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ITGlossary · Batteries
Fast Charging
A charging method that restores battery capacity quickly without damage by controlling current, voltage and temperature.
Technical level:Intermediate
The charger delivers a higher current at the start of charging and reduces it gradually as the battery fills, while constantly monitoring voltage and temperature. For a UPS this means runtime is restored faster after an outage, which matters in areas with frequent or back-to-back power cuts.
The speed depends on the battery chemistry and the charger current. Lead-acid (VRLA) batteries accept a limited charging current, while lithium batteries charge noticeably faster. Models designed for external battery packs often have a stronger charger for this reason.
A common mistake is adding extra batteries without checking the charger. Recharge time grows in proportion to the total capacity and can stretch to many hours.
Related terms
- Battery Charging CurrentThe amount of current supplied to charge a battery, regulated by the UPS system.
- DC ChargingFast charging in which the station converts power to direct current and feeds it straight into the battery, typically at 50 to 350 kW.
- CCS2 (Combined Charging System)The European connector standard that adds two DC pins below a Type 2 plug, allowing fast DC charging through the same vehicle inlet.
- 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.
- Smart ChargingCharging that adapts current and voltage to battery condition and temperature, or an EV charger’s power to the site’s available capacity.
- C-rateThe charge or discharge current expressed as a multiple of battery capacity, e.g. 1C for a 100 Ah battery means 100 A.