With just a little bit of maths you will make sure that your batteries and motor are a good fit. This doesn't only apply to motors in electric cars and lithium batteries, but that is the example I will give you as I am most familiar with it.

You will need to do the same match of source power and load power-demand when installing a heat-pump, figuring out if you can run your hairdryer on your off-grid batteries or to design an IoT device.

This is the Power Electronics knowledge base, there are also separate sections for EV batteries and low-voltage vehicle control.