The case for adding a VOC detector to a battery pack or energy storage system is now well established. When lithium-ion cells begin to fail, the breakdown of their electrolyte releases volatile organic compounds, often well before temperature sensors react. Detecting those compounds early buys valuable time to isolate the pack, warn occupants and prevent a fire. Not every VOC detector is suited to life inside a battery enclosure, and seven questions separate those that are from those that are not.<\/p>\n
Many VOC sensors on the market are designed for indoor air quality in homes and offices. They are tuned to typical household pollutants, report a broad air quality index and often assume stable conditions. A battery pack is very different. The compounds of interest are electrolyte solvents and their decomposition products, concentrations can rise from trace levels to very high values in seconds, and the sensor must respond to both.<\/p>\n
Metis Engineering’s Cell Guard uses metal oxide semiconductor VOC sensing optimised for electrolyte decomposition products, with a range of 0 to 6,553.5 ppm. According to Metis, it works consistently across NMC, LFP and LMFP chemistries without recalibration.<\/p>\n
A single VOC reading is useful, but on its own it can be ambiguous. Adhesive curing, a cleaning solvent or a small change in ambient conditions can all shift the baseline. The strongest detection strategies combine VOC data with other measurements that change during a venting event.<\/p>\n
Pressure is the most important partner. When a cell vents inside a sealed or semi-sealed enclosure, it produces a measurable pressure change. Cell Guard measures absolute pressure from 0.3 to 1.2 bar with a resolution of 0.0001 bar and an update rate of up to 50 Hz, so even the pressure step from a single cell venting in a large pack can be picked up. Seeing a VOC rise and a pressure step together gives the control system confidence to act.<\/p>\n
Humidity and dew point add long-term value. Moisture ingress can compromise insulation and lead to short circuits, and in liquid-cooled packs, cooling below the dew point risks condensation on terminals. Cell Guard measures relative humidity, absolute humidity and dew point alongside air temperature, and an optional triple-axis accelerometer records shocks up to \u00b124g, providing evidence of impacts that may have damaged cells.<\/p>\n
This is a question many engineers only ask after installation. Large energy storage systems frequently use significant quantities of adhesive and sealant, and background VOC levels can remain high for a long time. A detector that relies purely on VOC concentration may either alarm constantly or have its thresholds set so high that it becomes insensitive.<\/p>\n
Metis addresses this with hydrogen-capable variants. Cell Guard with Hydrogen and H Guard add hydrogen detection from 0 to 20% by volume and are designed to identify thermal events reliably in environments where ambient VOC levels remain elevated.<\/p>\n
Battery failures do not only happen while a vehicle is being driven or a storage system is cycling. Some of the most serious incidents occur while a vehicle is parked or a system is idle. A VOC detector that is only active when the main system is awake leaves a gap.<\/p>\n
Low power monitoring modes close that gap. In this mode, Metis sensors continue to observe the enclosure but do not transmit on the CAN bus until a configured threshold is breached. The hydrogen variants draw less than 1 mA in this state. When a threshold is crossed, the sensor wakes the CAN interface and toggles a 500 mA low-side drive output, which can wake the wider system or drive an alarm directly.<\/p>\n
A battery enclosure sees vibration, thermal cycling, electrical transients and, in some cases, condensation. Look for evidence of testing to recognised automotive standards. Cell Guard has been developed in line with ISO 26262 processes and tested to ISO 7637-2:2011, ISO 16750-2:2012 and ISO 16750-4:2010. It is used by OEMs and Tier 1 suppliers in ASIL B applications and has been deployed in more than 500 systems. At 11.5 by 50 by 54.5 mm, it is compact enough to fit in most enclosures.<\/p>\n
Finally, consider the integration burden. A detector that outputs an analogue signal or uses a proprietary interface will need signal conditioning or custom software. Cell Guard communicates over CAN bus with configurable address and baud rate and is supplied with a DBC file, so data can be decoded immediately by the BMS, vehicle controller or data logger. For large stationary installations, more than 100 units can be daisy chained on one network.<\/p>\n
Claims are easy to make. Independent evidence is harder to come by. Sandia National Laboratories tested Cell Guard alongside two competing products and published the results in the Journal of the Electrochemical Society. Cell Guard detected the thermal event in under 60 seconds, while a hydrogen-only competitor took seven minutes longer.<\/p>\n
A good VOC detector for battery packs and energy storage is one that is tuned to the right chemistry, cross-checks its readings, stays alert when the system is idle, survives the environment and integrates without friction. To discuss the right Metis sensor for your battery system, contact info@metisengineering.com.<\/p>","protected":false},"excerpt":{"rendered":"
The case for adding a VOC detector to a battery pack or energy storage system is now well established. When lithium-ion cells begin to fail, […]<\/p>\n","protected":false},"author":27,"featured_media":4051,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[226],"tags":[],"class_list":["post-4050","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-reference"],"acf":[],"yoast_head":"\n