Powerwall Journey with reused e bike cells ( 20 kwh )

caosmen

New member
Joined
Nov 10, 2019
Messages
28
Hello everyone,

first of all something about me. I am here since i saw a youtube video from Peter Metthews and thaught never ever will it be true.
So i got one "dead" ebike battery for free and tested it. Less then 10 % missing power and i thaught ok i will do it too. :D

I am not a electrican person, so i have to learn alot but the house part with all the wires a friend will help me.
But i want to learn as mutch as i can since i wanted to be electrican in when i was a child. But became programmer ;)


Right now i have 30 kwpPhotovoltaik at my roof and a Tesla Powerwall 2 (13,5 kwh)running. I am living in germany and from march to October i am 99 % off grid.

Plan:

Add a new 10-15 kwp system just to south, for the new battery and to be in the winter also at 70 % off grid.
Building a 20 kwh Battery for storage.



Setup , so far as i read in here ,will be done with:

10 kw 3 phase hybrid MPPT Inverter 48 V
Battrium
Rack to store all the batterys

How it looks like right now:


image_mclrlp.jpg


Tools i made myself:

Thanks to average joe


image_wlymsw.jpg




Questions right now are :

My Rack is 80 cm long, 60 cm witdh and 100 cm high. What is the best setup for the Batterys. i dont wanna waste alot of space in the rack. I could make a shelf and make them close to 240p = around 60 cm length. idk so far what will be the best way.

I wanna build a very "safe" system since it will run in my cellar. So i just would like to get the batterys charged and discharged with 500 mA and not more.

If i understood in the mppt manual i can set the current and need to calculate my battery that i will just charge and discharge my system by 500mA. Is this true ?


Happy to be here

If there is a chat somewhere i can ask questions and google alot i also would like to know.

thanks

caos
 

richie241

Member
Joined
Nov 6, 2018
Messages
34
Hallo und herzlich Willkommen :)

Nice Project, in Germany its very popular to get and recycle eBike Batterys for free :)
From my view much better than laptop batterys.

The safe way is always good.
You can set max charge / discharge in Batrium, also criticalvalues for shut down the system.
 

jdeadman

Well-known member
Joined
Mar 28, 2017
Messages
932
Have a look at some of the other projects and those with youtube Vids are great. With that inverter you will want to run 14s for liion or 16s for Lifep04 cells.

Have a look at Dromer's Channel as he has some experiences with that 3 phase inverter.

Cheers
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
Hi everyone,

last week i hopefully finished my coming batterie design.

i tryed to use daromers youtube video for some calculations:


Cap: 2500 mAh

14s = 14 x 3,7 V = 51.8 V

3 x 6 Battery Holder = Space for 360 Cells

image_biwvbq.jpg

[size=small]360 / 14 = 24 Parallel = 14s 24p[/size]

i would like to copy the pack design with busbars etc. from jehugarcia. Daromer als did a 48 Volt Pack Design but i more like the easy way of jehu.
Idk about the electrical diverence but when i just look in pack building it looks more easy.

image_ydntxi.jpg




Wh:

2,5Ah x 24= 60

60 x 3,7 = 222 ah
222 x 14 = 3.108 wh


With this long pack i use the depth of my rack very good.

Now i need to understand if this huge amount of batteries and amps is ok or far to mutch.

Any suggestions are welcome

thanks

Nils






Besttigt
 

jdeadman

Well-known member
Joined
Mar 28, 2017
Messages
932
For What hour you take the Ah and multiply it by the average voltage you will be running. So for a Pack that has 14s of 2.5Ah cells each Parallel Set will be 60Ah then take your Voltage for a 14s set you will generally run 3.5V/cell to 4.1V per cell or 49V to 57.4 you take those 2 numbers and add them up then divide by 2 you will get 53.2V
Now 53.2 x 60Ah = 3192 or 3.19Kwh
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
Thanks alot jdeadman. like i said just used daromers calculation but i understand why you do it that way.

thanks for the reply
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
image_xomjbf.jpg
Hi all,

just a quik update:

4200 Cells are testes, 3200 can be used and 600 waiting right now for 2 weeks to get used in the powerwall or not.

Today i spent after idk alot of month searching Ebike Accus and cracking them 6 hours to add the first 2000 cells in a 14S.

Tomorrow i am adding the rest, after that i can start solder both sides. I guess this will take 1 or 2 weeks so the next batch can be added.

Right now 3200 Cells are AVG 2850 mAh. Oldest Testcells from October had still 4.17 Volt ... I realy love Ebike Accus that are normaly waste here in Germany.
 

Cell-King

Member
Joined
Sep 23, 2019
Messages
42
Hi caosmen, Can you explain what Ebike Accus are? I'm guessing they are old ebike cells, but how are you sourcing them, calling bicycle shops?
 

Wolf

Well-known member
Joined
Sep 25, 2018
Messages
1,414
Cell-King said:
Hi caosmen, Can you explain what Ebike Accus are? I'm guessing they are old ebike cells, but how are you sourcing them, calling bicycle shops?
Accus is german for batteries.(Accumulator as it accumulates electrons)so any battery in german is called an Accu.
Wolf
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
Thanks Wolf,

sorry i thaught i better write accu since in there are single cells connected.

Yeah i almost phoned 200 Shops, or probably 3x more,in Germany and drove alot. Everytime when i was in holiday i called all Bike Shops at the Road to find a store that is willing to give me some Packs.


I just have now 5 regular Shops who give me "Dead" Ebike Packs. So its alot of effort but worth it since i got them if you dont calc any time or using the car for free.

Nils
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
Hi all,

small Update:
4 of 14 Packs are build :D

Takes again time but looks awesome


2.jpg
 

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OffGridInTheCity

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Joined
Dec 15, 2018
Messages
1,512
Fantastic work! I know it can be slow going... but at some point you'll hook it all up and it's going to work and you'll tend to forget all the hours and hours and hours of hookup and just enjoy having it work.

I realize see this is the negative side of the pack AND they aren't soldered to the buss yet so the pack is likely not yet finished? But I notice you have the fuse wire across cells instead of 'cell -> buss bar only' and just note that they will burn thru better if you snip the excess. I've done a row of red circles to illustrate what I'm trying to say. :)
1611849777656.png
 
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caosmen

New member
Joined
Nov 10, 2019
Messages
28
Fantastic work! I know it can be slow going... but at some point you'll hook it all up and it's going to work and you'll tend to forget all the hours and hours and hours of hookup and just enjoy having it work.

I realize see this is the negative side of the pack AND they aren't soldered to the buss yet so the pack is likely not yet finished? But I notice you have the fuse wire across cells instead of 'cell -> buss bar only' and just note that they will burn thru better if you snip the excess. I've done a row of red circles to illustrate what I'm trying to say. :)
View attachment 23610

Hi there,
yeah i wanted to cut all these last curcuits when i am done with all packs.

I am happy that you like the pack.

Next Update when everything is connected in hopefully 2 month :D
 

ajw22

Well-known member
Joined
Nov 16, 2018
Messages
584
The amount of copper you're using is... something. Certainly not lacking.

Clearly it's not finished, but the two spots of soldering you tried between the main horizontal bus and vertical branch does not look good. Needs more heat to make the solder properly flow into both parts, though not too much heat to start melting the plastic parts. Not sure if that's even possible with that much heat sucking copper. If it proves unmanageable, I'm sure you could halve the vertical bus strands without too much issue.

And you should try to use less solder on the cells. Reduces the area and amount of heat applied to the cell, saves money on solder, too. This is plenty to hold the fuse in place:
20200708_092903.jpg
 

caosmen

New member
Joined
Nov 10, 2019
Messages
28
The Amount of Copper is calculated that i can use the Powerwall for at least 8 kwh and puffer. I always like to have puffer in my ideas.

Solder i know i did way tooooo mutch on it. First Packs had nearly 4x more solder then needed .... Started as a rookie in soldering. Wrong Iron, wrong temperatur etc. i hit all the mistakes you can do in the past

Thanks for your reply
 
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