Parallel vs Series for Leisure Batteries: What You Need to Know

Are you looking to upgrade your Campervan or boat's battery system? Understanding the difference between wiring your batteries in series and parallel might be an essential part of optimising your power capacity. 

In this article, we'll break down the benefits and drawbacks of each wiring method, so you can make an informed decision for your next van or boating adventure.

Let's start with a brief overview.

Series vs Parallel - A brief overview of Leisure Battery wiring options

In a series connection, the positive terminal of one battery is connected to the negative terminal of the next, resulting in a higher overall voltage. This is ideal for applications that require a higher voltage, such as powering large appliances. 

On the other hand, a parallel connection involves connecting the positive terminals together and the negative terminals together, resulting in a higher overall capacity. This is ideal for applications that require a longer battery life, such as powering lights or a small fan.

• Series connection = higher voltage (v)
• Parallel connection = higher capacity (ah)

So, which approach should you choose? It depends on your specific power requirements. If your system requires a higher voltage output, such as for larger appliances or equipment, a series connection may be more suitable. However, if your priority is longer usage time and higher capacity, a parallel connection may be the way to go. Ultimately, choosing between series or parallel is down to your required load and systems design as we'll discuss in more depth throughout this blog.

What is Series Wiring in Lithium Leisure Batteries?

Series wiring is when multiple lithium leisure batteries are connected end to end, with the positive terminal of one battery connected to the negative terminal of the next battery. This setup increases the voltage of the batteries but not the capacity, meaning that the total voltage output is equal to the voltage of each battery added together.

Using our Fogstar Drift batteries as an example; wiring two 280ah 12v batteries in series will not affect the overall amp hours of the battery, but it will increase the voltage (v) of the battery bank to a 24v system. This means our two 280ah 12v drifts, wired in series, will become a 280ah 24v battery bank.

Advantages and Disadvantages of Series Wiring Lithium Leisure Batteries

Series wiring allows you to increase the voltage of your lithium leisure batteries, which is often necessary for high-demand applications. Because of the increased voltage, charging your batteries becomes more efficient and effective. However, there are a couple of disadvantages to this approach. There is a risk of uneven discharge if one battery 'wears out' faster than the others, it can cause an uneven discharge throughout the entire system, leading to further damage.

Also, if one battery fails, the whole system fails. With series wiring, the battery circuit is not complete unless all batteries are functioning properly. This means if one battery fails, the whole system fails.

What is Parallel Wiring in Lithium Leisure Batteries?

Parallel wiring is a method of connecting multiple lithium leisure batteries with the aim of achieving higher overall capacity, while keeping the voltage the same as a single battery. By connecting the positive terminals of each battery together and the negative terminals together, you can effectively increase the amount of charge the batteries can hold.

For example, two Fogstar Drift 12v 105Ah batteries connected in parallel would give you a total capacity of 210Ah, but the voltage would still be the same as one 12v battery.

Advantages and Disadvantages of Parallel Wiring Lithium Leisure Batteries

Parallel wiring increases the overall capacity and runtime of the batteries, making it ideal for applications that require a long duration of power. Additionally, if one battery fails, the others will continue to operate. It is especially important to closely manage the charge and discharge cycles of batteries that have been wired in parallel.

Whilst a good BMS can protect your system against overcharge and unbalanced cells, there is a greater risk of unequal battery charging with parallel connected batteries. It may be worth investing in a SmartShunt to monitor the charge and discharge cycles of your batteries more closely.

How to Choose the Best Wiring Configuration for Your Lithium Leisure Batteries

When it comes to wiring your Lithium Leisure Batteries, choosing between series and parallel configurations can impact the overall performance and lifespan of your batteries. Here's what you need to know:

• Wiring in series means connecting the positive end of one battery to the negative end of another, increasing the overall voltage but keeping the same capacity.
• Wiring in parallel means connecting the positive ends and negative ends of two or more batteries, increasing the overall capacity but keeping the same voltage.
• In general, series configurations are best suited for applications that require higher voltage, while parallel configurations are ideal for those that demand longer run times.
• Before choosing a configuration, it's important to determine your specific power needs and consult with a professional to ensure proper installation and wiring.

How many Lithium Leisure Batteries can I connect in Series or Parallel?

It's important to stipulate that all Leisure Battery brands are very different. They all utilise different Battery Management Systems (BMS), and many on the market may not give you an option to connect in Series or Parallel. Check before you purchase your batteries!

Our Fogstar Drift range of Leisure Batteries contain a JBD BMS that has been specially programmed to allow up to four (4) batteries to be connected in Series or Parallel. 

Now for the important stuff.

When connecting Leisure Batteries in series, the rule of thumb is to never exceed 48 volts. So, if you have 12 volt batteries, you can connect up to four in series.

You also need to ensure that the batteries you connect in series and in parallel are;

• the same brand of battery
• the same amperage of battery
• the same voltage of battery.

Trying to connect mismatched batteries is not going to end well for your electrical system, your precious electronics or your expensive batteries.

To Conclude...

When it comes to wiring Lithium Leisure Batteries, it's important to consider your power and energy requirements to determine whether to connect them in series or parallel.

While series wiring ensures higher voltages, parallel wiring provides longer run times. Both methods have their pros and cons, so it ultimately comes down to your specific needs. By understanding the differences between the two methods, you can make an informed decision on which wiring approach is the most suitable for your applications. 

To reiterate, it's important to always get advice and support from a professional when it comes to your installation. Using a trained technician can help prevent against any damage when fitting you battery, and with the right wiring in place, you can optimise the performance and longevity of your Lithium Leisure Batteries for a more enjoyable and stress-free power supply experience.

Looking for a new Lithium Leisure Battery? Take a look at our Fogstar Drift range. Comprised of EVE Grade A Prismatic Lithium Iron Phosphate (LiFePO4) cells, integrated JBD Battery Management System (BMS), built-in Heating, Bluetooth with App - prices start from just £369 for our 12v 105ah.