Originally posted by Xmas The K1000 and most of the Pentax meters are sophisticated from memory two metering cells for even coverage and a third cell acting as a on off switch if the light level is below the two cells range the third cell (and transistor) switches off the metering circuit and waits for the light level to increase, with a very low standby current drain. A cap or ERC or dark gbag is normally ok, a cap might be risky for light leaking in via view finder. The meter circuit works ok unless the battery has high internal resistance, mercury, silver, alkaline or zinc hearing aid same reading 1/3 stop on mine, high and low light.
While the electronic switch will turn the metering circuit off at or below EV2 I don't think enough light comes through the viewfinder to trigger the electronic switch unless it is already right on the tipping point, or you shine a strong light into the viewfinder itself. In my experience a lens cap is all that is necessary. Unless I am using it my camera just sits on my desk with lens capped and that is enough to keep the battery fresh.
From the OP's perspective, if he is draining the battery even while the lens cap is on then he most likely needs someone to open up the camera and figure out where in the circuit the current is going to ground. Since the meter works when he installs a new battery then he is either not shutting the circuit down by darkening with a lens cap or bag or something else, or the shutoff circuit isn't working.
One he can take care of himself, the other requires someone to open up the camera.