The lead acid battery works well at cold temperatures and is superior to lithium-ion when operating in sub-zero conditions. Lead acid batteries can be divided into two main classes: vented lead acid batteries (spillable) and valve regulated lead acid (VRLA) batteries (sealed or non-spillable). 2. Vented Lead Acid Batteries
Acid burns to the face and eyes comprise about 50% of injuries related to the use of lead acid batteries. The remaining injuries were mostly due to lifting or dropping batteries as they are quite heavy. Lead acid batteries are usually filled with an electrolyte solution containing sulphuric acid.
2. Vented Lead Acid Batteries Vented lead acid batteries are commonly called “flooded”, “spillable” or “wet cell” batteries because of their conspicuous use of liquid electrolyte (Figure 2). These batteries have a negative and a positive terminal on their top or sides along with vent caps on their top.
Vented lead acid batteries vent little or no gas during discharge. However, when they are being charged, they can produce explosive mixtures of hydrogen (H2) and oxygen (O2) gases, which often contain a mist of sulphuric acid. Hydrogen gas is colorless, odorless, lighter than air and highly flammable.
Vented lead acid: This group of batteries is “open” and allows gas to escape without any positive pressure building up in the cells. This type can be topped up, thus they present tolerance to high temperatures and over-charging. The free electrolyte is also responsible for the facilitation of the battery’s cooling.
3. Valve Regulated Lead Acid Batteries (VRLA) Valve regulated lead acid (VRLA) batteries, also known as “sealed lead acid (SLA)”, “gel cell”, or “maintenance free” batteries, are low maintenance rechargeable sealed lead acid batteries. They limit inflow and outflow of gas to the cell, thus the term “valve regulated”.