How to Save Money When Buying low voltage busbar
Busbar help for my bank | DIY Solar Power Forum
Am I wrong in thinking that the most the amp flow could be is the max my inverter could draw?
Safe assumption but size everything to handle the rating of the fuse. If you are using a 400A fuse make sure everything can handle that.
Also be cautious and plan how to limit potential for shorts between the cells, and between cells and the fuse. With 930Ah that is like a small Chernobyl if it shorts out and you can't stop it.
I would strongly suggest considering a fuse between the first 3P2S block and the second as well.
Putting together a 3P4S bank with twelve 310Ah cells and a REC active BMS. I could use some help with Busbars. Will it be ok to buy 1/4" x 1" copper and make my own? Will the longer, 6 terminal lengths be a problem? Thanks in advance!
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Size the busbar for the current you want to draw. Bigger is always better, but as others have noted, make sure you have a fuse that will protect your wire. Usually your wire is what will limit current, both voltage drop and temperature rise.
Handy charts to correctly size 110 copper busbars. https://diysolarforum.com/resources/busbar-selection-table.104/
Safe assumption but size everything to handle the rating of the fuse. If you are using a 400A fuse make sure everything can handle that.
Also be cautious and plan how to limit potential for shorts between the cells, and between cells and the fuse. With 930Ah that is like a small Chernobyl if it shorts out and you can't stop it.
I would strongly suggest considering a fuse between the first 3P2S block and the second as well.
Would a mega fuse between the two packs work?
I used 0.125" x 1.5" Copper Rectangle Bar for my single runs and 0.125" x 4" Copper Rectangle Bar for the 1S6P connections in the middle
The 1/8" is plenty thick enough to carry all the current you need and much easier to drill -- 1/4" copper grabs the bit a lot more
I have made Busbars with a drill press and with a handheld battery drill -- The handheld drill worked rather easy (surprisingly)
A machinist friend of mine showed me to put masking tape on the metal where I wanted to make my marks --then use a 1/8" bit just to make dimple in the metal --then drill the holes the size you need --- Slow is better and clamp your work down -- nothing worse than a spinning piece of bar stock
I use plenty of tape over all the terminals I'm not working on -- I had a mishap with my wedding band that taught me well ( millisecond short had my ring glowing and burnt a ring around my finger -- I decided to rotate my connections 90 degrees from your diagram -- therefore your pos and neg terminals are further apart -- this way you have two 3 hole busbars / two 3x3 square busbars / one 6 hole busbar
Am I wrong in thinking that the most the amp flow could be is the max my inverter could draw?Reality is probably that you will be limited by available breaker size and wire size.
You are going to need bigger wire than 4/0 if you plan to push a constant 900a.
For bus bars there is simply no reason to use smaller than 1/4".
Would a mega fuse between the two packs work?
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This image shows what the Everlander guy did. He's pretty sharp and typically well thought out designs so would not hesitate to copy this idea. It's also not a theoretical view as he's been all over with this system design. You can see the mega-fuse between bus bars in the bottom. His is a 5P4S design I believe.
Putting together a 3P4S bank with twelve 310Ah cells and a REC active BMS. I could use some help with Busbars. Will it be ok to buy 1/4" x 1" copper and make my own? Will the longer, 6 terminal lengths be a problem? Thanks in advance!A quarter inch by one inch should be able to handle approximately 400 amps with a temperature rise of 30 degrees Celsius. So about 300 amps. The longer busbar should not be a problem, just keep the screw holes as small as possible/reasonable. You might want to consider 3 separate battery packs and BMS to give some redundancy. Even using contactors, you will have problems being able to handle 900 amps. @FilterGuy has a nice resource on fuses. He certainly knows more than I do about the subject.
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DC Fuse and breaker Sizing and Placement
To get the paper, click on the orange button at the top of the page The attached presentation gives the fundamentals for picking fuse/breaker sizes and describes where in the circuit they should be placed. You can download the presentation by...And Will has a very comprehensive resource as well.
Bussman: Selecting Protective Devices
Free PDF teaching how to select and use over current protection devices: Based upon the NEC® This comprehensive guide to electrical overcurrent protection and electrical design considerations is based on the NEC®. With over 300 pages...For me, I expect 140 to 150 amps as maximum draw, so I have a 200 amp class T fuse, as well as a 200 amp Bussmann breaker (mainly as an off switch).
Class T fuses are expensive, but regular fuses may not work when confronted with the amps lithium cells can produce. You might want to run a straight edge across your terminals --- when you clamp these cells together the terminal heights are not always the same -- if you're using these cells with the m6 shallow threads and thick busbars you'll pull the treads out before they make good contact -- this really isn't much of an issue with a 2 hole busbar -- I was really surprised how much cells terminal heights differed
I have made Busbars with a drill press and with a handheld battery drill -- The handheld drill worked rather easy (surprisingly)Good advice on making your own there. The wedding ring is something to watch out for, since there is easily enough amps to totally vaporize your ring. Not just get hot, but literally make it a cloud of rapidly expanding gas (aka explode).
A machinist friend of mine showed me to put masking tape on the metal where I wanted to make my marks --then use a 1/8" bit just to make dimple in the metal --then drill the holes the size you need --- Slow is better and clamp your work down -- nothing worse than a spinning piece of bar stock
I use plenty of tape over all the terminals I'm not working on -- I had a mishap with my wedding band that taught me well ( millisecond short had my ring glowing and burnt a ring around my finger -- I decided to rotate my connections 90 degrees from your diagram -- therefore your pos and neg terminals are further apart -- this way you have two 3 hole busbars / two 3x3 square busbars / one 6 hole busbar
This image shows what the Everlander guy did. He's pretty sharp and typically well thought out designs so would not hesitate to copy this idea. It's also not a theoretical view as he's been all over with this system design. You can see the mega-fuse between bus bars in the bottom. His is a 5P4S design I believe.
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Maybe it's just me, but he starts out the video by explaining he blew up his solar controller by not turning it off properly.
I'm not sure I would take his build as "this is what you want". The cells he uses are high quality, but if memory serves me correctly, he has those because he killed his first set (not the CALB). I could be wrong about that.
As someone else noted, he makes me cringe the way he handles busbars and tools. @chops728 - I still have a crooked finger from a similar incident from many moons ago. I switched to a silicone ring way before they became the cool thing
You didn't say what your max amp load was, but if it's 400 amps or less 1/4" x 1" bars are fine.
Even in a high temp rise of 65°C they are good for a little over 600 amps.
Just as important will be a clean contact area & shrink tubing the bars between cells to prevent accidental shorting.
Putting together a 3P4S bank with twelve 310Ah cells and a REC active BMS. I could use some help with Busbars. Will it be ok to buy 1/4" x 1" copper and make my own? Will the longer, 6 terminal lengths be a problem? Thanks in advance!how did this go?
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Low voltage | Busbars | CAPLINQ
Low voltage busbars are used primary in switchgear equipment for residential or industrial use. The switchgear equipment may contain single busbar or double busbars, and the types of switchgear may be solid-, air-, or gas-insulated. In all cases, the rated voltage of low voltage switchgear does not exceed 690 Vac. Though this is high voltage compared to the outlets in your house, these are still quite low voltages compared to the 12kV to 38kV used in medium voltage busbar applications. In these case, the thickness of the epoxy coating used is much, much less than for medium voltage busbars. The purpose of the epoxy coating powder is the same however: to insulate the busbars from each other and to prevent dangerous arcing faults.
Parameters considered for epoxy coating powders for low voltage busbars include:
- Can the epoxy coating powder be applied in a thin enough layer in order to optimize the cost/performance of low voltage applications?
- Can the epoxy coating powder be used in an outdoor environment or for outdoor applications?
- Can the epoxy coating powder be made to be flexible to maximum design efficiency and to bend the busbars after coating?
For many years, CAPLINQ has supplied a range of epoxy coating powders developed for low voltage (up to 690V) busbar and switchgear equipment. CAPLINQ is one of the few epoxy coating powder suppliers qualified for use in Power Distribution Switch Boards and also electric vehicle charging stations. Given the critical nature of the application, the time and costs involved to pass UL-certification, major Power Management Companies rely on CAPLINQ and their family of UL-capable epoxy coating powders. All the products offered by CAPLINQ for busbar applications are UL capable and can be subject to test upon agreement with the end customer.
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Three products stand out in the CAPLINQ product line for low voltage busbar applications.LINQSOL BCP-, LINQSOL BCP- and LINQSOL BCP-. These are all close alternatives to the legacy products DK15-, DK15-, DK15- DK15-E.
The "One Powder Solution": LINQSOL BCP-
Cost effective environmental resistance with LINQSOL BCP-
If you are only making low voltage busbars with electrostatic spraying, nothing beats the value for money you can get from LINQSOL BCP-. This low voltage epoxy powder is widely applied in various low voltage busbar applications (<600V) as an insulation and moisture-proof protective layer. This busbar insulation epoxy powder allows high production efficiency thanks to its fast curing characteristics. It is strongly recommended for electrostatic spraying (60-80KV) coating. It offer the best cost-performance ratio.
LINQSOL BCP- offers Process Flexibility
LINQSOL BCP- applies at low voltage copper and alumina busbars (600V) with a coating thickness of 0.3~1mm. This epoxy powder brings high productivity with low pre-heat temperature and quick curing. Due to its fine-grind process, it can be used with both electrostatic spray and fluidized bed dipping.