Can a dead lithium ion battery be jump started?


To answer this question accurately, we need to be very careful about our language. When considering a “dead” Dragonfly Energy battery pack, it is important to note that the cells that comprise the pack are not dead. The battery management system disconnects the cells from the pack terminals when the cells fall below a prescribed voltage (2.2 volts). In this case, the battery management system prevents the cells from being further discharged, but it does allow them to take a charge. So, yes a “dead” battery pack may be jump started by simply applying a charging voltage until the cells regain an appropriate voltage, allowing the battery management system to reconnect for discharge.
HOWEVER, many Li-ion battery systems on the market are made from large prismatic cells connected to an external management system. We have had customers bring “dead” prismatic cells to our facility asking if they can be salvaged. In these cases, the cells were somehow allowed to be discharged to dangerously low voltages (less than 1V). If a cell (prismatic, pouch, or cylindrical) is excessively discharged, the copper metal substrate on the anode begins to dissolve into the electrolyte. When it is recharged, the copper metal reforms, but this reformation could easily cause an internal short leading to a potentially dangerous situation – especially for a large prismatic cell which packs a large amount of energy in a single chamber. So, no, dead Li-ion cells should not be brought back to life. They should be recycled.