Regular inspection and proper refilling of water is one of the most important maintenance measures for lead-acid forklift batteries . Errors at this point not only lead to loss of performance and a shortened service life , but can also compromise operational safety .
In this article you will find all the important information on the subject of refilling water – compact, practical and state-of-the-art.
Do you have to refill water in every forklift battery?
No. It depends on the battery type:
- Lead-acid batteries (wet batteries) require regular distilled water because water components evaporate during the charging process.
- Gel batteries and AGM batteries are maintenance-free. Refilling them is neither possible nor necessary—and should not be attempted.
- Lithium-ion batteries also do not require water.
Conclusion: Refilling is only mandatory for classic wet batteries (lead-acid traction batteries).
When should you refill water – before or after charging?
Refilling water should always be done after the charging process is complete.
Why?
During charging, the battery heats up, the electrolyte expands, and some of the water evaporates. If you add water before charging , the electrolyte may overflow during charging, leading to corrosion, a risk of short circuits, and a loss of capacity .
Which water is suitable for forklift batteries?
Only distilled or demineralized water may be used for refilling – not tap water .
Suitable water
- Conductivity below 10 µS/cm
- Free from lime, salts and organic substances
- DIN EN ISO 3696 / Type II or III compliant
Tip: Ideally, use industrial-grade battery water that is specifically designed for traction batteries.
How do you refill water correctly?
Step-by-step instructions:
- Complete the charging process and allow the battery to cool down
- Wear personal protective equipment (safety goggles, acid-resistant gloves)
- Carefully open the cell lid
- Check the electrolyte level (it should be about 1 cm above the plates)
- Only fill distilled water up to the mark if necessary
- Close the lid and check the battery
Which accessories are useful?
The following tools are recommended for safe and efficient maintenance:
- Automatic filling systems / Fall water tanks / Central refill system (ideal for larger batteries)
- Manual filling bottle or pump canister with dosing attachment
- Water treatment plant (if you want to produce your own distilled water)
- Refractometer or level indicator to check the fill level
- Collecting tray / battery tray for protection in case of overflow
- Acid-resistant protective clothing
What happens if no water is added?
If a lead-acid battery is permanently operated with a water level that is too low, the following damage can occur:
- Sulfation of the plates
- Overheating while charging
- Reduced capacity and service life
- Irreparable cell damage
These consequences are permanent and cannot always be reversed even through regeneration.
Aquamatic: Automatic refill system for greater efficiency and safety
The use of an Aquamatic system is particularly recommended for larger forklift batteries or in multi-shift operations. This is a centrally controlled filling system that supplies all battery cells with water simultaneously via a network of hoses and valves – precisely dosed and without the risk of overfilling.
Advantages of the Aquamatic system
- Time saving when refilling
- Avoiding errors and overflow
- Optimal water levels in all cells
- Increased occupational safety through contact-free filling
- Maintenance costs are significantly reduced
The system is fed either manually via a filling bottle or automatically via a central water supply. In combination with a fill level indicator, the ideal refill time can also be reliably monitored.
HK Handels GmbH offers suitable retrofit solutions and accessories for Aquamatic systems – contact us if you would like to make your battery care more efficient and safer.
Conclusion: Proper refilling extends the life of your battery
Regular and correct refilling with distilled water is crucial for the performance and service life of your forklift battery – but only if it's a lead-acid battery . Gel and lithium-ion batteries are maintenance-free and must not be opened .
With the right accessories, expert knowledge, and a little practice, battery care can be easily and safely integrated into everyday operations. HK Handels GmbH will be happy to advise you on suitable filling systems, battery fluid, and reconditioned batteries for your needs.
