Step 1: Needed Parts
*2x 3.7v li Ion battery
*2x resistors(330 ohms)
*1x6 volts relay
*1x6 volts zeener diode.
Step 2: Circuit Designing
It works in the design. now its time to test it practically.
Step 3: Constructing the Circuit.
second make parallel connection.then connect led with resistor.
third connect the relay i used jumper pins to connect them.
switch to series after connecting the relay now. See reason for connecting relay to the circuit in next step.
Step 4: Theory Behind the Relay !!!
So, to solve from this problem connect a 6v relay to the series output of the circuit in parallel with a 6v zeener diode.
this will cut the connection of battery from parallel output when the batteries are in series connection and when the batteries are in parallel relay will reconnect the battery.
Step 5: Note:
now one click to change the batteries from series to parallel.