Fuzzy Head
1 mW
Hello everybody
This is sort of a continuation of this thread which was about me trying to find out what I needed and needed to know to make a battery pack:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=47329
I am building a 36v lifepo4 battery pack and I have bought these parts and am in the process of constructing it and making sure all is ok:
http://eclipsebikes.com/headway-lifepo4-38120s-10ah-p-1011.html
http://eclipsebikes.com/lifepo4-432v-cell-30a60a-p-1041.html
http://eclipsebikes.com/lifepo4-battery-charger-p-1037.html
I got 13 cells so I could have 1 as a backup and for tests.
Everything arrived just over a week ago and I charged all the cells using a home made linear power supply one cell at a time (power supply had a cv of 3.60 and cc of about 1A) All charged very quickly to 3.60v implying they were fully charged recently. I left the cells in the original box for about a week and just put it all together.
I know with these lifepo4 cells it is critical that they not be overvolted, which is my concern here. I have started setting everything up and meticulously made sure everything was wired up correctly. Once done I decided to check my charger so I plugged it into the assembled battery pack and began checking the voltages of cells a few seconds later to make sure all was okay. I quickly noticed that the first cell I checked was about 3.8-3.9v. I unplugged the charger and checked all the voltages. They were all within normal apart from the 2 on the positive end. which were about 3.7v at this point. I touched the 2 bleed resistors for those 2 cells and they were slightly warm and within minutes both overvolted cells were down to exactly 3.6v the rest were at about 3.5v.
I suspect it may have been because I chose to charge the cells while they were already fully charged but am to inexperienced with these to be sure. Was this likely the case?
Was any damage done to my cells?
What are likely causes?
How would you advise I proceed?
Thank you
This is sort of a continuation of this thread which was about me trying to find out what I needed and needed to know to make a battery pack:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=47329
I am building a 36v lifepo4 battery pack and I have bought these parts and am in the process of constructing it and making sure all is ok:
http://eclipsebikes.com/headway-lifepo4-38120s-10ah-p-1011.html
http://eclipsebikes.com/lifepo4-432v-cell-30a60a-p-1041.html
http://eclipsebikes.com/lifepo4-battery-charger-p-1037.html
I got 13 cells so I could have 1 as a backup and for tests.
Everything arrived just over a week ago and I charged all the cells using a home made linear power supply one cell at a time (power supply had a cv of 3.60 and cc of about 1A) All charged very quickly to 3.60v implying they were fully charged recently. I left the cells in the original box for about a week and just put it all together.
I know with these lifepo4 cells it is critical that they not be overvolted, which is my concern here. I have started setting everything up and meticulously made sure everything was wired up correctly. Once done I decided to check my charger so I plugged it into the assembled battery pack and began checking the voltages of cells a few seconds later to make sure all was okay. I quickly noticed that the first cell I checked was about 3.8-3.9v. I unplugged the charger and checked all the voltages. They were all within normal apart from the 2 on the positive end. which were about 3.7v at this point. I touched the 2 bleed resistors for those 2 cells and they were slightly warm and within minutes both overvolted cells were down to exactly 3.6v the rest were at about 3.5v.
I suspect it may have been because I chose to charge the cells while they were already fully charged but am to inexperienced with these to be sure. Was this likely the case?
Was any damage done to my cells?
What are likely causes?
How would you advise I proceed?
Thank you