cr123a cells are actually something like 16340? I'm pretty sure. AW has it in his battery sale thread in the dealer's section if you REALLY want to know.
The 123A nomenclature indicates that it is 1 cell that is 2/3 the length of an A cell. A cells are around 50 mm in length and are 17 mm in diameter and are round. That means that a 123A cell should be similar to a 17340 ( I believe it actually works out to 33.33 mm in length). In theory, two of these would be a 17670.
Ok, great guys, so, 17650/17670 it sounds like... but what about the voltage, I assume it should be 2x3.7=7.2, right? Also, what chargers are capable of charging CR2's, 123's and theses 17650/17670's? Thanks!
The 17670 is the size of one Li-Ion battery. It will have a nominal voltage of 3.7 volts and be charged up to a maximum voltage of 4.2 volts. This single battery just happens to be the size of two CR123A cells in length.
Oh! So, you loose voltage, so, I am better off using 2 RCR123's, to get the higher voltage, eh? As long as they are protected, right? No issues with using 2 RCR123's, right? What about theses 900ma ones, any issues with them?