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Modular 14S 40+P Powerwall up to 20kWh
#1
Hi all,

my powerwall build is approaching and i have some questions about it.
After a half year of recycle & testing 2000+ cells, i sold all recycled stuff because im going 
to do my build with new cells - from a long view it is the best for my case (not the cheapest.. ;-) ) 

Key data for my build:

- Cells: LG INR18650-M36
- SolaX Hybrid SK-SU3700E G2
- Batrium BMS

I tested some LG INR18650-M36 and im going to use them from 4.05V - 3.20V.
By 500mA discharge the capacity is round about  2500mA.
I choose this cell because they have a good cycle life According to the data sheet:

charge 0.2C 1A to 4.10V, discharge 0.5C 1.675A to 2.85V
after 1000 cycles 80% capacity

I will charge/discharge with max 500mA per cell (when build is complete ~300mA)

I  start with a 14S 40P configuration what is 5.1kWh in my case.
After this setup is working well i will expand the packs by adding 40, 80 or 120 new cells to each pack.
Goal is max 20kWh (400A) = 14S 160P in this setup.

Would you recommend it that way? I think with all new cells this should not be a problem..?

I read a lot about the cell fusing.. im not sure what to use for my build.
Maybe Glas fuses with 1.5A? What Mainfuse should i use?
LG INR18650-M36 has 5A max discharge, SolaX Hybrid SK-SU3700E max 50A charge/discharge

sunny greetings
Richie
wim likes this post
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#2
Nice work. I think its fully doable.

I would have a main fuse of atleast 50A. The Solax should tell you what fuse to have. Then i would have 4-5x cell rating fuses.

So if we say that you fuse 50A and have 40p as start => That gives me 1.2A per cell and 4x that is 5A on cell level fuse. I actually think 4-5A is a good choice on those cells. The main fuse makes sure you dont overrate the cells as such and the cell level fuse make sure that you dont kill the packs by a cell going fully rouge. This is mot likely not going to happen with new cells and therefore i would go with that rating to.
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#3
(06-12-2019, 03:23 PM)daromer Wrote: Nice work. I think its fully doable.

Thx :-)

The SolaX Manuel recommends 63A Fuse
Do you have a recommendation for a model with remote trip for use with Batrium?

Sounds good, so i will go with 4A glass fuses on cell level - and spot welding :-)
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