Hello,
I have just got one battery charger of 12v 20Amp for repair purpose.
I was really surprised by its battery current sencing
method, it was as follows:

;1MHz oscillator with CD4049 @12v
;this 1MHz is fed to one terminal of small ferrite CT having 100 turns
; other terminal of ct is grounded with 470E
; voltage developed on this 470E is rectified by 1n4148 & capacitor,and this voltage is propotional to DC current flowing through CT.

Can any one has idea about such current sencing principle or any related web site.
I am not sure but I think DC current to be senced make CT core to saturate according to intencity of current and there by changing Inductance of ct and so get propotional voltage accross 470E.


Regards