Necessity of series connection of batteries: 1. The batteries are available with some specific terminal voltages. e. g. 6V, 12V, 24V, 48V etc. 2. If we want to have some terminal voltage other than these standard ones, then series or parallel combination of batteries are necessary. 3. The series connection of batteries is necessary to increase the terminal voltage. 4. The load voltage is equal to the sum of individual battery voltages. VL = V1+ V2 +V3 +V4
Necessity of parallel connection of batteries: 1. The batteries are available with specific current capacities. 2. To obtain higher current capacities batteries need to be connected across each other such that their similar polarity terminals are connected together. 3. The parallel connected batteries together supply the required load current depending on their internal resistances (they have identical e.m.f.s). 4. IT = I1 + I2 + I3 + I4 +……. is the total current capacity available when batteries of capacities I1, I2, I3, I4 ……. are connected in parallel, all having identical emfs.