>Metis Engineering revealed the beta model of its Manufacturing Battery Security Sensor, designed to observe the well being of a lithium-ion battery pack and detect cell venting, an early signal of catastrophic battery failure. Metis Engineering Managing Director Joe Holdsworth stated that the crew plans to make one or two minor modifications earlier than signing off on the ultimate spec of the Manufacturing Battery Security Sensors later this yr.
The beta variations of the Manufacturing Battery Security Sensor are the primary of the brand new streamlined design, optimized for manufacturing within the excessive volumes required by automotive OEMs. Items are already on trial with plenty of EV OEMs and battery producers. Preliminary suggestions has been unanimously constructive, based on Metis.
The sensor is designed to choose up a spread of environmental parameters, together with Unstable Natural Compounds (VOCs), Strain change, Humidity, Dew level and in addition has an non-obligatory Accelerometer to file shock masses. This knowledge can be utilized to crosscheck with different inputs, comparable to cell temperatures, to test for cell venting.
The sensor relays the information over a configurable CAN interface to a management unit, such because the car’s ECU, to alert the motive force that cell venting has occurred. The sensor also can set off the method to chop the circuit to the battery pack, giving it alternative to chill down with the target of stopping thermal runaway.
Limitations of present Battery Administration Methods. EV battery packs will have already got a Battery Administration System (BMS) fitted. In addition to managing the charging and discharging of the packs, additionally they try to observe the well being of the battery pack, though that is usually restricted to temperature sensors, one for each few cells and by monitoring for voltage modifications.
This technique works properly if it occurs to be the cell with the temperature sensor that goes unhealthy, but when the cell is a distance away from the sensor within the pack, by the point the sensor registers the change in temperature, if in any respect, it will very seemingly be too late. Detecting cell points by way of voltage fluctuations will also be tough within the brief time period as a result of different cells in parallel can prop up the voltage, disguising points with a cell.
The Metis Battery Security Sensor usually detects venting inside seconds.
There are a number of phases to a cell going into thermal runaway. First, there is a rise in temperature, typically induced when a battery is overworked, has a producing fault, or is aged. The rise in temperature causes the stress contained in the battery cell to rise. Finally that stress, if excessive sufficient, causes venting from the sealed battery cell. If load isn’t faraway from the cell then a thermal runaway can happen.
Cell venting
If a battery is pushed to failure after venting, it might probably catch hearth in a self-oxidizing response, which can most definitely end in a runaway response, setting off the cells round it, and inflicting the full lack of the car.
Thermal runaway
The Metis Battery Security Sensor additionally contains an non-obligatory Accelerometer, so it might probably monitor shock masses as much as 24G and affect period that the battery pack could expertise.
Ought to the EV be concerned in a collision, the sensor will present whether or not the pack skilled loadings above secure ranges and for what period. This may inform the choices as as to whether the battery pack requires a service, a second life in a home or industrial Vitality Storage System (ESS), or be despatched for recycling and any subsequent insurance coverage claims.
Battery packs get heat when they’re charged or discharged. To forestall overheating, most packs are cooled indirectly. If they’re cooled beneath the ambient temperature, they’ll dip beneath the dew level (the temperature at which the air can’t carry moisture and it condenses onto cooler surfaces), which may result in shorting and thermal incidents. The Metis Battery Security Sensor will monitor the dew level within the battery pack and set off a warning earlier than condensation settles on the battery terminals.
