Tiny 10mAh Li-polymer battery. What to charge it with?

[kender]

Folks,

There are extremely small Li-polymer batteries with 10mAh capacity. Like this one:

(source)

I’d like to charge a battery like this with a CCCV profile. The CC would be 0.7C, which is 7mA. So, I went looking for linear charger ICs (e.g. MAX1555). Some of them have an adjustable charge current, but, the lower limit doesn’t extend down to 7mA range. I wonder what folks are using for charging these batteries?

Any suggestion, insight or reference is really appreciated!

- Nick

 

[habibparacha]

Have you checked out for bq2057.

 

[erikl]

I’d like to charge a battery like this with a CCCV profile. The CC would be 0.7C, which is 7mA.

For such a small current you needn't bother about efficiency, I guess. Just create this current (perhaps via CV and pre-resistor) and use a 3V9 or 4V3 Z-diode in parallel to the accu, which limits the voltage to 4V1..4V2. If necessary, a 3V9 Zener + Poti. Temperature effect shouldn't make a problem at such low power; anyway such Zeners have negative tempCo.

 

[DeLorean]

I've used an LM317 and resistor to make a two terminal constant current source or sink down to 1.7 ma. It may work lower than that but that was for a string of LEDs.

 

[jeffrey samuel]

use CC cofig transistor that will give the current you need in stable grounds better go for it

other wise use some constant source of low power MOS they will be effective as power is low damage is not possible