As an established charging accessory brand, BWOO is frequently asked a concerning question:

Why does my charger make a sharp "hissing" or "buzzing" sound while charging?

For many users, this noise immediately raises safety concerns. Is something wrong? Is it dangerous to keep using the charger?

In this article, BWOO explains why chargers can produce audible noise during operation, what sounds are normal, and how users can perform simple checks to identify potential faults.

Where Does the Hissing Noise Come From?

Not all charging noises indicate a defect. Understanding the source of the sound is the first step.

Inductor Noise (Coil Whine)

The most common cause is inductor noise, also known as coil whine.

Inside a charger, inductors and transformers operate at high frequencies. As alternating current passes through the coil, it creates a magnetic field that can cause microscopic vibrations. These vibrations may become audible, especially under light load or unstable power conditions.

In well-designed chargers, this noise is usually minimal and barely noticeable.

Potential Circuit Faults

Louder, irregular, or harsh hissing sounds may indicate internal issues, such as:

• Electrical arcing caused by poor insulation or solder defects

• Capacitor degradation, leading to unstable voltage regulation

• Transformer overload, often due to component mismatch or aging

These conditions are not normal and may pose safety risks if ignored.

How to Check Whether a Charger Is Faulty

Consumers can perform a few basic tests at home to assess the situation.

Cross-Swap Test

Try using the same charger with a different cable and device.

If the noise remains, the charger is likely the source.

Load Comparison Test

Observe whether the noise changes under different charging loads:

• Does it only occur when charging fast?

• Does it disappear when the battery reaches a higher level?

Abnormal noise that worsens under load may indicate internal stress.

Visual and Smell Inspection

Before plugging in, check for:

• Discoloration or deformation of the casing

• Loose plugs or cracks

• Any unusual odor

Your senses often detect early warning signs before failure occurs.

Warning Signs You Should Never Ignore

Stop using the charger immediately if any of the following occurs:

Loud and Persistent Noise

The sound is sharp, piercing, and impossible to ignore.

Abnormal Overheating

The casing becomes too hot to touch comfortably for more than a few seconds (typically above 65°C).

Burning or Chemical Smell

Any burnt odor suggests internal circuit damage.

Intermittent Charging

The device repeatedly switches between "charging" and "not charging."

These symptoms indicate elevated risk and should not be dismissed.

BWOO's Safety Philosophy: Eliminating Noise and Risk at the Source

Why are high-quality chargers generally quieter and safer?

Precision Potting and Insulation

BWOO applies specialized insulating and thermally conductive potting compounds around transformers and coils. This stabilizes components, suppresses vibration, and improves heat dissipation—reducing both noise and thermal stress.

Strict Aging and Load Testing

Every BWOO charger undergoes extended full-load aging tests before shipment.

We do not accept the idea that "noise is normal." Stable, low-noise operation is a baseline quality requirement.

Multiple Protection ICs

BWOO chargers integrate over-current, over-voltage, and over-temperature protection. If abnormal conditions arise, power is cut off instantly to prevent further damage or safety hazards.

Conclusion

Chargers are consumable electronic products, and unusual hissing sounds should always be treated with healthy skepticism.

Before continuing use, users should verify safety through simple checks. From both a device protection and personal safety standpoint, replacing a questionable charger with a high-quality, certified product is often the most cost-effective insurance.

When choosing a charger, look for safety certifications such as UL, CE, and FCC—each represents extensive testing and compliance behind the label.