Zyklentest mit A123 Fepo4... UPDATE: bereits über 800Zyklen

Quote:

---

First results show a 6-7% decrease in capacity after 400 cycles, but same voltage capability even under 30A constant all the way.

---

Quote:

---

Hello again,

This time I am going faster, we are looking to "punish" the cell right? So I started cycling at 3C charge 6C discharge (charging up to 4'3V, discharging down to 2'0V) anf after 75 cycles WITHOUT ANY LOSS of capacity (mAh in/out) seen, I pushed a little further: charging to 4C discharging to 8C (really I am doing 9A charges and 18A discharges) wit the voltages said.
Today she will pass the 200 cycle mark with "overvoltage charging" (this is more than 600 cycles total, rememeber this is the SAME cell) and this morning before leaving home I saw a small decrease in mAh in/out (medium 1900 numbers).
In a couple of days I will be able to say more and make some discharge graphs to see if any damage has been done, but as I can see now, all I can say are good news. Incredible cells btw.
Regards
Josep

---

Quote:

---

Hi again,

The cell has got his 250 cycle-diet going up to 4'3V in charge, after the 400cycle+ done before (same cell).
I have not yet the discharge graphs here (before weekend I hope to upload them) but I have (more) good news: there has been a small loss of capacity, around 6%, close to that one detected after the first 400 cycles.
As I see it, this loss is perfectly in line with the original loss, detected to start around the 300 cycle mark. Rememeber this cell has now over around 700 cycles, and she is still giving high 1800mAhs with the same voltages as before.
So, if I have to say here and now, I will say this way: to my eyes THERE IS NO HARM DONE to a A123 cell when charged up to 4'30V. Those cycles were done at 3C then 4C charging (from almost 7 to 9A) with 6C then 8C discharging (13 to 18A).
Impressive, and now my question is... why A123 has not made by themselves more tests of their own cells charged to high voltages? They will be even more popular, and everybody with LiPo chargers can use them with no worries at all...

---

Quote:

---

When Altair announced new technology, and told that A123 internal resistance will not rise with cycle age, more likely even decrease.., it seemed to be unbelievable "bold claims".
Now, many users have reported that it was really true and this technology keeps working after many cycles, even better than brand new. That is simply great.

Of course, capacity decreases, but decreases so slowly.. Comparng to Lipo cells which must die after many cycles if used near maximum acceptable discharge power - just because of Lipo internal resistance increases and temperature gets higher and higher during discharge. This results in uncomparable cycle life between A123 and Lipos in high power applications

---