I’m using the official BOINC client. There are others available but I have no experience of them, so they may work differently than what I’m about to describe.
The official client is set by default to only crunch when plugged into power, and the battery charge is above 90%. I presume this is to let it recharge quickly, without the user worrying about battery life. Of course, this does mean you wont get any work done while not plugged in. The way they describe it is that you may, for example, charge it overnight so you can get some hours in then. In theory there should be no hit on battery life this way. If you want to run while on battery, you can configure it to do so. Similarly it will only transfer data over wifi not mobile data so shouldn’t eat into what is usually a more expensive allocation, unless again you configure it to do so.
Anyway, the first two units have completed and did take around 3 hours. I then set it to run on 4 cores and CPU-Z doesn’t report any drop in running frequency, so maybe I’ll get double the throughput. It does feel slightly warmer.
I tried to measure the power consumption with limited success. By connecting it up to a power supply at 5V I can monitor the current over the USB port. It was taking about 2.6W while crunching, and HIGHER than that when I suspended it. Don’t know what it was doing… I then noticed the battery charge was dropping. Basically my dumb simulated USB power supply wasn’t giving it enough juice. I connected it back to a dedicated USB charger, and saw it creeping up in charge once again. Note the USB standard allows higher currents from dedicated chargers, so maybe I have to fool it into thinking my test charger is one. Anyway, roughly speaking the power usage is probably somewhere in the 3 to 4W ball park. I’ll see if I can refine this later.