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Mockingbird Hill Farm(MHF) Powerwall 1
#1
This is also posted on another forum site, but it feels appropriate to document it here in different detail. This seemed like a good way to kick it off though...

The Background

A few years ago I moved my family back to the area where my wife and I grew up. Specifically the farm that my grandparents bought in 1968. When they bought it they did a lot of updates like running water in the house, an indoor toilet, electricity, etc. It hasn't really had any updates since then, so for the first year after we moved back I set about major system renovations. The electrical system in the house was replaced from the weatherhead all the way in with up to, if not exceeding, current codes. The primary reason for this was safety as nothing was grounded and most of the house was being run off two fuses. No breakers. So out with the old, in with the new. We are skookum now. 
So, now that the house was safe and livable I can start to look at peripherals like my shop. My shop is currently 15 feet of one end of a 40 foot High Cube shipping container. The container is next to a tractor shed that would be nice to have some electricity in, is 150' from the new main panel, and would require trenching through both gardens. Someday I would like to run a line out there, but that has not happened yet for many reasons. 
Enter Solar. I already had a handful of small panels, and initially setup a 45 watt system to charge 2 Optima Blue Tops I had picked up from a storage yard cleanout. It appears that those batteries may have set for too long as I cannot get them to take a good charge. Bottom line is I needed to replace them. Lead acid batteries worried me. I didn't want to worry about cooking them or topping off water all the time if I wasn't going to be using the shop regularly. So I started having many, many conversations with myself along these lines;
Where do I store them? 
Will they provide enough power? 
How much will I really need? 
Can I scale the system easily if I want to expand? 
How many panels will I need for that? 
Lifespan/cycles? 
Should I just trench in the grid power and forget it? But the power goes out sometimes. It would be nice if I could backfeed to the house. 
Grid tied system? No, no. That doesn't help me if the power goes out. 
Inverter. Two Phase? 
How many watts will I need if I want to back feed? Wow those are expensive. 
What about two inverters? Yeah, one to run my shop needs now and one I can turn on for high load or back feed applications. Hmm... but what system voltage should I run? 12? 24? 48?... 
What's the best battery type? AGM? Deep cycle Marine? Golf Cart? 
Are there other types of batteries? 
Edison Battery, what is that? 
Interesting. Can I build that? I CAN build it, but my wife says it's not in the budget. She is right.
Tesla. They do solar, what's this Powerwall thing.
[Image: amazing_o_309654.webp]

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How much are they going to cos..

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So it was back to lead acid. What's it going to take? At least 2 batteries, 6 volt, in series... but that life cycle and maintenance...

Wow, this guys got an awesome setup. Man it would take me forever to get there...

All this time I have been gathering parts that could be used in various configurations. I scored a deal on 3 - 100 watt Renogy panels during Prime Day last year. Then recently I caught those panels on sale for $109 each, shipped. So i bought 1 more to give me 400 watts in either 12, 24, or 48 volt configuration. My current solar controller is able to handle 12 or 24 volts. 

I have an APC UPS that has a display on it. a few weeks ago I discovered the 2 SLA batteries had gone out. I started wondering if I could use the leads from that to connect to my Bluetops and use that instead of SLA's. A little googling and I ran across Jehu Garcia on YouTube. Specifically this video.


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So yes, it can, and is being done! And here I am. On this journey, trying to decide how I really want to configure this setup while continuing to collect components. 

Also, the Bluetops are no good. They don't hold a charge so I started my latest obsession of collecting, testing, and sorting 18650's. Progress and questions will follow.
Wolf, hbpowerwall, LEDSchlucker And 1 others like this post
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#2
Welcome to the community


Quote:Wow, this guys got an awesome setup. Man it would take me forever to get there...

Yep, nod - it's not too bad!  Big Grin
BlueSwordM, Korishan, Church1182 like this post
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#3
As I mentioned in the first post, I have an APC UPS that the batteries hit end of life in. Rather than trying to replace those with more SLA packs, I had two thoughts. One was to dismantle the UPS and salvage the parts to integrate into a Powerwall, the other was to build a smaller pack that fits into the UPS battery compartment and leave it as is building a Powerwall later on with components rated for higher load. I bounced the idea around of installing a breaker panel and feeding one side of it with the UPS and later on adding a bigger inverter that I could wire outlets to and run heavier loads on as needed, then shut off the bigger inverter when not in use. This idea never really felt "right" and after some discussion over on another thread I am comfortably settled on that not being a good idea for many reasons. Possible to do, yes. A good idea? No.
One of the nice things about this UPS is it has a screen on it that tells you battery info, load, etc. I was able to plug in all 4 LED shop lights to the UPS and determine that with all 4 lights on it uses a little less than 180 watts. With some recent decisions and changes in what tools are going to be used in that shop I decided to order a 24V 800/1600 watt Pure Sine Wave inverter off Amazon that appears to be a decent value for what I need to do with it. For batteries, I ordered one package of 99 from eBay and should have gotten 2-3 as they have been testing out at new specs. They are LGABB41865 cells and of the 99, 2 were DOA, 7 have an AC Impedance of over 70 mOhms (82 to 133), and the other 90 are under 60 mOhms. I'm using a YR1030 meter with 4 wire probes to test. Capacity testing is under way with cells 71-74 on right now, and so far the first 70 have all been 2630 mAh or better, most around 2700 mAh, on the Opus BT-C3100 v2.2. 

So here we get to the question/verification. Trying to avoid the "Can't see the forest for the trees" scenario.
My threshold to commision my Powerwall into service is 200 W at 24V which means a 7S configuration. 200 W would allow me to turn on all 4 lights in my shop if I needed to. Typically I only have 1-2 on, and that is really the power usage I have in there 98% of the time.

Verification #1
200W/24V = 8.33 A (8330 mA)
If I plan to keep sustained operating load to 500 mA/cell, then;
8330 mA / 500 mA/cell = 16.7 cells or a minimum of 17P. Correct?
7S 17P would mean 119 Cells minimum.

Verification #2
The inverter is rated as being 800 Watts. The description also says don't plan on actually running it at that. Fair enough. For load calculations though, I'm assuming it would be possible to load it at 800 watts. As such,
800W/24V = 33.3 A (33,300 mA)
In order to run loads of 800 Watts and keep cells at a max of 500 mA;
33,300 mA / 500 mA/cell = 66.6 cells or a minimum of 67P. Correct?
7S 67P or 469 cells to load the system to 800 watts and keep cells loaded no more than 500 mA.
Wolf and BlueSwordM like this post
James 1:19-20

Not all those who wander are lost - J. R. R. Tolkien
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#4
Church1182,
You are using a YR1030?
Well then welcome to the community.
So lets make it simple  and stay away from too many decimals.Tongue
OK so your lights are 200W and at 120V draw 1.7A.
That 1.7A @ 120V translates to 8.3A @ 24V.
Just to confuse you 200W at 4V would be 50A.

If you want to draw 10A at 24V out of a battery pack at .5A per cell you need 7s20p  140 cells.
The first p of cells give you the Ah and the s just is the voltage multiplier.

I'm not sure you need to worry about the APC UPS but yes if you want to get 800W out of it then,
40A at 24V out of a battery pack at .5A per cell you need 7s80p  560 cells.

Wolf
BlueSwordM and Church1182 like this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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#5
(02-07-2019, 07:34 PM)Wolf Wrote: You are using a YR1030?
Well then welcome to the community.

I am! Primarily due to your work with it and review of it. I had been looking into them and there seemed to be quite the range of options, at least price wise. After reading what you have done with it, and at that price point, it seemed like a great value.

As for the rest of it, yes. I agree. Rounding up P in 10's is prefered in implementation. I have not decided just how I'm going to configure my packs yet though. With my current stock of 90 and still working on the local options for more batteries I'm leaning towards 10P or 20P packs so I can build them out and add them on until I hit my end goal of 7S100P or 5-6 kWh for this particular Powerwall. BMS and balancing is still being mulled over heavily.
Wolf and BlueSwordM like this post
James 1:19-20

Not all those who wander are lost - J. R. R. Tolkien
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#6
So I decided on a BMS and am covering the details of that on this thread. In researching the various options I was simply not comfortable with the low end options, and it seemed like other than the Chinese protection boards you didn't really have a lot of options from there to the Batrium level. There are a number of DIY options and I like the Stuart Pittaway/Colin Hickey diyBMS ver.2.1 software/3.0 board the most. The BMS build is going to be documented on the other thread, and I'll jump back over here once that's done and I'm building the Powerwall.
James 1:19-20

Not all those who wander are lost - J. R. R. Tolkien
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#7
Ran across a decent looking cell on AliExpress that was the same price as what I picked up from Tom on eBay. Being sold as a LiitoKala cell. It says Samsung under the wrapper. I need 70 more to commission my Powerwall so I gambled on 80 cells. They arrived yesterday and the first 8 went right into my two Opus units for capacity checking. I am cautiously optimistic. I checked voltage and AC Impedance on about half of them. Voltage is 3.62 +/- 0.1 and resistance has been either 17.5 or 25.5 +/- 0.4 mOhms. Capacity check finished this morning on the first 8. One was 2601, another 2622, and the others 2680 or better.
I don't have the parts yet to make a load cycle tester, so it will be interesting to see how they do once the cycles start.

James 1:19-20

Not all those who wander are lost - J. R. R. Tolkien
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#8
@Church1182, do not buy any of Liitokala 18650s please!

They are all Chinese fakes actually, and selling Chinese cells. Why do you think they always say Liitokala 30Q, or Liitokala 26F, and not the real manufacturer name?

Heck, look at one of the Liitokala Samsung 30Q listings.

These have 4 positive poles. Real Samsung 30Qs only have 3.

If they are selling fake cells, who says they aren't selling all rewrapped Chinese cells?

There have been reports of cells having too high internal resistance, or even leaking!
The power of lithium ion is in our hands!
We'll show them what we're made of!
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#9
(03-10-2019, 03:02 AM)BlueSwordM Wrote: @Church1182, do not buy any of Liitokala 18650s please!

They are all Chinese fakes actually, and selling Chinese cells. Why do you think they always say Liitokala 30Q, or Liitokala 26F, and not the real manufacturer name?

Heck, look at one of the Liitokala Samsung 30Q listings.

These have 4 positive poles. Real Samsung 30Qs only have 3.

If they are selling fake cells, who says they aren't selling all rewrapped Chinese cells?

There have been reports of cells having too high internal resistance, or even leaking!

To be fair their AliExpress store does not list any other name cells except their own. While their names are slightly misleading they are not downright dishonest. On none of their listings do they state the cells are genuine cells.

Reports of them leaking are a little disturbing though.

Above all, I would opt to buy from QueenBattery. Their prices are similar, and they have a good reputation for selling genuine cells.
Church1182 likes this post
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#10
Yeah, there's a good reason why I made this massive post:
http://budgetlightforum.com/node/60547

So many reports of fake cells, having too high internal resistance, changing titles to prevent refunds.

It's a horror honestly.
The power of lithium ion is in our hands!
We'll show them what we're made of!
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