Lithium Ion and Flywheel Backup Power vs. Lead Acid Batteries

New UPS battery solutions provide an alternative to traditional lead acid batteries

Time to replace your UPS battery? Perhaps it’s also time to learn more about the new UPS battery solutions available on the market. Compare traditional lead acid vs. lithium ion and flywheel backup power options by reviewing the information below. They are proven viable solutions and worthy of consideration when it's time to replace lead acid (VRLA and VLA) batteries.  

The most commonly utilized backup power source for uninterruptible power supplies has historically been lead acid batteries, either VRLA (valve-regulated lead acid) or VLA (vented lead acid, also referred to as wet cell or flooded). However, lead acid batteries come with inherent challenges, including relatively short life span (4-5 years), extensive maintenance requirements (semi-annually), and excessive weight & size. These in part have triggered the development of alternative energy sources for UPS battery power.

Lithium Ion Batteries

One of the most notable alternatives to lead acid is a lithium ion battery. There are various chemistries of lithium ion solutions and several make ideal UPS backup power options. Mitsubishi Electric has studied the landscape of the available emerging chemistries and confidently offers three of the best in its product offering, each possessing its own unique benefits.  When comparing a lead acid battery vs lithium ion, all three UPS battery solutions from Mitsubishi Electric offer advantages over VRLA, including extended operating time and energy density, reduced maintenance, and improved efficiency.

Learn more about lithium ion


Flywheels are protecting mission-critical applications around the globe. They have a small footprint, require very little maintenance over a 20-year operational life, can operate at elevated temperatures, are environmentally friendly and an economic alternative compared to other battery storage solutions. Up to 450KW of regulated DC power per flywheel is instantly delivered to the UPS providing backup power needed to start up and transition to the emergency generators during a utility outage. While the runtime is shorter than batteries, flywheels provide ample runtime for a seamless transfer to a facility’s generators during a power outage.

Flywheel backup power systems are frequently chosen as the energy storage device of choice for mission-critical applications including hospitals which are required to transfer to their engine-gensets within 10-seconds of a power outage.

Upgrade from lead acid to pure lead UPS batteries for enhanced performance.

Pure Lead batteries

In addition to lead acid vs. lithium ion and flywheel considerations, another option may be  upgrading to pure lead batteries.  In cases where an under five minute runtime is all that is needed, a pure lead solution can accomplish this with less cabinets and a smaller footprint than lead acid. Pure lead batteries deliver other desirable characteristics, such as prolonged lifespan, longer warranties, and higher tolerance for increased temperatures.  Of course, these more appealing features come with a higher price tag, so you will need to assess your priorities before of making a selection.