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Stefanseiner

Greetings from Germany with DIY Solar and 18650 Li-Ion battery

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Posted (edited)

Hello and greetings from Germany,

my name is Stefan,  I am a 37 years old and two years ago my wife and I bought an 115 years old farmers house which we now are renovating from the base to the roof.

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Since a few weeks our self-installed photovoltaik is up and running, and know I am planning to add a DIY powerwall which I will build out of old laptop and ebike batteries.

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I registered here because Google leads me several times to this forum and so I hope, I can get some help here - and be able to help others too.

regards

Stefan

Edited by Stefanseiner

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18 minutes ago, Stefanseiner said:

Hello and greetings from Germany,

Welcome Stefan, I hope you find all the answers to your questions here. 

I am interested to see the progress of your project. Please post updates?

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Hi Stefan, can you tell us a little more about your current PV system? Just curious, especially for the powerwall.

Gruess, Rik

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yes sure.

 

this is the outside connection box at the firewood place where the PV panels are installed, with DC switch and overvoltage protection.

In addition there is a 400V 3-phases vonnection (powered from inside house, not from the panels) for a wood splitter

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this is inside the house, the new Infinisolar E 5.5 kw inverter. Actual it's running just grid tied because the DIY battery isn't finished

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the battery will be made with 18650 lithium cells I get from defective ebike and laptop akkus (mostly ebike)

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most of the vendors of ebike akkus are using 18650 Li-Ion batteries inside, between 40 and 60 pieces

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after diassembling the akkupacks I test voltage, internal resistance and...

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...and remaining capacity with some Liito kala Lii500 Engineer charger. Most of the ebike akkus I got have defective BMS electronics and the batteries are just finde with a remaining capacity between 80% and 99%. I write the capacity at the cells and ...

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...now I have collected something about 3.000 or 4.000 Pieces, don't know exactly. Most of them are in the range between 2.500 and 3.500mAh

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actually I am sorting them by capacity in steps of 50mAh

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after this, I still have one test left, charging them up, waiting 4 weeks and after this testing the voltage. If voltage is down under 4,0V then the cell isn't good for use. The others can be used for the solar powerwall.

 

I am planing a minimum of 10 KWh, better 15KWh in total.

14s240p which means 240 cells parallel per pack and then 14 identical packs in serial so I can use a toal of 48V.

Normally you use only 13s for 48v but because I am using used batteries I will not stress them by charging them up to 4,2v each but a maximum of 4,0 or even 3,9 so they will last longer.

 

To build 14 packs with 240 cells each will take lots of time and I have some other projects running so this will be something for autumn / winter.

But I decided to start a smaller test-build with 14s40p out of the not-so-good laptop batteries with round about 2.100 - 2.200mAh

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If you have any questions please feel free to ask  🙂

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6 hours ago, Stefanseiner said:

this is inside the house, the new Infinisolar E 5.5 kw inverter. Actual it's running just grid tied because the DIY battery isn't finished

That's what I'm doing as well at the moment. You can read more here.

About your plans concerning the 18650 batteries I was on that course as well. Learned a lot from secondlifestorage. AFter a while I came to the conclusion that it was simply to much work and changed plans. Now I'm still building my own DIY battery but with new LiFePO4 cells.

Questions:

- Are you planning to feed your entire house with solar and battery?

- How much PV did you connect to your inverter?

 

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yes I read at secondlife too  :-)

And if I knew how much work this project would be - I guess I hadn't start this but now - I've done more then the half and so I will go on.

My plan is to feed the entire house, but first just with one phase because three phases inverter is very expensive. Maybe later I will upgrade, but first I will take the one phase with the most 24/7 consumers to cover the constant consumption.

The PV installation at the hybrid battery inverter has a peak of 2.720 watts.

I have another PV installation at the garden shed with 9,2KWp but without battery option inverter, it's a Fronius Symo 8.2

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On 2020/07/23 at 11:47 PM, Stefanseiner said:

My plan is to feed the entire house, but first just with one phase because three phases inverter is very expensive. Maybe later I will upgrade, but first I will take the one phase with the most 24/7 consumers to cover the constant consumption.

Stefan maybe you made a bit of a unfortunate choice. The Infini 5k plus like @Youda's off grid lab and I (among others) have would be more convenient because of its parallel capabilities. You can start with one like you do now and add more inverters later. But anyway the 5,5k is also a very nice inverter. What type of grid connection do you have? 3 x 25A?

That is a hell of a nice backyard you have there!

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On 2020/07/25 at 2:21 PM, RikH said:

The Infini 5k plus like @Youda's off grid lab and I (among others) have would be more convenient because of its parallel capabilities. You can start with one like you do now and add more inverters later.

Yes I thought about the option to add parallel kit inverters too, but three reasons why I didn't choose so: 1.) three inverters = 3 times standby consumption and this cheap chinese inverters are very thirsty, round about 50 watts per inverter I could read at some internet reports. And permenentely 150 watts will lower the battery at night very hard, especially in winter, where the sun in my region is nearly off and will not be able to charge the batteries every day at 100%. 2.) I made an mistake by ordering the wrong inverter first, an Infinisolar "V" series 5k model which can not set up via modbuscard and energy-meter in grid-parallel mode. To give it back to the seller I had to buy a new inverter at this seller - and at this time he hadn't had the "E" 5k just the 5.5k. and 3.) the smaller PV installation with 2,8KWp hasn't enough power to feed the house at all the three phases. Maybe lateron I will change the Fronius inverter at the bigger PV installation to an Infinisolar / MPP Solar Hybrid with 3-phases. We will see. Prizes are extreme actually, round about 3.000USD + shipping instead of 2.000 USD at normal for the 10k model, and this is even lot of money for me.

On 2020/07/25 at 2:21 PM, RikH said:

What type of grid connection do you have? 3 x 25A?

3x 63A is the house grid connection

On 2020/07/25 at 2:21 PM, RikH said:

That is a hell of a nice backyard you have there!

thanks very much  🙂

I am living there since two years and there is still lots of work to keep the weed and scrub down which is allover, but it's getting better.

Here some impressions of the beginning:

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can you see the pond?

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found some trees completely buried under blackberries with ahigh of 3.5 meters

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If you want to have a look you can try a "virtual walkaround" here:  https://mona-stefan.de/system/virtueller-rundgang

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The Victron inverters work well with Fornius inverters , instead of replacing the Fornius I'd look at getting a Multiplus II , maybe a 5Kva which you can parallel up or with 3 units configure into a 3phase connection.  And some very knowledgeable Victron people here.

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