GuyTec - Magic Fire Alarm (for Lithium batteries Version)

Magic Fire Alarm is an intelligent ESP32-based multi-sensor alarm that monitors sudden temperature rise rate or high and low temperature changes, carbon monoxide (CO) and hydrogen gas (H2) all simultaneously for rapid response to onset fires - and when any threshold is breached, it sends an immediate MacroDroid HTTP alert specifying the exact cause, which MacroDroid speaks out loud via your Android phone, even if on silent, this cuts down response time as every second counts, for greater safety.
No other consumer alarm product does this.

The Lithium version denotes it is for Lithium type battery protection.

Fully customisable thresholds and temperature sensors can be calibrated via any browser, or the free optional app.

Low cost (< $20) split Modular design with easy cheap replaceable parts for longevity, greater accuracy and flexible installation.

Can be used for frost detection, or general air condition, in addition to the Lithium or other fire alerts.

What Makes It Different

🗣️

Spoken Cause Alerts MacroDroid speaks the specific trigger — "Excessive Carbon Monoxide present", not just a beep

📈

Temperature Rise Rate Detects rapid temperature increase — catches fires before they reach threshold

🌡️

High Temperature Detects abnormal temperatures - threshold can be adjusted in relation to changing local temperatures whilst avoiding false alarms

🧪

CO + H2 Combined Monitors both carbon monoxide and hydrogen gas simultaneously, with independently adjustable thresholds

🌐

Full RestFul API Query status, adjust thresholds and control all settings and monitor remotely from any phone or browser

📱

Android App Optional free dedicated app with live gauges, toggle controls and configurable thresholds

❄️

Low Temperature Detects abnormal low temperatures - threshold can be adjusted in relation to changing local temperatures whilst avoiding false alarms. USeful for combined frost detection.

🔬

Lithium Sensors Lithium-chemistry generates gases and heat when instability sets in and the combined sensors try to detect this early.

📊

Monitoring Systems Any Home Assistant, Hubitat or other monitors can access the information real time via the RestFul API to create other mechanisms for reacting. EG. Narrow band temperature monitoring [inside threshold limits] for actioning other devices.

🚨

Alert Systems MacroDroid was chosen for it's immediate alert capability, but Home Assistant, Hubitat or other proxies could be notified to take immediate action, unless cancelled.

How Alerting Works

When a threshold is breached, the ESP32 sends an HTTP request to MacroDroid via it's WebHook on your Android phone, passing the trigger cause as a parameter. A MacroDroid macro receives this, extracts the cause and speaks it aloud [at full volume] via text-to-speech — even if the phone is on silent at any time, but it must still have Internet access.

Three separate sensors can trigger an alert, each with its own spoken message: [ in addition to :Fire Fire Fire" ]

Trigger	Condition	Spoken alert example	MacroDroid code received
🌡️ Temperature min	Temperature falls below threshold [frost detection]	Temperature is too low"	Low
🌡️ Temperature max	Temperature exceeds threshold	"Temperature is too high"	High
📈 Temperature rise rate	Temperature rising faster than configured rate	"Temperature is rising rapidly"	Rise
💨 Carbon Monoxide	CO level exceeds threshold	"Excessive Carbon Monoxide present"	CO
⚗️ Hydrogen	H2 level exceeds threshold	"Excessive Hydrogen present"	H2
Multiple	more than one sensor triggered	"Major fire in progress"	Many

Note: Like all network-connected alarms, Magic Fire Alarm requires an active internet connection, network and powered router for remote alerting and monitoring and a permanent local USB power source.

Status API Output

Call /status on the device to get the current state. Example response:

GuyTec Magic Fire Alarm (for Lithiums version) Settings and current state at 2026-04-12 08:11:23 System: On Alert Alarm: On Buzzer Alarm: On

Temperature High Threshold: 30.00
Temperature Low Threshold: 1.00
Temperature rise rate: 1.50

Temperature adjustment: -3.98 Current Temperature: 20.01 Min Temperature: 19.90 (2026-04-12 08:00:36) Max Temperature: 20.17 (2026-04-12 07:11:37) CO Threshold: 300.00 Current CO: 127.38 Min CO: 80.75 (2026-04-12 08:08:05) Max CO: 214.25 (2026-04-12 07:49:15) H2 Threshold: 300.00 Current H2: 94.13 Min H2: 39.63 (2026-04-12 07:37:19) Max H2: 143.50 (2026-04-12 08:10:33)

Android App — Live Dashboard

A dedicated Android app (Java, API 26+, tested on Samsung S9+) provides a live dashboard with colour-coded gauges, one-tap toggle controls and in-app threshold editing.

🔥 GuyTec Fire Alarm Updated: 2026-04-12 08:11:23

SYSTEM ON ALERT ON BUZZER ON

🌡️ °C 20.01

Thr: 30.00

💨 CO 127.38

Thr: 300.00

⚗️ H2 94.13

Thr: 300.00

Pull down to refresh · Auto-polls every 10 seconds · Tap gauges to set thresholds

Actual APP view

Full RestFul API Command Reference - compatible with Home assistant

All commands are plain HTTP GET requests. Use WebCmd or any browser. Replace 192.168.1.199 with your device IP.

Command	Description
http://192.168.1.199/status	Current settings and sensor readings, replace "status" with any of the following examples
alarm?system=on\|off	Turn the entire system on or off (eg. cancel false alarms)
alarm?alert=on\|off	Enable or disable phone alerting
alarm?buzzer=on\|off	Enable or disable the onboard buzzer
temp?min=1	Set temperature alarm lowthreshold (°C)
temp?max=35	Set temperature alarm high threshold (°C)
temp?rise=1.5	Set temperature rise rate threshold (°C/min)
temp?adjust=-2.5	Calibration offset — adjusts all temperature readings
temp?reset=temp	Reset min/max temperature records
temp?reset=co	Reset min/max CO records
temp?reset=h2	Reset min/max H2 records
temp?reset=	Reset all min/max records
Co?max=300	Set CO alarm threshold (ppm)
H2?max=300	Set H2 alarm threshold (ppm)

Comparison With Commercial Alarms

Feature	Magic Fire Alarm	Nest Protect	First Alert SC5	X-Sense
Temperature low monitoring	Yes	❌ No	❌ No	❌ No
Temperature high monitoring	Yes	Yes	Yes	⚠️ Basic
Temperature rise rate detection	Yes	❌ No	❌ No	❌ No
CO monitoring	Yes	Yes	Yes	Yes
H2 (hydrogen) monitoring	Yes	❌ No	❌ No	❌ No
Spoken cause of alarm	Yes, immediate via MacroDroid	⚠️ App notification only	⚠️ App notification only	❌ No
Remote alarm cancelling	Full, Buzzer or Alert, Wi-Fi needed	⚠️ Same Wi-Fi only, proximity required, blocked on high CO	⚠️ App silence, no granular control	❌ No
Open HTTP API	Full RestFul API	❌ Proprietary only	❌ Proprietary only	❌ No
Adjustable thresholds	All sensors	❌ Fixed	❌ Fixed	❌ Fixed
Temperature calibration	Yes	❌ No	❌ No	❌ No
Min/Max history logging	All sensors	❌ No	❌ No	❌ No
Custom Android app	Open source	⚠️ Google Home only	⚠️ First Alert only	⚠️ X-Sense only
MacroDroid integration	Native Webhook	❌ No	❌ No	❌ No
Subscription required	None	❌ Nest Aware	⚠️ Optional	None

What Was Discovered

Temperature high and low monitoring for alerting for frost or fire alerts
Temperature rise rate is a more reliable early fire indicator than absolute temperature alone
Temperature sensor used detects changes rapidly to avoid any delays in alerting
H2 monitoring is important for lithium battery installations — no commercial home alarm monitors this
CO sensors can give false positives from H2 — having a separate H2 sensor distinguishes the two causes independently
Buzzer is tested briefly at start-up
Blue light flashes till start-up complete, then each time it processes a RestFul API request
Blue light stays on during an alert
MacroDroid's spoken alerts are significantly more actionable than a silent push notification, example macros

GuyTec.com - Macrodroid Magic Fire Alarm alert macro

MacroDroid can receive the following alerts:
High, Rise, CO, H2, Many

For false alerts during configuration
shake to cancel macro and
shake again to re-enable macro

Requires active internet and powered router for remote alerting — buzzer works locally regardless
Temperature calibration offset essential — sensors typically read 2–4°C high when enclosed
Min/Max logging reveals ambient patterns that help set realistic thresholds for your environment

Start up mode

When the system is powered it will trigger both the buzzer alarm and also a trial voice alert on the phone [which can be used to check it is working as expected and test settings by restarting the unit with the restart button].

It may continue producing a buzz alert and voice alert at the first power up while the sensors initialise for anything up to a day.
To get around this, use the alarm?system=off for the first 24 hours, or adjust the thresholds accordingly

Eventual Downloads

Item	Description
📱 Android App APK	Java app for Android API 26+ (Samsung S9+ and above). Pre-configured for 192.168.1.199