Lithium-ion battery fire protection requires more than simply detecting visible smoke or an open flame.
Inside a battery enclosure, abnormal conditions may develop through several stages before a severe fire condition is reached. For this reason, battery safety monitoring can benefit from observing several different parameters rather than relying on only one sensing method.
The ANWETECH AT-GD209 Lithium-Ion Battery Multi-Sensor Thermal Runaway Detector is designed for early warning of lithium-ion battery thermal runaway and emergency alarm during developing fire conditions. Depending on the ordered configuration, it can monitor CO, H₂, VOC, smoke and temperature inside the protected battery enclosure.
This multi-parameter approach allows the detector to use different sensor signals and combinations of signals to classify abnormal battery conditions into different warning or alarm stages.
A conventional fire detector normally responds to a particular fire phenomenon, such as smoke or temperature.
Battery monitoring has a different challenge.
The AT-GD209 documentation describes lithium-ion battery thermal runaway monitoring as a process in which characteristic gases, smoke and temperature changes can be evaluated as conditions develop from an early abnormal stage toward smoldering and eventually open-flame fire.
This creates an important engineering advantage:
Different sensing parameters can contribute at different stages of the alarm logic.
Rather than using only:
Normal → Fire Alarm
a multi-sensor system can use a staged strategy such as:
Early Thermal Runaway → Initial Smoldering → Intensified Smoldering → Open-Flame Fire
The five-sensor alarm example supplied for AT-GD209 uses exactly these four internal stages.
AT-GD209 can be configured with a CO sensor with a measurement range of 0–1000 ppm.
Within the supplied alarm-logic examples, CO is not treated only as a final fire signal. Different CO thresholds are used together with other parameters to help determine different severity levels.
For example, the five-sensor configuration includes CO values such as:
These values participate in different combinations with H₂, VOC, smoke and temperature.
This demonstrates an important concept in multi-sensor battery monitoring:
A gas reading does not necessarily need to be treated as an isolated alarm. It can become more meaningful when evaluated together with other battery-condition signals.
For engineering applications, the actual alarm thresholds and enabled logic should always follow the delivered AT-GD209 configuration rather than assuming that every detector uses the same values.
AT-GD209 can also be configured for H₂ detection from 0–1000 ppm.
In the supplied four- and five-sensor logic examples, H₂ is combined with CO, VOC, smoke and temperature at different alarm stages.
For example, in the five-sensor configuration:
This illustrates why a configurable battery detector can be more flexible than a single-parameter detector.
Instead of depending on one sensor alone, the system can compare several abnormal conditions before escalating the alarm level.
VOC monitoring is another configurable function of the AT-GD209.
The supplied alarm logic expresses VOC thresholds as:
These values are retained as AD sensor values because the supplied technical documentation does not define them as ppm or another physical concentration unit. They should therefore not be converted into ppm.
Within the five-sensor alarm logic, VOC values are evaluated together with CO, H₂, temperature and smoke.
For example:
Early-stage logic can include combinations such as:
Higher-stage conditions use increased VOC values together with other parameters.
From a system-design perspective, this means VOC sensing contributes another independent parameter to the detector's multi-sensor decision logic.
Multi-sensor battery monitoring does not eliminate the importance of smoke detection.
AT-GD209 supports a configurable smoke function, with the source manual stating an adjustable smoke alarm threshold of:
1.0 dB/m
Smoke is used in several alarm combinations in the supplied logic.
For example, smoke alarm can participate directly in Level 2 conditions and can also be combined with CO, H₂, VOC or temperature in higher-level alarms.
The key difference is that smoke becomes one part of a broader detection strategy, rather than the only information available to the system.
This is particularly useful when the objective is not only to identify an established fire condition, but also to monitor developing conditions inside the battery enclosure.
AT-GD209 supports temperature measurement over the range:
-40°C to +125°C
according to the final technical documentation.
In the supplied alarm examples, temperature thresholds are used progressively:
For the five-sensor example, temperature can participate at every stage of the alarm sequence.
For example:
Level 1 – Early Thermal Runaway
Temperature reaches 55°C.
Level 2 – Initial Smoldering
Temperature reaches 65°C.
Level 3 – Intensified Smoldering
Temperature reaches 75°C.
At the highest stage, temperature may be combined with elevated gas readings and/or smoke to identify an open-flame fire condition.
This illustrates how temperature can be used together with gas and smoke information to support staged alarm decisions.
The important feature is not simply that AT-GD209 can contain several sensors.
The real engineering value comes from combining those signals through multi-sensor alarm logic.
For example:
CO + H₂
may indicate one condition.
CO + VOC
may indicate another.
VOC + H₂
can also form part of the alarm logic.
As conditions become more severe, these gas signals may be combined with smoke and higher temperature before the highest alarm stage is reached.
The final manual explains that AT-GD209 uses available sensor data to classify conditions from early warning through developing fire stages.
This creates a more structured alarm strategy:
Multiple parameters → Alarm logic → Alarm level → System response
For the five-sensor configuration example, AT-GD209 provides four internal alarm stages.
The detector identifies an early abnormal condition and increases its sampling frequency.
More significant gas, smoke or temperature conditions are detected and the Level 2 alarm is uploaded.
Higher temperature or defined multi-parameter combinations indicate a more severe developing condition.
Defined combinations of CO, H₂, VOC, smoke and temperature reach the highest alarm condition.
At Level 4, the detector can:
Upload the Level 4 alarm + activate the 24 VDC active output.
The latest confirmed active-output specification is:
24 VDC, maximum 2 A
with continuous output while active and no output after system reset.
Battery safety monitoring normally needs to communicate with a larger control system.
AT-GD209 supports:
For battery applications, CAN can be used to connect the detector to a compatible Battery Management System (BMS).
RS485 can also be used where supported by the ordered configuration.
A compatible controller can receive detector information through CAN or RS485 and can form part of a wider alarm or fire-extinguishing control architecture.
For traditional fire alarm systems, however, CAN or RS485 should not automatically be assumed to be directly compatible with the fire alarm control panel.
Where connection to a conventional or addressable fire alarm panel is required, the panel input type and communication method should first be confirmed. A suitable interface relay or monitor module may be necessary.
AT-GD209 is not positioned as a conventional ceiling-mounted room smoke detector.
The product documentation states that it is normally installed inside a lithium-ion battery enclosure.
The mounting position should allow the configured sensors to monitor the protected air space while keeping the detector's sensing openings unobstructed.
The protected space stated in the manual is:
1 m³
Typical integration scenarios therefore include:
The exact sensor configuration should be selected according to the battery enclosure and project requirements.
The main advantage of combining CO, H₂, VOC, smoke and temperature detection is that the safety system can evaluate several types of abnormal conditions instead of depending on one signal.
In a properly configured AT-GD209 system:
Gas monitoring provides additional parameters for identifying abnormal battery conditions.
Smoke monitoring contributes detection of developing combustion conditions.
Temperature monitoring provides an independent indication of increasing thermal severity.
Multi-sensor logic combines these signals to create different alarm stages.
CAN / RS485 communication allows detector information to be integrated with compatible monitoring or control systems.
24 VDC active output provides an additional configured output for alarm or control actions.
This creates a complete monitoring sequence:
Detect → Evaluate → Classify → Report → Respond
The ANWETECH AT-GD209 is designed for lithium-ion battery applications requiring configurable thermal-runaway and developing-fire monitoring.
Depending on the ordered configuration, it can support:
CO + H₂ + VOC + Smoke + Temperature
with:
For battery manufacturers, BESS integrators and fire protection engineers, this allows one compact detector platform to connect battery-condition monitoring, early warning and fire protection system integration.
