A flooded lead-acid traction battery that is properly maintained delivers the service life you paid for. One that is not can fail in half the time, and almost always for reasons that were preventable.
Get Free Quotes 👑This is the single most important rule and the one most often broken. Electrolyte expands during charging. If you fill to the correct level before charging, the expansion pushes acid out of the vents, which damages the battery, corrodes the tray and the truck, and leaves the cell short of acid afterward. Always water after a full charge has completed, when the level is at its highest and stable.
Fill only to the level indicator in each cell, typically a split ring or fill well. Overfilling causes the same acid overflow as watering at the wrong time. Underfilling exposes the plates, and a plate that has been exposed to air is permanently damaged. Use distilled or deionized water only, because tap water carries minerals that contaminate the electrolyte and shorten battery life. Never add acid to a cell, only water.
Most flooded traction batteries need watering roughly weekly under normal single-shift use, but the real interval depends on age, temperature, and charging. Check a few representative cells rather than guessing. A sudden increase in water consumption usually means overcharging, and that is worth investigating because overcharging damages the battery while it is also eating your maintenance time. Single-point watering systems reduce the labor substantially and remove most of the room for error.
A film of acid and dirt across the top of a battery conducts electricity between terminals and creates a slow self-discharge path. It also corrodes connectors and the tray. Clean the top with a neutralizing solution of baking soda and water, keeping it out of the cells, then rinse and dry. Check terminals and intercell connectors for corrosion and looseness while you are there, since a loose connection generates heat and voltage drop.
A hydrometer reading of specific gravity is the most direct measure of a flooded cell state of charge and health. Take readings on a fully charged battery for a meaningful comparison, and read across all cells rather than one. What matters most is the spread: cells that drift apart indicate the battery is losing balance, and the weakest cell will limit the whole unit. Record the readings over time, because the trend tells you more than any single measurement.
Flooded lead-acid batteries need a periodic equalizing charge, a controlled overcharge that brings all cells to a common state and reverses some sulfation. Most manufacturers specify roughly weekly. Equalize according to the manufacturer procedure rather than improvising, because excessive equalizing is itself a form of overcharge and causes water loss and plate damage.
Running a lead-acid battery down below about twenty percent remaining capacity on a regular basis permanently reduces the number of cycles it will deliver. If trucks routinely run flat before shift end, the battery is undersized for the duty or the charge plan is wrong, and no amount of maintenance will compensate. Operators should be trained to swap or charge before the battery gets deeply discharged rather than running it to the warning.
Battery electrolyte is sulfuric acid and charging produces hydrogen gas. Wear eye protection, face protection and acid-resistant gloves when watering or cleaning. Keep flames and smoking away from the charging area. Remove metal jewelry, because dropping a wrench or a watch across terminals produces an arc flash. Know where the eyewash and emergency shower are before you need them, and keep a neutralizing agent available for spills.
Lithium iron phosphate batteries need no watering, no equalizing, and no specific gravity testing, and they do not vent hydrogen in normal operation. Maintenance comes down to keeping terminals and connections clean and tight, keeping the battery within its rated temperature range, and attending to battery management system faults rather than ignoring them. The maintenance labor saving is one of the main reasons operations switch.
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Always after a full charge. Electrolyte expands while charging, so filling beforehand pushes acid out of the vents, damages the battery and tray, and leaves the cell short of acid afterward.
Distilled or deionized water only. Tap water carries minerals that contaminate the electrolyte and shorten battery life. Never add acid to a cell, only water, and fill only to the level indicator.
Roughly weekly under normal single-shift use, though it varies with age, temperature and charging. A sudden increase in consumption usually means overcharging and is worth investigating, since that damages the battery too.
It measures each cell state of charge and health. Read all cells on a fully charged battery and watch the spread, since cells drifting apart means the battery is losing balance and the weakest cell limits the whole unit.
Avoid going below about twenty percent remaining capacity on lead-acid as a routine, since that permanently reduces cycle life. Trucks running flat before shift end usually mean the battery is undersized or the charge plan is wrong.
Eye and face protection and acid-resistant gloves. Keep flames and smoking away, remove metal jewelry to avoid arc flash across terminals, and know where the eyewash and emergency shower are before starting.