Millions of people have watched the videos: a prankster taps a smartphone screen, and a moving e-rickshaw abruptly grinds to a halt. The drivers appear confused while the people filming laugh. On the streets, though, this social media ‘trend’ has created a real hazard.A series of videos on social media people using the BAT-BMS app to stop moving e-rickshaws. (ANI/Google Play Store)Behind the jokes is a basic flaw in how some electric three-wheelers are built. Many modern e-rickshaws use Bluetooth-enabled battery systems. To monitor battery health, manufacturers use apps like BAT-BMS and Lossigy.Some of these systems were built without any password protection or authentication. Anyone within Bluetooth range can download the app, connect to a nearby vehicle, and cut its power with one tap.In a test conducted by Hindustan Times with a driver's consent, an e-rickshaw was switched off remotely and could only be restarted through the same app.About the ‘e-rickshaw’ appBAT-BMS is a mobile app developed by Chinese manufacturer Shenzhen Grenergy Technology. It lets users wirelessly monitor Bluetooth-enabled lithium-ion battery packs, according to Google Play Store.According to the app's description, BAT-BMS offers the following features:Connects to compatible Bluetooth-enabled lithium batteries.Shows battery charge (SOC), voltage, current, temperature, cycle life and cell health.Tracks battery charge and discharge cycles.Works with phones that support Bluetooth 5.0 (BLE).Has a wireless range of up to 15 metres.Can monitor multiple batteries, but only one phone can control a battery at a time.How the 'kill switch' worksThe problem is not in the app itself but the way some battery systems are built.Many low-cost lithium-ion battery packs used in e-rickshaws come with Bluetooth turned on and no password protection. This allows anyone nearby to connect to the battery using apps such as BAT-BMS or Lossigy.After connecting, a user can tap the "Discharge Switch" inside the app.This immediately cuts power to the e-rickshaw and stops it from moving. The driver cannot restart the vehicle with the ignition key because the battery remains switched off.The battery must be turned back on through the app.E-rickshaws that run on older lead-acid batteries are safe because they do not have Bluetooth. Some newer lithium-ion batteries also use their own software or password protection, which blocks third-party apps from connecting.How drivers can prevent thisChange the Bluetooth password - Open the BAT-BMS app, connect to the battery and go to Settings or Parameter Settings. If the option is available, replace the default password with a new one.Turn off remote control features - Some battery systems include options like Remote Control Lock or App Control Lock. Can turn these on.Disconnect Bluetooth: Drivers who do not need Bluetooth can ask a technician to disconnect the Bluetooth module from the battery management system. The e-rickshaw will continue to work normally, but other phones will no longer detect or connect to the battery.