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ITGlossary · Protection and installation
Ambient Temperature
The surrounding temperature of the environment where UPS or batteries are installed.
Technical level:Basic
The temperature of the room where the UPS and batteries are installed directly affects their service life. Lead-acid (VRLA) batteries are designed for around 20–25 °C. A widely accepted rule of thumb says that every 10 °C above this roughly halves their life.
The UPS electronics also have operating limits, typically up to about 40 °C. Above these, the fans run constantly, efficiency drops and overtemperature protection may trip.
A common mistake is placing the UPS in a closed cabinet without ventilation, in an unconditioned storeroom or next to a heat source. If the room heats up in summer, plan for ventilation or cooling; the cost is usually lower than replacing batteries frequently.
Related terms
- Altitude DeratingReduction in the rated power of a UPS, inverter or generator when it is installed above a certain altitude, usually 1,000 metres.
- Operating Temperature and Humidity RangeThe limits of room temperature and relative humidity within which a device is designed to operate correctly.
- OverloadA condition where the connected load exceeds the UPS’s rated output in VA or W.
- Thermal RunawayAn uncontrolled temperature rise in a battery, where heat speeds up currents or reactions that produce even more heat.
- AC ChargingCharging with alternating current, where the vehicle's on-board charger converts it to direct current to fill the battery.
- Battery Service LifeThe years a battery keeps enough capacity, typically 3–5 years for VRLA at 20–25 °C, shortened by high temperatures.