Zag's Powerwall adventure (UK Build)

zag2me

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Sep 11, 2017
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106
It begins...

Only got 4 solar panels and a 600w micro inverter at the moment but the battery storage is the next stage.


image_vpaesf.jpg


Does anyone have any tips for mounting the powerwalls to the wood? Should I build some shelves in or buy a metal electrical box instead?

Powerwall Kit List
Batteries: https://www.fogstar-wholesale.co.uk/product/samsung-30q/
BMS: https://www.aliexpress.com/item/32811228650/32811228650.html
Series Connectors: https://amzn.to/2KIINKQ
Bus bar to series wire Connectors: https://www.ebay.co.uk/itm/311744812285
Mini Voltmeter: https://amzn.to/2KHipBa
14AG-16AG Butt connectors: https://amzn.to/2MONlwv

eBike Kit List
Battery Bag: https://amzn.to/2MOQIUy
48v Battery percentage meter: https://www.amazon.co.uk/gp/product/B01LVY1ODN
 

daromer

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We all do it differently. Some mount to the wall some do shelves. I prefer shelves since it takes less wall space but then its not a powerwall anymore but more of powershelf :D
 

zag2me

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Sep 11, 2017
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106
Today I bought:

- Home Electrical wire (for the bus bars)
- Resistors (for the fuses)
- Cell holders
- 400 new Samsung 30Q 18650 cells

Hopefully that should get me started.

Another question... what width should the bus bar cable be?
The electrical wires that came out of the house wiring are 3mm total (7 strand) and 5mm total(7 strand) at the moment.
 

daromer

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The busbar size depends on the current you want to carry. In general 1.5mm2 = 10A and 2.5mm2= 16A current in Sweden as typical household.

i use 6*2.5mm2 for my 80p packs with max 80A current. That gets me to e decent low voltage drop.
 

DarkRaven

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That depends on you load. The cells are rated for 15A continuous. 400 cells...7S57P? That would be 855A continuous, if wou want to use that you need quite substantial busbars :)
However, if you are only running your inverter at its max 600W then it would not be more than ~30A or about 500mA per cell. At 24V that is.
For that you should go for 4mm. Go for 6mm if you want to be on the very safe side of things. You said you have 3mm and 5mm, are you sure this is the diameter and you haven't missed the ? 3mm diameter is already more than 6mm, 5mm is over 20mm.
 

zag2me

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Sep 11, 2017
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New Samsung 30Q x 400 :)

Would you recommend I test and balance them, or just throw them into equal power packs?


image_oyluup.jpg
 

DarkRaven

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Well, even brand new cells have some slight variations. There is a minimum capacity and a rated capacity and sometimes a typical capacity as well. If you want to test them, sure, go ahead. However I would probably avoid the effort. Just check if their voltage is equal. They are charged at the factory to a certain standard, often accurate to a hundreth of a volt. Maybe their shipping voltage is even specified in the datasheet.

If they are equal then you are ready to go!
 

jdeadman

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Personally I'd test a sampling from each box. Say 10 from random locations. But definitely check the voltage and test any that are outside of the median voltage
 

wim

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I have used new Panasonic cells, tested a few but they are so close... not worth the time.
Only a quick voltage test and theninto the pack with them. :)
 

zag2me

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Sep 11, 2017
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Nearly finished with the new cells setup around the edge. Recycled cells all above 2600mah are going on the inside.

The lower mah recycled ones will be sold on Ebay UK to pay for the inverter at some point.

Am I right in setting this up as 7s 80p? Any better configurations you can think of?


image_brynro.jpg
 

DarkRaven

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Better is relative. What would be better for you? There is nothing wrong with 7s80p as such.
 

Korishan

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7s80p is what Pete has his massive array of storage built on. Same with darmomer (if I remember correctly).
The only problem would be is if that is one huge pack in the picture above. It would just be bulk to move around, that's all. Pete and others just have their 7s in separate packs.
 

wim

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Korishan said:
7s80p is what Pete has his massive array of storage built on. Same with darmomer (if I remember correctly)....

No, you do not remember it right.... :D They are using a14s80p (48v) setup. :p
 

Korishan

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duh! *face palm* :p

I had just woke up and still bleary eyed. thats what i'll blame it on ;)
 
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zag2me

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Sep 11, 2017
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Yep i've been pretty much copying Pete's setup. Just at 7s
 

Wattsup

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Feb 19, 2017
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Can I ask why you decided to go with 30Qs, since you bought new cells?
 

zag2me

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Sep 11, 2017
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Wattsup said:
Can I ask why you decided to go with 30Qs, since you bought new cells?

No real reason other than the size and price (270 for 100). They look pretty too :) they all test out around 2900mah so nice and regular.

I'm mixing and matching new and recycled cells. Nearly there....


image_cmxykf.jpg


Also thanks to a tip on this forum I found a nice plastic holder for the batteries banks.


image_mfvkuq.jpg
 

IronSky

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Jun 12, 2017
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zag2me said:
Also thanks to a tip on this forum I found a nice plastic holder for the batteries banks.


image_mfvkuq.jpg

Keep in mind, however, that your pack is quite big and does not tip it out. Maybe you should secure it upstairs or stick it with hot glue in the bowl. ;)
 
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