windows - How to measure how long it take's for a laptop's battery to charge

I have the following scenario:

I am testing several laptops with Windows 8.1 installed. One of the tests is to measure how much the battery lasts. For this task I use benchmarks like PeaceKeeper or PowerMark.

I also want to measure how long it takes for the battery to charge itself to 100% after it gets depleted. Any ideas on how to do that?