[xorlof]

Thanks for the initial feedback. Much appreciated Here are some answers/clarifcations. For devices, I am talking about the Kindle Touch (1.0). Why that model? Three reasons: 1) most importantly, I can get them cheap (with good battery life remaining), 2) it has a touchscreen so I can make an interface people can easily pick up and use, and 3) it was one of the last Kindles to have a speaker which I'd like to briefly use for the app.

Regarding battery, this was my thinking:

Kindles are conservatively (?) rated at one month of battery life at 1/2 hour of reading per day. It seems like you can hit that number even with wifi on. (Some ads from the kindle 3/4 era say 2 months after the Nook started making that claim.) So that is conservatively 15 hours of non-sleeping time, with the screen probably updating about once a minute. I'm hoping to hit 11 hours, which sounds easy enough (4 hours less than 15), but the devices I'd be using don't have brand new batteries (the batteries are in good shape though) and I'll be using Wifi. That's why I was saying I thought 11 hours might be cutting it close.

You asked about how long it takes to do the update? It will be contacting a local, non-overloaded web server retreiving small data sets, so I'm guessing less than a second to get the data. And I'm guessing about a second processing and displaying the data, even on the Kindle's reasonably slow processor. It's very straightforward in that regard. (The majority of per-minute updates will return no new data relevant to the currently active screen in the web app, so the only screen update will be to update the minutes-remaing-to-play-out-the-current-round countdown. After it's done displaying the update the cpu should go back to idle (or at least my web app won't be doing anything until the next per-minute update).

I don't want the device to ever go to sleep during the whole event though because ideally I want a person to be able to pick up the device at any time and interact with the web app--no "press power button to wakeup" instructions needed. This interaction time should be short--probably only in the range of a half hour total for the whole 11 hour day. I would recharge the Kindles each night.

Does that make sense?