Hans Kroeger
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- Joined
- Dec 30, 2020
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- 128
Digging in my notes I found the data of my "short circuit test" mentioned above:Some other interesting bits from that paper.
"Guo et al. found that the dissolution of SEI occurs within 0 to −10% SoC, severe copper dissolution then occurs below −12% SoC, with severe internal short circuiting occurring at or lower −20% SoC19. For the batteries used in this study, 0.5 V corresponds to −1.9% SoC and as such, in agreement with Guo et al.19, only SEI dissolution and gassing occurs."
The good news from this, is that while its very undesirable to discharge the cell below 2.0V, major damage between 2.0 and 0.5V takes a fair bit of time. If the cell is promptly brought back up, then capacity loss can be mitigated.
After dischaging my Headway 12 Ah cell down to 2.5 Volts, I connected a 2 Ohm resistor across the terminals. The voltage gradually dropped down to 0 V. I have no record about the timing. I removed the resistor 24 hours after I connected it to the cell. Then I charged the cell with 0.1 A up to 2.5 V. The charging current was then set to 1 Amp, and the cell was charged up to 3.55 Volts.
A capacity test afterwards revealed no loss of capacity.