PowerSupplyStatus

Info

PowerSupplyStatus is a constant enum that represents the current state of the external power supply (AC adapter). It is part of the PowerInfo interface and is returned by getPowerInfo() as well as emitted with every PowerMonitor event. Use it to determine whether the device is connected to a reliable power source.

Values

Value	Name	Description
0	NotPresent	No external power supply detected (e.g., running on battery with no charger)
1	Adequate	External power supply is connected and providing sufficient power
2	Inadequate	External power supply is connected but cannot deliver enough current
3	Unknown	Power supply status cannot be determined

Note

Because PowerSupplyStatus is a TypeScript const enum, its values are inlined at compile time. In JavaScript, you must compare against the raw numeric values (0, 1, 2, 3) unless you access the enum through the TypeScript compilation output.

Usage

PowerSupplyStatus is not something you query independently. It always appears as the powerSupplyStatus field inside a PowerInfo object. You obtain it in two ways:

1. Snapshot query -- call getPowerInfo() to read the current status once.
2. Real-time monitoring -- subscribe to PowerMonitor events; every event callback receives a PowerInfo object containing this field.

The most common pattern is checking powerSupplyStatus to decide whether to warn the user about an unreliable charger or to throttle power-hungry features.

Tips

Combine powerSupplyStatus with BatteryStatus and isCharging for a full picture. For example, Adequate + isCharging === false + remainingChargePercent === 100 means the battery is fully charged and the charger is still plugged in.

Example

TypeScript

import { getPowerInfo, PowerSupplyStatus } from '@eisland/windows-power-helper';

// Query the current power info snapshot
const info = getPowerInfo();

if (info) {
  // Check if the charger is connected but underpowered
  if (info.powerSupplyStatus === PowerSupplyStatus.Inadequate) {
    console.warn('Charger is connected but cannot supply enough power');
  }

  // Check if no external power is present
  if (info.powerSupplyStatus === PowerSupplyStatus.NotPresent) {
    console.log('Running on battery only');
  }

  // Check if power supply is normal
  if (info.powerSupplyStatus === PowerSupplyStatus.Adequate) {
    console.log('External power is connected and adequate');
  }
}

JavaScript

const { getPowerInfo } = require('@eisland/windows-power-helper');

// Query the current power info snapshot
const info = getPowerInfo();

if (info) {
  // In JS, const enum values are inlined as numbers at compile time.
  // Compare against the raw numeric value: Inadequate = 2
  if (info.powerSupplyStatus === 2) {
    console.warn('Charger is connected but cannot supply enough power');
  }

  // NotPresent = 0
  if (info.powerSupplyStatus === 0) {
    console.log('Running on battery only');
  }

  // Adequate = 1
  if (info.powerSupplyStatus === 1) {
    console.log('External power is connected and adequate');
  }
}

Notes

Note

The Inadequate status typically appears when a USB-C charger or docking station is connected but cannot deliver sufficient wattage for the device's current load. This is common with low-wattage phone chargers plugged into laptops.

Note

On desktop machines without a battery, powerSupplyStatus is usually Adequate as long as the system is running on mains power. However, on UPS-backed systems, it may temporarily read Inadequate or NotPresent during a power outage.

Tips

If you only need a simple "is the charger plugged in?" check, use the isOnAcPower boolean from PowerInfo instead of comparing powerSupplyStatus. The enum gives you finer-grained control when the distinction between Adequate and Inadequate matters for your feature.

Danger Avoidance

Caution

Do not assume PowerSupplyStatus.Adequate (value 1) means the battery is charging. The charger can be adequate yet the battery may already be full (isCharging === false). Always check isCharging separately if you need to know whether energy is actively flowing into the battery.

Caution

When using JavaScript (not TypeScript), never import the enum name PowerSupplyStatus expecting it to be a runtime object. Because it is a const enum, TypeScript erases it during compilation. You must compare against the raw numeric values (0, 1, 2, 3) directly, or use the TypeScript compiler's --preserveConstEnums flag to emit a runtime object.