Too low because some of the battery will discharge scrapped
. 2.5 volts per cell if placed below the battery's internal safety circuit will switch on the battery used on some good friends. However, if the battery down to 1.5 volts per cell below and to maintain the state for some time, and for safety reasons, do not charge the battery up. To avoid such situations from occurring, do not store the battery fully discharged. Should save some of electricity before the charge, and fully charged before use.
In a word, Avoid discharger complete and charge the Li-ion battery usually. It will damage the laptop battery at will reiterative. Please put the Li-ion battery to the shady place and do not cold frozen the laptop battery. Avoid place them in hot tempurature in car.Use the laptop charger often and avoid purchasing spare lithium batteries for storage.