What are the advantages of connecting electrical devices in parallel with the battery instead of connected them in series ?

Explanation

(a) When a number of electrical devices are connected in parallel are connnected in parallel, each device has the same pd across it as provided by the battery and it keeps on working even if other devices fail. This is not so in case the devices are connected in series because when one device fails, the circuit is broken and all devices stop working.
(b) Parallel circuit is helpful when each device has different resistance and requires different current for its operation as in this case the current divides itself through different devices. This is not so in series circuit where same current flows through all the devices, irrespective of their resistances.