Always

When handling batteries wear chemical resistant gloves, apron, boots, and safety goggles
Keep sources of ignition such as flames, sparks, electrical tools, hot objects and cell phones away from batteries that are being charged or have been recently charged,
Remove all metal objects from pockets that could bridge across battery terminals,
Charge batteries in well ventilated rooms designated for battery charging,
Whenever moving or lifting use only non-sparking lifting tools,
Wash hands thoroughly after working with batteries,
Switch off the charger before disconnecting the charging leads from the battery,
Make certain the charging leads are securely clamped in position before switching on the charger,
Allow a vented battery to stand for at least 20 minutes after disconnecting it from the charger before installing it in the vehicle