diff --git a/assets/js/components/HelpModal.vue b/assets/js/components/HelpModal.vue
index d649bb9b9..64fe1e185 100644
--- a/assets/js/components/HelpModal.vue
+++ b/assets/js/components/HelpModal.vue
@@ -136,13 +136,14 @@
 	</Teleport>
 </template>
 
-<script>
+<script lang="ts">
 import Modal from "bootstrap/js/dist/modal";
 import { docsPrefix } from "../i18n";
 import { performRestart } from "../restart";
 import { isLoggedIn, openLoginModal } from "./Auth/auth";
+import { defineComponent } from "vue";
 
-export default {
+export default defineComponent({
 	name: "HelpModal",
 	props: {},
 	computed: {
@@ -152,11 +153,15 @@ export default {
 	},
 	methods: {
 		openHelpModal() {
-			const modal = Modal.getOrCreateInstance(document.getElementById("helpModal"));
+			const modal = Modal.getOrCreateInstance(
+				document.getElementById("helpModal") as HTMLElement
+			);
 			modal.show();
 		},
 		openConfirmRestartModal() {
-			const modal = Modal.getOrCreateInstance(document.getElementById("confirmRestartModal"));
+			const modal = Modal.getOrCreateInstance(
+				document.getElementById("confirmRestartModal") as HTMLElement
+			);
 			if (!isLoggedIn()) {
 				openLoginModal(null, modal);
 			} else {
@@ -167,5 +172,5 @@ export default {
 			await performRestart();
 		},
 	},
-};
+});
 </script>
diff --git a/assets/js/components/Helper/SelectGroup.vue b/assets/js/components/Helper/SelectGroup.vue
index c3d796a06..0b7f26c16 100644
--- a/assets/js/components/Helper/SelectGroup.vue
+++ b/assets/js/components/Helper/SelectGroup.vue
@@ -26,7 +26,7 @@ export default defineComponent({
 	props: {
 		id: String,
 		options: Array as PropType<SelectOption<string>[]>,
-		modelValue: [Number, String, Boolean],
+		modelValue: [Number, String, Boolean, null],
 		equalWidth: Boolean,
 		large: Boolean,
 		transparent: Boolean,
diff --git a/assets/js/components/Loadpoints/SessionInfo.vue b/assets/js/components/Loadpoints/SessionInfo.vue
index 5d6ac39c2..7d9bf301c 100644
--- a/assets/js/components/Loadpoints/SessionInfo.vue
+++ b/assets/js/components/Loadpoints/SessionInfo.vue
@@ -32,7 +32,7 @@ import LabelAndValue from "../Helper/LabelAndValue.vue";
 import CustomSelect from "../Helper/CustomSelect.vue";
 import formatter from "@/mixins/formatter";
 import { getSessionInfo, setSessionInfo } from "./session";
-import type { CURRENCY, SelectOption } from "@/types/evcc";
+import type { CURRENCY, SelectOption, SessionInfoKey } from "@/types/evcc";
 
 export default defineComponent({
 	name: "LoadpointSessionInfo",
@@ -59,39 +59,44 @@ export default defineComponent({
 		};
 	},
 	computed: {
-		options() {
+		options(): Array<{
+			key: SessionInfoKey;
+			value: string;
+			valueSm?: string;
+			available?: boolean;
+		}> {
 			const result = [
 				{
-					key: "remaining",
+					key: "remaining" as const,
 					value: this.fmtDuration(this.chargeRemainingDurationInterpolated),
 					available: this.chargeRemainingDurationInterpolated > 0,
 				},
 				{
-					key: "finished",
+					key: "finished" as const,
 					value: this.fmtHourMinute(this.finishTime),
 					available: this.chargeRemainingDurationInterpolated > 0,
 				},
 				{
-					key: "duration",
+					key: "duration" as const,
 					value: this.fmtDuration(this.chargeDurationInterpolated),
 				},
 				{
-					key: "solar",
+					key: "solar" as const,
 					value: this.solarFormatted,
 				},
 				{
-					key: "avgPrice",
+					key: "avgPrice" as const,
 					value: this.fmtAvgPrice(this.sessionPricePerKWh),
 					valueSm: this.fmtAvgPriceShort(this.sessionPricePerKWh),
 					available: this.tariffGrid !== undefined,
 				},
 				{
-					key: "price",
+					key: "price" as const,
 					value: this.priceFormatted,
 					available: this.tariffGrid !== undefined,
 				},
 				{
-					key: "co2",
+					key: "co2" as const,
 					value: this.fmtCo2Medium(this.sessionCo2PerKWh),
 					valueSm: this.fmtCo2Short(this.sessionCo2PerKWh),
 					available: this.tariffCo2 !== undefined,
@@ -100,10 +105,10 @@ export default defineComponent({
 			// only show options that are available
 			return result.filter(({ available }) => available === undefined || available);
 		},
-		optionKeys() {
+		optionKeys(): SessionInfoKey[] {
 			return this.options.map((option) => option.key);
 		},
-		selectOptions(): SelectOption<string>[] {
+		selectOptions(): SelectOption<SessionInfoKey>[] {
 			return this.optionKeys.map((key) => ({
 				name: this.$t(`main.loadpoint.${key}`),
 				value: key,
@@ -151,16 +156,18 @@ export default defineComponent({
 			return this.fmtPricePerKWh(value, this.currency, true);
 		},
 		nextSessionInfo() {
-			const index = this.optionKeys.indexOf(this.selectedKey);
+			const index = this.selectedKey ? this.optionKeys.indexOf(this.selectedKey) : -1;
 			this.selectedKey = this.optionKeys[index + 1] || this.optionKeys[0];
 			this.presist();
 		},
-		selectOption(value: string) {
+		selectOption(value: SessionInfoKey) {
 			this.selectedKey = value;
 			this.presist();
 		},
 		presist() {
-			setSessionInfo(this.id, this.selectedKey);
+			if (this.selectedKey) {
+				setSessionInfo(this.id, this.selectedKey);
+			}
 		},
 	},
 });
diff --git a/assets/js/components/Loadpoints/session.ts b/assets/js/components/Loadpoints/session.ts
index 29aafa900..56a56da68 100644
--- a/assets/js/components/Loadpoints/session.ts
+++ b/assets/js/components/Loadpoints/session.ts
@@ -1,10 +1,11 @@
 import settings from "@/settings";
+import type { SessionInfoKey } from "@/types/evcc";
 
-export function getSessionInfo(index: number, fallback?: string) {
-  return settings.sessionInfo[index - 1] || fallback;
+export function getSessionInfo(index: number): SessionInfoKey | undefined {
+  return settings.sessionInfo[index - 1];
 }
 
-export function setSessionInfo(index: number, value: string) {
+export function setSessionInfo(index: number, value: SessionInfoKey) {
   const clone = [...settings.sessionInfo];
   clone[index - 1] = value;
   clone.map((v) => v || "");
diff --git a/assets/js/components/Savings/Savings.vue b/assets/js/components/Savings/Savings.vue
index 17db3a73a..0cecbde66 100644
--- a/assets/js/components/Savings/Savings.vue
+++ b/assets/js/components/Savings/Savings.vue
@@ -209,7 +209,7 @@ import Tile from "./Tile.vue";
 import LiveCommunity from "./LiveCommunity.vue";
 import TelemetrySettings from "../TelemetrySettings.vue";
 import CustomSelect from "../Helper/CustomSelect.vue";
-import settings from "@/settings";
+import settings from "@/settings.ts";
 import api, { allowClientError } from "@/api.ts";
 import { docsPrefix } from "@/i18n.ts";
 import { defineComponent, type PropType } from "vue";
diff --git a/assets/js/components/Sessions/SessionTable.vue b/assets/js/components/Sessions/SessionTable.vue
index f6da566eb..e05577fe5 100644
--- a/assets/js/components/Sessions/SessionTable.vue
+++ b/assets/js/components/Sessions/SessionTable.vue
@@ -161,7 +161,7 @@ import { defineComponent, type PropType } from "vue";
 import CustomSelect from "../Helper/CustomSelect.vue";
 import formatter, { POWER_UNIT } from "@/mixins/formatter";
 import breakpoint from "@/mixins/breakpoint.ts";
-import settings from "@/settings";
+import settings from "@/settings.ts";
 import type { CURRENCY } from "@/types/evcc";
 import type { Session, Column } from "./types";
 
@@ -187,7 +187,7 @@ export default defineComponent({
 	emits: ["show-session"],
 	data() {
 		return {
-			selectedColumns: settings.sessionColumns,
+			selectedColumns: [] as string[],
 		};
 	},
 	computed: {
@@ -417,7 +417,7 @@ export default defineComponent({
 				.filter(this.filterByVehicle)
 				.filter((s) => !loadpoint || s.loadpoint === loadpoint).length;
 		},
-		selectColumnPosition(index: number, value: Column) {
+		selectColumnPosition(index: number, value: string) {
 			this.selectedColumns[index] = value;
 			settings.sessionColumns = [...this.selectedColumns];
 		},
diff --git a/assets/js/components/TelemetrySettings.vue b/assets/js/components/TelemetrySettings.vue
index a973ea606..e54980db9 100644
--- a/assets/js/components/TelemetrySettings.vue
+++ b/assets/js/components/TelemetrySettings.vue
@@ -30,12 +30,14 @@
 	</div>
 </template>
 
-<script>
+<script lang="ts">
+import { defineComponent } from "vue";
 import api from "../api";
 import { docsPrefix } from "../i18n";
-import settings from "../settings";
+import settings from "@/settings.ts";
+import type { AxiosError } from "axios";
 
-function parseMarkdown(markdownText) {
+function parseMarkdown(markdownText: string) {
 	const htmlText = markdownText
 		.replace(/\*\*(.*)\*\*/gim, "<b>$1</b>")
 		.replace(/\*(.*)\*/gim, "<i>$1</i>")
@@ -43,12 +45,12 @@ function parseMarkdown(markdownText) {
 	return htmlText.trim();
 }
 
-export default {
+export default defineComponent({
 	name: "TelemetrySettings",
 	props: { sponsorActive: Boolean },
 	data() {
 		return {
-			error: null,
+			error: null as string | null,
 		};
 	},
 	computed: {
@@ -63,14 +65,17 @@ export default {
 		await this.update();
 	},
 	methods: {
-		async change(e) {
+		async change(e: Event) {
 			try {
 				this.error = null;
-				const response = await api.post(`settings/telemetry/${e.target.checked}`);
+				const response = await api.post(
+					`settings/telemetry/${(e.target as HTMLInputElement).checked}`
+				);
 				settings.telemetry = response.data.result;
 			} catch (err) {
-				if (err.response) {
-					this.error = parseMarkdown("**Error:** " + err.response.data.error);
+				const e = err as AxiosError<{ error: string }>;
+				if (e.response) {
+					this.error = parseMarkdown("**Error:** " + e.response.data.error);
 					settings.telemetry = false;
 				}
 			}
@@ -91,7 +96,7 @@ export default {
 			}
 		},
 	},
-};
+});
 </script>
 <style scoped>
 .form-check {
diff --git a/assets/js/i18n.ts b/assets/js/i18n.ts
index f000e50c8..d5b7762b5 100644
--- a/assets/js/i18n.ts
+++ b/assets/js/i18n.ts
@@ -48,11 +48,11 @@ export function getLocalePreference() {
 
 export function removeLocalePreference(i18n: VueI18nInstance) {
   settings.locale = null;
-  setI18nLanguage(i18n, DEFAULT_BROWSER_LOCALE as typeof i18n.locale);
+  setI18nLanguage(i18n, DEFAULT_BROWSER_LOCALE as keyof typeof LOCALES);
   ensureCurrentLocaleMessages(i18n);
 }
 
-export function setLocalePreference(i18n: VueI18nInstance, locale: typeof i18n.locale) {
+export function setLocalePreference(i18n: VueI18nInstance, locale: keyof typeof LOCALES) {
   if (!(locale in LOCALES)) {
     console.error("unknown locale", locale);
     return;
diff --git a/assets/js/settings.js b/assets/js/settings.ts
similarity index 73%
rename from assets/js/settings.js
rename to assets/js/settings.ts
index d3710d018..0bacaefdf 100644
--- a/assets/js/settings.js
+++ b/assets/js/settings.ts
@@ -1,4 +1,6 @@
 import { reactive, watch } from "vue";
+import type { THEME, SessionInfoKey } from "./types/evcc";
+import type { LOCALES } from "./i18n";
 
 const SETTINGS_LOCALE = "settings_locale";
 const SETTINGS_THEME = "settings_theme";
@@ -16,12 +18,12 @@ const SAVINGS_REGION = "savings_region";
 const SESSIONS_GROUP = "sessions_group";
 const SESSIONS_TYPE = "sessions_type";
 const SETTINGS_SOLAR_ADJUSTED = "settings_solar_adjusted";
-function read(key) {
+function read(key: string) {
   return window.localStorage[key];
 }
 
-function save(key) {
-  return (value) => {
+function save(key: string) {
+  return (value: string | null) => {
     try {
       if (value) {
         window.localStorage[key] = value;
@@ -34,29 +36,49 @@ function save(key) {
   };
 }
 
-function readBool(key) {
+function readBool(key: string) {
   return read(key) === "true";
 }
 
-function saveBool(key) {
-  return (value) => {
+function saveBool(key: string) {
+  return (value: boolean) => {
     save(key)(value ? "true" : "false");
   };
 }
 
-function readArray(key) {
+function readArray(key: string) {
   const value = read(key);
   return value ? value.split(",") : [];
 }
 
-function saveArray(key) {
-  return (value) => {
+function saveArray(key: string) {
+  return (value: string[]) => {
     save(key)(value.join(","));
   };
 }
 
-const settings = reactive({
-  telemetry: null,
+export interface Settings {
+  telemetry: boolean;
+  locale: keyof typeof LOCALES | null;
+  theme: THEME | null;
+  unit: string;
+  is12hFormat: boolean;
+  hiddenFeatures: boolean;
+  energyflowDetails: boolean;
+  energyflowPv: boolean;
+  energyflowBattery: boolean;
+  energyflowLoadpoints: boolean;
+  sessionInfo: SessionInfoKey[];
+  sessionColumns: string[];
+  savingsPeriod: string;
+  savingsRegion: string;
+  sessionsGroup: string;
+  sessionsType: string;
+  solarAdjusted: boolean;
+}
+
+const settings: Settings = reactive({
+  telemetry: false,
   locale: read(SETTINGS_LOCALE),
   theme: read(SETTINGS_THEME),
   unit: read(SETTINGS_UNIT),
@@ -66,7 +88,7 @@ const settings = reactive({
   energyflowPv: readBool(SETTINGS_ENERGYFLOW_PV),
   energyflowBattery: readBool(SETTINGS_ENERGYFLOW_BATTERY),
   energyflowLoadpoints: readBool(SETTINGS_ENERGYFLOW_LOADPOINTS),
-  sessionInfo: readArray(SESSION_INFO),
+  sessionInfo: readArray(SESSION_INFO) as SessionInfoKey[],
   sessionColumns: readArray(SESSION_COLUMNS),
   savingsPeriod: read(SAVINGS_PERIOD),
   savingsRegion: read(SAVINGS_REGION),
@@ -85,7 +107,7 @@ watch(() => settings.energyflowPv, saveBool(SETTINGS_ENERGYFLOW_PV));
 watch(() => settings.energyflowBattery, saveBool(SETTINGS_ENERGYFLOW_BATTERY));
 watch(() => settings.energyflowLoadpoints, saveBool(SETTINGS_ENERGYFLOW_LOADPOINTS));
 watch(() => settings.sessionInfo, saveArray(SESSION_INFO));
-watch(() => settings.sessionColumns, saveArray(SESSION_COLUMNS));
+watch(() => settings.sessionColumns as string[], saveArray(SESSION_COLUMNS));
 watch(() => settings.savingsPeriod, save(SAVINGS_PERIOD));
 watch(() => settings.savingsRegion, save(SAVINGS_REGION));
 watch(() => settings.sessionsGroup, save(SESSIONS_GROUP));
diff --git a/assets/js/theme.ts b/assets/js/theme.ts
index 41136c130..6dec221ef 100644
--- a/assets/js/theme.ts
+++ b/assets/js/theme.ts
@@ -3,9 +3,9 @@ import { THEME } from "./types/evcc";
 
 const darkModeMatcher = window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)");
 
-export function getThemePreference(): THEME {
+export function getThemePreference(): THEME | null {
   const theme = settings.theme;
-  if (Object.values(THEME).includes(theme)) {
+  if (theme && Object.values(THEME).includes(theme)) {
     return theme;
   }
   return THEME.AUTO;
@@ -19,10 +19,10 @@ export function setThemePreference(theme: THEME) {
   updateTheme();
 }
 
-function setMetaThemeColor(theme: Exclude<THEME, THEME.AUTO>) {
+function setMetaThemeColor(theme: Exclude<THEME, THEME.AUTO> | null) {
   const themeColors = { light: "#f3f3f7", dark: "#020318" };
   const $metaThemeColor = document.querySelector("meta[name=theme-color]");
-  if ($metaThemeColor) {
+  if ($metaThemeColor && theme) {
     $metaThemeColor.setAttribute("content", themeColors[theme]);
   }
 }
diff --git a/assets/js/types/evcc.ts b/assets/js/types/evcc.ts
index ad7fa050f..166c09356 100644
--- a/assets/js/types/evcc.ts
+++ b/assets/js/types/evcc.ts
@@ -95,6 +95,15 @@ export enum PHASES {
   THREE_PHASES = 3,
 }
 
+export type SessionInfoKey =
+  | "remaining"
+  | "finished"
+  | "duration"
+  | "solar"
+  | "avgPrice"
+  | "price"
+  | "co2";
+
 export interface Sponsor {
   name: string;
   expiresAt: string;