The TS-2 temperature sensor is an add-on component for the SC-2030 solar battery charger, by Bogart Engineering. The sensor is needed in most installations because the batteries are usually located away from the SC-2030. Consequently, they are likely at a different temperature than the SC-2030 itself. The TS-2 temperature sensor allows the SC-2030 to correct the charging voltage by the specified temperature coefficient. The SC-2030 has the coefficients for the lead acid batteries programmed in, and they can be adjusted according to the battery manufacturer specifications.