w0ss semi DIY powerwall V2

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w0ss

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Oct 15, 2019
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V1 was...

2xMPP solar 2424lv
32x86ah LifePO4 prismatic in 8s4p(8xDaly 1sbalancers )
6x195watt solar panels

V2 additions/reconfiguration
Reconfig LifePO4 to 16s2p(16xDaly 1s balancers)
Adds:
2x LG 189ah 51.8v ESS batteries(14s JH3 cells)
2x 6048 sunny island
Batrium watchmon5
midnite classic 250(stripped down version)
ABB 225A shunt trip breaker

My goal is a whole home UPS that can charge from a generator when there isn't enough solar.

LifePO4 and Li-Po are in parallel. Charging to a max of 57.12(3.57LifePO4/4.08LiPo)Sunny Island is currently configured for GenGrid operation. I will be using a manual transfer switch to switch to generator, the generator is a portable 5k inverter generator. I will get some pictures and such up
 

Korishan

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"a whole home UPS". this implies you'll use primarily grid and switch to battery when it goes offline. Is this correct? If not, then is your goal whole home powered solely by the solar/batteries?
 

w0ss

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Oct 15, 2019
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Primarily grid powered, to start at least then I will add extra solar to offset daily use. I am on a wierd solar tariff so I have two meters and the solar on my roof(9.5kw) goes right to the street without coming into my house. I will be adding a manual transfer switch to bring it in and AC couple with the Sunny Island during grid outages only.
 

w0ss

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image_rqthfw.jpg

Built a board to breakout the existing LG Chem battery connector. On to the next step!
 

hbpowerwall

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That's a huge expense for a UPS - also a huge step up from your V1!
 

w0ss

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Discharge test of the bank from 4.08(3.57) to 3.40(2.98) volts per cell was ~425AH. Nominal is 550ah(378 LiPo/172ah LifePO4).
 

w0ss

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image_rulmjb.jpg


Original BMS board and breakout board I designed with resettable fuses. Took advantage of the original mounting holes. They don't exactly line up but close enough for me :)
 

w0ss

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Oct 15, 2019
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Had some time today with the holiday here in the US. Got the boards mounted and connected together. Waiting for the Multimon8 to connect to my watchmon5, for now I have them paralleled on each cell.


Pretest test :)Each7s pairread cell one a little low(12mv). I soldered over the resettable fuse in case by chance they were both bad or out of spec. But looks like it was just the checker. Watchmon doesn't show cell one low.

image_zwujhq.jpg

Tested the setup as watchmon wants
image_qqewpp.jpg



All working.
image_dqvrhe.jpg
 

themiz

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Feb 8, 2020
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Hi w0ss. Newbie here. I purchased the LG ESS 189AH 48V from Battery Hookup. I'm not really sure where to start with it. My goal is to keep in my garage and add up to 12 - 300w panels to the roof. I have a 30 kwh Nissan Leaf that I would like to charge from Panels and the LG ESS at night.

What is the best way to interface with the LG ESS? Do I just connect to an inverter/charger?

Thanks in advance for any help.
 

w0ss

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Oct 15, 2019
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Best way is tough to say. Everyone here does things a little different. If you connect to an inverter/charger you typically want a BMS. If I had just one pack I would go with a Daly BMS and call it a day. If you want feel free to make a thread and I am sure many more will comment.
 

themiz

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Feb 8, 2020
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Thanks. So the work you are doing with the custom boards, is that just so you can interface with the on-board LG BMS? Is there a benefit of using that VS just bypassing and using a separate BMS as you recommended?
 

w0ss

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Oct 15, 2019
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The board I made is really just a breakout board of the cells and whatever else is connected. I wasn't able to talk to the existing "BMS" I use that in quotes since it has no disconnect so it looks like it is really a monitoring board with minimal balance resistors. my board just replaces it so I can use an external BMS.
 

themiz

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w0ss would you mind walking me thru how to connect this to a Daly BMS? Thanks
 

w0ss

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themiz said:
w0ss would you mind walking me thru how to connect this to a Daly BMS? Thanks
You have a few options.

1. You can purchase the connection that the board hasand then solder the Daly leads directly to it. Allied had the lowest cost when I looked for the connector.I did this for my first test. I then covered it all in hot glue to act as something of an insulator.

2. Another option would be to design a breakout board. I did that option and would be happy to share my design if you wanted to use it.

I have the pinout of the connector somewhere let me post that.


image_rtkolr.jpg
 

themiz

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Interesting. Yes I actually purchased that connector. These are 14s batteries, correct? I was thrown off by the fact there are 24 pins.

I'd be curious to see your board design, I though I have no idea how to get one made. Is there a place to send a design that will manufacture it?
 

w0ss

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Oct 15, 2019
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Here is a link to the board I designed. https://easyeda.com/william.carlson/bmsv2 I used JLCPCB which I think is the same company as EasyEDA. They will make the board and do the surface mount components(fuses).

The 24 pins are a bit confusing. It looks like the built in "BMS" board is setup as 2x7s monitoring boards. so 16 of the pins are voltage sense leads(2x8 for the 2x7s). I assume others in there are used for temperature sensors but I never really investigated.

EDIT:
One thing to mention is my board the holes don't align 100% to the stock mounting points. But they still mostly fit and I could screw down to secure the board.
 

Etn06448

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Apr 21, 2020
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Thank you for sharing your work with us. I just ordered 8 of these packs for my house. Regarding the board, is it just simple as uploading to the JLCPCB site, choose number of boards I want and that's it? Do the connectors come with the board when ordered or do I have to order the connectors and solder them in separately? Sorry for the newbie questions, never ordered PCB boards before. Besides the Batrium, would you recommend anything else for 8 batteries? Would it be better to go with 1 Watchmon 5 and parallel all those cells in parallel like you did, or add 7 of the Multimon (making it very costly). Another thought that I have is to do 8 separate active BMS. Any suggestions. Thank you.
 

w0ss

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Etn06448 said:
Thank you for sharing your work with us. I just ordered 8 of these packs for my house. Regarding the board, is it just simple as uploading to the JLCPCB site, choose number of boards I want and that's it? Do the connectors come with the board when ordered or do I have to order the connectors and solder them in separately? Sorry for the newbie questions, never ordered PCB boards before. Besides the Batrium, would you recommend anything else for 8 batteries? Would it be better to go with 1 Watchmon 5 and parallel all those cells in parallel like you did, or add 7 of the Multimon (making it very costly). Another thought that I have is to do 8 separate active BMS. Any suggestions. Thank you.
You would upload the board to JLCPCB and they will make it, I also had them do the SMT assembly as well. If you choose that option then all you would have to do is order andsolder on the connection that goes to the battery pack and the connector to your BMS. They are all thru hole and pretty easy.

For 8 batteries that is a tough one. My personal thought is put them in parallel with a watchmon4 and cellmons's. You get more balancing with the cellmons and if you have 8 189ah cells in parallel you might need more balancing than a watchmon5 can do. For two I haven't noticed any issues with the watchmon5. Maybe as a compromise you put 2 or 4 in parallel and get a few multimon's.
 

Etn06448

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Apr 21, 2020
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Looks like the part DB128H-5.08-12P-GN-S has been discontinued. Is there anything else that would fit your board? I think I have it almost figured out on JLCPCB website to make the order. Just making sure that the size of the board is 200mm x 65mm. Otherwise all the other options are default and add SMT at the top of the board.
Thanks for your help preparing to get this fun project on the way.
 
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