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Powerwall - First 1S60P - What do you think?
#1
Question 
Hello Guys, 

I have read here already for a few weeks, now its my first post.

I was impressed of your builds, so I also started to recycle old ebike batteries.
For testing the cells, I use 4xOpus and take the cells which are >80% SOH and after 30 day storage min 4.1 volt.

My goal is to build a home battery with 14S & Victron Energy MultiPlus, which I want control via mqtt.

For testing I already build a 6S5P and a 7S5P battery, which works great in my ebike.

Now I have finished my first 1S60P:

Every cell is soldered with a 5A glas fuse.
I want to max draw 30A per pack, so 500mA per cell. 


Negative side is also soldered for now, but I already ordered the kweld to speedup the assembly and don't stress the cell.

I think soldering on positive side is not a big problem..?

The pack is designed in fusion. I can share the file, if sb is interested (number of cells are changeable via parameter)

The Busbar are 2 twisted copper wires with 2mm diameter.
30A charge test looks great. 
But I am not sure, if it also could handle 60A? (If I put another 60P pack parallel).
Sure, the soldered connection between busbar and (currently) 10 awg can be done much better.

Finally I will use 10awg(for 30A)/8awg(60A) wire + AS150 connectors.

In the end there should be one reset-able circuit breaker between battery and inverter.
Something like this: S802PV-SD125
Would make it sense to also add a melt circuit breaker?

Do I miss something?

Happy recycling ^^
507PowerWall likes this post
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#2
I would like to know the logic behind glass fuse on positive and wire fuse or "no fuse" on neg.... is there any cosmetic reason ? or you think only positive should be fused?

Regards,
CG.
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#3
Welcome and very cool.  
As just friendly conversation - personally, I prefer 6awg twisted strand for 60amp / busbars (rather than 8awg) but if you test at full load and the wire remains room temp - then that's a 'real test' of your setup.  

>In the end there should be one reset-able circuit breaker between battery and inverter.
Yes, typically this can be thrown manually to disconnect the battery bank while working on the system - but also for the BMS to trip (as in shunt-trip type circuit breaker) if the BMS detects a problem. 

>add a melt circuit breaker?
I've not heard the term 'melt circuit breaker'.   Is that like a fuse?   Just curious... Smile

Thanks for sharing w/pics!

(07-26-2020, 07:32 PM)507PowerWall Wrote: I would like to know the logic behind glass fuse on positive and wire fuse or "no fuse" on neg.... is there any cosmetic reason ? or you think only positive should be fused?
The general design most of us follow is to fuse the positive - with axial fast blow or fuse wire (e.g. 30awg or smaller type of thing).  No need to fuse both as the goal is to disconnect the cell from the pack if the cell fails and becomes a short.   A 'fuse' on either end cause the cell to be disconnected from the pack. 
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#4
(07-26-2020, 07:32 PM)507PowerWall Wrote: I would like to know the logic behind glass fuse on positive and wire fuse or "no fuse" on neg.... is there any cosmetic reason ? or you think only positive should be fused?

Regards,
CG.
Because I think one fuse for one cell is enough.
If any cell breaks/short circuit it blow up the smallest fuse. Here you don't have any advantage if you have 2 fuses.

For now I don't now any situation where a second fuse could help?

(07-26-2020, 07:39 PM)OffGridInTheCity Wrote: Welcome and very cool.  
As just friendly conversation - personally, I prefer 6awg twisted strand for 60amp / busbars (rather than 8awg) but if you test at full load and the wire remains room temp - then that's a 'real test' of your setup.  

>In the end there should be one reset-able circuit breaker between battery and inverter.
Yes, typically this can be thrown manually to disconnect the battery bank while working on the system - but also for the BMS to trip (as in shunt-trip type circuit breaker) if the BMS detects a problem. 

>add a melt circuit breaker?
I've not heard the term 'melt circuit breaker'.   Is that like a fuse?   Just curious... Smile

Thanks for sharing w/pics!

(07-26-2020, 07:32 PM)507PowerWall Wrote: I would like to know the logic behind glass fuse on positive and wire fuse or "no fuse" on neg.... is there any cosmetic reason ? or you think only positive should be fused?
The general design most of us follow is to fuse the positive - with axial fast blow or fuse wire (e.g. 30awg or smaller type of thing).  No need to fuse both as the goal is to disconnect the cell from the pack if the cell fails and becomes a short.   A 'fuse' on either end cause the cell to be disconnected from the pack. 
Yes, with melt circuit breaker I mean a normal fuse(not resetable), like this: https://www.amazon.com/Earthquake-Sound-...B00EHZ8L1E 

Inverter is able to handle max 75A, I will use a 100A or 125A resetable fuse.
But in first step my battery is only capable of 30A. 

Ahh true, I forgot the BMS. I can set a max. current there, nice Smile
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#5
(07-26-2020, 07:42 PM)DaBoehla Wrote:
(07-26-2020, 07:32 PM)507PowerWall Wrote: I would like to know the logic behind glass fuse on positive and wire fuse or "no fuse" on neg.... is there any cosmetic reason ? or you think only positive should be fused?

Regards,
CG.
Because I think one fuse for one cell is enough.
If any cell breaks/short circuit it blow up the smallest fuse. Here you don't have any advantage if you have 2 fuses.

For now I don't now any situation where a second fuse could help?

I have seen many packs fused both end... in the same reason of use a 2P Breakers... that is why my question... 

By the way looks very clean and well build... thanks for sharing with all, keep going.

CG.
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#6
(07-26-2020, 07:58 PM)507PowerWall Wrote: I have seen many packs fused both end... in the same reason of use a 2P Breakers... that is why my question... 
I know what you mean - but there is the 'technical side of things' and the 'practical side of things'.   The 2P thing doesn't apply to isolating bad cells to protect a pack. 

In my case....
* I use 30awg as my fuse wire on the positive side which burns thru at 15-20a and is OK for my design - e.g. technical side of things.   However, this is wire is very thin and more difficult (for me) to manipulate  SO... 
* I use 27awg on the negative side because I had a whole bunch and its thicker and easier for me to maniplute.  Not sure what burn-thru is but its much higher and not intended as fuse wire.  Its just 'practical' for me to use Smile

Visually - the packs look very similar from a picture - e.g. 27awg and 30awg are not hugely different - but one is for technical reasons and the other is just because I had a bunch of it.

I sure you'll find many different stories behind the why people use this or that on their packs Smile
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#7
(07-26-2020, 09:32 PM)OffGridInTheCity Wrote:
(07-26-2020, 07:58 PM)507PowerWall Wrote: I know what you mean - but there is the 'technical side of things' and the 'practical side of things'.   The 2P thing doesn't apply to isolating bad cells to protect a pack. 

In my case....
* I use 30awg as my fuse wire on the positive side which burns thru at 15-20a and is OK for my design - e.g. technical side of things.   However, this is wire is very thin and more difficult (for me) to manipulate  SO... 
* I use 27awg on the negative side because I had a whole bunch and its thicker and easier for me to maniplute.  Not sure what burn-thru is but its much higher and not intended as fuse wire.  Its just 'practical' for me to use Smile

Visually - the packs look very similar from a picture - e.g. 27awg and 30awg are not hugely different - but one is for technical reasons and the other is just because I had a bunch of it.

I sure you'll find many different stories behind the why people use this or that on their packs Smile

You are right, and I didnt pay attention to the fack of the 2P which make sense... and is easier the wire... Im still waiting on my 32awg copper to use it in my setup.. 
I have a 10awg wire (PV double protected) with tinned cooper... Which Im thinking to test burst point... but if Im not mistaking is a 30awg....
So in your experience.... Tinned cooper or bare cooper for fusing ?.

CG
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#8
(07-26-2020, 09:50 PM)507PowerWall Wrote: So in your experience.... Tinned cooper or bare cooper for fusing ?.
I use tinned copper for easy soldering - e.g. specifically: https://www.amazon.com/gp/product/B01M0A...UTF8&psc=1
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#9
Melt wire fusing on pos side can drip metal into holes on cap. Fuse neg side.
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