here's the professor's latest response:
"George,
Again - my responses are in CAPS below
Jeff Dahn, FRSC
Professor of Physics and Atmospheric Science
NSERC/3M Canada Industrial Research Chair
Canada Research Chair
Subject: Re: Question RE: "Why do Li-ion Batteries die ? and how to improve the situation? "
Professor Dahn, if you have a chance, I have a few more follow up questions. I do very much appreciate your time answering my questions!
Since they are both cobalt based would the consumer care recommendations (store at lowish SOC, Lowish temperatures, tending to mid voltage cycling) for LiCo02 cells be the same as a LiNiCoAi02 or a LiCoAi02 cell?
YES
Also, does the rate of charge (0.5C vs. 1C vs 1.5C etc.) have any impact on the cell life?
YES - I WOULD AVOID CHARGING AT GREATER THAN C-RATE AND WOULD RECOMMEND C/2, ESPECIALLY FOR "ENERGY CELLS". POWER CELLS (E.G. IN TOOLS) WILL HAVE LITTLE PROBLEM WITH C-RATE CHARGING AND WOULD BE FINE. THE CELLS IN THE TESLA S ARE MORE AT THE ENERGY CELL END OF THE SPECTRUM.
have you tested NCA cells like the Panasonic NCR18650A and NCR18650B and would their care characteristics be the same.
WE HAVE LOOKED AT THE "A" AN IT IS VERY SIMILAR TO LCO CELLS
Nicad is less and less common in consumer electronics but is still used and I have several gadgets that have them. I have been treating these pretty much the same (store at lowish SOC, Lowish temperatures, tending to mid voltage cycling) accept every so often I do a complete discharge and full charge to reduce the tendency toward memory effect. In your opinion, is this on track? anything to add?
THIS IS GOOD. MEMORY EFFECT COMES WHEN CELLS ARE LEFT FULLY CHARGED OR FLOATED AT FULL CHARGE FOR LONF PERIOS OF TIME.
In general, I am amazed at how few of devices/chargers have any sort of BMS other than avoiding runaway combustion. It would make so much sense for every one of these devices to have a long life mode, where they could be left plugged in but only charge to about 50%. so many of these devices end up plugged in all the time, and it dramatically cuts down their shelf life. please consider explicitly recommending this in your research if appropriate. To many phones, computers etc are thrown away because the battery only lasted a year or two, when, if treated better, could have lasted 5-10 years. by applying this care regimen, peak performance of many products can be vastly extended. I've gotten 5 years out of an iphone, 5+ years out of a cordless shaver and long life out of many other products. This has required a lot of careful charging... it would be so much easier if I could set the SOC limit on each device based on my needs, such as at home near a charger vs traveling where I need max charge. we need someone like you to push the industry to make this kind of thing a standard! (no pressure :~). Tesla with it's slider option has nailed this. some way to adjust the end charge limit should be on all consumer products. a SOC meter that showed red at both ends, with green in the middle, would help this be more intuitive for consumers, who now simply think fully charged is the best, which simply leads to killing the battery prematurely.
THIS WOULD BE A GOOD THING. MOST HUMANS TREAT BATTERIES A BLACK BOXES AND DO NOT THINK OR CARE. YOU ARE A RARE SOUL!
OH and as an aside, the Tesla S is aluminum, so no need to worry about rusting :~) and the AC induction motor is brushless with the only contacts points being two bearing sets... potentially, this car should last a very long time!
I KNEW ALL OF THIS AND BRIEFLY FORGOT! "
