[r_fredrick_smith]

I have the 20D with the bp511 batteries. Two are Canon model and 4 are off brands that I paid $12.00 for each. All still work just fine for 200 shots or more. I've found that one of the Canon batteries is starting to weaken (the oldest). These batteries have no memory, so you can charge them to full power each time. They do have life however measured in number of recharge cycles. Few of us will encounter that if you have several batteries like myself. They do lose some of their charge on a regular basis when in storage. But if you shoot regularly, this has little effect. If you go on a big project, just be sure to recharge all your batteries if its been a long time since they've been charged.

cheers,
rfs