Your load
Enter the total power of the equipment you want to protect, in watts or VA.
For life-support or patient-connected medical equipment, check the equipment maker's UPS requirements and local medical electrical standards.
Add up the power of all the equipment you want to protect. You can find it on each device's label or datasheet. If the label shows VA, choose VA and we convert it: watts = VA × power factor.
Backup time needed
How long must the equipment keep running after the power goes off?
Options
Leave room for growth and choose a model, or let us recommend one.
All Ventrix Pro models at your load
| Model | Rating | Batteries | Load | Est. backup | Meets your target? |
|---|---|---|---|---|---|
| Ventrix Pro 1K-RT | 1 kW | 2 × 9 Ah internal | 84% | < 5 min | No, above 80% load |
| Ventrix Pro 2K-RT | 2 kW | 4 × 9 Ah internal | 42% | 14 min | No, too short |
| Ventrix Pro 3K-RT | 3 kW | 6 × 9 Ah internal | 28% | 23 min | Yes |
| Ventrix Pro 6K-RT | 6 kW | 1 pack | 14% | 55 min | Yes |
| Ventrix Pro 10K-RT | 10 kW | 1 pack | 8% | 1 h 14 min | Yes |
Ventrix Pro runtime chart
Estimated backup time at different loads for each model, using the battery condition and temperature you selected above. Cells with “—” are above the model's rating.
| Model | Batteries | 100 W | 250 W | 500 W | 750 W | 1 kW | 1.5 kW | 2 kW | 3 kW | 4 kW | 5 kW | 6 kW | 8 kW | 10 kW | Half load | Full load |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1K-RT | 2×9Ah | 1h 19m | 26m | 11m | 5m | < 5m | — | — | — | — | — | — | — | — | 11 min 500 W | < 5 min 1,000 W |
| 2K-RT | 4×9Ah | 2h 59m | 1h | 26m | 16m | 11m | 5m | < 5m | — | — | — | — | — | — | 11 min 1,000 W | < 5 min 2,000 W |
| 3K-RT | 6×9Ah | 4h 45m | 1h 39m | 42m | 26m | 18m | 11m | 6m | < 5m | — | — | — | — | — | 11 min 1,500 W | < 5 min 3,000 W |
| 6K-RT | 1×(16×7Ah) | 10+h | 3h 51m | 1h 43m | 1h 3m | 44m | 27m | 19m | 12m | 7m | < 5m | < 5m | — | — | 12 min 3,000 W | < 5 min 6,000 W |
| 10K-RT | 1×(16×9Ah) | 10+h | 5h 7m | 2h 19m | 1h 25m | 1h | 37m | 26m | 16m | 11m | 7m | 5m | < 5m | < 5m | 7 min 5,000 W | < 5 min 10,000 W |
Backup times are estimates for new, fully charged batteries at 25 °C, based on typical 12 V VRLA battery discharge data and inverter efficiency. Real runtime varies with battery age, temperature and the actual power drawn by your equipment, so allow a safety margin. Axtren recommends keeping the UPS load at or below 80% of its rating. Contact us to confirm sizing for critical sites or for longer backup times.
How is UPS backup time calculated?
The calculator adds up your equipment wattage (plus any growth margin), divides it by the UPS inverter efficiency and spreads it across the battery cells. It then reads the discharge time from typical constant-power data for 12 V VRLA batteries. More batteries or a smaller load give a longer backup time.
What is the difference between VA and watts?
VA (volt-amperes) is apparent power; watts are the real power your equipment uses. Watts = VA × power factor. Ventrix Pro UPS models have an output power factor of 1.0, so a 3 kVA model delivers up to 3,000 W.
How can I get a longer backup time?
Choose a 6K-RT or 10K-RT model and add external battery packs, or choose a larger UPS so the batteries discharge more slowly. For long-backup projects, contact Axtren sales for a sized battery configuration.
Why does battery age change the backup time?
Sealed lead-acid UPS batteries slowly lose capacity. After about three years they typically hold around 70% of their original charge, so the backup time drops. Test batteries every 6–12 months and replace them when the backup time is no longer enough.
Why should the UPS run at 80% or less?
Running below 80% leaves headroom for start-up surges and future equipment, keeps the UPS cooler and extends battery backup time.