Yeah, I brought this up as an issue in my original message on the Spyrus. I also pretty much assumed no one would really take me seriously until someone's batteries actually went dead.
I'll send Ian a special release today or tomorrow that continually burns cards so we can get a rough idea. There are unfortunately a lot of factors, including what kind of smart card is being used. I expect the battery life will correlate pretty well with the number of cards burned however.
I sent a message to Ian requesting this in January. You can buy those little ones by the pound. It would make for a reasonable last resort solution, but lets face it, poll workers can't be expected to dick with watch screwdrivers as part of standard operating proceedure.
Spyrus has told me that they plan to change the design to use a snap-on battery compartment cover, but wouldn't committ to a timeframe. Lets just say we are not their biggest customer so we can't exert much (any) pressure on them.
A fairly brute-force solution might be to just supply more than one of the things to each poll. This also helps the case where one unit grows legs. Given the price of five AVTS units typically used in a poll, supplying two Spyrus units doesn't seem like a big expense to me.
No, that is one nice thing about the design. You won't even loose the ballots stored in its memory.