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Planning my 4S40P portable power station
#1
Greetings,

Could anyone help to figure it out with schematics for batteries layout and soldering busbars?
Please see the attached picture. I assume that all POS and all NEG should be connected in the manner that a have attached, but this is only from the top. Could any know how these cells should be connected on the bottom side of this pack?


Andrew
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#2
No picture attached
Did you click on picture after it uploaded in image uploader.
Aslo use preview to verify the picture is in the post.
later floyd
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#3
(08-27-2020, 08:07 PM)floydR Wrote: No picture attached
Did you click on picture after it uploaded in image uploader.
Aslo use preview to verify the picture is in the post.
later floyd


Sorry, my bad. Picture attached
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#4
Nope, all wrong. You have Pos Pos, Neg Neg, Pos Pos, Neg Neg. nope. It'd be Pos, Neg, Pos, Neg. Basically what you have drawn is a 4s40p


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#5
(08-27-2020, 09:04 PM)Korishan Wrote: Nope, all wrong.  You have Pos Pos, Neg Neg, Pos Pos, Neg Neg.  nope.  It'd be Pos, Neg, Pos, Neg.  Basically what you have drawn is a 4s40p


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Yes, you absolutely right it was a typo. I have drawn 4S40P. In this case, I also allocate cells in the wrong order, right?
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#6
if you're going with 4s40p, then you the drawing is "sorta" correct. The drawing is 3s40p. (misspoke earlier)

Just connect 2-Pos and 2-Neg that are adjacent to each other (ie, row 1, 2, 3 & 4), and then on the flip side, you add the next section starting with row 3 (ie row 3, 4, 5 & 6).
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#7
(08-27-2020, 11:44 PM)Korishan Wrote: if you're going with 4s40p, then you the drawing is "sorta" correct. The drawing is 3s40p. (misspoke earlier)

Just connect 2-Pos and 2-Neg that are adjacent to each other (ie, row 1, 2, 3 & 4), and then on the flip side, you add the next section starting with row 3 (ie row 3, 4, 5 & 6).

Could you please check. Am I right?

(08-27-2020, 11:44 PM)Korishan Wrote: if you're going with 4s40p, then you the drawing is "sorta" correct. The drawing is 3s40p. (misspoke earlier)

Just connect 2-Pos and 2-Neg that are adjacent to each other (ie, row 1, 2, 3 & 4), and then on the flip side, you add the next section starting with row 3 (ie row 3, 4, 5 & 6).
What do you think about this option? Can I do this way, is this right?


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#8
The first one won't work, you'll create shorts. I highlighted the issues. Unless these were supposed to be alternating top/bottom.

The second one is better. Assuming the blue lines are the bottom side. Just a little tweaking. You should have more than 3 bus lanes. I would say minimum of 4, and go with the widest strip you have. Also the strips that run the length of the parallel groups should also be as wide as possible to fit the space. You don't want any hot spots from restricted current flow. If you think of current flow as water flow, you'll better able to visualize were the restricted flows would be at.

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#9
(08-28-2020, 08:22 PM)Korishan Wrote: The first one won't work, you'll create shorts. I highlighted the issues. Unless these were supposed to be alternating top/bottom.

The second one is better. Assuming the blue lines are the bottom side. Just a little tweaking. You should have more than 3 bus lanes. I would say minimum of 4, and go with the widest strip you have. Also the strips that run the length of the parallel groups should also be as wide as possible to fit the space. You don't want any hot spots from restricted current flow. If you think of current flow as water flow, you'll better able to visualize were the restricted flows would be at.



Few more questions with your permission.

1. If busbars will be1/8" Thickness, 1/4" Width - is it enough?
2. To be honest I didn't catch regarding "Just connect 2-Pos and 2-Neg that are adjacent to each other (ie, row 1, 2, 3 & 4), and then on the flip side, you add the next section starting with row 3 (ie row 3, 4, 5 & 6)" .Is it possible to show on the drawings?


Thank you in advance




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#10
(08-28-2020, 08:47 PM)AndrewBrown Wrote: 1. If busbars will be 1/8" Thickness, 1/4" Width - is it enough?
2. To be honest I didn't catch regarding "Just connect 2-Pos and 2-Neg that are adjacent to each other (ie, row 1, 2, 3 & 4), and then on the flip side, you add the next section starting with row 3 (ie row 3, 4, 5 & 6)" .Is it possible to show on the drawings?

1) That would probably be sufficient, yeah. It's about cross sectional volume to carry current. With 1/8 x 1/4 would give you approximately 105A capability. Remember, current will flow through the "entire" string of cells, not just added up at the ends (this is voltage). That would give you a very good margin to keep hot spots down. You could even go with a thinner material perhaps and still be fine. A 1/16 x 1/4 would give you about 70A.

2) Basically it's what your second drawing is. The blue lines connect the opposite side. The only reason I said 4 rows was because you had 2x20 arrangement. Had you had 1x40, then I'd said connect rows 1 & 2, 3 & 4, on the one side, and connect 2 & 3, on the other side. For each section of the series, you connect Pos to the Neg of the next section.
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