Which of the following instruments are used when performing a high-rate discharge test on a storage battery

The answer is a voltmeter and an ammeter.

In high rate discharge, an ammeter is used to indicate current and a voltmeter indicates a battery voltage. A call tester, on the other hand, gives the correct terminal voltage on full load of the battery cell. In addition, a hydrometer is used test and check the specific graving of the electrolyte.