Lux's Powerwall

L

Lux_Gamer

Member
Joined
Oct 11, 2016
Messages
63
Intro

With this topic i want to start my own powerwall/Solar shed.

Idea

These idea's can change any moment the more experince i get.
In my back yard stands a 2 by 2 meters shed the idea is that my projects will be all powerd by solar panels.
Until i get more solar panels i will have to do with one 40w panel (estimate).
The solar panel will charge my powerwall made from recyceld 18650 cells.
The powerwall will be feeding a couple of devices:

  1. A Raspberry pi B+ running boinc and a webserver for stats 3 watts.
  2. 2 Antminers 1,6ghash , 2 asic blockerupters 366 mhash total power 10 watt.
  3. Controll board 5 watt (estimate).
  4. Small water pump 5 watt.

Projects

All the individual projects that combine in one solar shed.

  1. Powerwall
  2. Controll panel
  3. Raspberry pi data logger
  4. Solar Bitcoins
    more projects will be added in the future

Powerwall

The powerwall will be build from 18650's.
The system will run on 24v so the pack will be 6s how many in parallel will be depending on the total amount of cells i can get.

Controll panel

I will be making a controll panel where everything comes together.
On the controll panel there will be a couple of volt and amp meters.
There will be a costum pcb with a solar controller.

Raspberry pi
The Arduino will measure everyrthing and sends his data to the rapsberry pi that host a web page where you can see al the data.
On the pi runs a boinc client to uses up all the unused clock cycles.

Solar Bitcoins
I have a couple usb bitcoin miners laying around that will be connected to the pi that runs the bitcoin client.
Yes i know i am not getting any reasonable amount of money but it is just for fun.
In a year i make 0,95 dollar cent or so.

End

Everytime there is someting new i will post a update.

bye for now: Lux
 
While your devices add up to only around 23 watts you have to remember that you might not always be getting a full 40watts of output from your panel and also you need to keep the system running through the night when there will be no solar so you need to be able to power the system and also store enough energy through the night. At a guess your not going to have enough power to be able to do that with the planned setup and would need more solar to make it operate 24/7.

I would also look to go 7s on the pack which fits in a little better with a 24 system.

Col
 
For this many loads, i highly doubt a 40Wp panel is enough. I bet you need at least twice as much. 100Wp panels are reasonabl priced. Much less cash per Watts than a 40Wp one-
 
Chickey said:
While your devices add up to only around 23 watts you have to remember that you might not always be getting a full 40watts of output from your panel and also you need to keep the system running through the night when there will be no solar so you need to be able to power the system and also store enough energy through the night. At a guess your not going to have enough power to be able to do that with the planned setup and would need more solar to make it operate 24/7.

I would also look to go 7s on the pack which fits in a little better with a 24 system.

Col
Click to expand...

Hi Col

Thanks for your respons.
Your a totally right about that i will not have enough solar power for 24/7.
The 40 watt is a estimate i have not tested in the real world.
Again your a right with the 7s pack i made a miss calculation.

Shoopinguin said:
For this many loads, i highly doubt a 40Wp panel is enough. I bet you need at least twice as much. 100Wp panels are reasonabl priced. Much less cash per Watts than a 40Wp one-
Click to expand...

Thanks for your respons.
Same as above it is a estimate i will be looking in a second solar panel.
The panel i have now was a gift.


Again Thanks for the comments.
Look forward for a update.

Bye for now Lux.
 
Update 01

Intro
My first batch of cells arived.
Next time i will take pictures with a good camera.

Photo's

image_dpmzmg.jpg


Opening the packs with a hammer and a screwdriver some people maybe scared of this, But if you do it correctly you dont damage the cells.

image_riqbyx.jpg


Sorting the cells by color

image_lngice.jpg


Charging
For now i am charging the cells with 2 tp4056's,
It is slow but there are more chargers on there way.

List of what i will be ordering for the charging proces:
8x tp4056
2x 18650 x4 holder

Cell processing
the past week i have been strugeling about how i will be testing the cells.
What is the right order to test the cells:

Measure voltage cell -> charge the good cells -> discharge the cells -> write the mah data on the cells -> charge the cells.
or
Measure voltage cell -> charge the good cells -> write the voltage on the cells -> store the for a week-> Measure the voltage for selfdischarging-> discharge the good cells-> Write the mah on the cells-> charge the cells

What is the rigt way? Does some one else have a better way?

Dischargers
I want to discharge the cells with a diy discharger.
Reason why i dont want to discharge with a imax b6 of some sort is that you only can discharge one cell at the time and they are more expensive.
I want to build 4 dischargers, Best would be if there be one arduino with 1 display with a couple buttons to scroll trough the values.
With 4 resitors and 4 cell holders.
only problem is that i can not edit or program the code maybe there is someone on this forum who find this a interesting project, i think a lot of people find it helpfull.
Now i have to buy 4 arduino's 4 lcd's the arduino and the lcd are the most expensive.

Bye for now and good luck with your own powerwalls.

Lux
 
Hi Lux,

I'm using an Opus BT- C3100 V2.2 Digital Intelligent 4 Slots LCD 10400 14500 Battery Charger, bought brand new off eBay for AU$50. Works great, just put your cells in the charger, select the mode and walk away.

John
 
Tesla101 said:
Hi Lux,

I'm using an Opus BT- C3100 V2.2 Digital Intelligent 4 Slots LCD 10400 14500 Battery Charger, bought brand new off eBay for AU$50. Works great, just put your cells in the charger, select the mode and walk away.

John
Click to expand...

thanks for you reply,

i have read al lot about the bt-c3100 charger/discharger but it is to expensive for me at this moment.
Maybe i find one second hand.

Lux,
 
Chickey said:
If you already have some 12v power supplies which have a 2.1mm barrel connector then you may want to consider the liitokala 4 cell charger/discharger which is very cheap, will be slightly lower tomorrow.

http://s.click.aliexpress.com/e/URjI6QJ
Click to expand...

Thanks for you suggestion i had never seen them before.
I have some ATX Psu at home they could deliver 12v.
I am gone a look in to them.

Lux,
 
Chickey said:
While your devices add up to only around 23 watts you have to remember that you might not always be getting a full 40watts of output from your panel and also you need to keep the system running through the night when there will be no solar so you need to be able to power the system and also store enough energy through the night. At a guess your not going to have enough power to be able to do that with the planned setup and would need more solar to make it operate 24/7.

I would also look to go 7s on the pack which fits in a little better with a 24 system.

Col
Click to expand...

Yep - I second Chickey's comment. More PV (when you can afford it) and 7S (3.7V x 6 is only 22.2V so you're better off with 3.7V x 7 = 25.9V nominal)

Have fun!
 
Lux_Gamer said:
Update 01
Dischargers
I want to discharge the cells with a diy discharger.
Reason why i dont want to discharge with a imax b6 of some sort is that you only can discharge one cell at the time and they are more expensive.
I want to build 4 dischargers, Best would be if there be one arduino with 1 display with a couple buttons to scroll trough the values.
With 4 resitors and 4 cell holders.
only problem is that i can not edit or program the code maybe there is someone on this forum who find this a interesting project, i think a lot of people find it helpfull.
Now i have to buy 4 arduino's 4 lcd's the arduino and the lcd are the most expensive.
Lux
Click to expand...

I was wondering about a multi-discharger too. Based on Adam Welch's design, I think it should be possible but each cells needs 2 analog inputs to monitor it and one digital output to trigger the MOSFET. The Arduino Uno has 6 analog inputs (I think the Nano is similar) which would limit you to monitoring 3 cells. The Arduino mega has 16 analog inputs so can potentially monitor 8 cells. Plenty of digital outputs for the MOSFETs on either.

If I get time I'll have a go at updating the code for mult-cell discharge monitoring, no promises as my wife and I are expecting a baby in 8 days........ :shock:
 
Its be a long long time!!!

In this post i will be reacting to the last comments after that i will be posting a update.


PaulKennett said:
Chickey said:
While your devices add up to only around 23 watts you have to remember that you might not always be getting a full 40watts of output from your panel and also you need to keep the system running through the night when there will be no solar so you need to be able to power the system and also store enough energy through the night. At a guess your not going to have enough power to be able to do that with the planned setup and would need more solar to make it operate 24/7.

I would also look to go 7s on the pack which fits in a little better with a 24 system.

Col
Click to expand...

Yep - I second Chickey's comment. More PV (when you can afford it) and 7S (3.7V x 6 is only 22.2V so you're better off with 3.7V x 7 = 25.9V nominal)

Have fun!
Click to expand...

I will be looking in to more solar panels but first i want to test everything what i alreadyhave.

Grazor said:
Lux_Gamer said:
Update 01
Dischargers
I want to discharge the cells with a diy discharger.
Reason why i dont want to discharge with a imax b6 of some sort is that you only can discharge one cell at the time and they are more expensive.
I want to build 4 dischargers, Best would be if there be one arduino with 1 display with a couple buttons to scroll trough the values.
With 4 resitors and 4 cell holders.
only problem is that i can not edit or program the code maybe there is someone on this forum who find this a interesting project, i think a lot of people find it helpfull.
Now i have to buy 4 arduino's 4 lcd's the arduino and the lcd are the most expensive.
Lux
Click to expand...

I was wondering about a multi-discharger too. Based on Adam Welch's design, I think it should be possible but each cells needs 2 analog inputs to monitor it and one digital output to trigger the MOSFET. The Arduino Uno has 6 analog inputs (I think the Nano is similar) which would limit you to monitoring 3 cells. The Arduino mega has 16 analog inputs so can potentially monitor 8 cells. Plenty of digital outputs for the MOSFETs on either.

If I get time I'll have a go at updating the code for mult-cell discharge monitoring, no promises as my wife and I are expecting a baby in 8 days........ :shock:
Click to expand...

It is good to hear that someone is interesting in to edit Adam's design.
Can you give us a update on how it is going if you had time for it?
I hope that everything is good with the baby!

mikesdiypowerwall said:
Solar Bitcoins sounds interesting
Click to expand...

Hi mike fun to see you on the forum i have been following and enjoying your channel.
Thanks for commenting.



Elwood said:
I'd love to see bitcoins generated by the sunand stored in used batteries, this is a great project! Any updates good sir?
Click to expand...

Thanks for commenting and showing interest in my projects.
The progress on the bitcoins is a bit slow first i want to focus on the powerwall after that i will focus on the bitcoins.


Thanks everyone who has been waiting and showing interest.
An update is coming soon.

Bye for now Lux,
 
Update:

Time has flown by since the last update.
I started to draw a flowchart for the powerwall in a online program called draw.io.
In the shed i have mounted an wooden board where everything will be mounted: battery's BMS Charge controller.
I contacted theperson at my local hackerspace that gave my the 40wp solar panel if he had more panelshe said yes, Now i have 3 solar panels in total on the shed.
So now i have 3 40wp solar panels for a total of 120wp.


Shopping:

I have been shopping around for parts that can help with the build of the lux powerwall:

Diodes for the solar panels:
image_qwjhic.jpg

280w (claimed) buck boost converter:
image_gdutmp.jpg

Small pump for a Solar aquaponics system:
image_gtkpuq.jpg

A handy PCB Ruler, I really recommend this ruler if you design circuit boards.
image_zreiku.jpg

Holders for the 7s 60p battery packs
image_wsmonb.jpg

pictures are links toaliexpress:

Next on the shopping list:
Fuse wire
Arduino current sensors
ATmega
Circuit boards

Designing:

To make everything clear for myself and others i began to make a flowchart in draw.io.
This is the progress so far.

I have made a start with a plan for the main circuitboard where everything comes together.
The brain of everything is a Atmega2560 from Atmel (wishme luck with soldering :D ).
There will be smaller boards connected with 34 pin floppy cables to the main board.
To measure all the differentvoltages from the individualpacks and solar panels i need a lot of analog inputs, so many the Atmega hasn't even enough.
So my plan was to use 74HC4067 16 channel multiplexers.

For the battery mounts i going to look into designing my own based on HBpowerwalls design but then for smaller packs (suggestions are welcome).
Now i must searchfor a designing program more advanced then GoogleSkechtupnow i am trying fusion 360.

In the mean while i have been coding a website where i can post my other projects it is coming along really while but it is sucking a huge deal ofmy time up.
here is a preview.
(the pictures i made my self i am really proud of them because i suck at photographing)

image_nzdrgy.jpg


Solar lithiumcharger:

Can someone give me a help at starting to search for a solar charge controller for my powerwall.
The goal is to have 3 40wpsolar panels 120wp total charging 7s60p 18650 powerwall.
The powerwall will be providing powerto:

24/7
  • Raspberry pi B+ 3 watt.
  • 2 Antminers plus 2 blockerupters 20watt.
5 hours a day
  • Some led lights 10 watt.
  • Pump 5 watt.

I cannot find much information what a charge controller for lithium does.
I know for example a tp4056 has a charge curve for lithium do you need that for a solar charge controller.
If i look for example at hbpowerwall he has an PCM60xconnected to the positiveand negative of the batterys.
But no there are no balance wires comingof the PCM60xto balance charge the cells.
Do you not need a balance charger if you have a lose BMS?
I hope you guys can help me with a start to learn more about solar chargers forlithium.
my end goal is to make my own solar charger.


Next on the to do list:

  • Finish the flowchart.
  • Route all the solar cables
  • Install Solar diodes
  • Mount the boost converter to the board.
  • Decide on a charger.
 
Charge curve for lithium is nothing special really. You cannot go above X volt that max for example common laptop cells are 4.2V.
Current should not go above lets say 0.5C. (1A) for most of those cells.
When the current reached lets say 1/20th of intial you shut of charging. In general for Leaf acid you set bulk and float to same level.
So basically its CV-CC charging. Lead acid for instance on the other hand demands a special charge curve... (depending on how you look at it)

This is for charging.

Next thing is that you should make sure that NONE of the cells go above 4.2V. This is done by some kind of BMS system. Peter and Me is using the Batrium BMS for this.

The BMS itself in its easiest form does only try to balance and keep the top voltage of each cell below set top voltage. You can of course hook in so it disconects the battery if something goes wrong. Currently neither me or Peter have feedback between the Batrium system and the chargers we are using and this is essential if you want to go all the way. Im currently partly looking into this on how to solve it. Ie the Batrium will talk to the charger/inverter and make sure that it stops charging if needed.

You can run without the BMS if you top balance and just keep an eye on the system too. This will work fine and works fine for many right now. Though personally i recommend active monitoring that will disconnect the load/charger if something goes wrong. This to save the batteries and your house :)
 
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