Lithium battery charge profiles

Started by offgridQLD, January 01, 2013, 12:54:07 AM

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ClassicCrazy

Quote from: RossW on January 29, 2017, 06:34:51 AM
Quote from: ClassicCrazy on January 29, 2017, 01:11:28 AM
Look at Calb cells here http://www.*********/

Your experience may be different.
My one and only dealing with them left me completely unimpressed with their lack of professionalism, their lies and misrepresentations, and ultimately an "oops" email sent by one of their staff to another that accidently included me.

I'd go so far as to say "dishonest", and I have gone out of my way to find stuff that never touches their grubby paws.

Strong words, but I've got the email trail to back it up.

To bring it back on track... under and over voltage "protection" is a failure device I chose to do without.
My inverter and charge controllers prevent over-voltage, and a backup monitoring-only system would alert me anyway. Under-voltage isn't likely to happen, since my inverter will call for a generator run if SoC gets low, OR voltage gets low, and even if the generator didn't kick in, the inverter low-voltage cutout is above the batteries minimum safe voltage.

I do however monitor individual cell voltages, which I find far more useful anyway.

Good to know about that experience you had Ross.  I ordered the batteries from them and they came as expected.  There are other Calb dealers - they all sell them and ship out of same place in California it seems. 

In regards to low voltage protection - yes the inverter will not run , but I had bad experience where the Classic itself ran them down below the safe point. My experience with the Calbs is that if you are doing bottom balancing like I am doing  gotta be real careful ! The voltage will take a dive and crash really fast. First mistake I made was I forgot  to derate my capacity to 80 from 100 SOC since I was bottom balancing and thought I had more in them than there was. And I think my inverter did not shut off like it was supposed to.  At the very least there should be an alarm when the voltage goes below a certain point. I think the problem with my Classic running them down when there were no other loads was because they were cold and capacity was decreased quite  bit. I didn't have the solar on since can't charge them below freezing. Lead acid is a much better choice if batteries are going to be very cold.

I just have small lithium setup so I could get the hang of them !

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

5 Minutes 2 Midnite

#151
This is a very helpful thread, and seems to be the big-daddy of Lithium-ion battery threads here. ? So I hope it's ok to wake it up from it's slumber.

I am looking for a latching relay for my new LiFePO4 array, and not having much luck. Wondering if any of you have located a suitable latching relay for either Low Voltage Disconnect (LVD) or High Voltage Disconnect (HVD) to protect your Lithium battery array.

Specifically, I'm looking for a NORMALLY CLOSED, LATCH ON OPEN contactor. 12vdc is ideal. When energized the contacts open, disconnecting the load, and stay open even if the 12v battery powering the relay dies.

Ever run across such an animal?
Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Midnite Classic 150 charge controller, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel,  QTY 2 Chinese made self-contained 200 AH wall mounted LFP power banks with built in BMS

ClassicCrazy

system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

5 Minutes 2 Midnite

@cniemand, believe it or not I have just read every one of your posts in this thread. Probably twice. Mainly because you seem to have had your LFPs for some time now, and you have posted lots of [helpful] details. Looks like it has been a year and a half since you last posted to this thread. Just wondering how your batteries are holding up. Capacity still about the same?

jim



Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Midnite Classic 150 charge controller, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel,  QTY 2 Chinese made self-contained 200 AH wall mounted LFP power banks with built in BMS

Cniemand

Still subscribed.

Larry : Are you still 'derating' your pack? Curious. I have never had that issue. When i first got them, i used a much lower charge voltage and inadvertently discharged them to the point the inverter shut it all down. After re-bottom balancing them and changing the voltage set points, no more worries. I found that it isnt a huge concern if you bottom balance them closely as when nearly empty, they aren't so far off to kill one another. My issues always were that the differences in capacity.... If i tried to use everything in them by fully charging them at higher voltages, a cell or two would really shoot up before others. Calbs tend to all be over 100ah regardless of buying '100ah' cells.

Ross : 3.5 years is awesome! Good stuff.

Five/Jim : Last month marked my 4th year running a full time offgrid LFP setup. Surprisingly I havent had any issues and have gone all this time without owning a generator. My stance is still the same of voltage setpoints and bottom balancing. Through both of those, the system has remained hands off (aside occasionally taking a multimeter to the bank for verification) With that, I am not 100% certain what my battery capacity is relative to day one. One of these upcoming sunny days I need to fully discharge the bank from 100% to ~0% and then back to Float with the house inverter off to get a more accurate measurement of what went into the bank minus charging losses. From an anecdotal perspective, I do not notice any difference in capacity. That is, my regular routine doesn't bring the SOC any lower. Typically I do not use more than 50-60% DOD. My usage could be considered mild to moderate. If we are to take Calb paperwork concerning cycle life, mine would mimic closer to 5000 cycle life. My lifetime Amp-hours currently is 104,356. Take that into my 100aH bank, I am sitting at 1000 cycles. Still running well without noticeable degradation of capacity.

Cloud
OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

Cniemand

My only issue with the whole system is one : About a month ago, the graphics panel on the Midnite solar 200v CC went funky on me. If i look straight on at it, it looks all black. If i look from an angle or underneath then I can read the screen as if it was normal. I purchased all my components from a dealer in Minnesota 4 years ago, but has since changed to a installer direct only company. I am not sure if I still fall under a warranty or not. I guess I can eventually purchase a new MNGP, but so far, I get by with just looking at it from a 45* angle. Still very happy with midnite solar products and the whizbang is the best invention ever. Surprised I waited a couple years to get one.
OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

Westbranch

#156
inquire via a "TICKET', on the main MidNite.com page , right under the Kid ad under the banner...  have to look for the link...
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

Cniemand

OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

ClassicCrazy

Quote from: Cniemand on July 21, 2017, 07:19:48 PM
Still subscribed.

Larry : Are you still 'derating' your pack? Curious. I have never had that issue. When i first got them, i used a much lower charge voltage and inadvertently discharged them to the point the inverter shut it all down. After re-bottom balancing them and changing the voltage set points, no more worries. I found that it isnt a huge concern if you bottom balance them closely as when nearly empty, they aren't so far off to kill one another. My issues always were that the differences in capacity.... If i tried to use everything in them by fully charging them at higher voltages, a cell or two would really shoot up before others. Calbs tend to all be over 100ah regardless of buying '100ah' cells.


Cloud

Not sure what caused it last year but most of my cells went way below 2 v . I had shut off the PV and the inverter because it was getting too cold to charge batteries but left the Classic on  and thought that there was a 50%  of capacity left. One day I went to look at Local Status App and the system was not on - so I went out and looked and the Classic was shut off due to low voltage and the cells were too low to run it. I don't think I was able to get the inverter to charge it because it wouldn't turn on either due to low voltage.

Was wondering how I was going to get myself out of that mess cause I only had small RC chargers and it was going to be a pain to try to get all 16 cells up one at a time. Then I thought to use my ebike 6 amp 48v charger and that did the trick and stimulated the cells enough to come up in voltage enough to turn on Classic and Inverter so I could charge them.

I had them off all winter because of below freezing temps and not able to charge them but I watched them to make sure they stayed up in voltage okay. This spring I turned them back on again and just have refrigeration loads on them and everything seems to work just fine - typically they only go down 30 % of their 80 amp stated capacity . Today we had very overcast day with warm temps so not much charging and they are at 40% but holding 52.2 v . Hopefully they will make it okay till sunshine tomorrow morning ! If I am worried before bed I will switch the refrigeration over to the other system.

Anyway - I don't know why the died that one time - that is problem with lithium - the voltage takes a dive very fast and really should have some kind of low voltage protection which I still don't have yet  other than inverter low cutoff.  So that is why I set them up at 80 ah to give me some buffer and not take them too low again. I don't know if the cells got damaged when they went below 2v though I think I caught them fairly quickly .

Larry

 
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Cniemand

If I recall correctly, an outback inverter disconnects down around 40v. For you and I with 16 cell systems, that means if the inverter is shutting down the system then each cell is at 2.5v, whereas we should consider 3.0v to be the absolute low 100%DOD.

Larry: Did you see the voltages all remain pretty close of each cell at that SOC? It no doubt does some effect to their capacity long term with bringing them down that low, but I suspect, like my own bank where I had the same occure once that they will all recover nicely.

LFP charge/discharge curves are very linear and the ends are very steep. Quite unique. At the ends it can be seen as a negative, whereas having most of the curve very linear makes for stable voltages.

I agree, Larry. Keeping away from an active BMS solution that could cause overvoltage destruction should one of the boards conk out is my philosophy, however, having a low voltage disconnect is a useful backup. I do not actively try to use the whole capacity of the cells (top end, 100ah came from Calb ~110-115) with my CC setpoints a overvoltage is not likely unless the cc fries. (If it did i suspect more likely no voltage would pass)

It has been a while since reading the Outback inverter manual. Doesn't it have a user defined disconnect voltage? If so, i would push it up to at least 48. Probably safer at 49 or even 50v.

( Somedays I think how nice it would be to have an outback mate to finally program the inverter for a LFP profile... Then i could setup a genny and have the software disconnects. BUT $3-400 bucks when i would use it once. "Set it and forget it" Meh. )
OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

Cniemand

Just looked the manual over. Our VFX3648 inverters have a voltage range of 42-68vdc. They cut out far too low for LFP chemistry.
The colored LEDs for battery status are as follows :

GREEN = 50v+ (The entire useful voltages of LFP would fall here)
YELLOW = 46-49.6v (At this point you are already beyond recommended 100%DOD or 3.0v per cell)
RED = 42v (2.625v per cell. Eeks)

Having a LVD at around 50v would keep all the cell voltages above where they start to crash.
OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

ClassicCrazy

Quote from: Cniemand on July 22, 2017, 04:53:07 PM
If I recall correctly, an outback inverter disconnects down around 40v. For you and I with 16 cell systems, that means if the inverter is shutting down the system then each cell is at 2.5v, whereas we should consider 3.0v to be the absolute low 100%DOD.

Larry: Did you see the voltages all remain pretty close of each cell at that SOC? It no doubt does some effect to their capacity long term with bringing them down that low, but I suspect, like my own bank where I had the same occure once that they will all recover nicely.

( Somedays I think how nice it would be to have an outback mate to finally program the inverter for a LFP profile... Then i could setup a genny and have the software disconnects. BUT $3-400 bucks when i would use it once. "Set it and forget it" Meh. )

I borrow an Outback Mate from a friend so was able to set it up - don't remember what I put the low voltage cutoff on the inverter at.
You can get the older model Mate for around $100  if you dig around on ebay . It might be a knockoff because there was a Chinese company that copied Outback Controllers and sell them for half the price.

I havent checked voltages on my cells for awhile. Last night I was -60 amps out of them and voltage was holding steady at 52.2 v so that is good enough for me - though I would like to run them all the way down sometime when I can watch them just to see how much capacity is in them. It could be that I can get more capacity  out of them at smaller loads than large loads.

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Cniemand

In an older pm I reread, you mention setting the lvd at 2.5v
OFF-GRID @ 8500FT : 2000w Array : 8 - CS6P-250P ; VFX 3648 ; WBjr ; MN CL200 #6738 ; FW #2079  
48v LiFePo4 : 16 - CALB CA 100 aH in Series - 5 kWh ; No Active BMS - Bottom Balanced
Charging Parameters : Bulk - 55v, Absorb - 5 EndAmps @ 55v, Float - 54v or 3.375v per Cell : ZERO EQUALIZE

ClassicCrazy

Quote from: Cniemand on July 22, 2017, 05:48:47 PM
In an older pm I reread, you mention setting the lvd at 2.5v
I will turn it up to 48v v if I don't have it there already .

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

5 Minutes 2 Midnite

Quote from: ClassicCrazy on July 22, 2017, 12:47:50 AM
Anyway - I don't know why the died that one time - that is problem with lithium - the voltage takes a dive very fast and really should have some kind of low voltage protection which I still don't have yet  other than inverter low cutoff.  So that is why I set them up at 80 ah to give me some buffer and not take them too low again. I don't know if the cells got damaged when they went below 2v though I think I caught them fairly quickly .

Very educational. Glad they came back for you. I just iterated through a low voltage cutoff thread over at the Arizona Wind and Sun forum to come up with a solution for my rig. Lots of good ideas for LVD were flushed out. Might be of interest...

http://forum.solar-electric.com/discussion/352277/desperately-seeking-normally-closed-latching-contactor-but-not-that-desperate
Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Midnite Classic 150 charge controller, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel,  QTY 2 Chinese made self-contained 200 AH wall mounted LFP power banks with built in BMS