Question

what are advantage of connecting electrical devices in parallel with the battery instead of connecting them in series​

Answer 1

Answer: if electric devices are connected in parallel then if even one appliance is not working then other device will work but when connected in series then if even a single device doesn't work then no other device will work . So parallel connection is preferred over series connection.

Answer 2

Answer:

there is no division of voltage among the appliance across each appliance is equal to the supplied voltage

the total effective resistance of the circuit can be reduced by connecting electrical appliances in parallel