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3 Ways to Connect Lead Acid Batteries

Safety is Important when Learning How to Connect BatteriesIntuitively people realize they can connect batteries together to increase voltage or capacity, but far too often they are not entirely confident on how to exactly configure the batteries to achieve the desired result. In some cases, as it turns out, they actually do know how to accomplish the desired goal, but just seem to get the terminology a little mixed up.

Even with simple procedures such as changing a battery, people seem to hesitate trying to remember which terminal to connect first. This creates doubt and doubt leads to second guessing, and second guessing leads to unnecessary change which can lead to catastrophic failure! So let’s just take a quick second to remind everyone about the terminology and how to connect batteries and disconnect batteries in series, parallel and the dreaded series/parallel combination.

Exploring Battery Safety First

This is one area you don’t want to mix up. You may skate by once or twice or for a lifetime without incident, but when 'The Incident' occurs and you may not be the one capable of telling the story! Yes, that is meant to grab your attention and no, 'The Incident' is not always so devastating. It could be as simple as a quick ‘pop’ or it could produce fantastic and incredibly bright fireworks giving you a sudden scare but nothing more. Still, possibly, you could incur physical reminders that alter your life in the short term but ultimately deposit you back to normalcy a few months down the road. And yes, you could blow something up and alter the course of your life forever!

Safety Rule #1 -- While Connecting Battery Terminals: Wear Gloves and/or Remove Jewelry

I am reminded of a story I read in Popular Mechanics of a dentist that was working on his car. He was disconnecting his battery terminals and was not wearing any protective gear. While working to loosen the cables his hand came down on the battery hold-down bracket creating a massive dead short.

The fact that his hand touched the bracket was not the issue. It was his wedding ring. His wedding ring touched the negative grounded metal as he disconnected the positive. The ring was touching the wrench which was touching the positive terminal. The ring instantaneously welded to the wrench and glowed red hot. They were able to cut the ring off at the hospital, but it was touch and go as the doctor monitored his third degree burns. He finally ruled out the need to amputate his finger a month or so after The Incident.

Safety Rule #2 -- When Installing a Battery Start with the Positive

There is a serious amount of stored potential energy available in a sealed lead acid battery. A shorted car battery, for example, can deliver several hundred amps in the blink of an eye. To put that in perspective that is more than an arc-welding machine.

To avoid fantastically failing your first welding class you should always connect the positive terminal first when installing a battery. When disconnecting a battery, remove the negative cables first.

Safety Rule #3 -- When Removing a Battery Start with the Negative

If you are like me you may have a tough time remembering this even though you have a 50/50 chance and perhaps work with batteries semi-regularly. So do what I do and create a word game to remind yourself what to do first.

Installing a Battery:

When you want to grow your life and tap your potential you should always focus on and start with the positive knowing full well you will deal with the negative soon enough.

Removing a Battery:

When you need to remove dead weight in your life you should start with the negative and positive outcomes will surely follow.

Call me crazy, but little word association tricks like this help me remember and keep me safe.

The Three Battery Configurations

There are three ways to connect your lead acid batteries—parallel, series, and a combination known as series/parallel. We cover each of these battery configurations in greater detail in our Battery Basics tutorial section of the site should you want to delve in a little deeper or reinforce what you already know.

How to Connect Batteries in ParallelPoint To Ponder: Never connect batteries of different size, type/chemistry, brand or age. It is also a good idea to make sure the batteries are of a similar state of charge. Connecting batteries that are different can lead to trouble.

How to Connect Battery in Parallel

The goal of parallel battery configurations is to increase your systems overall capacity. This is used when you want your application to run longer between charging. The voltage will not increase using this connection method.

Connecting in parallel is when you combine two or more batteries by linking the POS (+) of the first battery to the POS (+) of the second battery. In the same way the NEG (-) of the first battery is connected to the NEG (-) of the second battery. You would do the same for each battery added to the string. Generally the first battery POS (+) terminal and the last battery NEG (-) terminal have cables going to the application. Some folks simply pull power from the POS (+) and NEG (-) of the first battery. This last configuration obviously works, but will shorten the lifespan of your system.

If you wanted to ensure your system was perfectly balanced you would make some alterations to this pattern, especially once you add a fourth battery. Our parallel charging tutorial goes into much more detail on how to set up perfectly balanced parallel systems.

How to Connect Battery in Series

How to Connect Batteries in SeriesThe goal of series battery configurations is to increase your systems overall voltage. This is used when you want to generate more power to run faster, for example. The capacity will not increase using this method.

Connecting in series battery configurations is when you combine two or more batteries by linking the POS (+) of the first battery with the NEG (-) of the second battery. If only two batteries were used then you would have a cable coming off the NEG (-) of the first battery to your application and a cable coming off the POS (+) terminal on the second battery heading to the application.

Many of you have four or six batteries in series in your golf carts. In these scenarios you will find a cable joining the POS (+) of the second battery to the NEG (-) of the third battery. The POS (+) of the third battery connects to the NEG (-) of the fourth battery. And the pattern continues until you have reached the last battery in your series. The last battery in the series is what will have a POS (+) cable heading to the application.

How to Connect Battery in Series / Parallel

How to Connect Batteries in Series / ParallelThe goal of series/parallel battery configurations is to increase your system voltage as well as your system's overall capacity. This is often used in RV campers using four 6-Volt batteries to create a high capacity 12-Volt operating system.

You will have two or more banks of batteries in series/parallel battery configurations. Each bank of batteries will combine batteries configured in series to the desired voltage. The banks will then be connected together in parallel to increase the total system capacity. It is like you are combining two identical power plants together. Our Tutorial on how to connect and charge a series / parallel system will provide more images and details.

  • RockfordJohn

    It's been recommended to me that I attach battery charger cables to the auto battery cables when changing the battery thereby keep current flowing to the (computer,etc.) What do you say?