Most mainstream UPS (Uninterruptible power supply) vendors will be releasing Lithium Ion (Li-Ion) batteries in their products in the coming months (This article dated April 2018).

What are the features and differences of Lithium Ion (Li-Ion) over traditional Sealed Lead-Acid (SLA) battery currently used in UPS systems? This FAQ will help you to understand the new technology and where it may help you.

Why Li-Ion batteries in UPS now?

Rechargeable Li-Ion are already available with cell phones, computers, power packs and power tools for a number of years, but only recently have had the right balance of price, energy density, power, safety, and reliability for static UPS applications.

How are they different?

Li-Ion have a number of advantages over traditional batteries such as:

  • Longer lifespan 10-15 years vs 4-6 years for SLA
  • More energy density, meaning more runtime for less foot print. Around 3 times more energy per kilogram
  • More charge discharge cycles for a longer lifespan. Around 10 times more.
  • Quicker recharge time. Around 4 times faster

But like with everything, there are some disadvantages:

  • Higher initial CAPEX, that is they cost more. At this stage we are estimating around 2-3 times more for the batteries.

Can I use Li-Ion batteries with my existing UPS?

Only if the UPS manufacturer says that a specific Li-ion battery is compatible. Most offerings we have seen for small to medium sized installations (1-20KVA) are assuming a full replacement of the UPS.

Do I need to cool them?

Both SLA and Li-Ion batteries will see a degradation in cycle life as the temperature rises. However, in general, li-ion service life is less affected by higher temperatures. Many of the li-ion batteries being used in UPSs are designed for higher average temperatures (e.g. 40°C versus 25°C)

Are Li-Ion batteries safe?

All batteries, regardless of type, store energy, so if a battery is mishandled (thrown in a fire or over charged) there is the potential of a hazard.

Li-Ion batteries have had some bad experiences in the past, but great progress has been made in the chemistry changes, packaging, manufacturing processes and materials. This mean they are comparable to SLA batteries for safety.

As to whether the battery materials are hazardous, the US Government considers them not to be hazardous and, therefore, is safe for disposal in landfills

What is the TCO proposition?

If looking at the TCO (Total Cost of Ownership) Li-Ion batteries are a compelling option to consider.

If you consider the full potential service life, advantages include:

  • Doubling your UPS battery lifecycle, meaning less battery service calls
  • Reducing battery weight by 30%
  • Lowering your TCO by up to 35%


What do we recommend – Li-Ion or SLA?

As an experienced supplier and installer of UPS solutions, we provide the following recommendations on Li-Ion batteries depending on your requirement.

Requirement 1 – What is the desired total life of the UPS solution?

If you require an easier to manage longer life span on your UPS, consider Li-Ion. Maybe this is a remote site where you want a set and forget? Or you are protecting equipment that also has a 10-year life cycle.

Alternatively, if you are not too concerned on the TCO but more the CAPEX, the SLA batteries are still a viable option. Maybe you refresh your equipment every 3-5 years, so the UPS refresh cycle will match the equipment it is protecting.

Requirement 2 – Do the LI-Ion benefits match a particular business problem?

If you require a small footprint, reduced weight, greater charge cycles, quicker charge times and are happy to pay a premium then Li-Ion may well be the right solution for you.

Otherwise we see that SLA batteries will still be a viable option for at least the next few years.


Li-Ion batteries are coming and have significant benefits for UPS solutions for both Total Cost of Ownership and functionality.