parallel battery connection

Series Vs. Parallel Battery Connections Explained

Here we will explain the important differences between series vs. parallel battery connections. We will establish what that means for your battery bank as well. While researching lithium batteries, you’ve probably seen the terms series and parallel mentioned. We are going to explain this important detail here. It can be confusing if you’re new to lithium batteries or batteries in general, but hopefully, we can help simplify it. You can skip to the bottom of this post if you would like to watch a video explanation.

Let’s start at the beginning – your battery bank. The battery bank is the result of connecting two or more batteries together for a single application (i.e. a sailboat). What does joining more than one battery together accomplish? By connecting the batteries, you either increase the voltage or amp-hour capacity and sometimes both. This ultimately allows for more power and/or energy.

The first thing you need to know is there are two primary ways to successfully connect two or more batteries. The first is called a series connection and the second is called a parallel connection.

Series Battery Connections

Batteries connected in Series involve connecting 2 or more batteries together to increase the voltage of the battery system. The amp-hour rating stays the same. All batteries in a series need to have the same voltage and capacity rating. If they don’t you will end up damaging the batteries. To connect batteries in series, you need to connect the positive terminal of one battery to the negative of another. Do this until the desired voltage is achieved. When charging batteries in series, you need to utilize a charger that matches the system voltage. We recommend you charge each battery individually, with a multi-bank charger, to avoid an imbalance between batteries.

In the image below, there are two 12V batteries connected in series which turns this battery bank into a 24V system. You can also see that the bank still has a total capacity rating of 100 Ah.

Series battery connection diagram

Parallel Battery Connections

Parallel connections involve connecting 2 or more batteries together to increase the amp-hour capacity of the battery bank. However, your voltage stays the same. To connect batteries in parallel, the positive terminals are connected via a cable and the negative terminals are connected with another cable. Keep doing this until you reach your desired capacity.

A parallel connection is not meant to allow your batteries to power anything above its standard voltage output. It does increase the duration for which it could power equipment. The increased amp-hour capacity may require a longer charge time.

In the example below, we have two 12V batteries, but you see the amp-hours increase to 200 Ah.

Parallel battery connection diagram

Can RELiON Batteries Be Connected in Series or Parallel?

The standard lithium batteries can be wired in either series or parallel based on what you’re trying to accomplish in your specific application. RELiON’s data sheets indicate the number of batteries that can be connected in series by model. We typically recommend a maximum of 4 batteries in parallel for our standard product. There may be exceptions that allow for more depending on your application.

When using RELiON’s lithium batteries, there are a few items to note, specific to our series:

  • The HP Series batteries can be connected in parallel only.
  • The InSight batteries can only be connected in parallel and allows for up to 10 batteries in parallel.

Whether you’re seeking an increase in voltage or amp-hour capacity it’s important to understand the difference between parallel and series configurations, and the effects they have on your battery bank’s performance. Knowing the differences between these parallel versus series configurations allows you to maximize your lithium battery’s life and overall performance.

Here is a video that explains series vs parallel battery connections
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