That's what I expected. 1325/3400 = 0.39Ccircuit wrote: It says "charging current 1325 mA" which is 0.5C.
I hope so too. Panasonic has a reputation to keep. I would love to see the test done again at the 1C discharge and 0.39C charge. You only need 50 cycles to know if the high charge rate was the cause of the failure.circuit wrote: I really hope that Panasonic cell failed due to too high charging current. I do have one more cell, so will repeat the tests some day.
I'm impressed too. But I wouldn't expect 2000 cycles. I'd happy to get 75% capacity after 1000 cycles.circuit wrote: By the way, I was really impressed by LG cell. At this rough test it managed to give 500 cycles to 80% capacity... So in more practical 0.25C charging and average DOD of 70%, it should hold for 2000 cycles or more (just a guess).
Sorry, mistyped. charging current is 1625 mA, which is 0.5C. So all rates for Panasonic are the same as for LG. and that is logical, because Ri are similar too.SamTexas wrote:That's what I expected. 1325/3400 = 0.39Ccircuit wrote: It says "charging current 1325 mA" which is 0.5C.
Panasonic energy density is only 8% better than LG at mass, and only 4% in volume. While it is 37% more expensive than LG, which is a LOT.mvly wrote:I do like their energy density.
Yes, that is why Tesla has a crapton of them in every car. I am sure that they design the car to cruise at a 0.5-1C rate, so that the full capacity can be delivered without generating too much heat.mvly wrote:I guess the panasonic ones are only good with many in parallel. And at low discharge rate. From your data, I would charge slower to see what the effect is and also discharge slower.
I do like their energy density.
This is strange, because all rates are the same as for LG. Ri of LG cell is even higher, and so C rating should be lower than Panasonic's. And LG performed quite better at 1C.Cephalotus wrote:Panasonic NCR cells die early at 1C charge rates. This is nothing unexpected.
Charge them at 0,5C maximum (better 0,3C) and discharge them at 0,5C and they should live a lot(!) longer.
I don't know anything about LG and I'm unable to comapre them, but I know that Panasonic NCR cells do not like 1C charge rates. I asume that your cells also got quite hot? Panasonic gives more than 80% capacity after 2.000 clcles for new NCR types, but not at high carge rates. High discharge >1C is also problematic, but high cahrge seems to be really bad for them.circuit wrote: This is strange, because all rates are the same as for LG. Ri of LG cell is even higher, and so C rating should be lower than Panasonic's. And LG performed quite better at 1C.
If tested at 0.5C, LG would do a lot better, too.
both cells were not hot during testing. Maybe 45°C at max. LG was even warmer than Panasonic...Cephalotus wrote:Maybe you also need active cooling..
That's great. I look forward to seeing the results.circuit wrote:OK, will do 50 cycles at 1C discharge and 0.5C charge.
I'm looking forward to the results from this.circuit wrote:OK, will do 50 cycles at 1C discharge and 0.5C charge.
I wish I could see this data on the PD instead. 2.9AH and a 20AH capacity now that would make for a killer commuter pack.liveforphysics wrote:First, great work on your data collection!
NCR18650B is quite poorly suited towards most EV applications.
NCR18650PD on the other hand, is perhaps the best EV suited 18650 I've ever tested, and I think you would be very happily surprised doing the same cycling tests.