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Lux's Powerwall
#11
Chickey Wrote: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

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,
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#12
Chickey Wrote: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

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!
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#13
Lux_Gamer Wrote:Update 01
Dischargers
I want to discharge the cells with a diy discharger.
https://www.youtube.com/watch?v=WScPyfQz_f8
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

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........ Confusedhock:
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#14
Solar Bitcoins sounds interesting
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#15
I'd love to see bitcoins generated by the sun and stored in used batteries, this is a great project! Any updates good sir?

Come chat with us! http://chat.diypw.com/
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#16
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.


(11-13-2016, 08:44 AM)PaulKennett Wrote:
Chickey Wrote: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

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!

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

(11-14-2016, 02:07 PM)Grazor Wrote:
Lux_Gamer Wrote:Update 01
Dischargers
I want to discharge the cells with a diy discharger.
https://www.youtube.com/watch?v=WScPyfQz_f8
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

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........  Confusedhock:

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!

(12-17-2016, 09:50 AM)mikesdiypowerwall Wrote: Solar Bitcoins sounds interesting

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



(12-18-2016, 06:49 PM)Elwood Wrote: I'd love to see bitcoins generated by the sun and stored in used batteries, this is a great project! Any updates good sir?

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,
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#17
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 the person at my local hackerspace that gave my the 40wp solar panel if he had more panels he 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:

280w (claimed) buck boost converter:

Small pump for a Solar aquaponics system:

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

Holders for the 7s 60p battery packs

pictures are links to aliexpress:

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 circuit board where everything comes together.
The brain of everything is a Atmega2560 from Atmel (wish me luck with soldering  Big Grin ).
There will be smaller boards connected with 34 pin floppy cables to the main board.
To measure all the different voltages from the individual packs 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 search for a designing program more advanced then Google Skechtup now 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 of my time up.
here is a preview.
(the pictures i made my self i am really proud of them because i suck at photographing)


Solar lithium charger:

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

24/7
  • Raspberry pi B+ 3 watt.
  • 2 Antminers plus 2 blockerupters 20 watt.
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 PCM60x connected to the positive and negative of the batterys.
But no there are no balance wires coming of the PCM60x to 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 for lithium. 
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.

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#18
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 Smile
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