NiCD - Charging circuit - Using PIC

[prstein]

Hi Megahertz,

The invincible Darrel Taylor has spelled it all out for us!

http://www.picbasic.co.uk/forum/content.php?r=245

Best Regards,
Paul

[Megahertz]

Darell is as always THE GURU of all this stuff. The example speaks for itself, no more questions on that front.

But if I have understood it correctly, he is measuring the voltage through a voltage divider, what can I do for current sensing? I think for that I need to add a very small value resistance in series to the current path and measure voltage drop across it, when it is nearly 0, battery charge is full, but what next? How to make a connection with PIC?

OR

Is that in his circuit he is actually doing the same thing? one set of divider on one side of the series resistor, and the other set is on the other side of the series resistor. Keep measuring both sides until they are giving nearly same readings?

[prstein]

I know almost nothing about current sensing. What little I do know I got from the MAX712/713 datasheet. I need to let others respond to this one.

Best Regards,
Paul

[pedja089]

You can use 0.1R resistor, in serial with batery. And measure voltage drop on it. I=U/R
Because you use smal value resistor( to reduce dissipation) you need to amplify resistor voltage. You can use just simple Non-Inverting Amplifier. Or something like MAX4080. Look datasheet for details. I used it, and it very simple, and it give 0-5V output, wich is perfect to use with ADC.