Do you always use your MBP connected to a power outlet? If so, try running it until its battery is drained about 50%, then plug it into your inverter and see how much power it draws. My guess is it will draw about 50-60 W.
I've been using a pedal-powered generator to power my computer, phone, tablet, and LED lights for the last 5 years and have tested several laptops and other devices using it. I've found that most laptops draw from 12 W (11" Chromebook) to 25 W (older 15" Dell) when their battery is charged, but 40-60 W when charging.
The power supplies of most devices seem to have about a 50% safety factor, so a device that has a normal max power consumption of 50 W will use a 75 W power supply.
How much electricity can you generate? Just thinking off the top of my head, I'm a sucky cyclist so can only manage about 150W power output sustained, probably. I'm not sure I could handle more than an hour of stationary biking before I collapse in a puddle of sweat ;-) So that's about 150 WH...
Is that about right (ballpark), or have I missed something? It would probably power my laptop for the day, anyway... It's something to think about (since I love cycling, even stationary ;-) )
Most people seem to be able to comfortably produce 30 W over a sustained period of time.
If you're used to bicycling, dress appropriately, and work in a cool environment with a fan, you can produce 50-60 W.
Above that, it becomes difficult to maintain your concentration on your work while trying to pedal hard at the same time.
On most days, I maintain about 35-50 W, depending on the load.
So far this morning, I've ridden for 2 hrs, 5 minutes and produced 74 W-hr. The computer I'm using this morning is a Raspberry Pi2 with a 19" monitor. I'm also powering our DSL modem/router and a 12 V fan while recharging two tablets, four AA batteries, and my phone at the same time.
I wonder how much inefficiency there is due to the inverter and the computer's wall transformer. Would it be better to run DC from the generator to power a dc-dc converter (which might have its own losses)?
Yes, it's definitely better to power everything using DC if possible. The best, reasonably-priced inverter I've found still draws 2 W whether it's powering anything or not. But it's difficult to get the right voltage and connector for every electronic device you might want to power.
I've been using a pedal-powered generator to power my computer, phone, tablet, and LED lights for the last 5 years and have tested several laptops and other devices using it. I've found that most laptops draw from 12 W (11" Chromebook) to 25 W (older 15" Dell) when their battery is charged, but 40-60 W when charging. The power supplies of most devices seem to have about a 50% safety factor, so a device that has a normal max power consumption of 50 W will use a 75 W power supply.