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AJW22's modular 3d printed 30kWh PowerShelf
#11
What kind of 3D printer do you have?
Did you use PLA or ABS?
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#12
In this time I am to building in 80 cells by pack with plastic pieces 4x5 for 14s80p
If I could see before your very good conception I have to choose your principal concept
Congratulations very good choices
Just a question you have sold fuse wire in series with cells in parallel ?
Bye
Eric
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#13
(03-05-2019, 06:35 PM)Walde Wrote: What kind of 3D printer do you have?
Did you use PLA or ABS?

I used PLA on a CR-10 printer with the small 30cm x 30cm bed to print my current 14S92P battery brackets.
My next battery will be 14S108P, the maximum my printer can handle.
Quite confident that this design could be expanded to much larger packs if you have a larger print bed.


(03-05-2019, 08:41 PM)eric.peton@laposte.net Wrote: In this time I am to building in 80 cells by pack with plastic pieces 4x5 for 14s80p
If I could see before your very good conception I have to choose your principal concept
Congratulations very good choices
Just a question you have sold fuse wire in series with cells in parallel ?
Bye
Eric

Yes, I have 2 cells sharing 1 fuse wire that breaks at ca 4 Amps.  
My initial plan of using axial glass fuses on each cell seemed quite difficult to execute space wise, so I used AWG 40 wires as fuses.  I got the wires by separating the strands of a AWG 26 cable.
I am _maybe_ regretting this decision a little.  
The longish fuse wire (1cm ~ 6cm * 2 sides) has a lot more resistance than the axial glass fuses (fuse part is just 4mm), causing an estimated 2%~4% energy loss at max pack load of 25 Amps.  Twice that if you include charging and discharging.  Probably not a big issue once I have my 2nd parallel battery online.
The next time, I will probably use 32 AWG on at least the negative side.  That should reduce losses significantly while still giving some backup protection.  Perhaps also use 2 strands of 40 AWG on the positive side.
Also, 40 AWG wires are a pain to handle and solder.  And they break easily when stretched, so I needed to add some slack.
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#14
I really like the 3d printed cell holders but would prefer a slightly different configuration... are you in the mood for doing some STL design work for others with 3D printers but not the skills to design?
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#15
(02-27-2019, 01:23 PM)ajw22 Wrote: * Finally settled on a very simple 2x 2mm^2 straight solid copper bus bar, which should have no problem with my max 25A use.

You are aware that 50% of your cells are fused with 2x the current right?
In case of a short an outer cells will only see maximum the fuse-rating.

But an inner cells will se 2x this current before both leads blows.
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#16
Removed post - content updated and combined into my first post
Scottietheyoung and Chuffer like this post
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#17
(05-30-2019, 01:47 AM)ajw22 Wrote:
(05-29-2019, 04:24 AM)Hanssing Wrote:
(02-27-2019, 01:23 PM)ajw22 Wrote: * Finally settled on a very simple 2x 2mm^2 straight solid copper bus bar, which should have no problem with my max 25A use.


Todo:
1. Move batteries to bolted down dedicated rack (80% done)
2. finish another 14S104P battery (70% done)
*. add another 1kW GTI
*. harvest and build more 14S104P batteries (0%)
*. 3.2kW solar panels and another eSmart3 charger before winter (0%)


edit: attached pic and .stl of my latest pack (#8) and mounting bracket

Man this is really helpful. thanks so much for sharing the print design. I am printing one tonight to trial for my build. it looks like it could be a real winner for me.

thanks again!
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#18
Man I love the cell holders. I am having another go at printing a 104 pack. wish me luck finding level on my dodgy bed surface!
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#19
(05-30-2019, 01:47 AM)ajw22 Wrote:
(05-29-2019, 04:24 AM)Hanssing Wrote:
(02-27-2019, 01:23 PM)ajw22 Wrote: * Finally settled on a very simple 2x 2mm^2 straight solid copper bus bar, which should have no problem with my max 25A use.

You are aware that 50% of your cells are fused with 2x the current right?
In case of a short an outer cells will only see maximum the fuse-rating.

But an inner cells will se 2x this current before both leads blows.

Yes and no.  Suppose one of the inner cells short circuits.  On one fuse we have the 1 outer cell with 100mOhm of internal resistance.  On the busbar side we have 100 cells with effectively 1mOhm internal resistance.  So the vast majority of the current will be flowing from the busbar side, breaking that fuse virtually immediately.  So just during the briefest time the fuse requires to vaporize, more current will flow.

Perhaps of bigger concern is what might [not] follow that.  That 1 outer cell might not be able to supply enough current to break the fuse connecting it to the shorted cell.  Thus continue to discharge and heat up that area.
But considering most manufacturers weld up to 6 cell in parallel without fuses, it's probably not a huge safety issue.  But good thing I keep my system in a detached concrete bunker, just in case.



======================

Just a quick update for now, will post proper one with pictures in a few weeks:

Installed and running:
* 6.5kW of solar panels just for charging
* 2x 60A eSmart3 solar charger (limited to 28A ea)
* 1x 14S92P and 1x 14S104P batteries
* 2x 1kW GTI with limiter
Cycling happily between 4.05V ~ 3.40V, outputting up to about 13kWh AC.  Used just 40kWh from the grid this month vs 500kWh last year.


Todo:
1. Move batteries to bolted down dedicated rack (80% done)
2. finish another 14S104P battery (70% done)
*. add another 1kW GTI
*. harvest and build more 14S104P batteries (0%)
*. 3.2kW solar panels and another eSmart3 charger before winter (0%)


edit: attached pic and .stl of my latest pack (#8) and mounting bracket

check out print. External layers perfect... first INTERNAL structure layer is SKETCHY as! high speed and under-extruding. every subsequent layer is spot on. 




we got there though! this file works and its away. Thanks again for the awesome share.
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#20
Removed post - content updated and combined into my first post
Scottietheyoung likes this post
Modular PowerShelf using 3D printed packs.  30kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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