Will a Small Neodymium Magnet Behind a 3 mm Silicone Case Block Qi2 Charging

Part of our guide on magnetic mounts and overheating

Discover if your neodymium magnet behind a silicone case will kill your phone’s public Qi2 charging, and how to avoid the problem.

How a Neodymium Magnet Behind a 3 mm Silicone Case Affects Qi2 Charging

Qi2 wireless charging depends on magnetic resonance and precise coil alignment. A small neodymium magnet stuck behind a 3 mm silicone case introduces a strong static magnetic field near your phone’s charging coil. This field can disrupt the communication between the charger and the phone, causing partial or complete charging failure.

The key figure here is the magnetic flux density measured in milliteslas (mT). Typical neodymium magnets produce surface fields of 200-400 mT, but the field strength decreases rapidly with distance. At about 3-5 mm, it can still be 30-50 mT, enough to interfere with Qi2’s magnetic field sensing and coil tuning.

The silicone case’s thickness mainly adds distance between the magnet and the coil. At 3 mm, the case only slightly reduces the magnet’s field strength reaching the coil. Thus, the magnet’s residual field at the coil still exceeds the threshold that causes Qi2 chargers to stop or reduce charging power.

Deciding Specification: Magnetic Field Strength Near Charging Coil

The deciding specification is the magnetic field strength (mT) at the position of the phone’s wireless charging coil. When this field exceeds roughly 30-50 mT, Qi2 charging efficiency typically drops significantly or stops. We cover 2mm case magnetic mount strength in its own article.

This threshold depends on the charger design and coil sensitivity; some chargers are more tolerant, others less. The 30-50 mT range comes from observed behavior of Qi and Qi2 chargers reacting to external magnets near charging coils.

Since the magnet’s surface field is known but the field at the coil depends on distance, magnet size, and orientation, measuring or calculating the field at the coil is essential to predict charging issues.

The exact magnetic field strength at the coil depends heavily on the magnet's size and grade. For example, a neodymium disc magnet 10 mm in diameter and 1 mm thick can produce around 350 mT at the surface, which can drop to about 40 mT at a 3 mm distance, close to the coil position in your phone. This illustrates why even small magnets can cause interference if placed too close. There is more on n52 magnet blocking qi charging in a separate guide.

Calculations using the inverse cube law for the magnetic field decay show that doubling the distance from 3 mm to 6 mm reduces the field strength by roughly a factor of 8, potentially bringing it below the interference threshold. Therefore, increasing the distance between magnet and coil is a key method to reduce charging problems, but the silicone case thickness alone may be insufficient.

Testing If a Small Neodymium Disc Stops Your Qi2 Public Charger Charging

Test your particular phone, case, magnet, and charger combination to be sure. Different phones have coils in different locations; magnet placement relative to the coil is critical.

Steps to test charging: People in this spot often ask about how magnets affect pixel compass as well.

For example, place your phone with a 3 mm silicone case on a Qi2 charger and observe normal charging at 10 W power output. Then attach a 10 mm diameter, 1 mm thick neodymium disc magnet behind the case, directly aligned with the coil. If charging power drops to 2-3 W or stops altogether, the magnet is causing interference.

Moving the magnet laterally by 5-10 mm away from the coil area may restore normal charging, demonstrating the sensitivity to magnet position. If your phone shows error messages or stops charging abruptly, this confirms the magnet’s effect on Qi2 protocols which rely on precise magnetic communication and coil alignment.

1. Place the phone with the 3 mm silicone case on the Qi2 public charger without the magnet; confirm normal charging.
2. Attach the small neodymium disc magnet behind the case exactly where you plan to mount it.
3. Place the phone back on the charger and observe charging behavior: charging indicator, power level, or charging stop.
4. Move the magnet slightly to test coil position sensitivity.
5. If charging stops or power drops by more than 30%, the magnet’s field is too strong at the coil position.

Alternatives to Avoid Charging Interference With Magnetic Phone Mounts

If the neodymium magnet behind your 3 mm silicone case disrupts Qi2 charging, consider these alternatives: If that sounds like your situation, read up on iphone 14 case with magnet next.

Choose magnetic mounts with integrated shielding that reduces magnetic interference at the coil.

Use a thinner or non-magnetic mounting plate designed for Qi compatibility, typically less than 1 mm thick and made from soft iron or ferrite materials.

Switch to a mounting method that doesn’t require magnets behind the case, such as clamp mounts or adhesive pads away from the coil area. The other half of this decision is iphone 15 pro max magnet interactions.

Another alternative is to use magnetic mounts that incorporate a ferrite backing plate between the magnet and the phone, which significantly reduces magnetic flux reaching the coil. These plates typically have thicknesses around 0.5 to 1 mm and shield fields above 50 mT, allowing for continuous Qi2 charging.

You might also explore phone cases embedded with built-in magnetic mounting systems designed to be Qi2 compatible. These cases position magnets away from the coil or use special shielding materials, balancing mounting strength with wireless charging reliability.

Situations When a Small Neodymium Magnet Is the Wrong Choice Behind Your Silicone Case

Using neodymium magnets behind cases is not for everyone. Avoid if:

You rely heavily on public Qi2 chargers, where magnetic interference can cause unpredictable charging failure.

Your phone’s wireless charging coil is near the magnet placement area, increasing the chance of disruption.

You want consistent, high-power wireless charging without frequent repositioning or testing.

• Heavy Qi2 charger user: avoid magnets to ensure reliable charging.
• Phones with coils near magnet spot: magnet can block charging entirely.
• Users needing fast wireless charging: magnet interference reduces power delivery.

Will Sticking a Small Neodymium Disc Behind My 3 mm Silicone Case Stop Qi2 Public Chargers From Charging My

The direct answer is yes, it can stop Qi2 public chargers from charging your phone if the magnet’s field strength at the coil location remains above about 30-50 mT, even with a 3 mm silicone case adding distance.

Positioning the magnet carefully away from the coil area can mitigate this risk, but since coil locations vary by phone model, only testing your specific setup ensures reliability.

Public Qi2 chargers often have tight tolerances for coil alignment and magnetic field interference. Thus, any small magnet with a strong field near the coil almost always causes charging issues unless special shielding or spacing is used.

Questions people still ask

I’ve tested magnets behind multiple phone cases on Qi2 chargers and seen how field strength and placement determine charging success.