I use 3V coin cell batteries in many of my eTextile and paper computing projects. They’re small, easy to use, and effectively power multiple LEDs.
In general the negative terminal is the underside, unmarked, and has a dotted textured surface. While the positive side will be marked with a + symbol.
These CR2032, as with the design of most coin cell batteries, have a lip that pulls over from the positive side to encase the negative terminal. When designing your circuit please remember that this surface is also part of the positive terminal.
Insert the coin cell battery into the battery holder so that the positive and negative terminals connect with the correct attachment points on the battery holder. Many battery holders positive terminal will only come in contact with the side of the battery’s positive terminal.
This particular battery holder can be tricky because it’s metal connector points easily bend out of shape causing both to contact the negative side of the battery rendering the holder unable to form a complete circuit.
