Filled with acid, emitting flammable hydrogen gas, and with exposed lead terminals capable of providing thousands of amps, batteries are dangerous. If short-circuited, they can explode. Caution should always be taken when working on or around batteries. Keep combustion sources away.
Wear protective equipment whenever the battery enclosure is open. Eye protection (goggles) and gloves (acid-resistant for flooded batteries) should be worn at all times, and an apron, arm covers, and face shield may be warranted as well. Wear long sleeves, long pants, and work boots, making sure that no bare skin is showing. In case there is any accidental contact with acid, it’s much better to end up with a hole in your clothing than a burn on your skin!
Keep baking soda, distilled water, and paper towels or rags nearby to clean up any acid spill. A small emergency eyewash bottle is prudent as well. Always wash hands after working on batteries to remove acid as well as any lead that you may have inadvertently come into contact with.
A short circuit occurs if the positive and negative of a cell, battery, or battery bank become electrically connected. This can occur through the positive and any grounded metal parts as well. During a short circuit, large amounts of the energy stored in the battery are discharged in a fraction of a second. This can explode the battery or quickly melt the terminal and whatever was causing the short, and should be avoided at all costs.
Take these precautions to minimize the chance of a short circuit:
- Use insulated tools in and around an open battery box. A dropped metal wrench can easily touch both terminals. Remember to remove rings and watches as well.
- Before making battery interconnections, make a diagram that clearly shows each connection. Double-check it to avoid making a short-circuit connection by mistake.
- Cover all terminals except the two you are working on with clean, dry cardboard or rubber mats. Double-check intended connections against your diagram.
- Only have the tool you are actively using in your hand. Place ones you are not using at that moment away from the battery enclosure.
- Make sure there are no distractions. Other people on site should stay clear.
- Never disconnect a battery cable that is under load. Be sure to switch off/disconnect all power devices (inverter, DC loads, charge controllers) before attempting to remove or loosen any cabling. Remember that even with all devices turned off or disconnected, the batteries are still live.
Clockwise from top left: Distilled water, goggles, baking soda, chemical gloves, apron with insulated wrenches on top, hydrometer, and digital meter.
Use insulated wrenches for tightening connections to avoid accidental short circuits between the battery terminals.