In winter, some of the connected devices continue to draw a minimal quiescent current despite the main switch being turned off. Modern vehicles therefore often have an Undervoltage switch integrated into the on-board electronics, which completely disconnects the <a href="https://www.renogy.com/deep-cycle-batteries/">rv batteries</a> from the on-board power supply in good time before it falls under Undervoltage and suffers long-term damage.