I recently bought a compact digital camera and it came with a charger of 5V, 1A output. This is a wall charger and the cable is USB type as in android smartphones. I have another wall charger which is 5V, 2.1A output and this is from my Tablet.

My question is what can happen if I charge my compact camera with the tablet's charger?

Well I have already done it :) and it obviously charges faster than its genuine but can this harm the battery or even worse the camera?

  • \$\begingroup\$ possible duplicate of Choosing power supply, how to get the voltage and current ratings? \$\endgroup\$ – Ignacio Vazquez-Abrams May 23 '15 at 2:15
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    \$\begingroup\$ Well, there should be an internal circuit that limit the charging current to protect the battery, so it should not harm it. \$\endgroup\$ – GmodCake May 23 '15 at 2:31
  • \$\begingroup\$ Are you referring to battery chargers, or to USB power supplies? Perhaps edit to make that clear. \$\endgroup\$ – tomnexus May 23 '15 at 2:54
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    \$\begingroup\$ To clarify @tomnexus comment, the plug-in module with USB output, as you would use for a smart phone or tablet, is not a charger, it is a power supply. The actual battery charger is built into the phone, tablet, camera, etc. As such, using a higher power power supply is harmless as the battery charging is regulated by the built-in module. \$\endgroup\$ – DoxyLover May 23 '15 at 4:25
  • \$\begingroup\$ @tomnexus edited \$\endgroup\$ – NikosDim May 23 '15 at 4:35

The "charger" is actually a battery management IC inside the smart phone. Assuming your phone uses a Li-Poly battery, the battery will be rated at a nominal voltage of 3.7v and a fully-charged voltage of 4.2v or thereabouts.

The battery capacity of a LI-Poly battery in a smartphone is rated in mAh, and a typically value might be 1300 mAh. The charge rate is often denoted as C and signifies a charge rate equal to the capacity of a battery in one hour. For a 1300 mAh battery, C = 1300 mA.

The charging current is typically set externally to the charger chip using a couple of resistors. Values of 0.5C (650 mA in this case), 0.8C and 1C are common. A rate of 2C (2600 mA or 2.6A) would be classified as a fast charge.

Sometimes the resistor network can be adjusted by the microcontroller inside the phone, so it can set the charging current to either 100 mA or 500 mA when connected to a regular USB port, or to a higher value (e.g. 1C) when connected to an AC adapter, colloquially known as "wall-warts".

These AC adapters are not chargers, but simply AC to DC converters. The current available for charging will be limited by the output of the converter (i.e. if it supply 1A, the charger chip cannot charge the battery more than 1A), but if you replace a lower current wal-wart with a higher one, then the battery might be charged faster, however the charging current will still be limited by the charger chip -- whichever is lower, the AC adapter capacity or the charger chip setting.

  • \$\begingroup\$ Thanks for the answer. In other words the IC in the device will limit the current up to a value that will not harm the device/battery. \$\endgroup\$ – NikosDim May 23 '15 at 4:54
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    \$\begingroup\$ @NikosDim Correct. So it appears your charger IC was set up to be able to charge at greater than 1A, but your wall-wart limited it to a lower value. The battery in an iPad 3 is crazy big (11,500 mAh), basically the device is a battery with a screen attached. So it will typically be charged at a little under 0.2C. \$\endgroup\$ – tcrosley May 23 '15 at 5:12

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