Originally posted by Ontarian50 One thing to remember when adapting batteries to the Spotmatic, is that the battery compartment in the Spotmatic is "upside down" to what you might expect.
The battery cover is marked with a fine " - " for the negative contact of the battery, which means the positive side has to go into the compartment recess and make good contact with that small terminal inside. This is why the battery needs to be so small, and why you need some kind of gasket around it to keep it aligned. Original batteries had a wide metal flange attached to them. Later batteries made to fit the Spotmatic had a plastic gasket surround, usually clear or blue coloured. The plastic gaskets can be pried off dead batteries and re-used with a new silver oxide battery that fits (usually that 394 size).
So, yes, if you put the battery into the compartment the direction it looks like it goes, you will have reversed polarity, and the meter won't work.
Thank you! This is SO good to know. I had to remove the corroded battery and after cleaning up the spin on cap I couldn't see a positive or negative sign on it to know how to orient the battery.