Because a battery is “only DC”, people handle it the way they would never handle a wall socket — and that misplaced comfort is where battery accidents begin. A large lead-acid battery stores enough energy to weld the spanner dropped across its terminals, holds litres of corrosive acid, and after charging breathes an ignitable gas. None of this makes it dangerous to work with; all of it makes it dangerous to be casual with. Here are the handling rules, organised by hazard.
The acid: protect, neutralise, flush
Battery electrolyte is dilute sulphuric acid — strong enough to eat cotton overalls and injure eyes (the acid guide covers what it is; this is about respecting it). Working dress: rubber or acid-resistant gloves, apron and goggles, with no exposed skin below the elbow when moving flooded cells. Keep two things permanently within reach of any battery work: a clean bottle of water for eyes, and a bucket of sodium-bicarbonate solution — about 500 grams in 5 litres of water — for neutralising spills on floors, racks and cell tops. If acid reaches skin, flush with plain water immediately and generously — ten minutes or more; for eyes, flush continuously and get medical attention without debate. Floor spills get the bicarbonate treatment; take care the solution never enters a cell through the vents, where it would neutralise the working acid itself.
The electricity: nothing metal, nothing bare
A battery cannot be switched off. Before reaching over one, remove watches, rings, bracelets and neck chains — a metal band across two terminals becomes a heating element in milliseconds. Every tool used on a battery must be insulated, and the field fix is charmingly cheap: wind PVC electrical tape over the shaft and handle of an ordinary spanner and it is battery-safe. Terminals being prepared for connection should be brushed bright and silvery with a brass brush — with the vent plugs closed so debris cannot fall in — and connections made to the recommended torque, never beyond (lead posts deform). Cable lugs landing directly on battery terminals should be lead-plated, and every cable supported so its weight never hangs on the post.
The gas: one paragraph and one link
Toward the end of charge, every lead-acid battery electrolyses some water into hydrogen and oxygen. Managed with ventilation and flame discipline it is a non-event; ignored, it is how batteries explode. The subject has its own full article — why batteries explode, and how to make sure yours doesn’t — which pairs with this one. The short version: ventilate battery areas, keep flames, sparks and smoking away, and never leave vent plugs off longer than the job requires. And yes — sealed batteries can explode too; the article explains that honestly.
Transport and lifting: the paperwork and the back
Wet, acid-filled batteries travel as classified dangerous goods — Class 8 (corrosive), UN 2794 — and the hazard label belongs on the carton, or printed on the container if batteries ship bare. Use dummy transport plugs in place of working vent plugs for the journey, and treat any sign of leakage in a consignment as a stop-and-investigate event, not a wipe-and-forget one. On the receiving end: anything over about 25 kg is a machine’s job — forklift or hoist, lifting from the BOTTOM of the cell, never by the terminals, and never gripping the container walls hard enough to distort them. Warehouses handling flooded batteries want acid-resistant flooring; sealed types relax that requirement but not the lifting rules.
Topping up: water in, acid never
Routine level maintenance means demineralised water only — acid is never added in service; low levels mean water has been lost, not acid (the acid stays unless it was spilled — a distinction the filling guide explains fully). And do not overfill: an overfilled cell breathes acid mist onto its own lid and neighbours, souring the environment around the battery, while the added water dilutes the working gravity and quietly corrupts every reading that follows. Fill between the marks, at the end of charge, and log what each cell took — a cell drinking faster than its neighbours is telling you something.
Bank discipline: the quiet safety rules
System-level safety is mostly configuration hygiene. Build banks from matched cells and keep divergent ones out — a straggler cell in a long string is both a performance and a safety liability. Verify the installation’s earthing before the bank is connected. A battery monitoring system is a worthwhile investment on large banks — continuous cell-voltage eyes catch trouble while it is still cheap. And commission with a supervised trial run against realistic load before trusting the system with real work. The installation ritual itself — racks, polarity, torque, first charge — is covered in the complete guide. Terms in the glossary; and if a battery in your care is doing something that worries you, describe it to us — worrying early is the cheapest safety equipment there is.