Flooded lead-acid batteries lose water every time they charge, and what you top them up with decides how long they last. Demineralised water is the standard choice for forklift, truck and standby batteries.
Why tap water is the wrong choice
Tap water carries calcium, magnesium, sodium and chlorides. When a battery cell loses water, those minerals stay behind, and every top-up adds more. Over time they can coat the plates and interfere with charging, which shortens battery life. Demineralised water has almost nothing dissolved in it, so there is nothing to build up.
Demineralised, deionised or distilled?
For battery top-ups they do the same job. Demineralised and deionised (DI) water have the minerals removed without boiling, which makes them practical in drums and IBCs. Distilled water is boiled and condensed. Check your battery maker's recommendation and use whichever it names.
Topping up safely
- Top up after charging, not before, unless the plates are exposed.
- Fill to the level the battery maker sets, usually just above the separators. Do not overfill.
- Use a clean, dedicated jug or a battery watering gun labelled for demineralised water only.
- Wear eye protection and gloves: battery electrolyte is acidic.
Which pack size suits a battery room
A workshop with a few batteries usually suits a 20 L drum. A forklift fleet or battery room topping up every week is better off with a 200 L drum or a 1,000 L IBC, which costs about half as much per litre as 20 L drums. We deliver IBCs by tailgate truck and take the empty back free.
See demineralised water prices and sizes, IBC and bulk supply or the spec sheet.