battery charging circuit

Hello,
I am implementing a battery charging circuit for rtc, battery is used in Ni-MH
Circuit is:
Vcc=5v connected to p-junction of diode, n-junction of diode is connected to resistor and resistor is connected to +ve terminal of battery, -ve terminal of battery is connected to ground.

Junction between +ve terminal of battery and resistor is used as Vbat=3v and given to rtc

My doubt is how battery discharges i.e path for battery discharge?
is it self discharged, or it has hardware path for discharge?
is battery discharges through VCC when switched off or through ground?

My system works for 10 minutes and then it hanges. And I found that Vbat=4.7V
Then I switch off the machine and switch on after sometime, that time it works for 10 minutes and again hangs
Is it because of charging of battery??

thank u all...

My doubt is how battery discharges i.e path for battery discharge?

Click to expand...

Vbat=3v and given to rtc

Click to expand...

rtc has a ground...

Lithium would be the usual back up chemistry for an RTC.

And I found that Vbat=4.7V

Click to expand...

What is system Vcc? A resistor alone as a charging circuit will ruin your battery, and will try to charge it to Vcc....slowly.

You will need to post a circuit sketch to get any real help here, but if I were you, I would find a schematic using the same RTC chip you are using, and copy the back up circuit.

-fab