Lithium-ion battery chemistries should never have the voltage fall below 2 volts. This issue can happen when the battery is placed into storage for long periods of time or when discharged too much. With the voltage below 2 volts, both the cathode and the anode begin to break down.
Most battery pack chargers for lithium-ion batteries are designed to prevent overcharging. However, using the wrong charger can cause overcharging or over voltage of the lithium battery pack as well as swelling. In addition, a lithium battery pack should never be charged in cold temperatures (below 32°F).
If the voltage is below 2V, the internal structure of lithium battery will be damaged, and the battery life will be affected. Root cause 1: High self-discharge, which causes low voltage. Solution: Charge the bare lithium battery directly using the charger with over-voltage protection, but do not use universal charge. It could be quite dangerous.
A 12v Battery Pack was at 0V and wouldn't take a charge. Manufacturer Miady recommended starting up the sleeping BMS with a 9-volt battery across the terminals. I tried this -- it worked! Battery read just over 10V on voltmeter. Immediately connected to charger.
Root cause 1: High self-discharge, which causes low voltage. Solution: Charge the bare lithium battery directly using the charger with over-voltage protection, but do not use universal charge. It could be quite dangerous. Root cause 2: Uneven current.
A healthy lithium-ion battery should read within the expected voltage range. If the voltage reading is lower than expected, it may say a failing battery that requires attention. Understanding the expected voltage range for your specific battery is vital for interpreting the results.