Battery Troubleshooting Guide 101: Why Do Lead Acid Battery Swell-Up?

Are you concerned about the swelling up of your lead acid battery? Then, you should continue reading as here, we will reveal to you why lead acid batteries swell-up and how to avoid the problem.

Sealed lead acid batteries – both AGM and gelled electrolyte  can swell up and expand sometimes. This happens due to the construction of lead acid batteries which is referred to as “recombinant”. They are constructed in such a way to allow absorption of gasses released during the chemical process inside the battery.

The positive and negative plates are placed very close together with only the thickness of the divider separating them. They are tightly secured in the cell cavity resulting in very little extra space inside the battery. When the cell plates expand, it exerts pressure on the inside walls of the battery. This situation can cause the battery case to swell resulting in possible splits and cracks at various points of the battery.

Why Do Battery Cell Plates Expand?

The cell plates most often expand due to overcharging of the battery. The battery may also expand due to shorting of the terminals of the battery. Both these situations results in heating up of the cell plates inside the battery. The lead of the cell plates has a high expansion rate when heated.

The outcome is that the battery experiences extreme pressure inside that swells up and deforms it. The swelling-up of the battery may also cause great damage to the internal components and parts.

How to Avoid Swelling Up of the Battery?

Overcharging or short-circuiting of the battery is the only reason for swelling up of the lead acid battery. The problem is not inherent in the battery itself. In order to avoid swelling up of the battery you need to tackle the underlying cause of the problem.

You need to follow proper instructions in charging the battery. The culprit may be that you are using a wrong charger when charging the battery. If the charger is providing too much current, this may be the cause for battery swelling up. For instance, if you used 12V charger to charge a 6V battery it will most probably result in overcharging of the battery.

Whatever the reason for overcharging of the device, the end result is that it results in swelling up of the battery. To avoid the prospect of overcharging or short-circuiting of the battery, you need to take the following precautions:

• Use the right type of charger that is fully compatible with the battery.
• Ensure proper polarity when connecting the charger to the battery
• Shield the battery terminals to avoid short-circuiting of the battery
• Use a charger whose maximum charging capacity is lower than the battery

The above tips will help you to protect your battery from swelling up and expanding. Taking precautions will not only protect your battery from being damaged but it will also minimize the threat of fire caused due to overheating of the battery. Please feel free to check out our Battery Buying Guide for instructions on how to charge your SLA batteries.

You might also like: Will storing a SLA battery on a concrete floor discharge it?

On BatterySharks.com you can find quality replacements for the most popular models of SLA  batteries such as the CSB HR1234W, UB12120 and CP1290 battery.