Battery Replacement --- how does it work
 

due to testpoint, I am interested in the various contacts in a battery.

Normally I see four contacts on a motorola battery +ve -ve and two leads inbetween. normally the battery voltage is 3.7 volts.

When I try on some phones (motorola) by just connecting the +ve and -ve ends it does not turn on. Why is that ?. To power it, all four leads needs to be connected.

What is the purpose of the other leads ?

If I use a DC power supply, it will only have two leads, positive and negative. how can I use this as a substitute ?