I've noticed when using my Olympus OM-1 slr that to get a proper exposure I need to adjust the camera settings to be usually 2-3 stops larger (or shutter speeds longer) than what the light meter is telling my to expose at. Therefore the light meter's needle, instead of resting evenly between + and -, has to be at or past +. Could this indicate a battery problem? Such as the battery losing energy or being the wrong voltage? Or is it problem with the meter itself?
I'm using a 625A button cell battery. I can't recall when this began or for how long it's been happening as the OM-1 is not my primary camera.