Galaxy S7 won't Fast Charge if the screen is on

[Rob]

In addition to providing some battery tips, the official Galaxy S7 user guide makes some disclaimers regarding Fast Charging, and one of them we found particularly interesting: for Fast Charging to work the screen must be off.

Here are some more tips and info on Galaxy S7 Fast Charging, directly from Samsung:

About Fast charging

• Fast charging uses battery charging technology that charges the battery faster by increasing the charging power. The device supports Samsung's Adaptive fast charging feature and Qualcomm Quick Charge 2.0.
• To use Fast charging on your device, connect it to a battery charger that supports Adaptive fast charging or Quick Charge 2.0.

Increasing the charging speed

• To increase the charging speed, turn the device or its screen off when you charge the battery.
• While charging the battery when the device is turned off, the 5 icon appears on the screen.
• You cannot use the fast charging feature when the screen is turned on. Turn off the screen to increase the charging speed.

If the fast charging feature is not activated, on the Home screen:

• Tap Apps —, Settings —, Battery, and then tap the Fast cable charging switch to activate it.
• You cannot use the built-in fast charging feature when you charge the battery using a standard battery charger.
• If the device heats up or the ambient air temperature rises, the charging speed may decrease automatically. This is a normal operating condition to prevent damage to the device.

 

[malibu02]

In addition to providing some battery tips, the official Galaxy S7 user guide makes some disclaimers regarding Fast Charging, and one of them we found particularly interesting: for Fast Charging to work the screen must be off.

Here are some more tips and info on Galaxy S7 Fast Charging, directly from Samsung:

About Fast charging

• Fast charging uses battery charging technology that charges the battery faster by increasing the charging power. The device supports Samsung's Adaptive fast charging feature and Qualcomm Quick Charge 2.0.
• To use Fast charging on your device, connect it to a battery charger that supports Adaptive fast charging or Quick Charge 2.0.

Increasing the charging speed

• To increase the charging speed, turn the device or its screen off when you charge the battery.
• While charging the battery when the device is turned off, the 5 icon appears on the screen.
• You cannot use the fast charging feature when the screen is turned on. Turn off the screen to increase the charging speed.

If the fast charging feature is not activated, on the Home screen:

• Tap Apps —, Settings —, Battery, and then tap the Fast cable charging switch to activate it.
• You cannot use the built-in fast charging feature when you charge the battery using a standard battery charger.
• If the device heats up or the ambient air temperature rises, the charging speed may decrease automatically. This is a normal operating condition to prevent damage to the device.

 

[malibu02]

Fast charge stopped working. This morning I put it on the wireless charger as usual but noticed a brief message that fast charger was paused. I checked settings and the option was turned on but grayed out. I did a normal restart which didn't help. I also tried powering off the unit then putting it on the charger and still no change. I also tried it on the wired charger and this didn't work either. Slow charge seems to work ok. Has anyone else run into this issue?

 

[nuit123]

Using a USB power meter, I confirm the Samsung Galaxy S7 charges faster when the screen is off or the S7 is powered off.

Power draw from Samsung Adaptive Charger Adapter:
Fast Charge = Screen off or S7 powered off: 1.65 Amps or 1.09 Amps (varies about every 60 seconds)
Non-Fast Charge: 0.50 Amps

I see the exact same power results using a Quick Charge 3.0 USB Vehicle Charger.

Perhaps Samsung requires the screen be off while fast charging to avoid the extra 1.15 Amps of power overheating the phone.