The IoT sector is seeing a slow-down in acquisition activity, as companies realize that they can no longer, or rather no longer have to, buy a lead. There are plenty of vendors that can provide the necessary devices and services to launch an IoT project, without the risks associated with acquisitions. But sometimes a deal is too good to pass up, and that seems to be the case with Shell’s purchase of Sonnen, an established German provider of battery systems for energy storage. Centrica also invested in two startups this past week, taking stakes in GreenCom Networks and its IoT platform for demand-response (DR), as well as Mixergy, a University of Oxford spinout that is developing a water tank that…