Audrey Battery Solution?

Posting here because this is the closest thing I could find to an Audrey newsgroup.

I am using a 3COM Audrey. I would like to take it to the back yard or the middle of the living room without having to run a long AC cable to it. Can anyone recommend any battery solutions? I don't just mean an Audrey battery pack (since I don't think they exist); something like a UPS that I could charge from an outlet and then let the Audrey power from it for n hours would be good.

Thanks.