Beginners Guide to Processing 18650 Cells | Cell Database



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Portuguese Powerwall in Poland
#61
Or just use one of the Batriums expansion board relays to controll your 24v relay...
A little buck converter can supply the 24v, they are cheap and very efficient (if you buy a good one)

And on the side, a simple thermostat can do the controlling of the heating also, Wink
___________________________________
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup: http://www.diypowerwalls.com/t-Instant-powerwall
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#62
I installed 6 more 260W panels on the roof, and have 3 more waiting to be installed.
On a rare sunny day I got peak 2100W, and gathered 3.1kWh.
One thing that surprised me is that on cloudy weather, I don't get much more Watt than before.
With 3x260 panels I was getting ~40-50Watt, and now with 3x more I get only 60-80Watt. 
Do you think this is normal? I was expecting a bit more.
Let's see how much I get with 12 panels once I install them.

The temperatures here didn't go too low to need the heating inside the powerwall case.

I started to noticed one worrying thing, pack 1 is consistently below voltage than the rest of the packs.
It started at around 0.04v difference 1 month ago, and now it's at 0.08v.
I charged it all the way up (to 4.1v) a few time and let the longmons bypass on the rest of the packs, but this pack 1 is stubborn and does not want to get to the same voltage as the others.



So I'm suspecting that something is wrong with one or a few cells in this pack.
I'm thinking about taking it out, charge it up, and desolder all the cells to find out which one(s) are causing the trouble.

Have you had such similar situation? What did you do?

I now have a 1-0-2 switch between house, grid and powerwall, so I can easily turn usage of powerwall off and be able to do some work on it.

Also, we didn't got a sunny day here for 5 days in a row, so during off-peak hours it's actually not worth to use the powerwall (charging it from AC), since the waste on PIP/charging/discharging is around 2-3kWh.

I also noticed that I don't seem to be able to turn the PIP completely off, and even with on/off switch to off it's on all the time draining 12-15Watt from the battery.
I would like to be able to turn off the PIP but still be able to charge the battery from PCM.
I don't have separate breakers for PCM charger and PIP from the battery.

PIP Owners: Do you know if it is possible to completely turn off the PIP so that it doesn't drain anything from battery.

Starting to thing about wind turbines for the winter lack of sun.
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#63
Removed pack nr 1, charged it up, then desoldered all the cells and let it stay for 2 days, and the guilty cell easily was uncovered, since was at 3.8v and dropping (while the rest was at 4.08-4.10v). 
So I'm happy the first problem with a self-discharge cell was quite easy to fix, and it was only 1 cell. Which means that I either somehow missed this cell on the self-discharge test in the beginning, or it only started self-discharging after a couple months into the usage.

Anyway back to having all packs good balanced.


Then, I finally mounted the rest of panels that I had, and I now have:
- 6 x 260W on the roof, constant inclination of 40 degrees.
- 6 x 260W on my terrace on a variable inclination (0-55 degrees) system I build.

So I now have 3.12kWp waiting for good sunny days.

I know, should have made pictures or even videos of all of this to share with you guys, but the time pressure didn't allow me. Sorry Smile
Maybe on next days I'll be able to do some and post them.

I'm thinking about buying a Victron inverter of 1200VA which has an idle consumption of 6W (according to production specs), and connecting it to my low powered appliances, and leaving the PIP off for high power appliances, and turning it on only when needed.

This is because PIP is wasting me between 1.5-2kWh per day, and since my house consumption is 3-4kWh, that is a big percentage of wasting which I really don't like. This wasting is also on charging from AC, so the balance between being worth to charge on off-peak tariff and using during peak is really a thin line.
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#64
This is one of the advantages of a bms like Batrium... it helps to identify the "faulty" packs.
looking forward to see some pics... Wink
___________________________________
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup: http://www.diypowerwalls.com/t-Instant-powerwall
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#65
Some pictures of the panels and how I mounted them:





  




And I made a quick PNG for testing emoncms dashboard.

It works, you can check it out live values at: https://emoncms.org/dashboard/view?id=39520

Of course the lines are not expressing the real current transfers between devices, that would require a bit of more photoshoping and Javascripting.

wim and Korishan like this post
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#66
I decided to make an improved version (glowing circles and moving electrons) of the emoncms dashboard imitating tesla powerflow app.

There's a live version of my feed at:

https://diypowerflow.herokuapp.com/
 
If you want also to use it, I released the code at:

https://github.com/frnandu/diypowerflow

Feel free to suggest improvements.



And also added a new cool off-grid counter widget to grafana, will be nice following how much I can be off-grid during a 12 month period.

jm1 likes this post
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#67
Well I finally installed the ATS, following Daniel's instructions from http://diytechandrepairs.nu/automatic-tr...ms-how-to/

using a 1-0-2 switch to allow choosing priority between grid and solar (powerwall):



considering I have no electrician experience and also I wanted to connect the SDM120 meters inside the same box, it was a really hard challenge for me to not make a big spagheti cable mess.

It took me quite a bit of sweating, but I guess that why it's called DIY Smile



I didn't quite plan it since the ATS is quite bigger than mini DIN rail dimensions, so I had to cut off quite a bit of the box cover to fit it,
but it looks acceptable for my standards:



I'm quite happy now that I have the ATS working, which means I can now go on vacations relaxed that even if a critical situation on the battery causes the Watchmon to Shunt trip the breaker - thus turning off the PIP inverter - the ATS will fall back to grid and all my stuff in the fridge will not melt on the kitchen floor Smile

I'm quite gratefull to Daniel for his incredible help in providing such instructions.

I am now in an important milestone on my DIY powerwall journey. 
I fell I can now leave it working and go on vacations.
This was one of my main requirements to anchieve when I started it.
It is quite nice to finally have reached this goal Smile

And the off-grid counter is at:


Which means that in January, at the peak of polish winter I was able to be 1/3 of the time off-grid, I'm quite surprised with this result, I didn't expect it to be this good. 

What next now?

The need for more electrical energy will for sure increase, in 1-2 years time an affordable EV will be a good thing to invest, so this small 10kwh powerwall is quite nice to have now, but I will for sure have bigger energy needs in the near future, so here's what I'm thinking: 

- I want to add another 10kwh. I don't know when,  maybe even this year, but it's not critical, would be nice tough, we'll see, it will probably depend on how to get more cheap batteries.

- I still want to build a shed dedicated to the batteries, since now even though my garage is stand alone from the house, it still would be nice to not loose the car if by any means something very bad happens to the batteries and fire breaks loose. I will probably do it this summer.

- I'm still obsessed by the amount of waste the PIP is using. And playing with the idea of buying a small (1000W) victron inverter which is not that expensive and connect it to the small loads that are runninng 95% of the time - fridge, router, raspberrys and water pumps. I would need to come up with a good system that will turn the PIP on/off on-demand for the bigger loads (any ideas on how to control the PIP on/off switch programatically are welcomed)

- More panels. I still have a bit of roof space south facing, and a lot of roof space west and east facing. My pcm60x is maxed out with my 12 panels 3.1kWp, so I would either need another charger, or connect it to the PIP PWM solar charger I have. I'm curious how much difference would be between MPPT and PWN for such setup. I'm planning on testing 1 string of 6 panels on the pcm60x and 1 string of 6 panels on the PIP PWM at the same time (both strings will be at same angle) and gather data in order to be able to have graphs comparing precisely how much more efficient is the MPPT on the Pcm60x and the PWM on the PIP during several weather cloudiness.

- Servomotor for automatic setting of panel's angle, so that I don't have to manually set it myself 4 times per year. It's not a big issue, so it's low priority. But it would be really cool Smile  I have no experience playing with such stuff, so would require a bit of research. 

- Wind turbines. I guess that is the natural next step. Maybe a few of smaller vertical ones. I'm quite happy that Daniel is also interested in this subject, he will for sure find some good options for us that also want to harvest wind to follow. This might be the only way to increase the off-grid counter in winter here.
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#68
I got another pack (nr 6) with lower voltage constantly, even after trying to top balance it keeps 0.04v below the other packs.



So the same situation as with pack nr 1 before, probably a leaker which either I didn't test correctly or it just started leaking after a few months.

So took it down, charged it up with Icharger:



Even tough it's rated at 10amps, it only really charges max 7-8amps, even when i'm using an atx power supply capable of 350w:
 


Desoldered all the fuses and let it seat for 1 day.

3 things were not ok with this pack:

1) a leaker cell (got from 4.05v to 3.6v in just a few hours):



2) one fuse with melted (?) glass:



I'm not 100% if this wasn't like this from the beginning, but I think I would have noticed when soldering it. So how in the hell does this glass melt even tough the fuse inside is intact??

3) one cell with bad connection soldering on the negative side, it was kind of loose just barely making contact, so this might have caused some problems

I replaced the cell, soldered back all the fuses (replacing the melted one).

Now before connecting it back to the other packs, I wanted to get the voltage back down to the same as the other packs, so I tried to use this discharge meter that I saw Pete using in one of his videos:



https://pl.aliexpress.com/item/150W-DC-D...72034.html

It's supposed to do 150w, but on this pack at ~ 3.9v it only pulled ~23amp or 73w.
It might be that the cables that come with it are just crap (rated 18awg):



But even with the Icharger cables (16 awg) which are a bit better it didn't do much more.



The voltage accurancy on these things are way off:



Considering its low cost (~20USD)....I'd quote Daniel "you get what you paid for..." Smile

Anyway, I'm going to put pack nr 6 back into the powerwall and hope that it's fixed.

I also noticed that I had my PCM60x set on max charging current 40amp, so even on clear-sky sunny days, I was getting 2300w from my 3.1kWp panels, and I was convinced that well that's just the max that this winter angles get me. But now at max 60amps I can't wait for another sunny day and see how much it will do.

I contributed some changes to the solar-sis project on github from Daniel, in order to support some of the set commands that are missing and that I need to use for the PIP4048/5048 and the PCM60x.

I hope Daniel will review them and accept them, meanwhile you can try it out yourself if you're in a hurry:

https://github.com/opengd/solar-sis/pull/1

These allows for example to set the bulk/float voltages programatically, so one could set it a bit higher or lower depending on next few days sun prediction and if you need a battery which is more topped off at for example 4.15 instead of standard longer-life of 4.1.
Of course it still requires to set batrium bypass cell voltage on the longmons....I'm not sure if this will be possible programatically depending on sun prediction result.

I hope it will be usefull for somebody else.

"I'll see you guys on the next one" Wink
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#69
Glad to see the ATS implemented. I have not even had time to do that myself more than on the bench Smile

I will review your pull as soon as I just can here. I just am a bit behind on all other things working on right now Smile
Frnandu Martiński likes this post
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
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#70
Finally balanced all packs at 4.1v !! Smile

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