How to Check If Your Device Chargers Are Truly Effective
Discover simple yet reliable methods to test the performance of your device chargers without extra tools, ensuring your gadgets charge efficiently.
Have you ever noticed your phone charging for hours yet barely reaching 30%? Often, we blame the battery prematurely, but the real culprit might be your charger. In this guide, we’ll show you how to verify if your charger is delivering the power your device needs.
While USB testers are a popular tool for diagnosing charging issues, you can also assess your charger’s effectiveness using your phone’s built-in diagnostic mode—no additional equipment required.
Modern smartphones monitor charging voltage, current, battery voltage, and temperature internally. These details are accessible through the device’s service or engineering mode, sometimes called factory or test mode.
Note: If you’re unsure about accessing service mode, it’s best to avoid it. Incorrect usage may risk damaging your device.
For confident users, here’s how to proceed:
First, switch your phone to airplane mode to stabilize power consumption by disabling cellular signals, Wi-Fi, and Bluetooth. Also, turn off GPS and disable automatic screen brightness adjustments.
Next, enter the service mode using device-specific codes. For example, Lenovo phones often use ####1111# dialed in the phone app, while Samsung devices may use *#0228#. You can find the correct code for your model online. Avoid codes like *777# which may trigger costly carrier services. Airplane mode helps prevent accidental network charges. Service codes typically start with *# and do not require pressing the call button.
Inside the service menu, options vary by manufacturer. For Lenovo, navigate to Item Test → BatteryChargingActivity. On Samsung, scroll through parameters until you find charging current values.
The key metric to monitor is the charging current, labeled as Charging Current and measured in milliamperes (mA). When no charger is connected, this value should be zero.
Gather multiple chargers and cables, ideally with detachable USB connectors, to conduct a comprehensive test.
By connecting different charger and cable combinations to your phone, record the minimum and maximum charging currents observed over time. Here’s an example of such measurements:
Charging Current (mA) Across Charger and Cable Combinations (Min–Max)
| Cable 1 | Cable 2 | Cable 3 | |
| Charger 1 | 820–970 | 820–970 | 130–340 |
| Charger 2 | -150–0 | -130–0 | 0 |
| Charger 3.1 | 820–970 | 900–970 | 130–280 |
| Charger 3.2 | 820–970 | 820–900 | 280–410 |
| Charger 4 | 820–970 | 820–970 | 430–490 |
| Charger 5 | 411–485 | 411–485 | -73–58 |
Additionally, calculate the percentage fluctuation in charging current during the test:
Percentage Variation in Charging Current
| Cable 1 | Cable 2 | Cable 3 | |
| Charger 1 | 15% | 15% | 62% |
| Charger 2 | — | — | — |
| Charger 3.1 | 15% | 7% | 54% |
| Charger 3.2 | 15% | 9% | 32% |
| Charger 4 | 15% | 15% | 12% |
| Charger 5 | 15% | 15% | — |
Key Insights From the Test Results:
- Charging current readings are approximate and may step in increments, so avoid focusing on exact numbers.
- Your phone typically draws around 1,000 mA during charging, confirmed by chargers 1, 3, and 4 paired with cables 1 and 2.
- Cables 1 and 2 effectively transmit charging current with minimal resistance.
- Cable 3 has high resistance, resulting in significantly lower charging current. It’s only suitable for emergency use and may not maintain battery charge under active network usage.
- Charger 2 (advertised as 1A) actually discharges the device, showing negative current flow. Notably, Samsung phones display zero current instead of negative.
- Charger 4, an iPad charger rated at 2,400 mA, delivers the highest power output, even on high-resistance cables.
- Charger 3 is a dual-port charger rated at 3A total. Both ports charge well, but the second port supplies more current under heavy loads, such as tablets.
- Charger 5, a car charger, provides insufficient current for charging compared to others. It only maintains battery level during extended navigation use.
To give cable 3 some credit, under lighter loads it performs better—for example, it delivers 354 mA instead of the required 453 mA when charging a Samsung phone, which may be acceptable in some cases.
This testing approach helps identify the best charger and cable combinations for optimal device charging. Your results may vary, but the principle remains: find the highest current combinations and avoid those with low or negative currents.
Good luck with your charger tests!
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