Passing battery information to virtual machines

I'm thinking about moving my laptop into the virtualization age with the power of vfio. I want to install Debian and then pass though my GPU and peripherals. I will manage my wireless connections though openwrt.

The problem is, the VMs don't have a way of seeing the battery level of the host. This results in a short battery life. Is there is any way of passing though a virtual battery. I see a old issue on virtual manager but it seems dead. Shouldn't this just be a matter of passing though the block device?