🔋 UPS Runtime Calculator
Calculate exact battery backup time for your UPS. Supports CCTV systems, servers, home appliances — with temperature derating, battery health, discharge curve and load management.
CCTV Tool
Discharge Curve
Load Manager
Backup Runtime
—
at full load
Total Load
—
watts connected
UPS Capacity Used
—
of rated VA
Effective Battery
—
after derating
UPS & Battery Configuration
9 Ah
Check your UPS battery label — common sizes: 7Ah, 9Ah, 12Ah, 26Ah, 42Ah, 100Ah, 150Ah
12V
1
Parallel banks multiply capacity. Series banks increase voltage (already counted in voltage selector).
100W
Sum of all connected device wattages. Use Load Manager below to calculate automatically.
90%
Most UPS units: 88–92%. Online UPS (double conversion): 94–96%.
100%
New battery = 100%. 2yr old = ~85%. 4yr old = ~70%. Below 50% — replace battery.
25°C
Battery capacity drops ~1% per °C above 25°C reference. At 40°C capacity is ~85% of rated.
80%
Sealed lead-acid: 80% max for longevity. Lithium: 90–95%. Discharging deeper shortens battery life.
Chemistry affects Peukert factor and usable capacity at different discharge rates.
1.20
Lead-acid: 1.2–1.3. Lithium: ~1.05. Higher = more capacity loss at heavy loads.
Battery Status
—
—
backup time
Battery Discharge Curve
Load Manager — Calculate total watts from connected devices
Total load: 0W
· Load factor: 0% of UPS capacity
Runtime at different load levels
Battery & UPS Tips
🌡 Temperature matters
Lead-acid batteries lose ~1% capacity per °C above 25°C. At 40°C your battery is effectively ~85% of its rated Ah — plan accordingly.
🔋 Don't over-discharge
Discharging sealed lead-acid below 20% charge frequently will shorten its life. Set UPS cutoff at 20% (80% DoD) for best longevity.
⚡ Load vs runtime
Runtime is not linear with load. At 50% load you get more than 2× the runtime vs 100% load, due to the Peukert effect in lead-acid batteries.
🔄 Battery replacement
Most sealed lead-acid UPS batteries last 2–4 years. Replace when runtime drops below 50% of original or when the battery swells/leaks.
📡 CCTV planning
A 4-camera Hikvision DVR system (DVR + 4×6W cameras) needs ~50W. A 600VA UPS with 9Ah gives ~60–80 min backup at this load.
🏠 Inverter vs UPS
UPS provides instant power (0ms switchover). Inverter has 10–20ms delay. For computers/DVRs use UPS. For fans/lights, inverter is fine.
Runtime estimates are theoretical. Actual backup time varies by battery age, temperature, load type and UPS model. Always test with your actual setup.