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New LifePo4 batteries

Ciccino

New Member
Joined
Oct 13, 2021
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I have just received 16 320Ah LifePo4 I bought from PWOD. The seller specified new grade A batteries. After inspection at arrival, all batteries had no visual transportation damage, but it was obvious that the sides were not flat and most of the batteries were swollen to some extend. Placing them side to side, there was a gap ranging from 3 to 7 mm between the cells. Very concerned about this issue, I told the seller and replied me not to worry and to check whether the voltage was the same, which it was (3,27 V). Should I be concerned?
One other thing that worries me is that I charged one of the batteries to 3,65 volts at 5 amps charging rate (very moderate). I left the battery unconected and the next day, the battery voltage had dropped to 3,51 volts (from 3,65 v to 3,51 in 10 hours). Is this normal? I have not charged any of the remaining batteries yet.
Can you give some advice, please?
 
One other thing that worries me is that I charged one of the batteries to 3,65 volts at 5 amps charging rate (very moderate). I left the battery unconected and the next day, the battery voltage had dropped to 3,51 volts (from 3,65 v to 3,51 in 10 hours). Is this normal? I have not charged any of the remaining batteries yet.
Can you give some advice, please?
"Settling" of the cell to a slightly lower voltage is completely normal with any lifepo4 cell. I'm not an engineer but I remember the term "surface charge" getting thrown around.
 
Thank you for your avise, Robert!
I am no familiar with the term “surface charge” but I have been checking the voltaje drop in the battery, and after 10 hours it was at 3,51 volts (initial charge voltage was 3,65 v) after 24 hours, 3,47 v and after 36 hours, 3,45 v with no load whatsoever.
I can understand a light voltage drop after charging the battery at 3,65 v, but a 0,2 volt drop over a 36 hours period seems way too much ( that is decreasing SOC from 100% to 95% in 36 hours with no load connected).
Am I doing a faulty análisis?
 
In other words, the 'settled' voltage of the cell means that 3.45v is the true 100% full level.
 

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Cell voltage is a very poor indicator of state of charge. It always has been and is really so in Lithium batteries that have a very narrow voltage range.
Your cells sound find here.
 
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