(a) If it requires only a small amount of water to bring up the level of the electrolyte, remove the battery and give it a bench charge. See page 198. Only a brief charge may be necessary. Ask the driver when water was added last. If more than 1 month has pa.s.sed since the last filling, the upper parts of the plates may be sulphated, and the battery should be charged at a low rate.

(b) If it requires a considerable amount of water to bring up the level of the electrolyte, and the bottom of the wooden battery case shows no signs of being rotted, the battery has been neglected and has been dry for a long time, and the plates are mostly likely badly damaged. Open the battery for inspection.

(c) If only one cell requires a considerable amount of water to bring up the level of its electrolyte, and the bottom of the wooden battery ease shows no sign of being rotted, that cell is probably "dead," due to in internal short-circuit. To test for "dead" cells, turn on the lamps and measure the voltage of each cell. A dead cell will not give any voltage on test, may give a reversed voltage reading, or at the most will give a very low voltage. A battery with a dead cell should be opened for inspection.

(d) If the bottom part of the wooden battery case is rotted, and a considerable amount of water had to be added to any or all cells to bring up the level of the electrolyte, the battery has leaky jars and must be opened to have the leaky jars replaced by good ones.

If there is any doubt in your mind as to whether any or all jars are leaking, fill the cells with distilled water and let the battery stand for twelve to twenty-four hours. If at or before the end of that time the electrolyte has, fallen below the tops of the plates in any or all cells, these cells have leaky Jars and the battery must be opened and the leaky jars replaced with good ones. The electrolyte which leaks out will wet the bench or on which the battery is placed and this is another indication of a leaky jar.

General Inspection

In addition to the tests which have been described, a general inspection as outlined below will often be a great help in deciding what must be done.

1. Is battery loose? A battery which is not held down firmly may have broken jars, cracked sealing compound around posts or between posts and separators, and active material shaken out of the grids. There may also be corrosion at the terminals.

2. Are cables loose? This will cause battery to be in a run down condition and cause failure to crank engine.

3. Is there corrosion at the terminals? This will cause battery to be in a run-down condition and cause failure to start engine. Corrosion is caused by electrolyte attacking terminals. A coating of vaseline on the terminals prevents corrosion.

4. Is top of battery wet? This may be due to addition of too much water, overheating of battery, cracks around posts and between posts and cover, electrolyte thrown out of vents because of battery being loose, or electrolyte or water spilled on battery. Such a condition causes battery to run down.

5. Is top of case acid soaked? This is caused by leaks around posts or between covers and jars, flooding of electrolyte due to overheating or due to addition of too much water, or by electrolyte spilled on covers.

6. Is lower part of case acid soaked? This is caused by leaky jars.

7. Are ends of case bulged out? This may be due to battery having been frozen.

This general inspection of the battery can be made in a few seconds, and often shows what the condition of the battery is.

Operation Tests

Two simple tests may be made which will help considerably in the diagnosis.

Turn on the lights. If they burn dim, battery is run down (and may be defective) and battery needs bench charge or repairs. If they burn bright battery is probably in a good condition.

With the lights burning, have the customer or a helper step on the starting switch. If the lights now become very dim, the battery is run down (and may also be defective), or else the starting motor is drawing too much current from the battery.

Trouble Charts

For the convenience of the repairman, the battery troubles which may be found when a car is brought in, are summarized in the following tables:

All Cells Show Low Gravity or Low Voltage

A. Look for the following conditions:

1. Loose or dirty terminals or cell connectors. This may reduce charging rate, or open charging circuit entirely. Remedy: Tighten and clean connections.

2. Corrosion on terminals or cell connectors caused by acid on top of battery due to over-filling, flooding, defective sealing, lead sc.r.a.ped from lead-coated terminals, and copper wires attached directly to battery. A badly corroded battery terminal may cause the generator, ignition coil, and lamps to burn out because of the high resistance which the corroded terminal causes in the charging line. It may reduce charging rate, or open charging circuit entirely. Remedy: Remove cause of corrosion. Clean corroded parts and give coating of vaseline.

3. Broken terminals or cell connectors. These may reduce charging rate or open charging circuit entirely. Remedy: Install new parts.

4. Generator not charging. Remedy: Find and remove cause of generator not charging (see page 284).

5. Charging rate too low. Remedy: If due to generator trouble, repair generator. If due to incorrect generator setting change setting. If due to driving conditions increase charging rate.

6. Acid or moisture on top of battery due to defective sealing, flooding, spilling electrolyte in taking gravity readings, loose vent plugs. This causes corrosion and current leakage. Remedy: Find and remove cause.

7. Tools or wires on battery causing short-circuits. Remedy: Tell customer to keep such things off the battery.

8. Short-circuits or grounds in wiring. Remedy: Repair wiring.

9. Cutout relay closing late, resulting in battery not being charged at ordinary driving speeds. Remedy: Check action of cutout. See page 282.

10. Excessive lighting current, due to too many or too large lamps.

Remedy: Check by turning on all lamps while engine is running. Ammeter should show three to five amperes charge with lamps burning. In winter the charging rate may have to be increased.

B. Question Driver as to following causes of low gravity and low voltage:

1. Has water been added regularly?

2. Has impure water, such as faucet, well, or river water ever been added to battery?

3. Has too much water been added?

4. Has electrolyte been spilled and replaced by water?

5. Has battery been idle, or stored without regular charging?

6. Is car used more at night than in daytime? Considerable night driving may prevent battery from being fully charged.

7. Is starter used frequently?

8. What is average driving speed? Should be over 15 M. P. 11.

9. How long is engine usually cranked before starting-? Cranking period should not exceed 10 seconds.

C. If battery has been repaired. The trouble may be due to: