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Don M · 02-04-2017, 03:40 PM

To each his own - A LOT more is known about the care and feeding of lithium cells than was known when the Segs were first built. There are over 7500 of the 18650 form factor cells in a Tesla pack and they don't recommend storing them with a high state of charge . . . . but maybe Elon Musk doesn't know better??

Note that my recommendation above was for batteries removed from the machine, so there is no draw on them - They will not self discharge hardly at all in a year or two

"Test data confirms that storage of lithium-ion batteries is best if the cell is partially discharged. In one test by Cadex Electronics ( http://www.buchmann.ca ) after 1 year storage at 25°C the non-recoverable capacity remaining is 96% when stored at 40% initial charge level, but only 80% if stored with 100% initial charge level. This effect is reduced at lower temperature and is a non-issue at 0°C. At higher temperatures the effect is much worse. Cadex's recommendations are to store below 15° C at 40% of full charge (3.5 volts per cell). Our experience is that with cells stored at room temperature for 3 years that the non-recoverable capacity did not decrease."

I have a couple extra sets of Seg lithiums in long term storage right now and the voltage hasn't decreased by even a tenth of a volt over the past 6 months

I also long term stored one of my Lithium EV's following Mitsubishi's recommendation of a 30% to 40% SOC and there was no measurable discharge after a year - It has a 330 volt, 50 AH battery pack (worth about $10K) so I wasn't about to take any chances!

Don

02-04-2017, 03:40 PM	#6
Don M Member Join Date: Jun 2016 Location: Ocean Springs MS Posts: 242	To each his own - A LOT more is known about the care and feeding of lithium cells than was known when the Segs were first built. There are over 7500 of the 18650 form factor cells in a Tesla pack and they don't recommend storing them with a high state of charge . . . . but maybe Elon Musk doesn't know better?? Note that my recommendation above was for batteries removed from the machine, so there is no draw on them - They will not self discharge hardly at all in a year or two "Test data confirms that storage of lithium-ion batteries is best if the cell is partially discharged. In one test by Cadex Electronics ( http://www.buchmann.ca ) after 1 year storage at 25°C the non-recoverable capacity remaining is 96% when stored at 40% initial charge level, but only 80% if stored with 100% initial charge level. This effect is reduced at lower temperature and is a non-issue at 0°C. At higher temperatures the effect is much worse. Cadex's recommendations are to store below 15° C at 40% of full charge (3.5 volts per cell). Our experience is that with cells stored at room temperature for 3 years that the non-recoverable capacity did not decrease." I have a couple extra sets of Seg lithiums in long term storage right now and the voltage hasn't decreased by even a tenth of a volt over the past 6 months I also long term stored one of my Lithium EV's following Mitsubishi's recommendation of a 30% to 40% SOC and there was no measurable discharge after a year - It has a 330 volt, 50 AH battery pack (worth about $10K) so I wasn't about to take any chances! Don Last edited by Don M; 02-04-2017 at 03:50 PM..