Camera batteries losing charge?

Is it the batteries, the charger, or the camera? Rechargeable batteries seem to be losing their charge about twice as soon as in the past three years with Canon PowerShot A510, Sony NiMH AAs, and Sony Charger BCG-34HRMD. A few months ago, I got a low battery warning from the camera much sooner than I expected. I recharged the batteries, took only a few dozen pictures, and got the same message. I discharged then charged the batteries and soon after got the same message. I bought new batteries (same type), and having the same problem. If anything, I'm taking a lot less pictures these days and practice power-saving techniques (auto-off, display off on bright days, etc.) By the way, each time I got the low-battery message, I checked the batteries and they had indeed lost most of their charge.) Could it be the camera? Thanks.