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LiFePower4 Battery State of Health degradation...

I have 6 Lifepower4 packs that are just over a year old now. After reading this I checked mine.

Battery 1 is closest to the inverter. I never flipped the negative buss bar. all 6 of my batteries show 100% SOH. If all 6 batteries don’t see an absorption cycle for a few weeks batteries 1 and 3 will lag behind On the SOC meters by one green dot.

Cycles
1.91
2.84
3.84
4.86
5.83
6.78
 
JLBinTN said:
Down another 0.1% to 99.5% SOH! This trend is beginning to disturb me. The battery is being used within the specifications provided by Signature Solar. To the best of my knowledge, the battery temp has never dropped below 40 degrees, so charging below 32 degrees can't be a contributor to the issue. It has been discharged to 0% a couple of times and charged to 100% a couple of times due to Growatt software glitches, but as stated earlier, has almost always been operated between a 20% and 91% state-of-charge level. Battery was purchased 3/1/2022, so it has been in use for less than 11 months. I guess I better get that warranty information registered.
Click to expand...

Again, that number likely has no meaningful predictive value and is more likely a result of cell imbalance due to your habitual failure to regularly push all batteries to 100% SoC on a regular basis.

And:

sunshine_eggo said:
2nd reference
Click to expand...
 
sunshine_eggo said:
Again, that number likely has no meaningful predictive value and is more likely a result of cell imbalance due to your habitual failure to regularly push all batteries to 100% SoC on a regular basis.

And:
Click to expand...
As you may have surmised, I'm not particularly interested in your "likely" analysis. SOH is calculated in a specific way using a specific algorithm. If you have specific knowledge, please share. If not, then have a good day.
 
This is how SOH is calculated I think:

1) You set a WH or AH at the factory based on different states of charges
2) The BMS than compares what it was at time when it was new to what it is now
3) If it detects a difference then it deducts from the SOH
4) So in lamans terms, if you got 100AH new, but now you are only getting 95 AH then your SOH would be 95%
 
JLBinTN said:
As you may have surmised, I'm not particularly interested in your "likely" analysis. SOH is calculated in a specific way using a specific algorithm. If you have specific knowledge, please share. If not, then have a good day.
Click to expand...

That has been well documented to be influenced HEAVILY by cell imbalance.
 
JLBinTN said:
After roughly 350 charge-discharge cycles, my 5.12kw 48V LifePower4 battery's State of Health (SOH) dipped 0.3% to 99.7%. The Growatt SPF3000 All-in-one is set to cycle the battery between a 20% and 91% state of charge, but there have been one or two glitches where these parameters were exceeded. All that said, I'm wondering if a 0.3% decline in SOH over 350 cycles is reasonable, and what a chart of SOH vs Charge Cycles will look like over the estimated life of the battery (7000 cycles per the literature). Thoughts?
Click to expand...
I just recently came across this chart. It may be helpful.
 

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Brucenolan, excuse my ignorance but how do you get that tabulated information on each battery giving you the SOH and cycle information.
I have 6 EG4 lifepower4 batteries and would have to isolate each to use the software to check each one on its own, I think.
 
Johno1066 said:
Brucenolan, excuse my ignorance but how do you get that tabulated information on each battery giving you the SOH and cycle information.
I have 6 EG4 lifepower4 batteries and would have to isolate each to use the software to check each one on its own, I think.
Click to expand...
Hi John, each battery has a unique address set via dip switch and are then daisy chain together with short cat5 cables. laptop running BMS test software is connected and reads all battery data, up to 16 batteries
 
Jack Rabbit Off Grid said:
I have 6 Lifepower4 packs that are just over a year old now. After reading this I checked mine.

Battery 1 is closest to the inverter. I never flipped the negative buss bar. all 6 of my batteries show 100% SOH. If all 6 batteries don’t see an absorption cycle for a few weeks batteries 1 and 3 will lag behind On the SOC meters by one green dot.

Cycles
1.91
2.84
3.84
4.86
5.83
6.78
Click to expand...
It is curious to me that each battery seems to cycle somewhat independently of the other five even though they're all connected in parallel.
 
Johno1066 said:
Brucenolan, excuse my ignorance but how do you get that tabulated information on each battery giving you the SOH and cycle information.
I have 6 EG4 lifepower4 batteries and would have to isolate each to use the software to check each one on its own, I think.
Click to expand...
I do not have the short cat5 cables connected. I just move the adapter going from my laptop from battery to battery and the screen on the laptop refresh’s each time with the new information.
 
Thanks for your information. I just checked the BMS software and it does give the SOH and the number of cycles but I seem to recall that the batteries will be needed to come off the busbars to be checked and that the inverters need to be shut down. So if the inverters are shut down and also the PV input can you check each of the six batteries without disconnecting each from the busbars if you remove the comunication cables. Do you have to change the dip switches on the battery being checked to 0 or do you just put in the dip switch address into the software start address.
A little help from the forum could possibly prevent me from blundering around for hours trying to find the correct method so thanks for the help.
 
JLBinTN said:
After roughly 350 charge-discharge cycles, my 5.12kw 48V LifePower4 battery's State of Health (SOH) dipped 0.3% to 99.7%. The Growatt SPF3000 All-in-one is set to cycle the battery between a 20% and 91% state of charge, but there have been one or two glitches where these parameters were exceeded. All that said, I'm wondering if a 0.3% decline in SOH over 350 cycles is reasonable, and what a chart of SOH vs Charge Cycles will look like over the estimated life of the battery (7000 cycles per the literature). Thoughts?
Click to expand...

Now at 98.8% after 378 charge-discharge cycles. I haven't contacted Signature Solar yet, because I'm not certain I have a problem, but the rapid rate of change in SOH is a bit disturbing.
 
timselectric said:
The number does not mean much.
Just stop looking at it.
Problem solved.
Click to expand...
Yes, as I said earlier in the thread, most EVs degrade 5-10% in the first year then plateau off to the sunset. That degradation is based on actual capacity and is a different chemistry. I expect my LFP to last 8 to 10 years and would be happy if capacity was 90% after 10 years.
 
Ampster said:
Yes, as I said earlier in the thread, most EVs degrade 5-10% in the first year then plateau off to the sunset. That degradation is based on actual capacity and is a different chemistry. I expect my LFP to last 8 to 10 years and would be happy if capacity was 90% after 10 years.
Click to expand...
This particular LiFePO4 battery has degraded 1.2% over the last 50 cycles. I would expect a linear degradation over time, but maybe that's not how the chemistry works. Maybe it's zero for 350 cycles, big drop, then linear from there, or maybe it's choppy all the way to 0. That's the purpose of this thread; to solicit the experience of others with the same battery.

I received a direct message from a board member who experienced a slightly worse degradation problem with the same battery bought very near the same time as mine. After much troubleshooting, SS shipped him a replacement. $1500 is $1500.

I have no knowledge regarding the accuracy of SOH measurements, nor how the value is calculated. Something is being measured, and even if the absolute value of that measurement is imprecise, the change in that value over time should be meaningful.
 
The readings would be better if the cells were wrapped in orange instead of blue. But I like blue better. So, I ignore the readings.
 
JLBinTN said:
I would expect a linear degradation over time, but maybe that's not how the chemistry works.
Click to expand...
As I mentioned my only experience is from driving EVs which is a different chemistry. My expectations are from ten years of driving EVs and the degradation is not linear, rather a 5 to 10 percent drop the first year and then a fairly slow decline after that. EVs are required to have an eight year warranty and allowed a 30 percent degradation before the warranty kicks in.
 
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