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ITGlossary · Batteries
Hot-swappable Batteries
Batteries that can be replaced without turning off the UPS or disconnecting the load.
Technical level:Intermediate
In these UPS units the batteries sit in a drawer or plug-in pack, accessible from the front or rear. A technician removes the old pack and fits the new one while the UPS keeps supplying the load from the mains, with no need to shut down servers or other equipment.
This matters in installations that run around the clock, where every planned shutdown has a cost. It also reduces the time to restore service (MTTR) when a battery fails.
Bear in mind that during the swap the load is not protected against a power cut, since no battery is available. Carry out the replacement at a low-risk time, and always change the whole set with batteries of the same type and capacity.
Related terms
- User-Replaceable BatteriesUPS batteries that users can safely replace on their own, without needing a technician.
- Fast ChargingA charging method that restores battery capacity quickly without damage by controlling current, voltage and temperature.
- Battery Management System (BMS)A system that monitors and manages the performance, health, and charging of batteries.
- Deep-Cycle BatteryA battery designed to be discharged deeply and recharged again and again without wearing out quickly.
- Depth of Discharge (DoD)The share of a battery's capacity that has been drawn in a discharge, where 100% means fully discharged.
- 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.