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LiFePower4 Battery State of Health degradation...

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.
 
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?

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.
 
The number does not mean much.
Just stop looking at it.
Problem solved.
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.
 
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.
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.
 
I would expect a linear degradation over time, but maybe that's not how the chemistry works.
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.
 
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.
Just asking where you stand with this. Any outcome?
I have 4 of these packs, Only 75 cycles, few weeks ago, I noticed one of the packs SOC is lagging behind the other 3 by 30% !
SS told me it 'may" clear itself out.. It didn't. So, I took the problem battery out of the string ang gave it a full charge with the external charger. It charged to 100%, so I put it back in the string. 1 week later, it is once again lagging behind the rest. Losing about .5% a day. Going to call back and tell them the experiment failed...
 
Just asking where you stand with this. Any outcome?
I have 4 of these packs, Only 75 cycles, few weeks ago, I noticed one of the packs SOC is lagging behind the other 3 by 30% !
SS told me it 'may" clear itself out.. It didn't. So, I took the problem battery out of the string ang gave it a full charge with the external charger. It charged to 100%, so I put it back in the string. 1 week later, it is once again lagging behind the rest. Losing about .5% a day. Going to call back and tell them the experiment failed...
Currently at 97.9% SOH on 439 cycles. I'm not happy with the trend here. What is your battery's SOH%?
 
Currently at 97.9% SOH on 439 cycles. I'm not happy with the trend here. What is your battery's SOH%?
You should be happy this is how batteries work. SOH is determined by an equation. You have a 100ah battery so the equation equals your battery has around 98ah left. You lost 2ah not a big deal that is great for lifepo4 at almost 500 cycles. Batteries loose capacity over time it's going to happen no matter what.
 
Assuming it actually means anything...
Exactly... has anyone defined what SOH represents, or is there an industry-wide common usage of the term.

If a manufacture states a battery's "usable lifetime" is when it deteriorates to (say) 80% of its original capacity, then I would have logically expected at that point it would have a zero SoH, not 80% SoH. i.e. 100% SoH of health when new and 0% SoH when it has reached its end-of-life condition.
 
Exactly... has anyone defined what SOH represents, or is there an industry-wide common usage of the term.

If a manufacture states a battery's "usable lifetime" is when it deteriorates to (say) 80% of its original capacity, then I would have logically expected at that point it would have a zero SoH, not 80% SoH. i.e. 100% SoH of health when new and 0% SoH when it has reached its end-of-life condition.
Yes there is an actual equation this is not just made up. It's ( actual remaining capacity AH/ Rated AH capacity) for example 98ah/100ah= 0.98%.
 
My two 24v Lifepower 4 batteries are constantly giving unreliable percentage of charge due to my inconsistent usage as a weekend warrior at the cabin. I use the voltage as a more accurate indicator of SOC, but and hope that my Growatt AIO does as well. Last week end the Growatt told me that the batteries were at a 83%SOC. The voltage was 26.7v. I think the state of health indicator should be handled with the same skepticism. I could be way off though.
 
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