I think mine is rated between 20-26 pounds per day. Keep in mind though, it only holds 2-3 pounds at a time. If you plan on having cooler ice at the end of a long day at the parks in any quantity it isn't going to happen. You have to be there to dump it out regularly. That being said if you were hanging out at the campsite all day you'd make plenty.
The way mine works, the water reservoir is in the bottom, water is pumped up to a trough that has metal 'fingers' sticking down in it. The trough fills up, the fingers get freezing cold and makes these hollow ice nuggets. Depending on how you have it set when the nuggets get to the size you selected the fingers heat up. The trough moves out of the way as they heat up, dumping excess water back down in the bottom, then the nuggets fall off where the trough was and a paddle comes across and sweeps them into the holding basket. The holding area is not really chilled that I can tell, it just depends on the coldness of the ice to keep it from melting too fast. If it does melt any, the water drops through the basket back into the reservoir and the circle of live continues! I was kinda fascinated the first time I saw it make ice and after the first couple of cycles it starts getting really fast. It will cycle an average of every 10-12 minutes making about the equivalent of a regular ice tray at a time. It will stop making if it runs out of water or gets full, if you are away and it melts as soon as the sensor is not touching ice it just starts back up again.
When I have electric it always goes with me camping. I also use a Brita pitcher to fill it to make better tasting ice.