Lack of documentation on batteries? Trying to understand why LR1130 and LR1131 aren't equivalents
LR1131 and LR1130 are both 11mm diameter by 3.1mm thickness. That's what the 1130/1131 means. Note that the image below indicates some variance in dimensions, so both numbers are rounded anyway. L indicates alkaline cell, so the same chemistry as in your typical AA battery, just smaller. R simply means round; it's an indicator of the shape. R is by far the most common for this type of battery and I'm not actually aware of any other shape nomenclature, so it's very possible it just gets left off by some manufacturers.



So, in short, the two are in fact identical. I think you were sold bad batteries.

Incidentally, for a slightly better battery life, you can get SR1130/SR1131s. These use a silver oxide chemistry with a slightly (1.55V rather than 1.5V) higher voltage and slightly longer life.