Batteries - Safety Instructions

The applications described in this chapter use DC voltage. DC -Direct Current -has a polarity. Confusing the polarity will very likely immediately and irreversibly damage your equipment! I'll assume that you can handle a digital multimeter (DMM) to check out polarity. The DC voltages that are used in the described applications are not harmful when you touch conductors -but big lead-acid batteries can provide very high currents. A cable that creates a short between the terminals will immediately start to glow and burn its insulation. To prevent fire, there must be a fuse near the positive terminal of the battery at all times. That way the fuse will burn out before the cables do.

Lead acid batteries contain sulfuric acid that can cause severe burns. They release hydrogen when they are charged or have a short between terminals even when they are the sealed acid type. Proper venting is necessary to prevent explosions, especially if the batteries are of the flooded cell acid type. It's a good idea to protect your eyes with safety glasses when handling these batteries. I once met a battery “expert” that blew off three batteries during his career. Lead is toxic -make sure you dispose of worn out batteries properly. This may be difficult in countries that don't have any recycling infrastructure.