Alex Kapranoff » from archive
Charging Lithium-Ion Batteries – Battery University -
"Do not recharge lithium-ion if a cell has stayed at or below 1.5V for more than a week. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. If recharged, the cells might become unstable, causing excessive heat or showing other anomalies." ‎- Alex Kapranoff