The H-Watch is an opensource, long-lasting health monitoring wearable. Utilizing integrated NB-IoT technology, it offers direct, secure cloud connectivity. Although built with off the shelf components, its design focuses on low power consumption and on board intelligence. With an average power draw of just 5.9 mW, it achieves a 9-day battery life, which extends up to 20 days with its built-in solar harvester. The whole project is opensource.