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ITGlossary · Batteries
Lithium-ion Battery
A rechargeable lithium-ion battery with high energy density, long life and faster charging than lead-acid batteries.
Technical level:Intermediate
UPS units and energy storage systems mainly use lithium iron phosphate (LiFePO4), considered one of the safest and most thermally stable chemistries. Compared with a VRLA lead-acid battery, it is much lighter for the same energy, withstands many times more charge-discharge cycles and is less affected by temperature.
The upfront cost is higher, but the longer life means fewer replacements. This makes it attractive for solar PV systems with daily cycling and for sites with frequent outages or limited space.
A lithium battery needs a battery management system (BMS) and a charger suited to its chemistry. Never fit one in a UPS or inverter designed only for lead-acid batteries, even if the nominal voltage looks the same.
Related terms
- OPzS / OPzV Tubular BatteryStationary 2 V lead-acid cells with tubular positive plates, flooded (OPzS) or sealed with gel (OPzV), built for a very long life.
- Equalising ChargeA controlled charge at a higher than normal voltage that brings all cells of a lead-acid battery to the same state of charge.
- Eurobat Design Life ClassesA classification of sealed lead-acid batteries by their design life on float charge at 20 °C.
- Flooded Lead-Acid BatteryA battery with liquid electrolyte and vent caps that needs regular checks and topping up with deionised water.
- GEL BatteryA sealed lead-acid battery with its electrolyte in gel form, well suited to deep and repeated discharges.
- LiFePO4 (Lithium Iron Phosphate) BatteryA lithium battery with an iron phosphate cathode, a nominal 3.2 V per cell, high thermal stability and thousands of cycles.