Glubux's Powerwall

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Hi Glubux

i saw that you were using cells around 1200 mAh in the beginning. Did they work good or are they still in the packs? Trying to find out if lower capacity cells can be used, too. I don't want to use cells under 1500 mAh but everything above, maybe.

BTW i really like your build. Maybe some of your ideas will influence my build. The capacity goal per pack for example. This is great.
 
Thanks!

I no longer use 1200 mah but I still have 1300/1400 mAh 180 cells packs, surprisingly they do the job as the others.
And because I don't mix too much the different capacity cells, if the pack fails I'll only be removing a pack of old cells and won't have to save some 2000 mAh+ mixed with the 1300 ish

BTW remember I test my cells with Imax and they give lower results, for instance the highest I'v ever seen is 2700 mAh out of 10 000 tests!
 
So youre doing the packs from lets say 180 1500mAh cells wich is 270Ah and 135 2000mAh cells wich is also 270Ah. Am i right?

What is your actual Ah goal per pack? And you do 180p packs right? If fully equiped with cells?

I use SkyRC chargers wich also give me lower results.
 
Exactly, the target is around 250 Ah
However because I test the cells @ 1A but never exceed 300mA in use, I noticed with my first packs that a 100 Ah 80 cells pack has a bit more capacity than a 100 Ah 60 cells pack. So my rule of thumb is to ad a few more cells than the math says :

A pack with cells between 1500 and 1600 mAh with 160 cells is 1,55X160 = 248 Ah
With cells between 1600 and 1700 mAh I should normaly use 152 cells : 250/1,65 = 152 but I ad one more
With cells between 1700 and 1800 mAh I should normaly use 143 cells : 250/1,75 = 143 but I ad two more

And so on...

I hope this makes sense
 
Ok i also test at 1A so that makes sense to me. I think we can never get perfect balanced packs. Too many factors to change capacity...

I also noticed that the cells have a different amount of capacity in different voltage ranges. For Example LG F1L cells have around 3200 mAh when tested at 1A and Samsung 35E cells have around 3350 mAh when tested at 1A but in the voltage range from 3,3 to 4,0 V the LGs have higher capacity values.

My thought was to test 10 cells at a time in this voltage range and then arange them into packs afterwards...
 
My guess is most solutions works as long as you don't overdischarge unballance and then ovecharge the weakest pack.
 
Are these packs just large capacity 3.7 V and will be put in series with additional packs?
 
I'm thinking of a passive bleeder on each pack just in case one of them wants to go higher than expected.
 
I'v found this picture of the very first start of my powerwall, January 29th 2017, two year ago...

image_qnwpld.jpg

Those packs areperforming as the first day :)

I used 5500 kWh from my system for now
 
Glubux said:
I'v found this picture of the very first start of my powerwall, January 29th 2017, two year ago...

image_qnwpld.jpg

Those packs areperforming as the first day :)

I used 5500 kWh from my system for now
Click to expand...

Loved watching your project grow...
 
Glubux said:
I use a custom setting with a 56v limit for both absorption and float wich is 4v per pack, this way the current slowly decrease as the voltage reaches 56V.
Click to expand...

can you please share this your victron configuration. Thanks
 
Glubux said:
Very easy

Absorbtion voltage 56v
Float voltage 56v
Click to expand...

Wow that's nice and low I run mine at 57.4v top
 
Yeah with big powerwalls we have so much storage capacity I don't really see a need to go above 4v, I prefer to keep my cells as comfortable as possible to make them last longer.
It also add a safety margin if your packs are not perfectly balanced
 
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