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AJW22's modular 3d printed 30kWh PowerShelf
#21
(06-05-2019, 07:47 AM)ajw22 Wrote: Another quick update:

* Noticed a few days ago that Battery#2_Pack#11 was consistently ca 0.05V lower.  Log indicates this drift started about 2 weeks ago, getting worse every day => there's a leak!  Visual inspection found only 1 obvious candidate, which I replaced.  Took all in all about 5 min.
I thought about boosting the pack up to the same voltage as the other packs, but decided to see how the 50mA balancer would deal with this.
At 3.8V, it was leaking at a rate of about 30mA.  A more powerful balancer would have hidden this problem?
 

* Built the first rack, anchored to the concrete floor and wall.  Moved battery#2 (14S104P) into rack today.

* Still under construction battery#3 now has all its cells.  Fused pack#1, 13 more to go!  Before anyone comments about the cold solder joints: it's a very localized quick high temperature soldering and it's rock solid.
This latest design iteration uses just one long 5.5mm^2 wire as the busbar.  Plenty for my max 30A use.  Removing the insulation is a 1 step process, and no more twisting or splicing.  And it's well secured to the pack, no chance of accidentally ripping out fuses by pulling too hard on the connector.


just amazing stuff mate! LOVE the design and thrilled to be able to utilize it (thanks so much for sharing)

first print has lots of bridging. have removed them from half of the battery holders as in the pic and working on the other half now.


Cant wait to get the printing sussed so i can continue to produce these units.
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#22
Those 3d printers with long bowden tubes (the white nylon tube) like to continue extruding even when the extruder gear stops. Try using my Slic3r settings. Some of the methods I used to reduce this effect: decelerate extrusion before stopping; retract filament 6mm before travel, etc.

Make sure your 18650 cells fit. If your filament extrusion amount is too high, the walls become too thick and the cells might not fit.
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#23
(06-05-2019, 08:03 AM)ajw22 Wrote: Those 3d printers with long bowden tubes (the white nylon tube) like to continue extruding even when the extruder gear stops.  Try using my Slic3r settings.  Some of the methods I used to reduce this effect: decelerate extrusion before stopping; retract filament 6mm before travel, etc.

Make sure your 18650 cells fit.  If your filament extrusion amount is too high, the walls become too thick and the cells might not fit.

will try your slic3r settings tomorrow morning first thing. cells fit beautifully!
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#24
Removed post - content updated and combined into my first post
hbpowerwall and RikH like this post
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#25
What kind of breakers do you use for DC?
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#26
(06-09-2019, 07:45 AM)Maniac_Powerwall Wrote: What kind of breakers do you use for DC?


I use "2 pole DIN breakers" (common part, google it) rated for 440V DC and 25A, 32A and 63A.
If anyone is considering using these, make sure they're rated for DC current!

Oh, and these things are not failure proof. Over the years, I've come across 3 failed 2 pole breakers. 2 made by a reputable Japanese company. All of them failed with no externally visible damage, and just one pole in the always-open position.
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#27
(06-09-2019, 07:53 AM)ajw22 Wrote:
(06-09-2019, 07:45 AM)Maniac_Powerwall Wrote: What kind of breakers do you use for DC?


I use "2 pole DIN breakers" (common part, google it) rated for 440V DC and 25A, 32A and 63A.
If anyone is considering using these, make sure they're rated for DC current!

Oh, and these things are not failure proof. Over the years, I've come across 3 failed 2 pole breakers. 2 made by a reputable Japanese company. All of them failed with no externally visible damage, and just one pole in the always-open position.

What brands? So not the only the broken ones. Maybe better the working :-)
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#28
(06-10-2019, 04:55 AM)Maniac_Powerwall Wrote:
(06-09-2019, 07:53 AM)ajw22 Wrote:
(06-09-2019, 07:45 AM)Maniac_Powerwall Wrote: What kind of breakers do you use for DC?


I use "2 pole DIN breakers" (common part, google it) rated for 440V DC and 25A, 32A and 63A.
If anyone is considering using these, make sure they're rated for DC current!

Oh, and these things are not failure proof.  Over the years, I've come across 3 failed 2 pole breakers.  2 made by a reputable Japanese company.  All of them failed with no externally visible damage, and just one pole in the always-open position.

What brands? So not the only the broken ones. Maybe better the working :-)


For this project I used all cheapo Chinese items from AliExpress.  Note that I use them mostly for the convenience of quickly and safely disconnecting items, and only secondly as a last line of defense re overcurrent protection .  The chargers/BMS have their internal current limits set (1st to trip), have a fuse (2nd to trip), and only then the breakers come into play.


Breakers: 
TOMZN 2P xxA DC 440V Circuit breaker MCB C curve
Note that you MUST NOT REVERSE POLARITY, ie. (+) to left pole, (-) to the right.  Wrong connection might result in fire.
!!! Just realized that they are not suitable when the current can flow in the opposite direction, ie. supply at bottom and load at the top. !!!  It's probably ok in this case since max 60VDC is applied, but looking for a non-polarized replacement nonetheless 
Another thing to keep in mind is that these do not necessarily trip immediately.  A 32A breaker running 64A will trip only after anytime between 8sec ~ 2min.  At 38A, it's anytime between 5min and eternity!
https://www.aliexpress.com/item/2P-32A-D...4c4djOvgQN

Busbar:
Neat and convenient, but only 63A.  That's all flowing current combined, not per port.  Gets uncomfortably warm at that current.  I'm using only 30A now, but will eventually replace this with a higher current one.
https://www.aliexpress.com/item/Copper-B...4c4djOvgQN

Box:
I removed all tabs at the bottom&top to provide better cooling for the breakers and busbar.
https://www.aliexpress.com/item/9-12-way...4c4djOvgQN

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Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#29
is there a scad file for your latest 8 pack, as i need to modify the amount in parallel to suit my ender 3 bed size -230 x 230
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#30
(06-10-2019, 08:51 AM)simonisabella Wrote: is there a scad file for your latest 8 pack,  as i need to modify the amount in parallel to suit my ender 3 bed size -230 x 230

I attached "BatteryPack8.stl.zip" to the post on page#2 with all the other files "BatteryPack9.zip" on my first post.  You can change the pack size by changing "cells_x=14; cells_y=8;" towards the bottom of the file.
hbpowerwall likes this post
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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