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diy solar

Server Rack Battery vs DIY

EastTexCowboy said:
Good point. I think I caught a special on shipping on the last two I ordered from Signature Solar. I see Docan has a warehouse in Houston. I'm only about 1.5 hours away. I wonder if they will let you pick up at their warehouse and save the shipping costs?
Click to expand...
they will, but the prices for cells in houston are incl. shipping as far as i know
 
OffGridForGood said:
I did both, first bought a couple server racks to get my solar up and running,
then as I learned from others, and got my courage up, ordered 280Ah cells on Alibaba's (pay and pray) system and built my first DIY rack battery.
Let it run a few months and checked all cells were withing 3-millivolts so ordered more cells and built my second DIY rack battery. Repeat, cells stayed within a few millivolts of each other, so...
Now have my third set of cells on order, will be in by end of Feb.
I like to learn by doing, and take things one step at a time, and test/see if it works well. No problems so I built more. Not everyone is going to be comfortable to build their own battery, or be patient enough to wait for the cells. To each their own I say.
Cost-wise, the 280Ah cells cost about $1900 USD shipped, a BMS with active Balancer is about $70, through-wall battery terminals in 200A are $30, and a decent 2P 125A DC rated breaker for the battery is another $30, some wire and build your own case or set it up open on a shelf if you like. $750/100Ah approx cost. about half the cost of a factory finished rack battery in a nice case, perhaps more easily serviced. I like what I have learned doing my own. Like ET Cowboy, I like to build stuff becase I can more than becase of the money, the more I build the more I understand. If these last 10 years they did me well.
Click to expand...
Hi!

I'm having a hard time getting a decent breaker.

What have you used?

Thanks in advance
 
houseofancients said:
the 304 cells i ordered from china came to 109 usd per cell, same cell from a ( somewhat) local warehouse 149 usd

this isnt that hard to understand now is it ?

on a side note, i would very seriously consider on skipping the 280k cells, as most , if not all dont seems to live up to their specs, and may even be downrated 304 cells
Click to expand...
As I,'m in the process of accessing a new set of cells, could you please share the brand and source for yours?

Thanks in advance
 
What about these? Got 8 of them in my cart.

www.18650batterystore.com

EVE LF304 Grade B Cells - 3.2V LiFePO4 304Ah Battery

Price is per battery Grade B Cells - Original QR code is marked up and unreadable. BRAND NEW CELLS - Capacity tested - sorted and matched. Guaranteed to pull 304Ah+ We test all cells (IR, Voltage, Capacity, Visual inspection) returning anything that does not pull above capacity or has any other...
www.18650batterystore.com www.18650batterystore.com
 
SolaroSsaurius said:
Hi!

I'm having a hard time getting a decent breaker.

What have you used?

Thanks in advance
Click to expand...
To be clear: In my set up I installed a 2P 125A DC rated breaker in the battery (ie in each of five separate batteries that make up the rack) then from each postitive to a MCCB 1P 125A DC rated breaker to a Class T 125A fuse, and from the fuse to the 600A copper bus bar.
In each DIY battery I used a 125A 2P Tomzn DC rated breaker - this is my way to totally isolate the battery if I want to remove it from the rack while the rest of the rack remain in service. This is the Tomzn model TOB1Z-125 and is available on alibaba - if you buy a few at a time the shipping is a lot less per unit. My first one has been in service for about 1.5 years now. All good.
For the 1P positive breaker between the Pos on the battery and the T-Class I used a MCCB Tomzn TOM7Z-250 1P this is a moulded case breaker not a mini circuit breaker. Also available from aliexpress - IIRC these were about 36-40 bucks each. I use this to disconnect the battery while the battery remains "on" so I can check things like the battery total resting voltage or cell voltages with the battery isolated from the rack, but still on, just not sending or recieving any current from the PV or affected by the other batteries, by isolating the pos.
The T-class fuse between this breaker and the copper 600A bus bar in the rack case is my ultimate protection from a dead short. I put a T-class 125A fuse on every battery between the pos bus and the pos disconnect. Then from the both pos and neg bus to the Inverters, I have a smaller (I mean shorter) bus bar and 300A T-Class fuse (one on Pos, one on Neg) - my system has a max of 13,100W peak output, at 48 volts DC, ie 273A, and is supplied with five batteries each set to max 100A to a main bus bar.
 
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OffGridForGood said:
To be clear: In my set up I installed a 2P 125A DC rated breaker in the battery (ie in each of five separate batteries that make up the rack) then from each postitive to a MCCB 1P 125A DC rated breaker to a Class T 125A fuse, and from the fuse to the 600A copper bus bar.
In each DIY battery I used a 125A 2P Tomzn DC rated breaker - this is my way to totally isolate the battery if I want to remove it from the rack while the rest of the rack remain in service. This is the Tomzn model TOB1Z-125 and is available on alibaba - if you buy a few at a time the shipping is a lot less per unit. My first one has been in service for about 1.5 years now. All good.
For the 1P positive breaker between the Pos on the battery and the T-Class I used a MCCB Tomzn TOM7Z-250 1P this is a moulded case breaker not a mini circuit breaker. Also available from aliexpress - IIRC these were about 16-20 bucks each. I use this to disconnect the battery while the battery remains "on" so I can check things like the battery total resting voltage or cell voltages with the battery isolated from the rack, but still on, just not sending or recieving any current from the PV or affected by the other batteries, by isolating the pos.
The T-class fuse between this breaker and the copper 600A bus bar in the rack case is my ultimate protection from a dead short. I put a T-class 125A fuse on every battery between the pos bus and the pos disconnect. Then from the both pos and neg bus to the Inverters, I have a smaller bus bar and 300A T-Class fuse (one on Pos, one on Neg) - my system has a max of 13,100W peak output, at 48 volts DC, ie 273A, and is supplied with five batteries each set to max 100A to a main bus bar.
Click to expand...
Thank you very much for the detailed information.
I'll cross your breakers' reference # and confirm that they are all non polarized, as those prices seem quite interesting.

Again, thanks!!
 
SolaroSsaurius said:
and confirm that they are all non polarized
Click to expand...
Report back either way, it would be good to know!
Edit: at the time I purchased the Tomzn breakers, the marketing information indicated 'non-polarized', but to be honest I never found a proper technical manual to verify this. I installed the 2P MCB in the DIY batteries using the primary direction as 'out of the battery' - this could be up to 100A if my system was outputting max while two batteries were off-line; while the input, ie charging the battery - would be far lower amperage and normally split between 5 batteries. Charging by grid/generator is 30A.240vAC >7200W > 30A 48vDC per battery, and my max PV input is about the same (7kW).
Ditto the 1P MCCB on the POS is set (Line/Load) to support the primary direction as out of the battery, in my thinking this is the higher risk flow direction.
The T-Class 125A fuses are not directional, and I rely on these for my ultimate protection in either direction. Being hard to come by, I installed the 125A T-Class fuses only on the pos side between the 1P MCCB and the Rack Main Bus, I had planned to ALSO install T-Class fuses on the NEG side of each battery but was not able to source them at the time.
After the main Rack Buses, I feed a smaller 300A bus on the wall below each inverter, and each (Pos and Neg) have 300A T-Class fuses at this location as my ultimate protection against a dead short between the inverter and the ESS Rack.
Hope this all makes sense.
 
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Ultimately the DIY Batteries can be fun, a learning experience, and can save a bit of money, a bit more so if you are happy with a simple DIY case (or no case at all) but no warranty.
Both of my Factory Built Server Rack Batteries have a warranty. Hope I never need it. LOL.
 
DIY with grade A 304 would be around $3700 with a luyuan style box, thats 15KW with a JK BMS, I think this will be next build.
 
Xhumeka said:
Nice... where did you end up ordering from and what was the cost?
Click to expand...

18650 battery store.

135.00 each.

www.18650batterystore.com

EVE LF304 Grade B Cells - 3.2V LiFePO4 304Ah Battery

Price is per battery Grade B Cells - Original QR code is marked up and unreadable. BRAND NEW CELLS - Capacity tested - sorted and matched. Guaranteed to pull 304Ah+ We test all cells (IR, Voltage, Capacity, Visual inspection) returning anything that does not pull above capacity or has any other...
www.18650batterystore.com www.18650batterystore.com

Ordered daly 200 amp (8S) BMS off Amazon.
 
All this talk about cost per watt and I finally added my complete bank up, including the Hoffman box https://diysolarforum.com/threads/house-system-battery-box-hoffman.32305/

Capacity 54.9Kw

Cost with 1/4" x 1" copper busbars down the sides with plastic covers, Batrium Watchmon CORE with 4 K9's, ABB shunt trip breaker and a used Hoffman 18x18 box for ABB breaker and 24V power supply for CORE and shunt trip came to $0.191 per watt.

I could have used a cheaper BMS to keep cost down. It cost $1477 for the Batrium with shipping. ABB breaker was $250. The Batrium cost $0.0314/watt.

I'm quite happy at $0.191/watt.

Edit: T fuse per battery included, those were $65 each
 
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Checkthisout said:
18650 battery store.

135.00 each.

www.18650batterystore.com

EVE LF304 Grade B Cells - 3.2V LiFePO4 304Ah Battery

Price is per battery Grade B Cells - Original QR code is marked up and unreadable. BRAND NEW CELLS - Capacity tested - sorted and matched. Guaranteed to pull 304Ah+ We test all cells (IR, Voltage, Capacity, Visual inspection) returning anything that does not pull above capacity or has any other...
www.18650batterystore.com www.18650batterystore.com
Click to expand...

Very tempting, but since I'm not in a hurry I think I'm going to do another order from China.

I'm about to pull the trigger on an order of CATL cells from Shenzhen Hongxinda New Energy Co. described as:
-CATL 3.2V, the QR code is intact, Grade A, Brand new
-all cells will be tested prior to shipping and battery report provided showing capacities equal to or greater than 320Ah

$112 USD/cell (8 units) plus $309 shipping to Toronto Canada: $1205

If the cells pull the stated 320 Ah, it turns out to be 8,192 watt hours which equates to 14.7 cents per watt hour (for cells only, no housing)
 
Xhumeka said:
Very tempting, but since I'm not in a hurry I think I'm going to do another order from China.

I'm about to pull the trigger on an order of CATL cells from Shenzhen Hongxinda New Energy Co. described as:
-CATL 3.2V, the QR code is intact, Grade A, Brand new
-all cells will be tested prior to shipping and battery report provided showing capacities equal to or greater than 320Ah

$112 USD/cell (8 units) plus $309 shipping to Toronto Canada: $1205

If the cells pull the stated 320 Ah, it turns out to be 8,192 watt hours which equates to 14.7 cents per watt hour (for cells only, no housing)
Click to expand...

Yeah so plus BMS and peripherals.
 
Xhumeka said:
Very tempting, but since I'm not in a hurry I think I'm going to do another order from China.

I'm about to pull the trigger on an order of CATL cells from Shenzhen Hongxinda New Energy Co. described as:
-CATL 3.2V, the QR code is intact, Grade A, Brand new
-all cells will be tested prior to shipping and battery report provided showing capacities equal to or greater than 320Ah

$112 USD/cell (8 units) plus $309 shipping to Toronto Canada: $1205

If the cells pull the stated 320 Ah, it turns out to be 8,192 watt hours which equates to 14.7 cents per watt hour (for cells only, no housing)
Click to expand...

Tell them to send you a picture of the QR code first see if you can use the scanner app to make sure it can be read.
 
steviep19 said:
I don't understand the statement or even recommendations that buying a server rack battery is about the same price as building your own DIY battery.

With the long cycle life of Lifepo4, I think it ultimately comes down to the supporting components that make the difference. As long as you keep the batteries withing the proper voltage they'll last past any of the other parts.

In a DIY system, the BMS breaks, or a something comes loose you swap it out or tighten it. In a server rack battery, you pray the company you bought your server rack battery from is still in business, you fight with them for a replacement, or you ship it back to them and get it back months later. You cannot open it up, because it breaks your warranty. If they are no longer in business, you're harvesting the cells, then building a DIY battery anyways.

Also, due to the exceptionally long life of Lifepo4 there's deals to be found on used cells, just like buying a used car will save you money.

I currently have purchased:
1. 4 x Used BYD 24v battery packs from Batteryhookup April-2020 for about $1200 - I'm still getting about 100ah out of each, but these were purchased knowing they are heavily degraded. I picked them up from their warehouse. They're an awesome company. 200ah@48v
2. 32 x 200ah cells purchased from Alibaba in Jan-2021 for $2177 400ah@48v
3. 32 x 100ah cells purchased from Aliexpress March-2022 for $1249 200ah@48v
4. 30 x 280ah cells June-2022 for $2400 from Craigslist, then 2 x 280ah cells from ebay for $300. Found someone selling these cells locally he was going to use for RV project, but then it got to be too much for him. Two of the cells had shipping damage, so I didn't buy those and bought replacements on ebay. They're not matched, but they have been working great for the 6 months I've had them. 560ah@48v

I paid a significant less amount for the used batteries, but in both scenario's "new" from china and used DIY pricing is much better than the server rack battery. Even after purchasing a BMS & Wiring.

The SOK 48v 100ah battery is currently $1600 * 13 = $20,800
Used average of what I paid per 100ah: $7326 / 1360ah * 100 = $540 per 100ah

The racking from Home depot, bus bars, BMS's, Fuses, and Wiring didn't cost me $13,474, and I have a very modular, serviceable system.

I'm genuinely curious as to why someone chose Server rack batteries, other that they look better or they were easier to setup.
Click to expand...
Great post, ... I wish I saw this after two company battery problems ... build my own may very well be in the horizon.
 
Xhumeka said:
I'm about to pull the trigger on an order of CATL cells from Shenzhen Hongxinda New Energy Co. described as:
-CATL 3.2V, the QR code is intact, Grade A, Brand new
-all cells will be tested prior to shipping and battery report provided showing capacities equal to or greater than 320Ah
Click to expand...

I placed my order of 8 cells last night, shipping was actually a bit cheaper than originally quoted, the final bill was:

3.2V CATL "grade A" battery (capacity test of 320Ah) : $112/PCS*8=$896
The price of DDP by sea to Toronto Canada is $275
Total $896+$275=$1171 USD

I'll report back when I receive the cells and what I think of them after running my own capacity tests.
 
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