# Minimum amount of power need to charge a li-ion battery

by drprofesorxjr
Tags: battery, charge, liion, minimum, power
 P: 2 What is the minimum amount of power needed to charge a small lithium ion battery of 3.4 V and 2100 mAh?
 P: 140 A li-ion battery requires a special charging cycle!! It is DANGEROUS to just connect it to a power supply! Look at the site http://batteryuniversity.com/learn/a..._ion_batteries if you wanna learn more. Most li-ion chargers have specialized charging circuits that take care of security, overvoltage, short circuits and such. Be VERY careful with li-ion, they explode, they burn, they are not toys.
 P: 2 Thanks for the reply. I mean what is the minimum amount of current that can be used to charge a small li-ion battery?
 P: 140 Minimum amount of power need to charge a li-ion battery I would recommend you read through the link I sent. It specifies a charge current of 1 amp in the beginning. When the battery reaches its voltage the current is decreased until you see a special drop in the voltage across the battery. But read from the link and learn. Those guys know what they are talking about :)
 P: 330 You don't have to charge with 1A or whatever. I also doubt the 'constant-current' phase of the charge cycle really has to be constant. The point, as I see it, is to charge the cell with a current source (whatever it may be) until it reaches its float voltage at which point any further increase in voltage might – and eventually will – damage the cell. I can't see why there would be an inherent lower limit on the charge current.
 P: 166 There is more information here: http://www.microchip.com/stellent/gr...n/en028061.pdf I don't believe there is a minimum current level needed though I don't have the patience personally to test and find out if an extremely low current like 1-50ma actually works in practice.

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