Uninterruptible Power Supply an option for mid-tip charging during long-ish Segway Rides? Feasible?

I'm trying something tomorrow on my nearly 22 mile Segway ride. I'm going to bring along a 375VA UPS which will have a fully charged battery. When I stop at my destination, halfway point of my glide, and park the Segway, I'm going to turn on the UPS and plug a computer power cord from the Segway to the UPS. It should charge the Segway battery at LEAST a few minutes before all the battery juice in the UPS is completely drained. I wonder how much power it will actually transfer before the UPS battery is exhausted? I'm going to find out, and I'll report the findings back here as soon as I have them.