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

[drprofesorxjr]

What is the minimum amount of power needed to charge a small lithium ion battery of 3.4 V and 2100 mAh?

 

[Runei]

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/article/charging_lithium_ion_batteries if you want to 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.

 

[drprofesorxjr]

Thanks for the reply. I mean what is the minimum amount of current that can be used to charge a small li-ion battery?

 

[Runei]

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 :)

 

[gnurf]

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.

 

[justsomeguy]

There is more information here: http://www.microchip.com/stellent/groups/designcenter_sg/documents/market_communication/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.