Calb 180Ah Grade D (LOL) needed

[sunshine_eggo]

I appreciate the confidence you write with, it gives me (an Ignorant not Stupid man) confidence on how to proceed.

I'm a cocky bastid.

That said and according to your statements I will use maintain the four banks with the best matched cells (has to better) and the fifth I will use the 90AH with the other 7 cells including the 160Ah.

That's a little bit opposite of what I suggested. Yay on the 4, but building a battery with cells ranging from 90-160Ah is pushing it a bit. If it's temporary, before replacing some cells, then that's fine.

Each 8S battery has a capacity equal to the lowest capacity cell in the string.

I'm gonna have to step out on a limb here and say that in doing so with that last bank, it will require me to removing or increase the BMS variation setting as it will soon shut down that bank; yes I will top balance them to 3.65 before letting them carry any loads.

You really shouldn't be using a max to min cell variation for cut off ESPECIALLY if you have known cell variations. Setting it to 0.1 or 0.05 or 0.2V doesn't benefit the cells in any meaningful way and is usually just inconvenient as hell. If you have to set it to something, maybe 0.5 as things will have gotten pretty wonky at that point.

Top balancing + passive BMS balancing should be sufficient IF your cells have reasonable self-discharge rates. The most likely thing that's going to make this unworkable is if the self-discharge rates are too dissimilar.

Side note: I have tested all cells for IR and the difference is between .380 to .650 ohms

Did you find an inverse correlation? High cap cells were towards the low end of the range and low cap cells were at the high end of the range? That's consistent with cycle life and capacity degradation.

While those numbers aren't inherently bad, the high is nearly double, which means 2X the voltage drop for a given current. This may also prove to be problematic.

Passive balance should be set to occur any time the cells are above 3.40V and with > 20mV deviation. Ideally, you'll want your cells in the balancing range a couple of hours per day. Some BMS only balance during charge. Hopefully, that's not the case with the DALY. With the JBD/Overkill, you can enable/disable "balance during charge only" or whatever.

If you can tolerate a slower charge rate and still get fully charged, charging to 3.45V/cell, 27.6V and holding for two hours plus a float of 3.40V/cell or 27.2V should minimize charging stress and help ensure the balancers get lots of time to balance every day.

 

[CapnGil]

Ok, let's slow down here and recovien.... to summarize current status and future goal of buy a few older used Calb 180Ah cells.

1. Of the 44 cells I have, I plan to utilize 32 that rate within 139 to 155Ah's permitting me to build 4 banks that have a 1.92 to 6.61Ah deviation of the cells with each bank.

2. By doing so the lowest cell capacity within each bank will be close enough to maximize the total capacity available of all 32 cells. I do understand that any cell battery bank is only as good as its weakest cell. So the closer each cell can be matched within each bank the better... right?... yes

3. The lowest cells of bank read as follows; 140.27, 142.56, 146.08, and. 150.67. I realize the decimal reading are not critical, but they denote my long and grueling capacity testing process, so I earned the right to post them.... lol.

4. If I were to aquire a two Calb 180Ah cells that read in the 139 to 145Ah range cells I could supplement the two negative 90Ah and one 104.23 Ah cell permitting me to re-incorporate the totally mismatched 5th battery bank back to service. I am seeking a few extras used cells now as I am prepping for future degradation as they age and loose capacity.

5. I have two cells that read 160Ah plus and one 175Ah cell (they were in storage) which if I knew how to effectively lower their capacity I could bring that fifth bank on line. I'd only have to lower them to the high side 150Ah range and then shift all cells down, but I would do this only prior to installing because to re-organize all 40 cells once installed is a pain in the butt.

5. So does anyone have a few older Calb 180Ah cells reading around the 140 to 150Ah range or does anybody know of an effective means to remove 20 to 30 Ah's from a 180Ah Calb cell that doesn't take a gogillion years?

Communicating on Cell, Battery Bank, Capacities, Test Equipment, Monitors, etc. can be as involved as capacity testing 40+ cells.... lol

Be well All
Gil

 

[CapnGil]

Ok, let's slow down here and recovien.... to summarize current status and future goal of buy a few older used Calb 180Ah cells.

1. Of the 44 cells I have, I plan to utilize 32 that rate within 139 to 155Ah's permitting me to build 4 banks that have a 1.92 to 6.61Ah deviation of the cells with each bank.

2. By doing so the lowest cell capacity within each bank will be close enough to maximize the total capacity available of all 32 cells. I do understand that any cell battery bank is only as good as its weakest cell. So the closer each cell can be matched within each bank the better... right?... yes

3. The lowest cells of bank read as follows; 140.27, 142.56, 146.08, and. 150.67. I realize the decimal reading are not critical, but they denote my long and grueling capacity testing process, so I earned the right to post them.... lol.

4. If I were to aquire a two Calb 180Ah cells that read in the 139 to 145Ah range cells I could supplement the two negative 90Ah and one 104.23 Ah cell permitting me to re-incorporate the totally mismatched 5th battery bank back to service. I am seeking a few extras used cells now as I am prepping for future degradation as they age and loose capacity.

5. I have two cells that read 160Ah plus and one 175Ah cell (they were in storage) which if I knew how to effectively lower their capacity I could bring that fifth bank on line. I'd only have to lower them to the high side 150Ah range and then shift all cells down, but I would do this only prior to installing because to re-organize all 40 cells once installed is a pain in the butt.

5. So does anyone have a few older Calb 180Ah cells reading around the 140 to 150Ah range or does anybody know of an effective means to remove 20 to 30 Ah's from a 180Ah Calb cell that doesn't take a gogillion years?

Communicating on Cell, Battery Bank, Capacities, Test Equipment, Monitors, etc. can be as involved as capacity testing 40+ cells.... lol

Be well All
Gil

Correction to #5 above: and one new 185Ah Calb 180 Cell.

 

[sunshine_eggo]

Ok, let's slow down here and recovien.... to summarize current status and future goal of buy a few older used Calb 180Ah cells.

1. Of the 44 cells I have, I plan to utilize 32 that rate within 139 to 155Ah's permitting me to build 4 banks that have a 1.92 to 6.61Ah deviation of the cells with each bank.

Sweet.

2. By doing so the lowest cell capacity within each bank will be close enough to maximize the total capacity available of all 32 cells. I do understand that any cell battery bank is only as good as its weakest cell. So the closer each cell can be matched within each bank the better... right?... yes

Agree.

3. The lowest cells of bank read as follows; 140.27, 142.56, 146.08, and. 150.67. I realize the decimal reading are not critical, but they denote my long and grueling capacity testing process, so I earned the right to post them.... lol.

Fair. I've tested many thousands of cells of different types over several years, so I do not pass judgment...

4. If I were to aquire a two Calb 180Ah cells that read in the 139 to 145Ah range cells I could supplement the two negative 90Ah and one 104.23 Ah cell permitting me to re-incorporate the totally mismatched 5th battery bank back to service. I am seeking a few extras used cells now as I am prepping for future degradation as they age and loose capacity.

Sounds like you need 3?

Alternative:

Hold the five that you don't want to replace from #5 as spares for #1 through #4 and buy 8 180Ah cells.

5. I have two cells that read 160Ah plus and one 175Ah cell (they were in storage) which if I knew how to effectively lower their capacity I could bring that fifth bank on line. I'd only have to lower them to the high side 150Ah range and then shift all cells down, but I would do this only prior to installing because to re-organize all 40 cells once installed is a pain in the butt.

Or keep 160 and 175 and buy 6 new 180Ah. Have 3 spares.

alternatively, and I think this is fucking insane:

https://spiral.imperial.ac.uk/bitstream/10044/1/55495/2/Tracking%20degradation%20in%20lithium%20iron%20phosphate%20batteries%20using%20differential%20thermal%20voltammetry.pdf

Hold at 3.65V @ 60°C for 30 days will get you a 5% loss and 50% IR increase.

5. So does anyone have a few older Calb 180Ah cells reading around the 140 to 150Ah range or does anybody know of an effective means to remove 20 to 30 Ah's from a 180Ah Calb cell that doesn't take a gogillion years?

Communicating on Cell, Battery Bank, Capacities, Test Equipment, Monitors, etc. can be as involved as capacity testing 40+ cells.... lol

Be well All
Gil

 

[CapnGil]

Sweet.



Agree.



Fair. I've tested many thousands of cells of different types over several years, so I do not pass judgment...




Sounds like you need 3?

Alternative:

Hold the five that you don't want to replace from #5 as spares for #1 through #4 and buy 8 180Ah cells.



Or keep 160 and 175 and buy 6 new 180Ah. Have 3 spares.

alternatively, and I think this is fucking insane:

https://spiral.imperial.ac.uk/bitstream/10044/1/55495/2/Tracking%20degradation%20in%20lithium%20iron%20phosphate%20batteries%20using%20differential%20thermal%20voltammetry.pdf

Hold at 3.65V @ 60°C for 30 days will get you a 5% loss and 50% IR increase.

I'll look into that narrative on LiFePo4 degradation... now I understand where all your knowledge comes from.... smile.
Pass it on my friend, thanks.

As per goal...

I will stay with the 4 banks for now and at 80% usage (which I rarely reach) I'll have 11,500k Whr's which a gets me through two or three days if the sun doesn't come out in Miami Fl... Not.

Ok, onward for the re-install.

Thanks again
Gil

 

[CapnGil]

The tangential square of the volumetrical capacitance supercedes degradation through resistive loads as compared to photosetter modularutarater impulsive equations....

Layman terms..... WTF.... that tracking degradation report took two years off my life..... lol.

 

[sunshine_eggo]

That's some Turbo Encabulator shit right there.