Instant powerwall

wim

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Wattsup said:
What amp rating isyour fuse wire Wim, sorry if you already mentioned it

0.2 mm copper wire... did a test and itmelt around 5A at a lengt of 1.5cm and 3.5V
It was a simple test, not the fancy one that Avarage Joe did...
The cells i use are ratedfor 10A and i am sure the fusewire is gone before the current gets near 10A, so for me it will do.
 

daromer

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Its not the single cell current that is the problem or what you protect it against. Its all other cells..
If your cells can do 10A and you got 80 cells the rest can do 790A continuous.... Thats what is dangerous :D
 

wim

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That is very much true... ( only they are 90p packs, not 80p, so 890A...)
But what if suddenly 89 cells all together and at the same time short out and only 1 is still good and dumping current in the other ones... :D ;)
Then my little fusestill is gonnablow.... safety first!! :p
 

daromer

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:) Yeah you should always have some headroom. I test all my fuse wire with 1 cell. If that blows then it will work overall
 

jdeadman

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Something I was testing with a smaller pack. 20p. On high drain if one cell blows the current will grow across the rest of the cells and in my case I was testing 30A drain on 20 cells so it was only 1.5A each cell and I snipped one wire to simulate a issued cell, after about 10 seconds another started glowing red then popped. then another 10 seconds and the rest went at once. It was a neat test. the fuse wire I tried was 38AWG tinned copper wire. i tried it once with 34AWG TCW but I had to cut half of them to get one to blow.
 

Korishan

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what? no video? tsk tsk tsk :p
 

daromer

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That will happen if you pick to thin fuse wire! Its important to design correct from the start. For instance it yo go with 1A max on your cells and nominal of 0.5A the fuse wire should be able to deal with atleast 2A! If you dont you end up with headache :)

I always design with n+1 in mind so that makes it possible to run without 1-2-3 cells or more in each pack :)
 
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jdeadman

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Korishan said:
what? no video? tsk tsk tsk :p

Yea I was just messing around. Would have been good to see it in slow mo :)
 

Korishan

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no science experiment goes by without repeating to see if the results are the same ;)
 

wim

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daromer said:
That will happen if you pick to thin fuse wire! Its important to design correct from the start....

Yep, has to be big enough to carry max. expectedcurrents, and light enough to blow below max. cell current... that would be ideal.

jdeadman said:
Yea I was just messing around....
Messing around with 18650's ?? dangerous... i advise to not do it again. ;)

Korishan said:
no science experiment goes by without repeating to see if the results are the same ;)
Who will do it ?? Not me, i am done soldering like i sayd 10 post ago. :D
 

wim

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Time to takethe new packs in service, but first take them all out to check for broken fuses and so...
And add some protection.


image_cbuzhy.jpg


And in they went..


image_vytygv.jpg



Sooner or later we alldo something stupid, like going up ladders with orhands full batteries, or stumbeling around andshort out packs, or dropping nuts into packs...
Well, i had my little"accident" today, put a pack upside down into the rack... stupid ... :blush:


image_cfvoms.jpg


lots of sparks, fortunately without damage, except the bolt, atleast now i am sure it is solid brass... :)

I havenow 40 kWh ofstorage, will see if i need more, still have space to add one string.
Now have to change the settings in the Batrium watchmon to the new nominal capacity valueof 783Ah....
 

wim

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FrnanduMarti?ski said:
....did you rob a bank? ;)

Shhhhhhht, keep it quiet..... :D

At the price, no secret there, i payd 2,45 Euro/cell.
You can find them at nkon.nl, i bought them in 3 batches of 1260 cells, spread over 1 year.
Still a lot cheaper then2 Tesla powerwalls, and more power,... not counting work and accessories of course... i like to file that under "hobby" ;)

New cells take no time to prepare, test andsort, and they are all the same capacity, sure its more expensive... but if i had to use reclaimed cells, i probably gafe up longbefore reaching 40 kWh.

For the forth string, if i need it,i will be as always,watching for a real good deal.
 

Bertin_S2000

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wim said:
Time to takethe new packs in service, but first take them all out to check for broken fuses and so...
And add some protection.


image_cbuzhy.jpg


And in they went..


image_vytygv.jpg



Sooner or later we alldo something stupid, like going up ladders with orhands full batteries, or stumbeling around andshort out packs, or dropping nuts into packs...
Well, i had my little"accident" today, put a pack upside down into the rack... stupid ... :blush:


image_cfvoms.jpg


lots of sparks, fortunately without damage, except the bolt, atleast now i am sure it is solid brass... :)

I havenow 40 kWh ofstorage, will see if i need more, still have space to add one string.
Now have to change the settings in the Batrium watchmon to the new nominal capacity valueof 783Ah....
What kind of bolts and nuts are those? Where I can buy them
 

wim

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The melted ones ?... i have 1 for sale. :D

It are solidbrass M8 bolts, pretty standard... you can buy them at your local hardware store.
Not sure from ebay, because they are often just brass plated.
 

Bertin_S2000

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wim said:
The melted ones ?... i have 1 for sale. :D

It are solidbrass M8 bolts, pretty standard... you can buy them at your local hardware store.
Not sure from ebay, because they are often just brass plated.

Ok nice, thanks
 

hbpowerwall

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What you've created is nothing short of art!
 
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Korishan

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wim said:
Look at the lined up soldiers! They have NO idea they are headed for the meat grinder :p
 
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