Uhome LFP 2400 Voltage Falling Under No Load Conditions
In June 2022 I’ve had a Lux ACS 3600 and 4 x Uhome LFP 2400 batteries installed at my property (supplied and install by competent person) to store the surplus solar energy from an already installed roof top solar array. The system I thought had been working fine and was configured for 90% depth of discharge (DoD) in parallel for the batteries. I’d like to get some input from anyone with a similar system as to what happens with their battery voltages, does your system charge every other day in the winter?
When first installed in June, the good weather (sunny Aberdeen!) meant that the system was charging the batteries on a daily basis to 100% and I didn’t notice any issue.
However as we got into November and December, on the dark and poor solar production days, I have noticed that the pack voltage is falling once the 10% threshold for the pack is reached. So what normally happens is the voltage will gradually begin to fall over a period of hours and get to 49 volts at which point I assume that the battery management system kicks in and is triggering a charge from AC (mains), pulling approximately 360w and pushing around 1.5kWh into the battery pack every time.
What I have noticed happening and also has become more frequent, to the point of every other day at this moment in time. The pack voltage falling from 51volts to 49volts over a period of approximately 18 hours which I don't think is normal behaviour for this type of battery chemistry. I’ve got numerous 6S LiPo batteries from my RC hobby that have sat for months and lost little to no charge / voltage when I balanced and check them.
My question is I thought that Lithium Ferro-Phosphate (LiFePO 4) batteries have an initial short period of stabalising after disconnection from a load and then the voltage should remain pretty much constant with a very low self-discharge whereby the pack voltage remains the same for a long period (days or weeks)?
What i am seeing is worse than a Lead-acid battery that is damaged!
I’ve flagged this up to the supplier who changed the DoD to 14% to cover the loss of power and voltage fall, but this didn’t sit well with me as I believe that these batteries should work well at 90% DoD. Incidentally this didn’t solve the problem as the fall was/is so rapid that the system still was frequently charging from AC (mains) just on a slightly longer period (3/4 days).
I don't think that this is normal and suggests a faulty cell to me. Does anyone else Uhome LFP 2400 batteries have this type
I've attached an image from the Luxpowertek website from yesterday to show exactly what is going on (which I've sent to the supplier / vendor)
Any comments and thoughts would be welcomed.