I have 1 Olympus, 1 Hahnel and 1 cheapie from ebay. I can't tell the difference between any of them in use. However, I have read that there can be quality control differences in the real cheapies with a possible risk of fire if faulty. Probably a good bargain versus safety compromise is to go for a Hahnel which is a good brand, but still cheaper than Oly. In fact, I've got no idea if this is true, but my dealer told me Hahnel make batteries for Olympus, but then he was selling me a Hahnel at the time!