Connecting batteries in series vs parallel

We connect batteries in series and parallel to achieve our desired voltage and current because different systems require different voltage and current ratings, Not all ratings are available.  

Difference between series and parallel batteries

  • Parallel connection of batteries increases the current capacity Amp-hour output, While the voltage has no change.
  • In a series connection, we increase the voltage while we keep the current capacity Amp-hour rating the same.

Connecting batteries in series and parallel

As we know that an electric circuit consists of three main components. i.e. power source, Load, and conducting wire.

We also know that two combinations are common for connecting power sources and loads. These are parallel and series connections.

The procedure and calculating results for both load and power source in parallel and series combination are different. As in this article, we are targeting batteries, Therefore we only consider power sources.

Similarly, we know that when we add power sources in series, the voltages add up. While if we connect the power sources in parallel, the voltage will remain the same.

Series Combination

If a system requires more operating voltage and it is not possible to run with the existing power source we add power sources i.e. batteries. For this purpose, we use a series combination. In this type of combination, the voltage adds up.

When we add two or more batteries, It is necessary that the Voltage and capacity rating of each battery must be the same.

As during series combination, The Ampere rating (AH) remains, while voltage adds up, then if there is no chance to find one battery with the needed voltage we can use more than one battery cell to reach the voltage we need.

How do you connect batteries in series? This connection is by connecting the positive terminal (+ve) of the first battery to the negative terminal (-ve) of the other one.

Series battery connection
Series battery connection

Batteries in Parallel

How do you connect batteries in parallel? To connect two or more than two power sources i.e. batteries in parallel we connect positive terminals (+ve) of all batteries together with a single cable and negative terminals (-ve) of all batteries together with another cable.

In this style, the voltage rating of the power sources remains unchanged. While the current ampere-hour rating adds up.

This connection extends the operation time of the battery and increases the capability to operate larger loads.

Parallel bataries
Parallel batteries

Series / parallel connection

In many cases, we need to connect a number of batteries in series and parallel in the same combination to increase both voltage and current capacity.

This way is common in laptop batteries. The battery has about 9 cells each 3 of them is in series while this series group is connected in parallel to the other series groups.



  • If You need more voltage for a device operation, Add batteries in series.
  • If you need that the existing power source to last for more time,i.e. you want to increase Amp-hour connect batteries in Parallel.
  • You can use series/parallel connections to increase both voltage and current ratings.
  • Always use batteries with the same type, voltage, current, and age when connecting together.