Electrical reference chart
UPS Backup Time Chart
Use this worksheet after the calculator result to record UPS VA, watts, load watts, power factor, battery string, usable Wh, aging factor, temperature, and screened runtime.
Quick reference table
A UPS runtime chart is a calculator-led planning worksheet. For example, a 2.4 kWh usable battery at a 1,000 W load gives about 144 minutes before derating. Record VA, watts, battery age, temperature, and transfer plan before IT or facility review.
UPS runtime worksheet
| Item | Record from calculator | Follow-up |
|---|---|---|
| UPS rating | VA and watt rating | Confirm topology and nameplate |
| Load | Watts, VA, power factor | Separate critical and noncritical loads |
| Battery | Voltage, Ah, count, aging factor | Verify battery tray and replacement status |
| Runtime | Screened minutes and target | Compare with shutdown or generator plan |
UPS runtime operations review
| Operations item | Record on worksheet | Why it changes the runtime decision |
|---|---|---|
| Load tier | Critical servers, network, controls, optional loads | Runtime target should follow shutdown priority |
| Battery condition | Age, test date, replacement status, temperature | Old or hot batteries rarely match nameplate runtime |
| Transfer path | Generator handoff, ATS, shutdown script, alarm | Runtime needs an action before batteries deplete |
| Load growth | Spare capacity, planned racks, future VA/watts | A UPS that works today may miss the next load step |
How to use this chart
Record UPS nameplate
Write VA rating, watt rating, topology, battery bus voltage, and battery string data.
Document the load
Record measured watts, VA, power factor, critical load list, and target runtime.
Route maintenance review
Use the worksheet to assign battery replacement, load shedding, or shutdown-plan follow-up.
Formula basis
UPS runtime minutes = usable battery Wh / load watts x 60.
- Usable battery Wh is the energy available after efficiency, aging, temperature, and discharge factors.
- Load watts are the real-power load on the UPS.
- UPS VA and watt ratings must both be checked against the connected load.
- Battery string details define voltage, Ah, and parallel capacity.
Worked examples
Server room UPS record
Record UPS VA, watt rating, connected load, battery string voltage, Ah, aging factor, runtime, required runtime, and maintenance follow-up.
Network closet runtime triage
Keep switch watts, router watts, optional PoE load, battery age, room temperature, shutdown target, and generator transfer note in one runtime worksheet.
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Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.