Lead Acid vs. Lithium-Ion

Learn more about the differences between Lead Acid and Lithium-Ion batteries to understand what factors apply to your business the most.

Lead Acid vs. Lithium-Ion

Learn more about the differences between Lead Acid and Lithium-Ion batteries to understand what factors apply to your business the most.

Benefits of Lead Acid Batteries (VRLA, VLA, Pure Lead)

Lead acid batteries have been in the UPS industry for decades in many different designs and forms, including:

Pure Lead Batteries and advanced VRLA AGM battery designs are great options for UPS applications that require increased power/energy density.


These battery designs have a larger footprint compared to most lithium-ion battery chemistries, but there are many different proprietary designs that allow for operating the batteries up to 35°C or higher with derated design life spans. 

VLA is still used in UPS designs, though its utilization has dwindled in recent years due to its large footprint, quarterly required maintenance, and high cost compared to other lead acid battery types. 


The industries that implement UPS battery systems require increasingly higher levels of power each year, thus making batteries with higher power and energy density more popular. The more traditional VRLA and VRLA Pure Lead batteries may not be able to keep up with these demands in the market compared to increasingly more efficient and power dense battery types, like lithium-ion.

Benefits of Lithium-ion Batteries

Lithium-ion batteries were quickly adopted by the critical power industry starting around 2018. Since then, many chemistries have been introduced. The five main chemistries of lithium-ion in the UPS industry currently include:

  • Lithium Manganese Oxide (LMO)
  • Lithium Iron Phosphate (LFP)
  • Lithium Nickel Manganese Cobalt Oxide (NMC)
  • Lithium Titanate (LTO)
  • Lithium Nickel Cobalt Aluminum Oxide (NCA)

These different chemistries have various materials and proprietary designs that provide unique levels of performance, power density, energy density, safety, cycle life, and design life.

In its various forms, lithium-ion achieves higher power/energy density, specific energy, and energy efficiency when comparing a lead acid battery vs lithium-ion.

Lead Acid vs Lithium-ion for UPS Applications

When evaluating a lead acid battery vs lithium-ion for UPS applications, it’s important to consider all the relevant factors and compare them to your needs. Below are comparisons between Lead Acid and Lithium-ion variations that examine energy density, maintenance, design life, cycle life & expanded application, total cost of ownership (TCO), weight, footprint, and safety.

Energy Density

When comparing a lead acid battery vs a lithium-ion battery, lithium-ion has greater energy density. With power loads in the UPS industry increasing drastically, energy-dense battery solutions are imperative.


When comparing a VRLA battery vs lithium-ion battery specifically, lithium-ion has 3-to-5 times the energy density of VRLA, delivering the equivalent amount of energy in a significantly smaller footprint, and therefore, creating more flexibility in facility installation.


For lithium-ion, the yearly maintenance typically encompasses a visual inspection of the battery racks for warranty or performance guarantee requirements.


When comparing the recommended maintenance frequency of a VRLA battery vs. lithium-ion battery, lithium-ion is once a year, while VRLA’s maintenance visit frequency is twice a year, and VLA is four times a year (quarterly).

Design Life & Battery Replacement

Design life is shorter and battery replacements are more frequent for lead acid vs. lithium-ion batteries. Most lead acid batteries must be replaced at least once during the life of a UPS and require more frequent maintenance visits.


Lithium-ion for UPS systems can last 15-20 years before reaching end-of-life (70-60% capacity), so no battery replacements are expected over the typical lifetime of the UPS.


Compare Battery Life Cycles:

  • Lithium-Ion: 15-20 years
  • Wet Cell VLA & 20-year VRLA: Up to 15 years
  • Pure Lead: Up to 7 years
  • VRLA: Every 3-5 years

Cycle Life & Expanded Application

When comparing the cycle life of a VRLA battery vs a lithium-ion battery, lithium-ion generally comes out ahead. The increase in cycle life can support a battery system's implementation in an expanded application portfolio, such as Grid Interactive UPS use cases.


This also enhances the overall design life of most lithium-ion battery systems in traditional 5-15-minute UPS mission critical applications.


Lithium-ion can be cycled 25x more than VRLA, enabling longer lifespan, frequency response, and grid stabilization capabilities. Lithium-ion batteries also enable future possible grid interactive use cases, such as peak shaving.


Peak shaving saves utility costs by supporting load at peak demand. Batteries are discharged during peak demand and recharged during lower cost periods.

Total Cost of Ownership (TCO)

A longer design life and reduced frequency of replacement help decrease TCO. As batteries age, they need to be replaced. With VRLA batteries, the average life span is 3-5 years, depending on utilization.


VRLA Pure Lead batteries last slightly longer, with some manufacturers stating 6-10-year design lives. Even though VLA has an expected design life of 15 years, its quarterly maintenance demands can drive up costs over the life of the system.


TCO is also dependent on CAPEX, OPEX, recycling payback, and footprint costs. Overall, lithium-ion has a lower TCO due to its longer design life of 15-20 years, lower frequency of replacement, lower OPEX needs, and smaller footprint.


For lithium-ion batteries, over 65% of the total cost of ownership of the UPS system is reduced by lower maintenance, no battery replacement, and lower operating costs.


VLA is extremely heavy compared to lithium-ion batteries and can take up a lot of floorspace. The design of the battery room and floor need to be able to support the heavy weight. 


VRLA and VRLA Pure Lead batteries have a lighter weight than VLA batteries but are still heavy. Conversely, lithium-ion batteries have a much lighter weight, which can lead to less costly floor designs. The reduction in weight also makes shipment and service of the batteries easier.


Lithium-ion batteries have a more favorable footprint compared to VRLA, VRLA Pure Lead, and VLA batteries. At 40-60% smaller than VRLA, lithium-ion batteries for UPS allow more floor space for revenue-generating equipment.


That advantage can lead to compact, dense floor spaces that can reduce the size and cost of a building - or allow for greater power to be installed within the same footprint. Lithium-ion batteries can support the growing need for a more power dense battery chemistry with a smaller footprint.


If improperly maintained and operated, all battery options including VLA, VRLA, Pure Lead, and lithium-ion have the potential to cause thermal runaway or other safety issues.


In addition to proper maintenance and operating conditions, it is critical to monitor and manage a battery chemistry’s operations to prevent safety risks.


Lithium-ion has a safety advantage per UL listing requirements since that technology requires a battery management system that is tailored to the specific battery chemistry and includes proprietary safety protection control measures.


VLA has a high safety rating due to the anode and cathode plates being fully submerged in an excess of liquid electrolyte, in addition to the maintenance and attention required to successfully operate a VLA battery system.

*The variety of commercial applications, including electrical vehicles and battery energy storage systems, and the need to tailor specific lithium-ion chemistries to the required use case leads to a more complex safety profile than past battery types. The safety score here represents the use of lithium-ion batteries in a UPS application using top-tier battery cells and a lithium-ion chemistry that is properly used, controlled, and maintained.



In traditional mission critical UPS applications for standby power of 5-15 minutes of runtime, a lithium-ion battery is generally on float most of the time. In this application, the battery discharges infrequently over the course of the year and limits the thermal stress in discharge and charge operations. Lithium-ion batteries have an integrated battery management system (BMS) that is specifically tailored to the chemistry and design of the battery system, offering proprietary specialized controls for charge rate, voltage, temperature, and protection settings.


This level of control and monitoring, paired with the traditional mission critical UPS application of 5-15 minutes of runtime, makes lithium-ion - in many ways - safer than VRLA and VRLA Pure Lead batteries. Lithium-ion cells that are obtained from a top-tier battery manufacturer undergo sufficient quality control procedures and meet the industry safety standards. 

Lead Acid

Lead acid batteries are on float most of the time as well, but they do not have a battery management system that controls charge, discharge, and temperature protections of the system. Lead acid systems rely on third-party battery monitoring software platforms that utilize generalized predictive data models and algorithms.


However, the lead acid battery monitoring and the thermal runaway protection device is not specifically designed for the battery and does not have the level of control and protection a lithium-ion battery management system can provide.

Battery Upgrades

We're Lithium ReadyTM. Are You?


Lithium-ion is the increasingly popular and advantageous alternative UPS battery solution to traditional lead acid models.


The mission critical industry is moving towards lithium-ion batteries for many reasons that support a lower TCO, such as reduced maintenance and longer operating life.


When it’s time for you to upgrade your UPS battery, Mitsubishi Electric can help you weigh between lead acid vs. lithium-ion and pick the best option for your critical power system.