microSD and battery life - can't find a resolution.

[Mentalepsy]

I've been trying to find information on this issue, both on this board and on the rest of the internet, but I haven't found anything really definitive or helpful. I've also written to Sandisk support, but they were predictably useless.

I bought an 8-gig Clip+ a few months ago, and I get about 13 hours of playback on a full charge, which I'm happy with. However, if I insert a microSD card, even if there's nothing on it, the playback time is cut in half to about 6-7 hours, which is ridiculous. What confuses me even more is that I was previously using the same card in a Sansa Express, and it had no noticeable effect on the battery life.

The card is a Transcend 2GB. I've also tried a Sandisk 2GB with similar results.

So, I'd like to hear from people who use microSD cards - what kind of card are you using, and does it drain your battery much faster? Has anyone had this problem and successfully resolved it? Has Sandisk acknowledged that this is expected behavior? Is there something particular I need to be looking for in a microSD card?

Thanks.