Another DIY Powerwall in Germany (15 kWh)

Hi!

Finally the upgrade is finished. Now 3920 Cells = ~ 30 kWh.
Also new: Active cell balancing using those linkable 1S balancers. Why? Because full charges will be very rare during winter time with the large powerwall, so the passive balacners will not balance at all during winter --> scary.

Also changed my online monitoring a bit. It's german, but you can probably guess what is what ;)
https://emoncms.org/Chicken

Also updated the cell counter now :p



image_lchmxj.jpg



image_djuwjc.jpg



image_atpnvp.jpg


best regards,
Alex
 
Note that on Batrium you can set when to balance :)

But the 1s will hopefully work as well. Not that much cheaper though.... Not for 28s or bigger.

NICE work btw !!
 
Yep, Batrium completely configurable - but that is one sweet setup - you should be proud!
 
IronSky said:
Hallo Alex,
auch von mir herzlich Willkommen :)

Super work you have done there. I also use batteries from e-bikes, but unfortunately I have not as many as you.

Sometimes you have also bad luck with the E-bike batteries and does not get 18650 cells. They are Li-poly or very different formats.

for example cells from Koga Akku :
image_nctxzm.jpg

image_xxbjsw.jpg


The best experiences I have made with the batteries of Bosch and Gazelle. There were always 18650 in it.

Viel Glck noch mit deinem Projekt , vielleicht kann man sich ja mal helfen bei den Akkus.

Schne grsse aus NRW

Iron
Click to expand...
He Iron,

Are that cells lifepo4 chemistry?
I had also this ebike batteries but came too the conclusion that the bms was not good for this kind off chemistry. The charge was setup for li-ion chemistry but the cells are lifepo4. So they where overcharged and puffed. Did you come too the same conclusion?

Chicken said:
Most of the time the packs are glued together with ordinary hot glue which perfectly melts together with the heat shrink wrapping. In rare cases, you can just peel it of (probably if the glue was not hot enough to melt the heat shring wrapping) but usually the wrapping also disintegrates. I think trying to dissolve the glue will also dissolve the wrapping.
So I think destroying the wrapping + rewrapping is the best method :)
Click to expand...

You can use your hair blower and then peeling it off

Chicken said:
...1420 good ones so far and another 600 just arrived today :D

should be enough for my upgrade!


image_miystg.jpg


best regards,
Alex
Click to expand...

Where do you get it from?
 
Hi Alex,

very nice work, congratulations!

Concerning the balancers: Are you aware that they'll also try to equalize bad (high IR) or even shorted cells, up to 10A balancing current? I use the same devices and just added switches to turn them off, just to see how my packs behave without active balancing...

And I'm very interested in your measuring setup. Could you supply more details on how you get, save and display the values?

Have sun!
Oliver
 
Hi!

I know that they try to balance everything. Shorted cells should blow my fuse wire and are out of the pack and the IR should also not be a problem. With 3920 cells, even at full load/maximum charging power I'm never > 200 mA/cell. In usual load/charging conditions, I'm generally < 100 mA/cell, mostly even < 50 mA/cell. At normal background load it's 14 mA/cell ;)

As charging / discharging occurs between ~ 3.35 V and ~ 4.08 V at those very low loads, I'm expecting a long lifespan of the cells.

The whole measuring is done by my inverter (MPP Solar PIP 5048 MS) and the values are uploaded every few seconds to emoncms.org (I have attached a micro PC to the inverter). The online dashboard can then be configured using the uploaded values. It's not very difficult.

best regards,
Alex
 
Joost2 said:
IronSky said:
Hallo Alex,
auch von mir herzlich Willkommen :)

Super work you have done there. I also use batteries from e-bikes, but unfortunately I have not as many as you.

Sometimes you have also bad luck with the E-bike batteries and does not get 18650 cells. They are Li-poly or very different formats.

for example cells from Koga Akku :
image_nctxzm.jpg

image_xxbjsw.jpg


The best experiences I have made with the batteries of Bosch and Gazelle. There were always 18650 in it.

Viel Glck noch mit deinem Projekt , vielleicht kann man sich ja mal helfen bei den Akkus.

Schne grsse aus NRW

Iron
Click to expand...
He Iron,

Are that cells lifepo4 chemistry?
I had also this ebike batteries but came too the conclusion that the bms was not good for this kind off chemistry. The charge was setup for li-ion chemistry but the cells are lifepo4. So they where overcharged and puffed. Did you come too the same conclusion?


Click to expand...

In this post, you can read what information I have found out about the Batteries. Maybe it will help you :)


http://secondlifestorage.com/t-GP4105054T1000P-10000mha-cell-3-6V-any-info?pid=9596#pid9596

(I apologize for spamming your post Chicken)
 
Looking amazing!
Your positive and negative on each pack are on the same side, as opposed to opposite like most do. Have you noticed any difference in the voltage of the cells at the front compared to the rear? Or can you measure it? under load and not.
Thanks
 
The-J-Man: I run on same side as well without issues 1.5 year after. Though i have not retested the cells but i also have very very low current and very thick busbars so the resistance that do create that issue is none or very low.
 
Hi!

The current flowing is way too small to have any effects on the voltage across the packs. At those currents, you can put the busbars at any location you want.
Unfortunately, no sun anymore right now :( ... waiting for spring... or at least some sunshine :D

best regards,
Alex
 
Would you mind posting about all you circuit breakers, shunts and so forth that you use. All the way from the panels to the batteries?
Im in Germany too so it would be good to know the units too. Kind of a headache finding ones that are conform to the regulations and blah blah blah, while also still learning about them in general.

thanks mate
 
Hi!

Panels -> PIP is devided into 3 strings, each string has its own DC breaker (2x 16A and 1x 10A).
PIP -> Battery 200A DC breaker
Grid -> PIP: 48A AC breaker
PIP -> Consumers: 48A AC breaker
of course, each consumer string has its own 16A AC breaker.
That's all.

best regards,
Alex
 
Chicken said:
Hi!

Panels -> PIP is devided into 3 strings, each string has its own DC breaker (2x 16A and 1x 10A).
PIP -> Battery 200A DC breaker
Grid -> PIP: 48A AC breaker
PIP -> Consumers: 48A AC breaker
of course, each consumer string has its own 16A AC breaker.
That's all.

best regards,
Alex
Click to expand...

Thanks!! Do you also have model numbers and manufacturers ::) would help me a lot :)
 
Hi!

No, running off grid since end of february. I'm currently even wasting quite a lot of energy by cryptocurrency mining ;)
I'm adjusting my consumption so that I don't run out of battery but also don't give away too much solar energy during the day.

best regards,
Alex
 
HI all.

@Chicken Could you tell me what a balancer are you used in your project on photo?
Which one do you think is better and why?
Also, give me some links for these balancers, because I have to choose one for my 15s160p project.
 
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