VRLA vs lithium-ion UPS batteries
VRLA (valve-regulated lead-acid) batteries are cheaper to buy and work in almost every UPS, but they last a few years and age quickly in a warm room. Lithium-ion batteries cost more up front, last several times longer and weigh less, but only work in a UPS designed or approved for them. Eaton gives lithium-ion UPS batteries 10 to 15 years against 3 to 5 for lead acid [1], and APC expects most of its VRLA batteries to last three to five years [2].
Key facts
- VRLA service life: three to five years for most APC VRLA batteries[2]
- Lithium-ion service life: 10 to 15 years, against 3 to 5 for lead acid (Eaton)[1]
- Heat and VRLA: every 8 °C rise cuts VRLA life in half (APC rule of thumb)[2]
- VRLA operating range: 5 to 35 °C, with an average below 25 °C (CSB)[3]
- VRLA in storage: about 3% self-discharge per month at 25 °C (CSB)[4]
- Weight: lithium-ion about 40% lighter than comparable lead acid (Eaton)[5]
- Room temperature: 20 to 25 °C ideal for lithium-ion, and the same 0 to 40 °C maximum as lead acid (Eaton)[6]
VRLA or Lithium-Ion UPS Batteries for a Data Centre?
Sealed lead-acid (VRLA) is cheaper and fits almost every UPS: APC expects 3 to 5 years of life, halved by every extra 8 degrees of heat. Lithium-ion lasts 10 to 15 years (Eaton), weighs less and shrinks routine readings, but it only works in a UPS whose charger, battery management and firmware support it, with the maker's approval.
In this video
- 0:00 VRLA or lithium-ion UPS batteries for a data centre?
- 0:16 How long does each last?
- 0:40 What does lithium-ion change?
- 1:02 Can you switch an existing UPS to lithium?
- 1:21 Talk to Symetrix Canada
Transcript
Sealed lead-acid or lithium-ion UPS batteries for a data centre? The lead-acid kind is cheaper, and it fits almost every UPS made. Lithium-ion lasts about three times longer and weighs about 40 percent less. The catch: it only works in a UPS built for it.
How long does each last? APC expects most of its sealed lead-acid batteries to last 3 to 5 years, and every 8 degrees of extra heat cuts that in half. Eaton gives lithium-ion UPS batteries 10 to 15 years, against 3 to 5 for lead acid. CSB rates sealed lead-acid operation at 5 to 35 degrees, with the average below 25.
What does lithium-ion change? Weight comes first: Eaton puts lithium-ion batteries about 40 percent lighter than comparable lead acid, which matters in older buildings with floor limits. Maintenance changes too: a battery management system monitors the cells' temperature and voltage balance. Alarms, connections and the room temperature still need eyes.
Can you switch an existing UPS to lithium? Not as a drop-in. The charger, the battery management and the firmware all have to support the chemistry, and the maker has to approve the battery system. And a damaged or modified lithium pack is a fire risk: a swollen or hot block of either chemistry stops the job.
Not sure what your UPS takes? Symetrix Canada tests, replaces and recycles both chemistries, and tells you which one your UPS is built for. Reply and quote within 4 business hours. Call 1 (438) 800-0382. Find Symetrix Canada on the web.
Service life and what it costs over time
The purchase price is the smaller part of the comparison. A VRLA string is replaced several times over the life of a UPS frame; a lithium-ion system may last as long as the frame itself. Each VRLA replacement brings the cost of the blocks, the labour, the disposal and the risk of the swap itself. For a site that keeps its UPS for a decade or more, the total cost often favours lithium-ion even though the first invoice does not.
Heat
VRLA life falls fast with temperature: APC’s rule of thumb is that every 8 °C rise halves it [2]. A battery cabinet in a warm plant room, or a room run warmer to save on cooling, uses up VRLA life well ahead of schedule. Lithium-ion does not change the room target. Eaton gives lithium-ion and lead-acid UPS batteries the same 0 to 40 °C maximum operating range, with 20 to 25 °C as the ideal [6]. Cool the battery room for either chemistry.
Weight, space and floor loading
Eaton puts lithium-ion batteries at about 40% lighter than comparable lead acid [5]. Its lithium-ion 9PX gives more runtime in the same footprint, without external battery cabinets [7]. That matters in older buildings with floor-loading limits, in edge rooms, and anywhere a VRLA battery cabinet would take space the IT equipment needs.
Compatibility and safety
Lithium-ion is not a drop-in replacement. The UPS charger, its battery management and its firmware all have to support the chemistry, and the UPS manufacturer has to approve the battery system. Fitting lithium modules to a UPS designed for VRLA because they physically fit is not an upgrade.
Maintenance
VRLA strings need regular measurement block by block, because one weak block limits the whole string (see battery maintenance). A lithium-ion system has a battery management system that monitors cell temperature and voltage balance and can disconnect the string [8]. Alarms, connections and the room still need checking.
Standards cited
- IEEE 1188 (VRLA maintenance, as quoted by battery manufacturers)
Common questions
Is lithium-ion better than VRLA for a UPS?
It lasts longer [1] and weighs less [5], but it costs more up front and needs a UPS that supports it. For a three-phase UPS kept a decade or more, it can win on total cost, because a VRLA string is replaced several times over the life of the frame.
Can I put lithium-ion batteries in my existing UPS?
Only if the UPS manufacturer supports lithium-ion for that model, with the matching battery system and firmware.
How long do VRLA UPS batteries last?
APC expects most of its VRLA batteries to last three to five years [2], less in a warm room.
Do lithium-ion UPS batteries need maintenance?
Yes. The battery management system monitors cell temperature and voltage balance [8], but alarms, connections, firmware and the room temperature still need checking.
Sources
- Eaton, Lithium-ion UPS FAQ, FAQ
- Schneider Electric, What is the expected life of my APC UPS VRLA battery? (FA158934), FAQ answer
- CSB Energy Technology, VRLA Battery User Manual (Operation and Handling, Rev Dec 2024), operating temperature
- CSB Energy Technology, VRLA Battery User Manual (Operation and Handling, Rev Dec 2024), storage
- Eaton, Lithium-ion UPS FAQ, FAQ, rackmount installation
- Eaton, Lithium-ion UPS FAQ, FAQ, network closet temperature
- Eaton, Lithium-ion UPS FAQ, FAQ, primary benefits
- Eaton, Lithium-ion UPS FAQ, FAQ, safety
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