Dell Power Companion is confusing and maybe misleading

I bought a Dell Power Companion. Seems like a reasonable idea for a battery, but it's so poorly documented that I'm confused.

It has no written documentation. It only ships with a few pictures. One of the pictures shows plugging your laptop's charger into it to charge it. Fine.

The other series of pictures is labelled "Charge your device". It shows two steps: 1) plug the Power Companion into your laptop. 2) Push the little button on the Power Companion. Why do I push this button? It charges with or without me pushing it. On the printed "documentation" it labels this button with the universal power on/off symbol (the circle with the vertical line in it). But this button doesn't appear to turn anything on/off. It simply lights up the five tiny white charge level indicator lights. But if I hold the button down for a long time and then release then it turns on just one charge indicator LED (the one representing full charge). What does this special mode mean?

One of the little lights will turn orange sometimes when I plug in the charger and other times it won't. I assume ths means "charging", but why does it sometimes not turn on?

Next question: It doesn't charge my laptop. It powers my laptop, but won't charge it. In Win 8, if I hover on the battery icon it says, "plugged in, not charging". I guess this is ok. The laptop runs, and it's presumably a more efficient use of the power than charging the laptop's battery. But Dell's product web page (accessories.us.dell.com/.../productdetail.aspx;l=en&s=dfo&sku=451-bblz) says that it should charge the laptop: "the two USB charging ports let you simultaneously charge a pair of mobile devices in addition to your Dell Laptop." It also says, "The Dell Power Companion is designed to deliver in-bag charging, so your devices are charged when you need them." I have yet to see this thing charge my laptop.

Finally, there is a photo on the product web page showing the charger being plugged into the Power Companion, and the Power Companion being plugged into the laptop. This makes sense to me, and what I would assume this would do is first charge the battery of the Power Companion, then charge the battery of the laptop, all while powering the laptop for use. Or maybe charge the batteries in the opposite order. But does it do this? Nope. It powers the laptop and charges the Power Companion, but again, I have yet to see this thing charge my laptop.

This really ***! If I plug both things in over night, then in the morning I want them both to be charged. That's not possible here. I have to either wake up in the middle of the night and unplug the Power Companion to start the laptop charging, or I have to bring two chargers with me.

My laptop is a late 2013 Dell XPS 15.