I would love to find some reasonable prices flexible battery terminal connector that could handle 280 - 300 amps for the 280Ah LiFePO4 cells. ... Still looking via search internet and this forum, while also considering my DIY options like Johncfii's above.

 

[Capt Bill]

I already owned a hydraulic crimper (a cheap Chinese version that works quite well), so the cost was $3 per interconnect. And I know the ampacity for sure.

In my desire for same flexible battery terminal connectors, Your (Johncfii) DIY connector looks like the best option I have seen to date, except for the DIY time required; and along side some picture with no sales link of some bus bars that (looked like they) had a flexible centers. I also own a hydraulic crimper, and would rather find a 280 Amp rated fix I could buy that would fit with adding battery cell compression. ... I gotta say: I think it is a little retarded (being a past mechanic into specification standards) to be selling LiFePO4 cells with solid bus bars while having compression standards listed in their data sheets on battery cells; when the cells are likely to change dimensions (slightly) when running higher amps in and out, especially on cells that are not perfectly flat on the side planes. I WISH FLEXIBLE BUS BARS WERE SUPPLIED AS A REGULAR PART OF THE LiFePO4 SALES !!! That is My Two Cents REQUEST to the LiFePO4 SUPPLIERS (IF any of them ever read this thread) !!! ... while I am mostly appreciating the good deal prices of what I have obtained so far. :+)

 

[Gazoo]

Specs say braided wire has just a 50 amp rating. I would love to find some reasonable prices flexible battery terminal connector that could handle 280 - 300 amps for the 280Ah LiFePO4 cells. ... Still looking via search internet and this forum, while also considering my DIY options like Johncfii's above.

I should have directly linked to this one. It has a max current rating of 150 amps.

32760

Ground Strap, 100mm Long, M6 Holes,

www.galco.com

Part number is 32760. Icotek rates the current current between 132-157 amps.

MB Ground Straps Made of Flexible E-Cu Stranded Wires with Connecting End Pads

Ground straps manufactured with highly flexible E-Cu stranded wires. Available in a variety of lengths and cross-sections.

www.icotek.com

Going by the cross section of 16 mm² I think it's equal to a 6awg cable. Might be good enough for my use with a 2000 watt 24 volt inverter and I will most likely only use around half of that. But...I want everything to be sized to be able to handle the full 2000 watts which is 100 amps.

Icotek has others with much higher current ratings but they have 10.5mm holes which are way to big IMO.

I WISH FLEXIBLE BUS BARS WERE SUPPLIED AS A REGULAR PART OF THE LiFePO4 SALES !!!

I totally agree. I would not have minded paying extra for them. But at the time when I ordered my cells I did not realize expansion would be a problem using the solid bus bars. And I have been charging at .05C rates. Having watched my cells expand and contract I think the use of solid bus bars is a bad idea.

 

[Sanwizard]

I have some EVE 280Ah cells slowly making their way across the ocean. I've been thinking about how to make the bus bars for the terminals and I think I'd prefer something more flexible than solid bar stock. I've seen some threads with homemade copper lugs attached to tinned copper braid. Is there an economical source of these ready-made? Thank you

This may be a good source: https://www.altestore.com/store/sol...ridge-grounding-strap-expansion-joint-p11047/

 

[Capt Bill]

This may be a good source: https://www.altestore.com/store/sol...ridge-grounding-strap-expansion-joint-p11047/

Looks Interesting; but IMO: Pricey Plus a bit iffy for 280 Amps ... the 1C rating of the EVE 280 Ah cells (even though my DIY 24v set might only see up to 0.5 C or 140 Amps / I have my main battery wires sized and fused for 300 Amps.

 

[Sanwizard]

Looks Interesting; but IMO: Pricey Plus a bit iffy for 280 Amps ... the 1C rating of the EVE 280 Ah cells (even though my DIY 24v set might only see up to 0.5 C or 140 Amps / I have my main battery wires sized and fused for 300 Amps.

Yeah, depends on your use case. In my case, my LV6548 only pushes 125Amps max charge, and my loads are nowhere near that. But if you need a constant 280amps, they may be too light.

 

[Solar123456]

Yeah, depends on your use case. In my case, my LV6548 only pushes 125Amps max charge, and my loads are nowhere near that. But if you need a constant 280amps, they may be too light.

how have the grounding straps ended up working?

 

[Sanwizard]

how have the grounding straps ended up working?

Grounding straps? If you mean bus bars, I bought some from LtDan that are great. My batteries are not grounded, but the panels are, as well as the AC side.

 

[Supervstech]

Grounding straps? If you mean bus bars, I bought some from LtDan that are great. My batteries are not grounded, but the panels are, as well as the AC side.

I think he meant how are the bussbars made from grounding straps holding up.

 

[Sanwizard]

I think he meant how are the bussbars made from grounding straps holding up.

Ah.. I never ended up going that way. WAY too expensive.

 

[Solar123456]

Oh sorry, I must of misread. I thought you were using the flexible braided copper straps.

 

[K8MEJ]

FWIW, amateur radio enthusiasts ("hams") use tinned copper braid a lot for bonding our radios, mixers, computers, test equipment, etc. to common RFI ground planes. It's easy to find tinned copper braid. Check out Ham Radio Outlet, DX Engineering (not a place for low pricing), GigaParts, etc. For example, I have some flat copper braid from ABR Industries in my parts drawers. I took some 1/2" copper pipe - the hard drawn, thicker type - and two pieces of 1" wide braid to make a flexible bus bar to get around a situation where I couldn't quite line things up right to use the solid copper bus bar I used elsewhere in my project. It carries my max current of 200A with no heating. I saw the idea somewhere on this forum months ago and used it to good success. You can see the marks my vice made and the holes aren't perfectly centered, but it works very well.