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diy solar

Quick way to obtain (or make) busbars inside usa

hipringles

Solar Enthusiast
Joined
Jan 31, 2021
Messages
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Finally got my 32 cells for the 48V system, but it only came with 32 bus bars. I need another ~16 bars to interconnect the cells into series. Does anyone know of an american supplier? Nothing comes up from ebay/amazon with quick shipping...

Alternatively, could wire be used? The battery will be NMT 100 amps, so I am thinking a 2awg wire (~3.5 inches each) interconnecting the cells into series could work, but the conect to the cell is a bit less ideal than a busbar.
 
How about using 30 busbars to make two 16s batteries, the last 2 busbars to parallel the ends for 16s2p, and interconnect intermediate terminals with skinny wires and ring terminals for 2p16s?

High current should only be flowing in the strings.
Low current comes from BMS to balance cells.
 
2 16S batteries require 2 BMS rather than 1

Yes, but that was just the first phrase I wrote.
Follow the progression I described and sketch it out. In the end it is 2p16s and will work with 1 BMS.

You wanted to use busbars in both X and Y direction. I'm saying the current between cells at the same voltage is near zero so that's the place to use skinny wires. Use busbars for the high current path.

I'm great at drawing pictures in my head and sometimes get the engineering correct. I'm just lazy about drawing pictures on the computer.

As I think about it, I do have concern about making sure current splits evenly at the ends and doesn't redistribute across skinny rungs of the ladder.
The typical diagonal connection we do for positive/negative cables on two strings of batteries (16s2p) wouldn't be ideal in the 2p16s configuration.
You would want both positive and negative cables to branch evenly where they connect. That's a pair of cables, a pair of busbars, or middle bolt hole on one bus bar.
 
aaah I see what your saying! The current going across skinny rungs is a concern... For all things being all I'm ok paying the $70 for 1awg welding cable to make busbars, if that seems sufficient?

Or are you saying as long as we pull from the ""middle" point of the 2p16s pack this should be a non-issue? :)
 
(Ends of the 16s of course, not not middle of which could imbalance 12V or 24V out of 48V)

Connecting the two +48V terminals with a "V" or "Y", same for the two negative terminals, should keep current pretty well balanced. In that case skinny rungs should be OK. But one bad connection and suddenly all the current would crowd over to one side and go through a single cell. I guess that would be a hazard, and without fuses to protect every rung it would be best to use heavy enough rungs that they won't burn up.

Do you have female threads in aluminum terminals? Welded on male studs? Forum members have had lots of fun with stripped threads and resistive contacts getting hot.

Cables and ring terminals work too. Dissimilar metals and corrosion is something to consider - it appears aluminum to tin and tin to copper is better than aluminum to copper. Stacked terminals results in less bolt engagement, so studs with nuts could be better. If cells are clamped, or closely spaced and try to spread apart when they well, rigid busbars could apply stress on terminals. A variety of design choices.

I haven't build any of these. I do have 8s AGM, and for that I used 10" crimped cables 4/0. Not nearly as many as your busbars.
 
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