Diagnose your Makita LXT battery pack in three steps.
Plug the Arduino into USB (the OBI firmware must already be flashed), then click Connect.
This browser can't access the serial port, so the browser version of OBI-1 can't connect to the Arduino. Use the desktop app instead — it has native serial access and needs no browser setup.
Place a battery in the holder so it makes contact with the interface pins.
Reads the model, cell voltages, temperatures, charge count and status in one go.