The electric truck driver charges and changes the battery daily. The lead-acid battery releases hydrogen (flammable from approximately 4 vol% in air) and contains corrosive sulphuric acid; lithium-ion can go into thermal runaway. Here is safe charging location, ventilation, battery replacement, eyewash and fire preparedness — the practical battery chapter behind the propulsion entry.
Introduction
On an electric truck the battery is both the energy source AND part of the counterweight. This makes daily charging and battery change a routine task — and one where most serious incidents happen when routine slips. This article goes deep into battery work itself; see the fuel article for the broader choice between electricity, gas, diesel and hydrogen.
Two battery types — two risk images
- 01Lead-acid (traction battery): robust and cheap but releases hydrogen during charging and contains liquid sulphuric acid. Often requires water top-up and good ventilation at the charging area.
- 02Lithium-ion: charges quickly, requires no water top-up and does not release hydrogen during normal charging — but the main risk is thermal runaway, a self-reinforcing, hard-to-extinguish fire.
Lead-acid: hydrogen is the fire hazard
During charging — especially towards the end and during equalisation charging — the battery splits water and releases hydrogen. Hydrogen is the lightest of all gases, collects under the ceiling and forms a flammable/explosive mixture with air from around 4 vol-% (the lower explosion limit). A spark from a switch, static electricity or a cigarette can ignite it. Therefore:
- 01The charging area must be well ventilated so hydrogen is removed at the source and below the ceiling — size the ventilation according to the charger and battery manufacturer's instructions.
- 02Open fire, spark-producing work and smoking are prohibited on and around the loading area.
- 03Open the battery compartment lid during and after charging so gas doesn't accumulate.
- 04Avoid interrupting the charging current during spark generation near the battery.
Lead acid: the acid is caustic
The electrolyte is dilute sulphuric acid, which causes serious burns on skin and especially eyes. When filling water, checking electrolyte level or any work where splashes may occur, use acid-resistant gloves and eye protection/visor, and there must be eye wash or emergency shower within reach. Also check the safety data sheet (SDS) for the specific battery.
Short circuit and arc
A traction battery can deliver extremely high current. If a tool or a watch strap is placed across the two poles, an arc forms with sparks, splashing metal and burn risk. Never place metal objects on top of a battery, remove watches and jewellery when working on batteries, and use insulated tools.
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