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Battery and fire safety
Lithium, lead-acid and what burns.
Lithium, lead-acid and what burns.
A battery stores a great deal of energy and will release it as fast as the circuit lets it. Nothing in the battery limits a short circuit, so the wiring is the only limit: it can glow, melt its insulation and start a fire. Add the chemistry (acid, explosive gas, thermal runaway) and a battery deserves respect even at 12 V.
A 12 V battery can deliver hundreds of amps or more into a short. It is the short that is dangerous, not the shock from touching the terminals. Keep metal tools and jewelry away from terminals, and cover them.
The fuse protects the wire, so it goes in the positive lead as close to the battery as practical. A fuse at the radio leaves the whole cable unprotected. Size it to the wire's rating, not the radio's appetite, and use a fuse rated for DC and for the very large fault current a big battery can deliver. See Wire gauge and fusing.
| Type | Main hazards | Precautions |
|---|---|---|
| Flooded lead-acid | hydrogen gas while charging, which can explode; corrosive acid | ventilate; no sparks or flames; eye protection |
| Sealed lead-acid (AGM, gel) | valves can vent gas if overcharged | correct charger; do not charge a swollen case |
| Lithium iron phosphate | more stable, but still burns if shorted, overcharged or crushed | pack with a battery management system (BMS) |
| Other lithium-ion and LiPo | thermal runaway: overheating, venting, hard-to-extinguish fire | protection circuit; never charge damaged cells |
In thermal runaway, a cell's own heat triggers reactions that make more heat, and it can spread to neighboring cells. Causes include overcharging, a short, physical damage and high temperatures.
Overloaded cords and power strips, amplifier vents blocked by clutter, hot dummy loads, power resistors and soldering irons all start fires. Keep a smoke alarm in the shack and a suitable fire extinguisher within reach. Never use water on burning electrical equipment: cut the power first if you can do so safely.
Run a generator outdoors, away from doors and windows, with a carbon monoxide alarm indoors. Let it cool before refueling, and store fuel away from it.