# What would happen if two batteries are connected in parallel?

Battery is a device that supply electrical energy to electrical circuit. It convert stored chemical energy into electrical energy. There are two terminals in a battery. The terminal with higher potential is called positive terminal and terminal with lower potential is called negative terminal. The parallel combination of battery is shown in the circuit diagram. Here we are interested to know what would happen if two batteries are connected in parallel?

Assuming both batteries are identical,

When two identical batteries are connected in parallel it will double the current capacity and the output voltage remains the same as a single battery.

For example, suppose two batteries of same rating i.e. 1800 mAh, 12 V are connected in parallel, the output voltage of parallel circuit is remain 12 V butt current capacity becomes 3600 mAh. If you connect more identical batteries in parallel the output voltage will remain same but current capacity goes on adding.

We need to connect batteries in parallel when a single battery cannot do the job. Parallel combination of battery increases output energy.

In short, If batteries are connected in parallel, the total output voltage is remain same but the output current capacity increases.

I hope you have got to understand about parallel combination of identical batteries but if batteries connected in parallel are not identical then it would not work as we discussed above.

## What would happen if two batteries of different voltage rating are connected in parallel?

If two batteries of different voltage rating are connected in parallel, they will fight each other and try to balance the voltage. The few things which could happen if two batteries non identical batteries connected in parallel.

In case of small voltage difference between two batteries the current will start flowing from higher voltage battery into lower voltage battery. Which is not good for batteries. When the voltage is balanced, the current flow will cease. But if there is a big difference in voltage there can be serious destruction, a large current may flow through battery having lower voltage. It may overheat and possibly explode. In this case, the voltage will never balance and the high current will remain flow until the low voltage battery has been destroyed.

Other than this, if there is a difference in internal resistance, it affect how the current goes in and out of each cell. Although it is never advisable to connect two non identical batteries in parallel because it does not make any sense it is useless and may destroy the batteries.

In short, when two non-identical batteries are connected in parallel, current will flow from higher voltage battery to lower voltage battery. Which is not good. Small voltage difference between these two batteries can balanced but if voltage difference is high it may destroy lower voltage battery.

## Find the total current flow through circuit?

When three 6 V parallel connected batteries are connected across 100 ohm resistor. Find the total current flow through circuit.

Solution: Given in the question resistance of resistor (R) = 100 ohm

As all the batteries are connected in parallel, therefore total output voltage remain same (V) = 6 Volt.

Hence, current flow through circuit can be calculated easily by

V = IR

Here ‘I’  represent the current flow through circuit.

I = V/R

I = 6/100

I = 0.06

Current flow (I) = 0.06 ampere.

In short, when three 6 volt parallel connected batteries are connected across 100 ohm resistor, the current flow through circuit is 0.06 ampere.