LED indication in a charger circuit
This is a simple design that should get the job done without using complicated components:







simulate this circuit &ndash; Schematic created using CircuitLab

3.5 Ohm resistor converts the current (200 mA) to 0.7 V which is enough to open the transistor and thus make the led work. 3.5 Ohm 0.25 W is enough for your application. When the battery is charged there is going to be no current through the 3.5 Ohm resistor, thus the transistor and the LED are off.

If you can guarantee that no more than 200 mA is going to go through the battery you don't need the 1 Ohm resistor. The 1 Ohm resistor is to protect the transistor from over 0.7 V voltages.

You may choose the components and may need to change the values of the resistors according to your application.