Lead Acid batteries are used in UPS applications. This is primarily because of cost. Newer technologies such Lithium-ion are not considered generally due to their high cost (approx.3x). Li-ion and other technologies under development for renewable energy application may become viable at some point, but not in the near future.
“In South Africa, winter is usually characterised by power supply issues. Couple this fact with a power grid that for multiple reasons, is not performing, and questions abound. Will power supply utility companies cope? How bad will the rolling blackouts be? An uninterruptible power supply (UPS) systems with a reliable battery backup are essential to any business or enterprise with a need to remain productive.”