Maximise the lifespan of block batteries with regular maintenance

15 January 2026

Achieving the best performance and longest possible lifespan from a block battery hinges on proper maintenance. However, this doesn't mean the same thing for every battery. For example, the care required for an open lead-acid battery differs significantly from that of a sealed AGM or gel model. That's why our Energic Plus experts share this professional guide on how to keep block batteries performing at their best.

The golden rule: correct charging

The importance of correct charging in battery maintenance should not be underestimated. Adhering to the best practices for charging can significantly extend the life and performance of block batteries. Some key charging instructions to take into account are:

Charge immediately: Charge the battery as soon as you’ve finished using it. Never leave a lead-acid battery in a discharged state for extended periods, as this can lead to sulfation, which reduces the battery’s capacity and lifespan.
Avoid deep discharge: Make sure that the battery’s capacity doesn’t fall below 50%, and certainly not below 20%, before recharging it.
Full charge: Always ensure that the battery is fully charged after each discharge. If the battery won’t be used for a long time, check the voltage after three months for open lead-acid batteries or after six months for gel and AGM batteries, and recharge if necessary.
No interruptions: Never interrupt the charging cycle, as this can prevent the battery from reaching its full capacity. For lead-acid batteries in particular, it can also lead to sulfation.

General periodic maintenance

The following general checks should always be performed monthly or with every charge cycle, regardless of the type of block battery (lead-acid, AGM or gel):

Visual inspection: Check the battery casing for cracks, swelling or leakage.
Check the cable connections: Ensure that the terminals are still secure, as loose terminals can cause heat and voltage drops.
Clean the housing: Keep the top of the battery clean and dry to prevent creepage currents and self-discharge.
Remove corrosion: Inspect the terminals for any white and greenish/bluish deposits. This is corrosion, which needs to be cleaned off. Start by disconnecting the battery, removing the negative pole first and then the positive one. Then, clean the terminals and poles with a wire brush. Use a battery acid cleaner and neutraliser to clean the battery cover and the area around the terminals. Avoid using excessive liquid and remove any excess cleaning product so that the battery is completely dry after cleaning. To complete the job and prevent future build-up, apply a thin layer of acid-free petroleum jelly (such as Vaseline) to the terminals before reconnecting them.

Maintaining lead-acid block batteries

In addition to the general periodic maintenance mentioned above, the following actions are explicitly required for open lead-acid block batteries (both wet and flooded):

Check the water level monthly or after every 5 to 10 charging cycles and top up if necessary. Add demineralised or distilled water to the maximum level indicated, which is usually approximately 1 cm above the battery plates. Never add acid. Also, note that topping up can only be done after the battery has been charged.
Measure the acid density 2 to 4 times a year. Use a hydrometer to take a reading from each cell. The values should be consistent and within the manufacturer's specifications. Large differences indicate problems with the cells.

Additional safety measures are required when maintaining open lead-acid batteries, as corrosive acids and explosive gases are released during charging and refilling. These types of batteries should therefore only be maintained in a well-ventilated area, and always while wearing the appropriate personal protective equipment (PPE), including safety goggles, acid-resistant gloves, and an apron.

Maintaining AGM and gel block batteries

Although these types of block batteries are considered maintenance-free, the following considerations are still required:

Do not open: Never attempt to open the battery’s valves or caps, as they are hermetically sealed.
Proper charger: Always ensure that the charger uses the correct AGM or gel charging profile to prevent overcharging and damage.
Storage: If the battery will be stored for an extended period, ensure it is fully charged beforehand. AGM and gel batteries should always be stored in a cool, dry place. Additionally, check the battery's voltage every three months and recharge it as needed.

Battery regeneration

Subjecting block batteries to a regeneration session every six months or once a year can reduce their gradual ageing and capacity loss due to sulfation. The Energic Plus battery regenerator is ideal for this purpose.

Find out even more about Energic Plus

Read some of our other blogs to find out more about industrial batteries, chargers, and advanced battery maintenance solutions from Energic Plus:

How to charge traction batteries correctly
How to discharge lead-acid batteries
How to choose the right high-quality battery charger
Things you should know before using a battery charger
Why machines should not be used while charging
Why a high-frequency charger is the better choice
How to choose between a built-in and a stand-alone charger
Save batteries with the Energic Plus battery regenerator
5 tips to maintain a starter battery
How to maintain lead-acid batteries
How to install block batteries correctly and safely
3 phases for correctly installing traction batteries
How maintenance extends the life of traction batteries

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About the authors

This blog post is brought to you by your Energic Plus team.

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