It seems very unlikely that the empeg could have drained a functioning battery completely in such a short time. It does present a very small load even when off, due to the linear regulator for the 5v analogue line, but this is on the order of a couple of mA. A good battery should sustain that for weeks.

It sounds like your battery is either faulty (low acid in one or more cells?) or you have another load on it somewhere. The last time this sort of thing happened to me it took ages to track down, and eventually turned out to be a faulty alternator. It was putting a 5A load across the battery when in the right position! I suspect it was a faulty diode in the rectifier.

pca