We are going out of town next Friday (to Europe) and I wanted to get a backup battery for my canon 20d. I realize I should have looked into this sooner, but you know how it is getting ready for a trip, then realize how much you haven't done yet? So I see that B&H and Adorama are both closed pretty much til my plane leaves. I looked on ebay, but just about everything on there is a generic brand. I need a Canon BP-511a, 7.4V, 1390mAh (Li-ion). So would you get a generic brand or find a Canon battery somewhere? The generic brands on ebay seemed to have a different mAh, like 1600 or so. I'm assuming that it's important that it's the same? And I don't have any photog stores around here... just the usual elec chain stores (best buy, etc) and a tiny Ritz camera at the mall. So i will probably definitely have to buy online. Thanks in advance!