In this picture you can see the location of the battery temperature sensor.
It is important to mount this directly to the battery post so it senses the temperature of the bank correctly. The temp sensor should be mounted to the battery which has the most potential to get warmer than the others. For example, if your battery compartment backs up next to an engine room bulkhead, then the battery closest to that bulkhead would get the temp sensor.
The sensor also needs to be connected directly to the negative terminal, and not the positive terminal. This sensor has the ability to fry the charger if connected to the + terminal and then accidentally shorted. This sensor CAN NOT be fused and sense temp correctly, so, by ABYC standards, it can not be connected directly to a + post.
Always keep in mind, when stacking terminals on a battery post, that the highest current potential terminal is always placed on the bottom. In this case the two 2/0 negative cables go below the temp sensor ring terminal. There is also a limit of four terminals per battery post. Use buss bars if you need more than four items on a battery post.
ABYC standards now also prohibit wing nuts on battery terminals if any wire connected to the battery is larger than 6GA AWG. Use standard nuts with locking washers or nyloc nuts if you have enough thread left for the nylon in the nyloc nut to thread over.