Connecting in series is the most common way of connecting batteries. A series connection can yield a higher voltage and cause less current to flow through each battery. Connecting in parallel increases amp-hour capacity, but voltage stays the same.
Also, for series connection, if one or more of the connected cells are damaged, then it’s possible for them to “drag down” other cells, causing them to be over-discharged. But, in parallel connection, if one or more batteries are damaged, they won’t affect any others.
Below is an overview of the main differences between series and parallel connections and their advantages and disadvantages.
Connecting Batteries in Series
The most common way of connecting batteries is by connecting them in series. That means the positive terminal of one battery connects to the negative terminal of the other. This arrangement provides a low voltage-high amperage output which is perfect for powering devices like car headlights or electric fence chargers that require a lot of power over a short time.
Advantages of Connecting Batteries in Series
Using a battery as an energy source is that they are inexpensive, lightweight, and provide a low voltage but high amperage output, perfect for powering devices like car headlights or electric vehicles. In addition, connecting them in series provides more voltage to power your energy-intensive appliances.
Other advantages of connecting batteries in series include:
- Connecting in series increases the voltage. That is because the voltage for each battery is added together, but the capacity remains the same. For example, two 12 volts 100 Ah batteries connected in series will produce 24 volts at 100 Ah.
- You can still connect multiple batteries in parallel to increase the capacity, providing you maintain the same voltage for each bank, e.g., 24 volts at 200 Ah (2 x 100 Ah).
- Using multiple banks of batteries connected in series is useful when space is an issue. You cannot fit a single bank battery large enough to meet your requirements, e.g., 6 x 12 volt 100 Ah batteries could be connected as 2 x 12 volt 600 Ah banks or 3 x 12 volt 400 Ah banks (2 banks connected in series and then linked together to form a single bank).
Disadvantages of connecting batteries in series
The main disadvantage of connecting batteries in series is that they yield higher voltage that necessitates an inverter if you want to power appliances that require low voltage.
Another disadvantage of connecting batteries in series is there is a limit to the number of batteries to connect at a time. The limit varies from manufacturer to manufacturer. For example, some manufacturers allow the connection of up to four 12 volt batteries to produce 48 volts. Therefore, you should check with your manufacturer before connecting more than three batteries in a series.
Connecting Batteries in parallel
Batteries are often connected in parallel to increase the voltage or current. Connecting batteries in parallel increases the intensity of their electric field compared to connecting them in series. A parallel connection will yield a higher voltage and cause more current to flow through each battery.
A battery’s physical characteristics as battery type, capacity, and size determine its voltage or current. As such, connecting batteries in parallel increases the intensity of their electric field compared to connecting them in series.
There are some advantages and disadvantages to connecting batteries in parallel:
Advantages of connecting batteries in parallel
- Increase Overall Capacity: Connecting batteries in parallel increases the capacity of your battery pack. Each additional battery added to a parallel connection will add another amp-hour (Ah) to your pack, thus increasing its capacity.
- Increase Power Output: With more amp hours at the same voltage, this means that you can pull more amps from your pack for long periods before discharging it.
- Connecting batteries in parallel increase a battery bank’s capacity while keeping the voltage constant. So you can use a single cell charger to charge all of them simultaneously.
- Keep Voltage Constant: Because more batteries are adding their amp-hours together without increasing voltage, you can have a wide variety of battery capacities together and maintain the same voltage.
Disadvantages of connecting batteries in parallel
- Batteries in parallel connections must closely match to function correctly. If one battery discharges more than the other, it will act as a load on the other battery. That can cause damage to the cells and shorten their overall life expectancy.
- Connecting batteries in parallel will increase the capacity of a battery bank, but it will not increase the voltage. In fact, if you connect batteries of different voltages in parallel (even if they’re the same chemistry), you’ll lower the bank’s voltage.
Should You Connect your Batteries in Series or Parallel?
When answering this question, the one thing to keep in mind is that batteries are often connected in series or parallel to increase the voltage or increase amp-hour capacity. Therefore, you can connect your batteries either in series or parallel, depending on the purpose of using them.
Water heaters, freezers, and refrigerators are some examples of home appliances that use series connections, whereas parallel batteries connection is.
If you’re unsure how to use your batteries, getting LiFePO4 batteries can be good. LiFePO4 has many advantages compared to other rechargeable batteries, making it an attractive option for many applications, including EV, RV, off-grid energy storage, etc.
