When most safety professionals think of carbon monoxide (CO) risks in industrial settings, propane-powered lift trucks are often the usual suspects. And rightly so, propane combustion, especially when incomplete or inefficient, releases dangerous levels of CO into enclosed environments like warehouses or factories. But what if you’ve already made the switch to electric forklifts and eliminated combustion sources entirely? Should CO monitoring still be a concern?
Surprisingly, yes.
The source of the issue isn’t the lift trucks themselves but rather what powers them: their batteries and, more specifically, the battery charging stations. In these zones, unseen chemical reactions can introduce new risks that require just as much vigilance and monitoring. And failing to understand the causes behind these readings can lead to false alarms, unnecessary evacuations, wasted resources, or worse.
That’s why safety professionals, environmental health and safety (EHS) managers, and facilities engineers need to be aware of how common gases like hydrogen (H2) produced by everyday operations like battery charging can interfere with carbon monoxide sensors and compromise the integrity of gas monitoring programs.
Knowing when, where, and how to monitor for CO accurately, especially in non-combustion environments, is critical to keeping workers safe, operations compliant, and facilities running efficiently.
The Known CO Risk: Propane-Powered Forklifts
Propane-powered forklifts have long been a mainstay in warehouse operations due to their efficiency and power. However, one of their biggest drawbacks is the production of carbon monoxide during fuel combustion.
CO is a colorless, odorless, and deadly gas that can accumulate quickly in poorly ventilated indoor spaces. Workers exposed to CO can experience symptoms ranging from headaches and dizziness to loss of consciousness or even death.
To mitigate this risk, warehouse operators and safety managers routinely use combustion analyzers to ensure engines are properly tuned, reducing CO emissions to safe levels. The Testo 340 Combustion Analyzer is a go-to solution for this. Designed specifically for tuning industrial engines, the Testo 340 allows safety teams to monitor combustion gases, including CO, and adjust engines to minimize emissions and improve efficiency.
The Unexpected Problem: CO Readings in Electric Lift Truck Warehouses
Given the risk of CO with propane systems, many facilities are shifting toward electric lift trucks as a cleaner, safer option. However, while this move eliminates one significant source of carbon monoxide, it doesn’t completely remove the risk. In fact, many warehouses that exclusively use electric lift trucks still report elevated CO readings.
The culprit? Battery charging stations.
Electric lift truck batteries—especially lead-acid types—can release H₂ during charging, particularly during overcharging or when batteries start to deteriorate. Over time, hydrogen sulfide (H₂S) can also be emitted due to battery decomposition.
These gases pose their own safety concerns (hydrogen is flammable, for instance), but there’s another hidden complication: gas sensor cross-sensitivity.
Beyond the Warehouse: Hydrogen Presence in Industrial Processes
It’s important to note that hydrogen presence isn’t limited to battery charging stations. A variety of industrial applications and processes can also release H2 into the air, such as the following:
- Metal heat treating
- Annealing operations
- Hydrogen fuel systems
- Chemical manufacturing
- Electroplating or chemical etching
- Laboratories using hydrogen cylinders
In any of these scenarios, among others, standard carbon monoxide sensors may yield false data unless proper hydrogen-compensated technology is in place. Monitoring both CO and H2 is a smart strategy that provides a higher level of protection and operational insight. This approach helps prevent false alarms and build a more complete picture of the gas dynamics in your facility.
How Hydrogen Can Falsely Trigger Carbon Monoxide Alarms
Many standard CO sensors in industrial use today are based on electrochemical sensors, which are designed to detect the presence of carbon monoxide by generating a small electrical current when CO molecules interact with the sensor’s chemical elements. This interaction is highly sensitive and generally very reliable—unless there are other gases present that can mimic or interfere with the electrochemical signature of CO.
Hydrogen is one such gas.
When H2 is present in the air, as it often is around battery charging stations, it can cross-react with the sensor’s electrode and produce a signal that is mistaken for carbon monoxide. This issue is known as cross-sensitivity.
To put the scale of this problem in context: just 100 parts per million (ppm) of hydrogen can result in a false CO reading of 40 ppm. In some facilities, H2 levels can reach several hundred ppm during intensive battery charging operations, and that means sensors can easily show dangerously high CO readings—triggering alarms, evacuations, or shutdowns—despite no carbon monoxide being present.
The consequences go beyond mere inconvenience: False alarms disrupt operations and erode confidence in safety systems, and misdiagnosed readings may result in unnecessary maintenance or equipment replacement. Worse of all, these inaccurate readings can mask real CO threats if sensor reliability is called into question and leads to complacency or ignored warnings.
Standard CO sensors are not designed to distinguish between H2 and CO. For facilities with battery operations, continuing to rely on these sensors can lead to unreliable data and potentially unsafe decisions.
A Smarter Solution: Hydrogen-Compensated Carbon Monoxide Detection
To solve this issue, EHS professionals are turning to hydrogen-compensated CO sensors. These advanced sensors are specifically engineered to separate the signal generated by hydrogen gas from that of carbon monoxide, providing accurate CO readings even in hydrogen-rich environments.
These hydrogen-compensated CO sensors still use electrochemical technology, but they incorporate a filtering or dual-electrode system that recognizes and subtracts the hydrogen component from the total signal. The result is a true CO reading with a resolution of 10 ppm, unaffected by H2 interference, even at concentrations as high as 2000 ppm.
They allow for confident, accurate air quality assessments, especially in areas where hydrogen may be present due to battery charging or certain industrial processes. Hydrogen-compensated CO sensors also help safety managers avoid false positives that cause downtime, detect actual carbon monoxide hazards without confusion, and build a reliable safety culture rooted in trust and real-time insights.
Personal Protection with the ToxiRAE Pro CO-H2 Compensating Detector
For wearable, on-person monitoring the ToxiRAE Pro CO-H2 Compensating Personal Detector is an ideal solution. This rugged device is worn by personnel working in high-risk zones like battery rooms and charging stations. With a resolution of 10 ppm, the CO-H2 compensated sensor continuously monitors CO while filtering out hydrogen interference up to 2000 ppm to deliver accurate readings that workers can trust.
Scalable Monitoring Options for Your Facility
For broader facility-wide coverage, RAECO Rents offers a range of multi-gas monitors that include H2-compensated CO sensors. These devices provide continuous area monitoring across areas like maintenance shops, production zones, or energy storage rooms.
Available models include the following:
- MultiRAE Standard PID: A highly versatile, all-purpose multi-gas monitor for complex environments that supports advanced logging and sensor customization
- MultiRAE Lite CO2: Designed for areas where both carbon monoxide and carbon dioxide are a concern, including confined or poorly ventilated spaces
- MultiRAE Lite PID: Includes a photoionization detector in addition to a CO sensor, making it ideal for facilities where volatile organic compounds (VOCs) must also be monitored
These monitors are fully compatible with interchangeable sensor configurations, allowing safety teams to deploy flexible, scalable sensor strategies across multiple zones based on the unique conditions of your facility.
Why Rent from RAECO Rents?
Buying this kind of high-end gas detection equipment can be expensive, especially for short-term projects, compliance audits, or temporary risk assessments. At RAECO Rents, we make it easy and affordable to deploy the right tools without the burden of ownership.
With RAECO Rents, you get:
- Access to calibrated, ready-to-deploy instruments without the hassles of ownership
- Expert technical support and training to help you choose and configure your sensors
- Flexible rental terms for both short-term needs and long-term projects
- An updated inventory with the latest sensor technologies
Our fleet of instruments is regularly updated, quality-checked, and supported by real people who understand industrial hygiene, safety, and compliance. Whether you’re assessing a new facility, conducting periodic safety audits, or responding to a compliance issue, we’re here to help you get the job done right.
Prevent CO Sensor Cross-Sensitivity Monitoring Errors
Carbon monoxide threats don’t disappear with the shift to electric forklifts. And false readings caused by hydrogen can cause just as much disruption as real CO risks. By understanding how sensor cross-sensitivity works and adopting hydrogen-compensated carbon monoxide detectors, you can monitor more accurately, avoid costly false alarms, and support a safe and compliant workplace.
If your facility uses battery-powered equipment or conducts processes that may produce hydrogen, now may be the time to reevaluate your CO monitoring strategy.
Are you ready to upgrade your gas detection game?
Contact RAECO Rents today to speak with our expert team and get the right equipment for your team.
