Request : disable USB charging

So, I’m in Kyiv. We get power cuts. When the power goes out, wifi goes out.

I have a mobile phone, I’ve bought a SIM, I have mobile broadband.

I can hook that up to the laptop via USB, and that works just fine…

…except…

…the phone has a lovely fully charged battery, which it could and should be running from, but it’s actually now being charged up by the laptop. As you can imagine, this is not what I want in this situation; both should be running off their own batteries.