Electrical Tests for Batteries

Question 1

open-circuit voltage test

Answer 1

In this test, a voltmeter is connected to a disconnected battery to test the voltage. If the battery fails to produce any voltage in this test, it’s discharged and will need to be either recharged or replaced.
A battery can pass the open-circuit voltage test but still fail to produce the needed voltage when connected to a circuit. In this situation, the battery will need to be tested while connected to a load to determine the problem.

Question 2

A light-load test

Answer 2

can be performed next to determine a cell’s ability to produce voltage under a light load. The instrument used in this test is the cell analyzer or the cadmium-tip tester.
In a light-load test, the battery caps are removed. Next, the tips of the cell analyzer are used to probe inside the battery and make contact with each of the cell connectors. Each of the battery’s cells are tested individually.

Question 3

cell analyzer

Answer 3

The cell analyzer places a voltmeter in parallel with the cell under test. The cell analyzer also places a large-value resistor and a series-connected ammeter in parallel with the cell. In the light-load test, only one cell is tested at a time at a low current.
All the cells tested should display a steady reading of 2.0 VDC, and each should display the same current. If one cell displays a lower voltage or current than the others, the battery should be replaced.

Question 4

high-rate discharge test

Answer 4

In this test, a variable resistor (a rheostat) is connected into the circuit along with a voltmeter and an ammeter (Figure 24). The rheostat places a heavy load on the battery, and the voltmeter and ammeter measure the battery terminal voltage after 15 seconds of discharging.

Question 5

full-charge hydrometer test

Answer 5

If a battery passes the specific gravity test but later fails in service, you the full-charge hydrometer test to determine the battery problem. Perform this test as follows:

1. Remove the battery from service. Adjust the electrolyte level as necessary by adding distilled water.
2. Fully charge the battery at a slow rate.
3. Use the hydrometer to measure the specific gravity of the electrolyte in each cell. Full-charge hydrometer readings less than 1.230 indicate that the battery is defective and should be replaced.