Question:

“What could be the cause of a mobile phone’s battery charging more slowly than usual? My Optus X Wave android phone, purchased in April 2020, has recently begun to take 8 hours to charge, a significant increase from the usual 70 minutes. Despite adhering to the recommended charging practice of maintaining the battery level between 15% and 85%, the issue persists. After testing with a Chromebook charger, which completed the charge in the expected 70 minutes, I determined that the problem lies either with the USB charger or the cable. Subsequent purchases of a new 5V 2A USB charger and a 1-meter USB to USB-C charging cable revealed that the latter was the solution, as the phone now charges at the higher rate. Could you provide insight into the technical aspects of this issue and confirm whether the charging cable was indeed the culprit?”

Answer:

When a mobile phone begins charging more slowly than usual, it’s a problem that can stem from various sources. The case of the Optus X Wave android phone, which started taking 8 hours to charge instead of the usual 70 minutes, is a classic example of such an issue. Despite following the recommended charging practice of keeping the battery level between 15% and 85%, the problem persisted, indicating that the battery itself might not be at fault.

The troubleshooting process revealed that using a Chromebook charger resulted in a normal charging time, which suggested that the issue was likely with the USB charger or the cable. After replacing the USB charger did not resolve the issue, switching to a new 1-meter USB to USB-C charging cable did the trick, as the phone began charging at the higher rate again.

To delve into the technical aspects, we need to understand the basics of how charging works. The charging rate of a device depends on two key factors: voltage (V) and current (A). The product of these two gives us the power (W), measured in watts, which is the rate at which energy is transferred from the charger to the phone’s battery. The formula is given by:

$$ P = V \times I $$

where \( P \) is power in watts, \( V \) is voltage in volts, and \( I \) is current in amperes.

For the Optus X Wave phone, the original charger was rated at 5V 2A, which means it should provide a power output of 10 watts. However, over time, charging cables can degrade due to physical wear and tear, corrosion, or other factors, leading to a reduced ability to carry the current efficiently. This degradation can significantly lower the power transfer rate, as was evident when the old charging cable’s output dropped to about 2 watts.

Confirming the Culprit

The replacement of the charging cable and the subsequent restoration of the charging speed confirm that the cable was indeed the culprit. It’s important to note that not all USB cables are created equal. Some may be designed only for data transfer and not for charging, while others may not adhere to the specifications required for fast charging. Therefore, when purchasing a new cable, it’s crucial to ensure that it supports the necessary power transfer for your device.

In conclusion, slow charging can be caused by various factors, but in this case, the charging cable was the issue. Regularly inspecting and replacing the charging cable when necessary can help maintain optimal charging performance for your mobile devices. Always opt for high-quality cables that meet the required specifications for your phone to avoid similar issues in the future.