feat: add multi-battery monitoring

- Report battery data for individual devices
- Select a representative battery for legacy fields and alerts
- Average named battery data independently
- Display multiple batteries in system charts
- Add cross-platform coverage and transport tests

internal/alerts/alerts.go

@@ -55,6 +55,7 @@ type SystemAlertStats struct {
 	Temperatures map[string]float32            `json:"t"`
 	LoadAvg      [3]float64                    `json:"la"`
 	Battery      [2]uint8                      `json:"bat"`
+	Batteries    map[string]uint8              `json:"bats"`
 	ExtraFs      map[string]SystemAlertFsStats `json:"efs"`
 }
 

internal/alerts/alerts_system.go

@@ -63,7 +63,7 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 		case "GPU":
 			val = data.Info.GpuPct
 		case "Battery":
-			if data.Stats.Battery[0] == 0 {
+			if !hasRepresentativeBattery(data.Stats.Battery, data.Stats.Batteries) {
 				continue
 			}
 			val = float64(data.Stats.Battery[0])
@@ -167,6 +167,7 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 		stat := systemStats[i]
 		// subtract 10 seconds to give a small time buffer
 		systemStatsCreation := stat.Created.Time().Add(-time.Second * 10)
+		stats = SystemAlertStats{}
 		if err := json.Unmarshal(stat.Stats, &stats); err != nil {
 			return err
 		}
@@ -235,6 +236,9 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 				}
 				alert.val += maxUsage
 			case "Battery":
+				if !hasRepresentativeBattery(stats.Battery, stats.Batteries) {
+					continue
+				}
 				alert.val += float64(stats.Battery[0])
 			default:
 				continue
@@ -297,6 +301,10 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 	return nil
 }
 
+func hasRepresentativeBattery(legacy [2]uint8, batteries map[string]uint8) bool {
+	return legacy != [2]uint8{} || len(batteries) > 0
+}
+
 func (am *AlertManager) sendSystemAlert(alert SystemAlertData) {
 	// log.Printf("Sending alert %s: val %f | count %d | threshold %f\n", alert.name, alert.val, alert.count, alert.threshold)
 	systemName := alert.systemRecord.GetString("name")

internal/alerts/alerts_system_test.go

@@ -199,7 +199,7 @@ func TestSystemAlertsOneMin(t *testing.T) {
 	testOneMinuteSystemAlert(t, "LoadAvg1", 4, setLoadAvgAlertValue, [3]float64{4.1, 0, 0}, [3]float64{3.9, 0, 0})
 	testOneMinuteSystemAlert(t, "LoadAvg5", 4, setLoadAvgAlertValue, [3]float64{0, 4.1, 0}, [3]float64{0, 3.9, 0})
 	testOneMinuteSystemAlert(t, "LoadAvg15", 4, setLoadAvgAlertValue, [3]float64{0, 0, 4.1}, [3]float64{0, 0, 3.9})
-	testOneMinuteSystemAlert(t, "Battery", 20, setBatteryAlertValue, [2]uint8{19, 0}, [2]uint8{21, 0})
+	testOneMinuteSystemAlert(t, "Battery", 20, setBatteryAlertValue, [2]uint8{0, 1}, [2]uint8{21, 0})
 }
 
 func TestSystemAlertsTwoMin(t *testing.T) {

internal/entities/system/system.go

@@ -34,6 +34,7 @@ type Stats struct {
 	MaxNetworkRecv float64             `json:"nrm,omitempty" cbor:"-"`
 	Temperatures   map[string]float64  `json:"t,omitempty" cbor:"20,keyasint,omitempty"`
 	Fans           map[string]uint16   `json:"f,omitempty" cbor:"36,keyasint,omitempty"`
+	Batteries      map[string]uint8    `json:"bats,omitempty" cbor:"37,keyasint,omitempty"`
 	ExtraFs        map[string]*FsStats `json:"efs,omitempty" cbor:"21,keyasint,omitempty"`
 	GPUData        map[string]GPUData  `json:"g,omitempty" cbor:"22,keyasint,omitempty"`
 	// LoadAvg1       float64             `json:"l1,omitempty" cbor:"23,keyasint,omitempty"`
@@ -43,7 +44,7 @@ type Stats struct {
 	MaxBandwidth [2]uint64 `json:"bm,omitzero" cbor:"-"`                   // [sent bytes, recv bytes]
 	// TODO: remove other load fields in future release in favor of load avg array
 	LoadAvg           [3]float64           `json:"la,omitempty" cbor:"28,keyasint"`
-	Battery           [2]uint8             `json:"bat,omitzero" cbor:"29,keyasint,omitzero"`    // [percent, charge state, current]
+	Battery           [2]uint8             `json:"bat,omitzero" cbor:"29,keyasint,omitzero"`    // [percent, charge state]
 	NetworkInterfaces map[string][4]uint64 `json:"ni,omitempty" cbor:"31,keyasint,omitempty"`   // [upload bytes, download bytes, total upload, total download]
 	DiskIO            [2]uint64            `json:"dio,omitzero" cbor:"32,keyasint,omitzero"`    // [read bytes, write bytes]
 	MaxDiskIO         [2]uint64            `json:"diom,omitzero" cbor:"-"`                      // [max read bytes, max write bytes]

internal/entities/system/system_test.go

@@ -0,0 +1,37 @@
+package system
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/fxamacker/cbor/v2"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestStatsBatteryTransport(t *testing.T) {
+	stats := Stats{Battery: [2]uint8{0, 1}, Batteries: map[string]uint8{"Primary": 0, "Mouse": 75}}
+
+	jsonData, err := json.Marshal(stats)
+	require.NoError(t, err)
+	var jsonPayload map[string]any
+	require.NoError(t, json.Unmarshal(jsonData, &jsonPayload))
+	assert.Equal(t, []any{float64(0), float64(1)}, jsonPayload["bat"])
+	assert.Equal(t, map[string]any{"Primary": float64(0), "Mouse": float64(75)}, jsonPayload["bats"])
+
+	cborData, err := cbor.Marshal(stats)
+	require.NoError(t, err)
+	var decoded Stats
+	require.NoError(t, cbor.Unmarshal(cborData, &decoded))
+	assert.Equal(t, stats.Battery, decoded.Battery)
+	assert.Equal(t, stats.Batteries, decoded.Batteries)
+}
+
+func TestStatsLegacyBatteryPayload(t *testing.T) {
+	data, err := json.Marshal(Stats{Battery: [2]uint8{50, 4}})
+	require.NoError(t, err)
+	var payload map[string]any
+	require.NoError(t, json.Unmarshal(data, &payload))
+	assert.Contains(t, payload, "bat")
+	assert.NotContains(t, payload, "bats")
+}

internal/records/records.go

@@ -186,6 +186,9 @@ func AverageSystemStatsSlice(records []system.Stats) system.Stats {
 
 	// necessary because uint8 is not big enough for the sum
 	batterySum := 0
+	batteryCount := 0
+	batterySums := make(map[string]uint64)
+	batteryCounts := make(map[string]uint64)
 	// accumulate per-core usage across records
 	var cpuCoresSums []uint64
 	// accumulate cpu breakdown [user, system, iowait, steal, idle]
@@ -232,8 +235,15 @@ func AverageSystemStatsSlice(records []system.Stats) system.Stats {
 		for i := range stats.DiskIoStats {
 			sum.DiskIoStats[i] += stats.DiskIoStats[i]
 		}
-		batterySum += int(stats.Battery[0])
-		sum.Battery[1] = stats.Battery[1]
+		if hasBattery(stats.Battery, stats.Batteries) {
+			batterySum += int(stats.Battery[0])
+			batteryCount++
+			sum.Battery[1] = stats.Battery[1]
+		}
+		for name, percent := range stats.Batteries {
+			batterySums[name] += uint64(percent)
+			batteryCounts[name]++
+		}
 
 		// accumulate per-core usage if present
 		if stats.CpuCoresUsage != nil {
@@ -379,7 +389,15 @@ func AverageSystemStatsSlice(records []system.Stats) system.Stats {
 	sum.LoadAvg[2] = twoDecimals(sum.LoadAvg[2] / count)
 	sum.Bandwidth[0] = sum.Bandwidth[0] / uint64(count)
 	sum.Bandwidth[1] = sum.Bandwidth[1] / uint64(count)
-	sum.Battery[0] = uint8(batterySum / int(count))
+	if batteryCount > 0 {
+		sum.Battery[0] = uint8(batterySum / batteryCount)
+	}
+	if len(batterySums) > 0 {
+		sum.Batteries = make(map[string]uint8, len(batterySums))
+		for name, total := range batterySums {
+			sum.Batteries[name] = uint8(total / batteryCounts[name])
+		}
+	}
 
 	// Average network interfaces
 	if sum.NetworkInterfaces != nil {
@@ -467,6 +485,10 @@ func AverageSystemStatsSlice(records []system.Stats) system.Stats {
 	return sum
 }
 
+func hasBattery(legacy [2]uint8, batteries map[string]uint8) bool {
+	return legacy != [2]uint8{} || len(batteries) > 0
+}
+
 // Calculate the average stats of a list of container_stats records
 func (rm *RecordManager) AverageContainerStats(db dbx.Builder, records RecordIds) []container.Stats {
 	allStats := make([][]container.Stats, 0, len(records))

internal/records/records_averaging_test.go

@@ -602,6 +602,28 @@ func TestAverageSystemStatsSlice_BatteryLastChargeState(t *testing.T) {
 	assert.Equal(t, uint8(0), result.Battery[1]) // last record's charge state
 }
 
+func TestAverageSystemStatsSlice_BatteriesIndependentSamples(t *testing.T) {
+	input := []system.Stats{
+		{Battery: [2]uint8{80, 4}, Batteries: map[string]uint8{"Primary": 80, "Mouse": 0}},
+		{Battery: [2]uint8{60, 3}, Batteries: map[string]uint8{"Primary": 60}},
+		{Battery: [2]uint8{30, 4}, Batteries: map[string]uint8{"Mouse": 40}},
+		{},
+	}
+	result := records.AverageSystemStatsSlice(input)
+	assert.Equal(t, map[string]uint8{"Primary": 70, "Mouse": 20}, result.Batteries)
+	assert.Equal(t, uint8(56), result.Battery[0], "representative battery excludes absent samples")
+	assert.Equal(t, uint8(4), result.Battery[1], "representative state comes from its latest sample")
+}
+
+func TestAverageSystemStatsSlice_ZeroRepresentativeBattery(t *testing.T) {
+	result := records.AverageSystemStatsSlice([]system.Stats{
+		{Battery: [2]uint8{0, 1}, Batteries: map[string]uint8{"Primary": 0}},
+		{},
+	})
+	assert.Equal(t, [2]uint8{0, 1}, result.Battery)
+	assert.Equal(t, map[string]uint8{"Primary": 0}, result.Batteries)
+}
+
 func TestAverageSystemStatsSlice_ThreeRecordsRounding(t *testing.T) {
 	input := []system.Stats{
 		{Cpu: 10.0, Mem: 8.0},

internal/site/src/components/routes/system.tsx

@@ -125,7 +125,7 @@ export default memo(function SystemDetail({ id }: { id: string }) {
 
 					<FanChart {...coreProps} />
 
-					<BatteryChart {...coreProps} />
+					<BatteryChart system={system} {...coreProps} />
 
 					{hasGpuPowerData && <GpuPowerChart chartData={chartData} grid={grid} dataEmpty={dataEmpty} />}
 				</div>
@@ -191,7 +191,7 @@ export default memo(function SystemDetail({ id }: { id: string }) {
 						<BandwidthChart {...coreProps} systemStats={systemStats} />
 						<TemperatureChart {...coreProps} setPageBottomExtraMargin={setPageBottomExtraMargin} />
 						<FanChart {...coreProps} />
-						<BatteryChart {...coreProps} />
+						<BatteryChart system={system} {...coreProps} />
 						<SwapChart chartData={chartData} grid={grid} dataEmpty={dataEmpty} systemStats={systemStats} />
 						{pageBottomExtraMargin > 0 && <div style={{ marginBottom: pageBottomExtraMargin }}></div>}
 					</div>

internal/site/src/components/routes/system/charts/sensor-charts.tsx

@@ -3,7 +3,7 @@ import AreaChartDefault from "@/components/charts/area-chart"
 import { batteryStateTranslations } from "@/lib/i18n"
 import { $fanFilter, $temperatureFilter, $userSettings } from "@/lib/stores"
 import { cn, decimalString, formatTemperature, toFixedFloat } from "@/lib/utils"
-import type { ChartData, SystemStatsRecord } from "@/types"
+import type { ChartData, SystemRecord, SystemStatsRecord } from "@/types"
 import { ChartCard, FilterBar } from "../chart-card"
 import LineChartDefault from "@/components/charts/line-chart"
 import { useStore } from "@nanostores/react"
@@ -14,18 +14,60 @@ export function BatteryChart({
 	grid,
 	dataEmpty,
 	maxValues,
+	system,
 }: {
 	chartData: ChartData
 	grid: boolean
 	dataEmpty: boolean
 	maxValues: boolean
+	system: SystemRecord
 }) {
-	const showBatteryChart = chartData.systemStats.at(-1)?.stats.bat
+	const batteryNames = useMemo(() => {
+		const names = new Set<string>()
+		for (const record of chartData.systemStats) {
+			for (const name in record.stats?.bats ?? {}) {
+				names.add(name)
+			}
+		}
+		return [...names].sort()
+	}, [chartData.systemStats])
+	const hasNamedBatteries = batteryNames.length > 0
+	const showBatteryChart = hasNamedBatteries || chartData.systemStats.some((record) => record.stats?.bat)
 
 	if (!showBatteryChart) {
 		return null
 	}
 
+	if (hasNamedBatteries) {
+		const dataPoints = batteryNames.map((name, index) => ({
+			label: name,
+			dataKey: ({ stats }: SystemStatsRecord) => stats?.bats?.[name],
+			color: `hsl(${(index * 360 + 226) / batteryNames.length}, 65%, 52%)`,
+		}))
+		return (
+			<ChartCard
+				empty={dataEmpty}
+				grid={grid}
+				title={t`Battery`}
+				description={`${t({
+					message: "Current state",
+					comment: "Context: Battery state",
+				})}: ${batteryStateTranslations[system.info.bat?.[1] ?? 0]()}`}
+			>
+				<LineChartDefault
+					chartData={chartData}
+					maxToggled={maxValues}
+					dataPoints={dataPoints}
+					domain={[0, 100]}
+					legend={true}
+					tickFormatter={(val) => `${val}%`}
+					contentFormatter={({ value }) => `${value}%`}
+					itemSorter={(a, b) => b.value - a.value}
+				/>
+			</ChartCard>
+		)
+	}
+
 	return (
 		<ChartCard
 			empty={dataEmpty}
@@ -34,7 +76,7 @@ export function BatteryChart({
 			description={`${t({
 				message: "Current state",
 				comment: "Context: Battery state",
-			})}: ${batteryStateTranslations[chartData.systemStats.at(-1)?.stats.bat?.[1] ?? 0]()}`}
+			})}: ${batteryStateTranslations[system.info.bat?.[1] ?? 0]()}`}
 		>
 			<AreaChartDefault
 				chartData={chartData}
@@ -210,15 +252,7 @@ export function TemperatureChart({
 	)
 }
 
-export function FanChart({
-	chartData,
-	grid,
-	dataEmpty,
-}: {
-	chartData: ChartData
-	grid: boolean
-	dataEmpty: boolean
-}) {
+export function FanChart({ chartData, grid, dataEmpty }: { chartData: ChartData; grid: boolean; dataEmpty: boolean }) {
 	const showFanChart = chartData.systemStats.at(-1)?.stats.f
 
 	const filter = useStore($fanFilter)

internal/site/src/types.d.ts

@@ -151,6 +151,8 @@ export interface SystemStats {
 	g?: Record<string, GPUData>
 	/** battery percent and state */
 	bat?: [number, BatteryState]
+	/** battery percentages by device name */
+	bats?: Record<string, number>
 	/** network interfaces [upload bytes, download bytes, total upload bytes, total download bytes] */
 	ni?: Record<string, [number, number, number, number]>
 }