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.
Sulphuric acid electrolyte spilled from lead acid batteries is corrosive to skin, affects plant survival and leaches metals from other landfilled garbage. Therefore, lead acid batteries are considered as hazardous waste and shall not be placed into regular garbage.
However, due to the corrosive nature the elecrolyte, all batteries to some extent introduce an additional maintenance component into a PV system. Lead acid batteries typically have coloumbic efficiencies of 85% and energy efficiencies in the order of 70%.
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”.
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.