This circuit protects the battery against some of the common dangers seen in batteries, such as overcharge, over discharge, short circuit/over current, and temperature, however they cannot reverse thermal runaway. Protected batteries are generally safer to use in your devices.
Protected batteries are less likely to ignite and cause damage.
Most protected batteries have these components:
- PTC: Protect against over heating and indirectly over current. Will automatically reset.
- Pressure Valve or CID: Will disable the cell permanently if the pressure is too high in the cell (this can be caused by over charging).
- PCB: Will protect against over discharge, over charge, and over current, depending on design. The PCB will reset automatically or when the battery is recharged.
As with any protective measure, this is not designed to replace common sense. Treat protected batteries with the same caution and respect you would treat an unprotected battery with and do not rely solely on fail safes like the battery’s internal protection as a last resort effort to avoid failure.