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. Although these UPS battery solutions may currently be used less frequently for backup power, 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.

Advanced battery technologies available for new and retrofit UPS solutions

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 certainly not a new technology and like anything else, they have advantages and disadvantages.  On the plus side, they have a small footprint, require very little maintenance, and are an economic alternative compared to other solutions.  On the minus side, they have a relatively short runtime, and therefore have a more limited scope of applications.  However, they represent an attractive solution for industries desiring the absence of potentially hazardous materials or those comfortable with runtimes of 60 seconds or less.

Flywheel backup power is frequently chosen as the energy storage device of choice for hospitals due to the absence of (spillable) lead acid.

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.