The first step is to immediately evacuate all people and pets from the area where the odor is detected. The Li-ion battery smells weird, slightly sweet, with a faint but distinct chemical smell. It's a clear warning sign from your device's power source. The odor signals that the battery has suffered damage, is overheating, or has entered an unstable process known as thermal runaway. This off-gassing releases a mixture of toxic. Recognizing the characteristic smell of battery acid is crucial for personal safety, as it serves as an early warning sign of potential exposure. However, when specific stress conditions arise, various chemical processes can generate.