A swollen lead-acid battery in your solar battery bank can be a serious danger to your system and to you. Swelling in a battery always indicates a problem—but what exactly is the problem? What’s causing your battery to swell? There is most likely one reason for this. Keep reading to learn what that reason is, and how you can prevent this from happening to your batteries.

The Culprit: Overcharging

The most common cause of battery swelling is overcharging of the battery. When a battery is overcharged, the cell plates inside of it expand too much, putting pressure on the battery case and leading to swelling. If the swelling gets bad enough, this can cause the battery case to split and crack.

Many people think that charging a lead-acid battery is like charging the battery in a cellphone—you just plug it in, and when the battery is fully charged, it’ll stop charging, right? That actually is true, but only if you’ve connected the battery properly and with the right equipment.

Now that you know why your battery is swelling, it’s time to talk about how to prevent overcharging from occurring in the first place.

Stopping the Problem

To prevent overcharging, you have to tackle the underlying problem, and there are a few of those. One common reason for overcharging is using the wrong charger. For example, if you have a 24V charger and a 12V battery, this will supply too much current to the battery and cause overcharging and swelling.

Make sure you’re using the right type of charger—not only one that provides the proper voltage, but also one that is fully compatible and of high quality. The charger’s maximum charging capacity should be lower than the battery.

When connecting your battery to the charger, ensure proper polarity in the connections. Reversed polarity can also lead to battery swelling. Be sure you shield the battery terminals to avoid short-circuiting the battery and causing permanent damage to it.

Victron Energy’s Solution

While overcharging can’t be completely avoided, Victron Energy has developed a 4-step adaptive charge curve that increases battery life and reduces the odds of overcharging and battery swelling. This curve helps to regulate the charge in the battery more efficiently, maintaining a charge for longer without fear of overcharging. Many of their modern products, including their AGM and gel batteries, are less likely to experience this issue and the resulting swelling and cracking of the battery case. If you’ve experienced swollen batteries in the past and want to reduce your odds of experiencing it again, invest in a Victron Energy battery and be sure to follow the charging tips above.