18650 Garden-Powerwall with 50KWh in Germany

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Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
the last two weeks I finished my powerwall project. On the ToDO list:

28 batterie packs 60p
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At the end it's more effort then the bigger 120p packs because of twice of the amount of busbars
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I solder the fuse wire in one piece and at the end I cut the unnecessary pieces
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almost ready
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just need to solder the fuse-wires to the busbars
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next step: balancing all the packs
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pretty dangerous so close together, I do recommend not to do so
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for me it works well but I_ve done this just several times
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_11.jpg


on the other side there are sitting the 120p packs, but they need some time to balance too
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after 48h of balancing the 60p are balanced and ready for installation
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they will support the 11KWh system at the pigsty
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all wires are 16mm² as well as the busbars
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I decided to take the BMS plate out again and make a modification
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I want to add a external voltmeter to the locker so I can see the battery status while walking past the locker without connecting to the bluetooth app, so I have to add a shunt
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_29.jpg


then back again with the bms and with all battery packs. Two systems with 14s60p each fits into one compartment
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_30.jpg


next is to customize the bms wiring harness
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Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
on the right side the two older systems, left the two new with identical capacity
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_33.jpg


at the app there are four systems now
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because the voltages didn't fit there is a huge current at the moment of adding the two new systems to the older ones
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_35.png


4,5V difference.
But it doesn't matter, all cables and BMS are good for 60A continous current
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_36.png



after installing the battery packs I want to add a voltmeter too
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_37.jpg


the "Dremel" clone works well with the good grind discs from a dental supply
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_38.jpg


on this picture the display is with default settings therefore the battery status is wrong, you have to manually set the max and min voltage first
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phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_43.jpg


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last step is to complete the fire safe insulation. Now, the system in the pigsty is finished
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next step: the other system at the garden shed
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_45.jpg


to the already existing two systems of 14s120 there comes another 14s120p
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_46.jpg


phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_47.jpg


I add a shunt too
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_53.jpg


it's designed for 200A. Each battery system will be limited to 120A
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_55.jpg


phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_56.jpg


cables and busbars in 35mm² copper
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_58.jpg


the bms wiring harness has to be extended
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_59.jpg


phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_61.jpg


just stuck together, without some cable management at this point
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Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
here we go, the three systems inside the locker at the garden shed
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the moment of connecting
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now that it works I can do some cable management
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phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_66.jpg


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phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_69.jpg


cables for the voltmeter
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phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_72.jpg


and the front insulation
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now three of a total of four compartments are fully equipped (the smaller locker in the pigsty has one compartement left too)
phoca_thumb_l_KW09_DIY_18650_Powerwall_Spind_fertig_74.jpg



So, now at this point I finish my powerwall project because weather is getting better and I have lots of plans for my garden.

At the end here are some facts summed up
  • 75KWh of usable capacity
  • 10.800 cells 18650 from used and defective laptop and ebike batteries
  • voltage range single cells: 3,30 - 4,05V
  • voltage range 14s systems: 46,0 - 56,6V (exception: 16s system at the garage)
  • maximum total output power: 16,4KW
  • duration of this project: 11 month -> very first start was in april last year

Thanks a lot to pete for his videos with very good explanations and the possibility to take part of the whole building process, this definitely encourages people which are new to this things to get it on. And for this community too.

I learned lots of things from this YT channels and can't recommend them strong enough to others
 

ziporah

New member
Joined
Apr 26, 2021
Messages
26
Hey Stefan, great thread. Do you use the current limiting function on the BMS?
I'm planning to start my first build with a 14S80p pack, but I want to limit the current in my packs to 500mA per cell, thus max 40A in this stack. I plan to upgrade my packs in the future when I have enough cells, to add another 14S80 pack and be able to pull 80A total. I want to buy a 5KVA inverter for my future plans already, I know I can limit the current there, but when I extend the packs I don't want it drawing more current from this pack, since I don't know what cells I'll get I might go for a bigger or smaller pack in the future.
 

Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
Hi. I guess the BMS can't limit the current in the way you want to.
The value "max. current" is a hard limit like a fuse, not a limitation which smoothly drops the current down to this value.

If the "max current" is higher then the value you set (for at least 10 seconds or so) then the bms will go into safe mode and cut off the load.
After 60 seconds it will release the load again an if it exceeds the "max current" again it will cut it off again.
BMS_failure_over_discharge_current.png
 

italianuser

Member
Joined
Feb 25, 2020
Messages
335
Amazing Stefan, I "watched" the whole post as if it was a documentary. And thanks for writing the descriptions and model number of the pieces you used, I took note and will try to find them over here where I live 💯 :giggle:
 

Bib60

New member
Joined
Mar 6, 2021
Messages
17
Hi
I love your project :)
About PowerWall Bracket, is 2mm steel plate is enough to hold battery packs or need more or less thickness ?
i have 3900 cells (13S10P x 30) to fix on the wall ;-)
Thanks a lot
 
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Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
cheap plasma cutter, see on the second page of this thread:
 

annalivan

New member
Joined
Jul 24, 2021
Messages
1
As far as I understand, you have built a solar panel in your garden. I must say that it looks impressive. You have done a great job, but very useful. This solar battery will provide your home with electricity, and it is very, very cool. I have also been thinking about installing a solar battery for a long time, but I always do not have enough time. After work, I only have enough time to put my garden in order a little and make sure that raccoons do not spoil my garden furniture.
If I decide to install a solar panel, I will definitely use your instructions. By the way, thank you for sharing your experience.

___________________________________
www.gardenfurniture.co.uk
 
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