diy solar

diy solar

Anyone buying these 305ah envision cells?

I have been lurking on them, great price.
But looking on some numbers:
envision---> 70%SOC gives a 6000cyles.
EVE B grade -->80%SOC gives a 8000 cycles.

So cycle life is less, what about self life?
If even doing 1 cycle a day it would still be 16 years for envision and 21 years for eve.
how would you get out max?
365x(70% of 280ah)=715.400x16=11.446.400
365x(80% of 280ah)=817.600x21=17.169.600 eu
What does this mean?
After there border there is still 70% left or in eves case 80% left of the original capacity.
I think after twice the life span the numbers willlook like this:
365x(40% of 280ah)=408.800x16+715.400x16=17.987.200
365x(60% of 280ah)=613.200x21+817.600x21=30.046.800

so for after 32 years or after 42 years it depends on what you want and need, how old you are and how big your battery is or is going to be.
I doubt that one with a resonal battery could do 1 cycle a day, most of us do more than 10kwh a day and most of us have 50kwh+, plus the sun does not always shine enough, not all have wind or water generators implemented in our system.

For me and my wife with max 30 years working life left incl two ev's(soon) i think i still would go with EVE.
However, they are very tempting....buy a set extra? so 5 sets of Envision or four sets of eve to make it balance?
Price wise it is the same.
365x(40% of 280ah)=408.800x16+715.400x16=17.987.200x5?
365x(60% of 280ah)=613.200x21+817.600x21=30.046.800x4?

Something else to consider, new technologie, like sodium or other new not invented chems.

Just some food for thoughts, i must say very honest they are very tempting, very tempting....
 
100kwh-hunter said:
I have been lurking on them, great price.
But looking on some numbers:
envision---> 70%SOC gives a 6000cyles.
EVE B grade -->80%SOC gives a 8000 cycles.

So cycle life is less, what about self life?
If even doing 1 cycle a day it would still be 16 years for envision and 21 years for eve.
how would you get out max?
365x(70% of 280ah)=715.400x16=11.446.400
365x(80% of 280ah)=817.600x21=17.169.600 eu
What does this mean?
After there border there is still 70% left or in eves case 80% left of the original capacity.
I think after twice the life span the numbers willlook like this:
365x(40% of 280ah)=408.800x16+715.400x16=17.987.200
365x(60% of 280ah)=613.200x21+817.600x21=30.046.800

so for after 32 years or after 42 years it depends on what you want and need, how old you are and how big your battery is or is going to be.
I doubt that one with a resonal battery could do 1 cycle a day, most of us do more than 10kwh a day and most of us have 50kwh+, plus the sun does not always shine enough, not all have wind or water generators implemented in our system.

For me and my wife with max 30 years working life left incl two ev's(soon) i think i still would go with EVE.
However, they are very tempting....buy a set extra? so 5 sets of Envision or four sets of eve to make it balance?
Price wise it is the same.
365x(40% of 280ah)=408.800x16+715.400x16=17.987.200x5?
365x(60% of 280ah)=613.200x21+817.600x21=30.046.800x4?

Something else to consider, new technologie, like sodium or other new not invented chems.

Just some food for thoughts, i must say very honest they are very tempting, very tempting....
Click to expand...
Lol..
Funny how eve went from 4000 cycles to 8000 without significant changes ?
30 years life will NEVER happen
 
100kwh-hunter said:
I have been lurking on them, great price.
But looking on some numbers:
envision---> 70%SOC gives a 6000cyles.
EVE B grade -->80%SOC gives a 8000 cycles.

So cycle life is less, what about self life?
If even doing 1 cycle a day it would still be 16 years for envision and 21 years for eve.
how would you get out max?
Click to expand...
To be honest I think that is all academic. I only have 14.3kWh (16 x EVE LF280Ks), push them really hard and in 15 months the cycle count is only 263.

Calendar aging will be, by far, the biggest factor. Not sure in my case whether the limiting calendar aging factor will be me or my LiFePO4's, but either way, I know that in less than 5 years time they will be so much cheaper than they were 18 months ago. Hence decisions on cycle life of them I made in 2022 will be irrelevant.
 
100kwh-hunter said:
to80% of state of charge, if you are using 100% then you will have no more then 4000 left.
EVE also has several species of cells, their not only for automotive industrie.
Click to expand...
It takes me several days to run a complete cycle of my battery bank. Calendar aging will have a bigger effect long term than using that power. I run to about 98% SOC and don't worry about it. When the cells are done, then I move on.

At 80% SOC, you will find there will be problems with cell balance.
 
100kwh-hunter said:
So it is clever to buy then or stick with EVE?
Click to expand...
Imo they were a clever purchase. But I think that will be person dependent.
I have a large bank desire. Reasonable prices on reasonable equipment will help me get there
I perceive these cells as both. Only time will tell, but I paid less than half the cost of an eg4 6 battery rack for the same capacity so I feel like I won
 
Zwy said:
At 80% SOC, you will find there will be problems with cell balance.
Click to expand...
All my banks have a 1A balancer, turn on every 3 months as long as needed, usually 3 days, when in 5 days, something is pretty wrong, i think
But some folks have stated those envision are pretty time resistant.
I think i will give it a go, again you get what you pay for?
 
100kwh-hunter said:
All my banks have a 1A balancer, turn on every 3 months as long as needed, usually 3 days, when in 5 days, something is pretty wrong, i think
But some folks have stated those envision are pretty time resistant.
I think i will give it a go, again you get what you pay for?
Click to expand...
How can you balance cells effectively below 3.4V?
 
Zwy said:
How can you balance cells effectively below 3.4V?
Click to expand...
You can't. But I've found it does help as a temporary solution for packs that are way out of balance.
Example - I currently have mine set to turn on at 3.39V with float set to 54.4V (3.4V / cell)
I have/had a cell that was running pretty bad driving the pack voltage up, with the above voltages I was able to keep the runner balancing a bit sooner and remaining cells lower... Runner would hit 3.5xV with the rest ~3.45V. When bulk V was attained the rest would rest while the runner would bleed off.

Note I'm far from and expert and am using passive balancing JBDs. The above worked for me and isn't optimal.
If I were When I start running a passive balancing BMS I would set balance to initiate at 3.42V and not worry about it.

I'm willing to learn more everyday... Feel free to school me more.
 
42OhmsPA said:
You can't. But I've found it does help as a temporary solution for packs that are way out of balance.
Example - I currently have mine set to turn on at 3.39V with float set to 54.4V (3.4V / cell)
I have/had a cell that was running pretty bad driving the pack voltage up, with the above voltages I was able to keep the runner balancing a bit sooner and remaining cells lower... Runner would hit 3.5xV with the rest ~3.45V. When bulk V was attained the rest would rest while the runner would bleed off.

Note I'm far from and expert and am using passive balancing JBDs. The above worked for me and isn't optimal.
If I were When I start running a passive balancing BMS I would set balance to initiate at 3.42V and not worry about it.

I'm willing to learn more everyday... Feel free to school me more.
Click to expand...
Balancing is effective pointless below 3.45.
What will work is a float just above 3.45-ish and keep them there to the balancer can do it's thing.

Best in any case is to do a proper top balance before you put them in series/production
 
houseofancients said:
Balancing is effective pointless below 3.45.
What will work is a float just above 3.45-ish and keep them there to the balancer can do it's thing.
Click to expand...
I was doing that until I, most likely, read way to far into plating / degradation holding at higher voltages. My thought process was get as many cells down while bringing the runner down with the passive balancer.
It has definitely worked, my deviation has improved significantly.
houseofancients said:
Best in any case is to do a proper top balance before you put them in series/production
Click to expand...
I agree 100%. My two 230 packs were top balanced per the guide; they are much better than the non top balanced pack.
I was excited to get another pack online to take advantage of the finished ground mount and I'm impatient.
 
42OhmsPA said:
You can't. But I've found it does help as a temporary solution for packs that are way out of balance.
Example - I currently have mine set to turn on at 3.39V with float set to 54.4V (3.4V / cell)
I have/had a cell that was running pretty bad driving the pack voltage up, with the above voltages I was able to keep the runner balancing a bit sooner and remaining cells lower... Runner would hit 3.5xV with the rest ~3.45V. When bulk V was attained the rest would rest while the runner would bleed off.

Note I'm far from and expert and am using passive balancing JBDs. The above worked for me and isn't optimal.
If I were When I start running a passive balancing BMS I would set balance to initiate at 3.42V and not worry about it.

I'm willing to learn more everyday... Feel free to school me more.
Click to expand...
Great minds think alike, I changed my Batrium to start balance at 3.39V some time ago. https://diysolarforum.com/threads/issues-balancing-with-batrium-bms.54418/post-930976

That would be the lowest cell voltage, once the lowest cell hits 3.39V, bypass is enabled. I have some cheap cells from Amy that weren't matched for internal resistance and a few are runners. When bypass starts, the highest cell is already above 3.5V. Some day these will go in my electric golf cart and I will install some better matched cells.

These were top balanced as a complete 16S pack. With a BMS until one cell hit 3.65V. Then in parallel until amps dropped to nothing. Those cells still won't hold balance. I could add an active balancer to help with balance on those cells, most likely when they go into the cart I'll install one. The Batrium does a pretty good job with 0.75A passive balance. It does generate heat on the K9 heatsink. I could add a fan and increase bypass amps. I have never seen the need to however.
 
The spec sheet on these cells says they are at 100% SoC at 3.348V. What voltages are you folks using when you test the capacity? I've got a 4-pack on a charger that goes to 3.65V per cell, still pushing its 10A max rate into cells at 3.36V each. OC voltage looks like it's going to settle between 3.50V and 3.55V when I disconnec tthe charger, so still above the spec.
 
My input on these cells, I purchased some from a UK company called Fogstar, Envision 305Ah grade b.

After receiving the cells, checking each visually, running an Internal resistance check on each cell to compare against the name plate rating and finally a top balance of all cells to 3.65v per cell in parallel before assembling the pack in to a 16s configuration in the supplied Seplos case with 200Amp BMS. unfortunately these do not perform very well at all at anything over a 0.2c discharge rate when the SOC is around 50%, barley 210Ah usable before low voltage cut off at 2.9v per cell, after cut off they bounce right back up to 3.1v per cell showing these are very low grade cells possibly heavily pre-used and re wrapped. I repeated the test after a full charge to 3.60v per cell then a further discharge with a 0.1c discharge rate and achieved a little over 279Ah this time. They seem to perform better at higher discharge rate around 3.3v per cell and then it all goes downhill once they are around the 3.2v mark. Appreciate they are B grade cells but not being able to pull 50Amps at a 50% SOC before a low cell warning isn't what i expected. I have tested and built many different cell types and manufacturers / grades and these are very very poor quality.

For some reason my review on their website keeps being removed.
 
Here you can see (highlighted) when a 40Amp DC load is applied at around 45% SOC 3.1v per cell, the cell voltage drops off a cliff down to 2.9v in under a minute. Test performed today, 15 Degrees C temp from a fully charged pack that was ticking over around 10Amp discharge all day. You can see the voltage bounce backup after the low voltage cut off around 11.30
1703692161498.png

1703692407099.png
 
shavermcspud said:
My input on these cells, I purchased some from a UK company called Fogstar, Envision 305Ah grade b.

After receiving the cells, checking each visually, running an Internal resistance check on each cell to compare against the name plate rating and finally a top balance of all cells to 3.65v per cell in parallel before assembling the pack in to a 16s configuration in the supplied Seplos case with 200Amp BMS. unfortunately these do not perform very well at all at anything over a 0.2c discharge rate when the SOC is around 50%, barley 210Ah usable before low voltage cut off at 2.9v per cell, after cut off they bounce right back up to 3.1v per cell showing these are very low grade cells possibly heavily pre-used and re wrapped. I repeated the test after a full charge to 3.60v per cell then a further discharge with a 0.1c discharge rate and achieved a little over 279Ah this time. They seem to perform better at higher discharge rate around 3.3v per cell and then it all goes downhill once they are around the 3.2v mark. Appreciate they are B grade cells but not being able to pull 50Amps at a 50% SOC before a low cell warning isn't what i expected. I have tested and built many different cell types and manufacturers / grades and these are very very poor quality.

For some reason my review on their website keeps being removed.
Click to expand...
This not normal behavior for these cells, and no where near where my tests and builds are ending up..
Contact fogstar, have them swap them out..
I believe you are in the uk correct ?
Get on the phone with them

@Ben@Fogstar..
This can't be right
 
houseofancients said:
This not normal behavior for these cells, and no where near where my tests and builds are ending up..
Contact fogstar, have them swap them out..
I believe you are in the uk correct ?
Get on the phone with them
Click to expand...
I know, I have built probably 80+ packs now and not seen any quite this bad even from B grade cells. I've had them two weeks now, a week to top balance them and then assemble them and test. Unfortunately they are not open at the moment due to Christmas.
 
shavermcspud said:
I know, I have built probably 80+ packs now and not seen any quite this bad even from B grade cells. I've had them two weeks now, a week to top balance them and then assemble them and test. Unfortunately they are not open at the moment due to Christmas.
Click to expand...
Yeah, I'd contact them, make sure they make you whole
 
18650 battery store just started shipping those pre-orders. I assume it's a new batch from China so hopefully they are just as good or better.

My 24V bank is big enough that it never gets pushed hard in terms of C so I can't speak to the post above (maximum is 0.12C for charge or discharge). They stay balanced very well with JBD passive balancing and it very rarely gets a chance to balance the way I have it set up.

Still experimenting with the BMS settings to try and maintain the most accurate state of charge reading for each battery in the bank between full charges.
 
Last edited:
You must log in or register to reply here.

Similar threads

M
WTB: 4 New ENVISION 305Ah Grade B Cells - 3.2V LiFePO4 Battery -- DFW-Texas
Replies
0
Views
254
mudflap5
M
T
First time battery bank build.
Replies
11
Views
2K
Aridom82
Aridom82
P
30kWh Envision Import & DIY
4 5 6
Replies
133
Views
9K
OrigamiTiger
O
D
First DIY Battery - Advice Needed
Replies
15
Views
791
featherlite
F
R
Gangfeng 280 Cells
2 3
Replies
64
Views
5K
Coydon
C

diy solar

diy solar
Back
Top