Question about cellphone charger

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Yoko Sabi

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Hi, I measured the amperage on my cellphone charger. I measured 2 different cellphones with 2 different batteries.

The output of the charger is 5v 1 amp.

The first battery has 3.7v 1 amp. I measured .420 amp while charging.

The second battery has 3.7v 1.4 amp. I measure .980 amp while charging.

My question is, I am getting 2 different results, what factors affects the values?

Thank you so much.
 

Thank you. These are Li batteries. On the first battery, do you know why .420 amp not 1 amp? Thanks.
 

different cellphones = different charging circuits = different behaviour and different efficiency = different current

different batteries = different states = different charge rates = different current
 
The current on the charger is a max current rating not a guarantee that that current will flow. V = IR, the voltage is fixed from the charger and the resistance will be determined by the charging circuit which will pull the current to make the statement equal.
 
If I know the ratings of the charger and the battery, is there are formula to get the current?
 

reidintransit said:
The current on the charger is a max current rating not a guarantee that that current will flow. V = IR, the voltage is fixed from the charger
Click to expand...

The current rating is the MAXIMUM current the charger can supply at that voltage.

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Yoko Sabi said:
If I know the ratings of the charger and the battery, is there are formula to get the current?
Click to expand...

You seemed to have missed the point. A proper charger charges at a current set by the state of the battery. There is no magic formula. It depends on the battery and charger.
 

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