Setting the battery charge level within Linux

In Windows you can use the "Dell Power Manager" app or whatever it's called to set specific charging behavior. For example, I set it to only charge up to 80%, since I'm usually using the thing plugged in and I'll get a lot more life, long term, out of my battery if it's not sitting at 100% all the time.

There is a similar functionality in the BIOS.

Now these settings "work" when I'm booted into Ubuntu 16.04, in that the limits are respected but I would also like to change them from within Linux. The main use case is that *sometimes* I know I'm about the take the machine on the road so I'd like to charge up to 100%. Having to shut down everything and boot into the BIOS to do this is a pretty big pain so in practice I just live with my 80%.