So took Sandy into JCT 600 for the brake light sorting. It done nice new one fitted. While I was there I asked about the software update I had done last week. It's the energy management system. It would seem that it may have been set too high or too low. When it decides it below the set threshold it starts to shut things down one of the first being the start stop. This is to get the battery level back up. If it gets lower it start to cut things like aircon heater blower and so forth. This to conserve the battery. Hope this helps.