Interesting recovery of the discharged cell. Is the particular chemistry more tolerant to it than is typical for li-ion? I recall mentions of nasty side reactions, like copper being consumed at low voltages. Any plans to cycle that cell?
Yep, I will cycle it this weekend.Punx0r said:Interesting recovery of the discharged cell. Is the particular chemistry more tolerant to it than is typical for li-ion? I recall mentions of nasty side reactions, like copper being consumed at low voltages. Any plans to cycle that cell?
okashira said:okashira said:0V test now at .....
I should have set the multimeter to log to see just how much capacity comes from the cells all the way down to 0V. :-/
It's been nearly a year since I put these cells in the 0V storage test.
I disconnected the resistor about a month ago and voltage still read about 0.002V.
Over the past month, the cells increased in voltage to about 0.4V.
I went ahead and hooked up one to my tester and charged it with 0.1A to 2V, then 0.3A to 2.8V, then 0.5A to 4V. Then I let the cell rest to see if voltage dropped. Nope, held 3.99V like a champ.
Went ahead and charged to 4.2V with 0.1A cut. And ran a 3A discharge.
The cell showed like 94% full capacity, maybe DCIR picked up a little bit. However, it still holds a charge and works great. I'll run a few more cycles soon.
Cephalotus said:
Not the same. Very similar chemistry.They use two cell types, a NMC cell for daily storage and a NCA cell (I'm assumeing the same as in the Tesla S) for the "weekly storage" system:
Hillhater said:The indications are that Tesla push these cells to 7C (20+ Amps) in the S for brief periods.
Do we know what the output limit is for say 3-5 secs ..dead short Maybe ?
Im guessing it might be 40-50A, but only at a voltage of around 2 volts ?
..anyone done the test ?
okashira said:Their DCIR drops significantly at higher temps up to 55°C or so, and is much higher at lower temps.
Perhaps they traded off low temp performance for high temp performance, and as a result, they are more durable at higher ambient temps. This makes sense as a battery will always be above ambient temps and it's easier to heat then cool.
okashira said:okashira said:0V test now at .....
I should have set the multimeter to log to see just how much capacity comes from the cells all the way down to 0V. :-/
It's been nearly a year since I put these cells in the 0V storage test.
I disconnected the resistor about a month ago and voltage still read about 0.002V.
Over the past month, the cells increased in voltage to about 0.4V.
I went ahead and hooked up one to my tester and charged it with 0.1A to 2V, then 0.3A to 2.8V, then 0.5A to 4V. Then I let the cell rest to see if voltage dropped. Nope, held 3.99V like a champ.
Went ahead and charged to 4.2V with 0.1A cut. And ran a 3A discharge.
The cell showed like 94% full capacity, maybe DCIR picked up a little bit. However, it still holds a charge and works great. I'll run a few more cycles soon.