diy solar

diy solar

Valence u 27 12 v 130 amphr questions

Wycowboy

New Member
Joined
Dec 30, 2020
Messages
75
Hi all~!
Im new here but not that new to solar. My wife and I have built own off grid home in Wyoming and we power it with a 2400W system

We are pretty very happy with our system except our batteries which we are pretty disappointed with. we have 8x 6 v 200 amp hr amg batteries and feel we have lost a lot of performance over the 3 years we have been running the system.

I am looking at upgrading to LIfe batteries. and was thinking about buying 8 of the Valence u27 batteries while. My questions are. 1 is there any problem with storing the valence batters for a year or 2 until our Lead acid batters really croak?
and secondly will my midnight controller work with these?
thirdly do I need an external BMS for these in addition to the one that I believe is built in to each battery.

I would truly appreciate any help our advice!

Thanks so much!
J
 
Welcome to the forums.

Valence is now owned by LithiumWerks. It's not clear to me that they are either easy or economical to purchase. Folks seem to locate surplus/used ones in good condition, but I wouldn't want to count on that.

Storage of LFP batteries at 50% SoC in mild to cool temperatures can be done indefinitely. Check voltage annually.

You currently have 8 * 6V * 200Ah = 9.6kWh of AGM, of which only 4.8kWh is usable (you don't want to discharge below 50%). AGM cycle life is typically about 1200 cycles, so after 3 years, it's not surprising you're seeing degradation, particularly if you weren't religious about not taking them below 50%.

Assuming this is a 24V system, you could DIY a LFP battery with 7.2kWh of capacity (with a spare cell) for about $1100 w/BMS. Since there's no urgency, that's what I'd do.
 
Thanks for the in put.
There are Valence for sale on ebay for about 1/2 the price of battel born. which I was also looking at. Although I like the Idea if a DIY LFP battery at 7.2 kWh. I have a 48 Volt System so not sure what that doed to the #s Is there a link to the DIY LFP build.
Any thoughts on the midnight controller , It should work with any LFP set correct?
Thanks a gain!!! Truly appreciate it!

On our Lead batteries, we almost never took them below 50% they seem to shut down around 68% and when it get s low we just take everything except a few lights off line.
 
That would require 16 cells. The 280Ah are the most cost effective $/kWh, so you would be at about $2000 for 14.4kWh. That would include a 100A OverKillSolar BMS.

You could use smaller cells, but I don't have a handle on those, and they would likely be significantly more $/kWh.
 
Ok so me being new here, I hope I not asking too many questions. but let me make sure I am understanding what you are saying.

You are saying that as apposes to buying the Valence or other commercial batteries for 4-8K$ I can build my owns set.
is that correct? If so what does that involve ?where do I get the Cells and other parts? is there a good link ot video for the project? what other parts or consideratosn do i need to llink them into my system?
I have the skills to do this, but is would be new to me.

I am very excited about his idea. !
=)
Thanks sooo much!
Jeff
 
Ok I am starting to get caught up on what you are talking about. Do you have a recommend raw cell that provides that 280 amp hr?

Is this the cells your were thinking of? It says 100 amp hr so how would that get me to 14.4 kwh? or am I looking at the wrong cells

THakns!! this is great info!

 
Last edited:
Ok so me being new here, I hope I not asking too many questions.

That's why this forum exists.

but let me make sure I am understanding what you are saying.

You are saying that as apposes to buying the Valence or other commercial batteries for 4-8K$ I can build my owns set.
is that correct?

Yes

If so what does that involve?

Buy cells with double bus bars
Buy Overkillsolar BMS
Buy 30V/10A power supply ($70 or so)
Wait two months for cells to arrive
Top balance cells
Build battery box or other clamping mechanism
Connect cells in series
Connect BMS
Configure BMS
Configure chargers and loads as needed to address battery change
Use battery.

where do I get the Cells and other parts?

There are a couple of trusted sources by members of this site:


and

User: @Michael B Caro

is there a good link ot video for the project?

There are multiple threads showing how and it's very easy. Look for the top balancing guide in the Resources section. Search for "battery build" in the search bar.

what other parts or consideration do i need to llink them into my system?

Generally, no.

I have the skills to do this, but is would be new to me.

Piece of cake

I am very excited about his idea. !

THAT'S THE SPIRIT!
 
great! you are too kind=)
Help me out with the math, If my existing system is 48V , eight 6v 200 am p hour batteries all in series. so 200x 8 = 1600 amp hs? but probably only 800 amp hrs usable. is that correct?

The cells that I Found on l were 3.2 v and 100 amp hrs , I would need 16 of them to get 48 volts What would the amp hrs be of that set up?
I am hoping to double the usable capacity of my existing bank. would the 16 doo that? or am I looking at 32 of the 3.2 v cells?

What does the 30v-10 amp power supply do?

Thanks so much! this is really helpful!!
 
Those already have 400 to 700 cycles on them and as was noted used in delivery trucks. Also those batteries require an external BMS to communicate with the internal BMS. Don't get me wrong, I love the Valence 40ah batteries I have. I have two of them connected in parallel and between the two I get better than 75ah's. But they have a full blown BMS built into them.

I think you can do much better building your own pack and your cost per kwh will be much less.

I ordered 8 EVE cells from Michael and for what I paid I have no complaints. He takes care of everything so that helps with peace of mind these days. It's easy to order cells off aliexpress or alibaba but I like having after sales support from someone that lives in the same country I do. I suggest you check his group buy thread. Currently the Lishen 272ah cells have become popular and cost less than the EVE cells.

What does the 30v-10 amp power supply do?
That is used for parallel top balancing the cells. I suggest you read through the Nordkyn material as it pretty much explains everything.

Assembling a Lithium Iron Phosphate Marine House Bank | Nordkyn Design
 
Back
Top