Just got a "new" analog Honeywell Pentax Spotmeter (no, not digital, the cheaper, older one with the needle). I am using a 1.5 V battery with a stack of copper washers, and when testing it against my old Gossen averaging meter the readings look right on, so the difference in voltage from the 1.3V mercury battery it was designed for and this 1.5V does not seem to be affecting the readings. Am I missing something? I have not shot any film with it due to lack of time. Anyone with experience in this please let me know.

Also, the meter is always "on". I have not found a lens cap for it yet. Will using a lens cap save battery life? Obviously it's good lens protection, and I hate the thought of my battery's juice being wasted. The cap seems to be a 46mm inside screw or a 47mm slip-on...again, anyone can confirm this?

Thanks!