I am trying to make equipment to measure temperature in small mammals, probably attached to a neck collar. The collar needs to be very lightweight (e.g. <3g total) so I am planning to use a lithium coin cell battery, perhaps the 16mm ones or posssibly 12mm. I was thinking of buying one with contacts attached and just glueing it to the board to save weight.
Apart from the connection to the board I don't want to run the risk of the contacts on the battery touching anything else, and it would be better if it is somehow covered to make it much more difficult for the animal to scratch or bite (I would try to make it so that the entire collar comes off if the animal uses enough force rather than just the battery). I'm also not sure about the requirements for waterproofing. The animal will probably get wet and might drag the collar in a river when drinking.
Can I cover the battery (and probably rest of the circuit apart from the sensor) with some type of sealant or do these batteries need vent holes to be safe? Any suggestions on lightweight ways to enclose and protect anything from the enviroment, (ideally which could somehow be removed later to replace the battery, even if requiring tools) would also be appreciated. perhaps I could use some type of material or something and heatshrink inside that, but I'm concerned about water also. Thanks!!! :)