Need to replace wet cell batteries for a 24v system

[CaptMichel]

Need to replace wet cell batteries for a 24v system
I have a solar system with only 400w panels and a full automatic 24vdc , 120/240 vac magnum power inverter charger
Need to update my solar power eventually but 1st want to replace my wet cell 12 x 6v 230amps connected in series paralle
I am looking for some infos for the best DIY Lit batt 24v and or buying already assemble 24vdc batt I need a good reserve
So will need to connect many 24v batt in parallel or could also use the option to use 12v batt series parallel
Anyone with good infos appreciate your time and your help
Thanks

 

[snoobler]

12*6*230= 16.6kWh

Only half of which is usable, so 8.3kWh.

You could purchase 16 280Ah LFP cells and create 2 24V batteries in parallel

This would give you 13.9kWh or 11.1kWh of usable. This would cost you about $2000 total.

 

[CaptMichel]

That sounds awesome at a very good price, thanks for your answer
Any suggestion in a already built battery pack ? to see the price difference.
Do you have a preference of a good honest dealer to buy it from ....
Thanks again very much for your reply

 

[snoobler]

Packaged batteries tend to be 4-6X higher.

Forum-trusted DIY sources:

Introducing the New & Improved Shenzhen Luyuan Technology Co.

Dear Members of DIYSolarForum, With the experience I gained while working with Shenzhen Xuba Electronic Co., which I am infintely grateful for. I was introduced to a group of very enthusuiastic and most helpul people which helped me to grow & improve my own knowledge which helps me to better...

diysolarforum.com

280ah cells

I started out negotiating with 12 companies to place a large order of these cells about 3 weeks ago. I have now narrowed it down to one supplier and will be placing an order next week. By placing a large order I have been able to get a good price and also to negotiate shipping DDP directly to...

diysolarforum.com

 

[CaptMichel]

You mentioned
*This would give you 13.9kWh or 11.1kWh of usable. This would cost you about $2000 total.*
This sound excellent but what else will I need BMS etc etc will it run my 4kw inverter
I am welling to do some work here but also want to see once its all set and done the price difference
right now there is 3 x 24V 170Ah LiFePO4 Power Block cost $4,300 and gives me 13,2kw
Thanks fro your time and your help again

 

[snoobler]

$2000 includes the price of 2X Overkillsolar BMS. You'd have 2X 8S 24V batteries, each with their own BMS capable of 100A EA, so 4800W continuous output. Maybe buy a spare cells and some other bits... another $150.

Assuming you mean Bigbattery 24V 170Ah Power Block, you also need to factor in the 80%. 3X of those batteries would provide you 13.1kWh of total capacity and 10.4kWh of usable.

My prices included shipping. With shipping, the PowerBlocks would be $5000 + sales tax ($415 for me).

$2150 for 11.1kWh usable
$5415 for 10.4kWh usable

Build touch time would likely be about 12 hours once you factor everything in, and you'd need to spread that out over a couple weeks.

 

[CaptMichel]

Is there a way to contact you or is this not appropriate to ask on the forum

 

[snoobler]

Huh?

 

[CaptMichel]

Is there a way to contact you email or tel number !

 

[snoobler]

You can click my name and "start conversation". Is there something we need to discuss we can't discuss openly in this thread?

 

[CaptMichel]

Absolutely not we can discuss here
I’m new to forum and I just want all infos parts etc before making my final decision and where to order tel and email etc.

 

[snoobler]

There are two main sources for cells (repeated from above):

Introducing the New & Improved Shenzhen Luyuan Technology Co.

Dear Members of DIYSolarForum, With the experience I gained while working with Shenzhen Xuba Electronic Co., which I am infintely grateful for. I was introduced to a group of very enthusuiastic and most helpul people which helped me to grow & improve my own knowledge which helps me to better...

diysolarforum.com

and

https://diysolarforum.com/threads/280ah-cells.10607/ @Michael B Caro

Both sources are keyed in to what folks want to accomplish with builds on this site.

Brand availability and specific capacities vary, but when you order all from one source, you get all of one brand/capacity.

I would order 17 of the 272-280Ah cells. No matter what is said, they are not grade A cells. There's no guarantee that they will meet capacity. Will they meet all other specifications (resistance, self-discharge, etc.)? Yes. Will they meet 95%+ of the rated capacity? Almost certainly. My 9 recently purchased 280Ah Eve cells tested to >97.2%+ rated capacity with one exception, and it was 94.6%. The extra is in case there's a problem with one, and you don't have to wait a couple months to get another cell. It's also useful as a spare should you have a failure in the future.

BMS available from: https://www.mobile-solarpower.com/raw-lifepo4-deals-page-676969.html

Balancing resource:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

The video is an overview - there are some details that are missing. Make sure you download and operate from the PDF on that page (orange download button at top right of page).

There are many examples of builds on this site.

One thing I don't think we discussed is that LFP can't be charged below freezing. This is also true of the battery pack you linked. The BMS I linked protects the cells from charging at low temperatures.

 

[CaptMichel]

Excellent info
Thanks
I will study some more and get back to you
I looked at some tesla 25.2v 5.2kw
But don’t know much about the final reliability net output etc.

 

[snoobler]

I would urge you to stay away from the Tesla products. They are less favorably configured for 24V. 25.2V is their MAX operating voltage. The cells themselves do not have the same high cycle life as the LFP cells, and you can only use about 60% of the rated capacity and get comparable life, so the 5.2kWh Tesla module that costs about $1200 typically only yields 3.12kWh of usable capacity.

They also need a BMS and are the type of Lithium that has catastrophic outcomes when operated outside their limits.

 

[CaptMichel]

Thanks for the good advice I have put a little bit of research on that as I was browsing through the Internet and I agree with you I will stay away from them.
Thanks for taking the time I appreciate it