Please keep us posted on this one. I bought a ProMaster EN-EL18 replacement at my camera store as a spare when Nikon batteries were not available and it was all that was in stock. It was fine at first, but now doesn't charge past 98%. This means that it doesn't reset the picture count, and probably is not counting charge cycles (or however it keeps track of battery age). It works fine and without error, but discharges much faster than my Nikon batteries (even the older, non-revision ones) whether under load or just sitting in the camera. The interesting thing is that the store was selling it at the same price that they normally charge for Nikon batteries, which is discounted from the list price but higher than most here report paying for 3rd party batteries. $59.95, I think.