One problem that I usually come across is the current ratings on mobile phone chargers. Right now, I need a 1A charger (which was shipped with my phone) and I have a 0.7A charger handy. Both the chargers have a 5V output.

I read here Charging devices - Voltage and Amperage that:

Correct voltage rating and too low current rating may cause damage. Slightly too low may be OK with computers an similar.

Now I am wondering:
1. What happens if I connect my phone to this charger ? Is it safe or will it cause problems later on?

I have a 220V / 50Hz / Single Phase supply.
Phone: Samsung Galaxy S3 (if this is even relevant) and the charger I have is from Samsung Galaxy S3 Mini


closed as off-topic by Kaz, Leon Heller, Joe Hass, Daniel Grillo, Nick Alexeev Dec 30 '13 at 18:48

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Kaz, Leon Heller, Joe Hass, Daniel Grillo, Nick Alexeev
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  • \$\begingroup\$ Lover current should only result in a slower charging process. \$\endgroup\$ – Gunnish Dec 30 '13 at 16:55
  • \$\begingroup\$ @Gunnish Are you sure it wont harm ??? \$\endgroup\$ – Fasih Khatib Dec 30 '13 at 16:55
  • \$\begingroup\$ I've seen at least one USB charger that simply refused to charge too great of a load, shutting down entirely instead. But that was seven years ago. \$\endgroup\$ – Stephen Collings Dec 30 '13 at 17:05

A one-time use should be safe.

But since you're dealing with Samsung, be careful. Their last Galaxy presented a few problems.


There should be no problem. The device detects the highest current the charger is able to supply and adjust its internal resistor so the voltage is at an acceptable level. If the current is to low, the device stops charging.

If you notice that your device is constantly starting/stopping the charging process, you should disconnect the charger.


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