Understanding Compatibility Between Apple’s 140W Power Adapter, MagSafe 3, and Alternative Charging Solutions for MacBook Pro (2021)
If you’re a MacBook Pro user, especially with the 16-inch M1 Pro model from 2021, you might encounter some perplexing charging issues involving Apple’s high-wattage adapters and MagSafe cables. Recently, some users have observed that while their MagSafe 3 cable functions flawlessly with other power sources and their 140W Apple power adapter charges fine via USB-C, the two don’t seem to work together. Here’s a detailed look into this issue and some practical advice for finding safe, cost-effective replacement chargers.
Scenario Overview
- MagSafe 3 Cable: Works perfectly when plugged into a different power adapter.
- Apple 140W Power Adapter: Fully operational when connected via USB-C to a supported port.
- Combined Use: When attempting to connect the MagSafe cable to the 140W adapter, charging does not initiate.
Diagnostic Findings
Running Apple Diagnostics indicates that hardware components, including the charging port, are functioning correctly. The MacBook charges normally over USB-C, suggesting the port and cable are in good condition. This points to a potential compatibility or communication issue between the MagSafe cable and the 140W power adapter.
Possible Causes
Several factors could contribute to this incompatibility:
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Power Delivery Protocols: The 140W adapter is designed primarily for USB-C charging, supporting the fast-charging protocols via Thunderbolt ports. MagSafe 3 relies on a different communication protocol, which might not be fully supported when used with the high-wattage adapter.
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Cable and Adapter Communication: Apple’s proprietary charging system involves data exchanges between the power source and the cable. If the cables or the adapter don’t communicate properly, charging may be withheld to ensure safety.
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Firmware or Compatibility Constraints: Certain combinations may be intentionally restricted due to technical or safety standards.
Insights and Recommendations
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Compatibility Clarification: Officially, MagSafe 3 cables are designed to work seamlessly with Apple’s own power adapters and some third-party chargers, but incompatibilities can occur with specific combinations, especially with high-wattage adapters.
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Alternative Charging Solutions: If replacing or upgrading your charger, consider reputable, certified third-party chargers that support USB Power Delivery (USB-PD) at the required wattage. For example, some GaN (Gallium Nitride
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