Car Battery Inspection

Symptoms of Problems Caused by the Battery

The following symptoms will be noticed when a drop occurs in the battery voltage:

Either the starter motor will fail to operate or it will barely operate, thus making it impossible to start the engine.
The headlights will be very dim or they will not light at all; furthermore, the brightness of the headlights will vary as the throttle opening is changed. (Specifically, the lights will get brighter when the accelerator pedal is depressed and dimmer when it is released.)
The battery electrolyte level will drop at an increased rate.

NOTE:

When compared with older vehicles, today’s automobiles contain many more components which consume electricity. On a rainy night, for example, a modern vehicle’s headlights, fog lights, wiper, rear-window defogger, and air conditioner will all be turned on; furthermore, the audio system may also be used. In such a condition, the battery level will decrease even while the vehicle is being driven, and this could eventually lead to the battery becoming fully drained.

Battery Inspections

The following four principal checks are performed on the battery:

Visual check
Electrolyte-level check
Specific-gravity check
Load test

NOTE:

In the majority of cases, it will not be possible to carry out either an electrolyte-level check or a specific-gravity check on maintenance-free batteries. However, the equivalent inspection can be performed using the indicator which is attached to such a battery.

Battery Service Life

It is not possible for batteries to maintain their initial performance levels indefinitely. As a battery is repeatedly charged and discharged, a wide range of changes take place within the electricity-storage medium, and performance levels will gradually decrease (i.e., the battery capacity will drop). Eventually, the output voltage will fail to increase even after charging, or alternatively, the level may raise only to then drop suddenly. When such a condition has been reached, the battery in question must be replaced.

Because the service life of a battery is highly dependent on mode of use and other similar factors, it is not possible to specify for how long a battery may be efficiently put to use. Consequently, specific gravity checks and load tests should be employed to determine when performance has dropped to an unacceptable level.

Note that battery performance will also be impaired as a result of the following:

If the battery is fully discharged and allowed to remain in this condition for an extensive period of time, it will become very difficult to subsequently charge that battery; alternatively, even if charging is possible, the battery’s performance level (or capacity) will drop rapidly.
If the electrolyte is allowed to freeze, this will also have a detrimental effect on battery performance.

Furthermore, if a short-circuit or some other similar type of problem were to occur within the battery but charging was still possible, a sudden drop in output voltage could occur when starting of the vehicle is attempted. If such a condition were to occur, therefore, starting of the vehicle would not be possible and replacement of the battery in question would be required.

Battery Visual Check

Visually and manually check the battery for the following:

Cracking or distortion of the battery case, or damage to terminals

The battery case should be inspected for any cracking, distortion, or other similar problems, and the terminals should be inspected for damage. Furthermore, the battery should be inspected for leaks occurring as a result of these factors. If the case is dirty, it should be cleaned using warm water and baking soda, and it should then be wiped completely dry. If any cracking, distortion, or fluid leakages are identified, the battery must be replaced.

Rusting

The battery terminals and the battery-cable clamps should be inspected for rusting. If rust is found on these components, it should be removed using sandpaper. Then, after reconnecting the battery-cable clamps to the battery terminals, grease should be applied to the connection points to protect against further rusting.

Battery-cable looseness or disconnection

The battery cables should be inspected for poor connection caused as a result either of detachment of the battery-cable clamps or of looseness in the clamp connections. Any loose clamps should be securely tightened.

Battery-fixture looseness or disconnection

The fixtures used to secure the battery in place should be inspected for looseness. If the battery is mounted poorly, vibration could cause its internal components to be damaged or could result in breakage of the case; consequently, any loose fixtures should be securely tightened. Note, however, that excess tightening could also lead to breakage of the case, and adequate care should be taken during this operation.

Check cables
Check holddown
Check cable connections
Check terminal corrosion
Chack electrolyte level
Check case

Battery Electrolyte Level Check

When performing an electrolyte level check, it is important that each of the cells be inspected individually. In this, it should be confirmed that the level of electrolyte in each cell should be positioned between the upper and lower marks on the battery case. If the level is below this range, remove the cap and add distilled water, taking care not to exceed the upper mark.

Electrolyte levels drop as a result of over-charging, evaporation of water, and other similar factors, and if an insufficient amount of electrolyte is available within the battery, plates and separators will be exposed, thus leading to a reduction in battery performance. Furthermore, if the battery contains an excessive amount of this fluid, the surplus could overflow and consequently damage the body and/or other vehicle components. Accordingly, the electrolyte level should always be positioned between the upper and lower marks. Note also that if distilled water is added during winter months, there will be a possibility of freezing if the specific gravity of the resultant electrolyte mixture is too low; accordingly, charging of the battery should be carried out as soon as possible.

Battery Specific Gravity Check

The specific gravity of the battery’s electrolyte decreases in direct proportion to the discharging of the battery; consequently, it is possible to determine the current degree of battery charging by measuring the specific gravity.

Specific gravity is measured using a hydrometer. When taking a reading from this instrument’s scale, ensure that the glass tube is oriented vertically and that the float does not come into direct contact with this tube. The liquid will move up the scale as a result of surface tension, and a reading should be taken from the scale at the highest point of this liquid (i.e., Position A from the diagram). Specific gravity also changes in inverse proportion to temperature-i.e., the specific gravity increases as the temperature drops and vice versa. Consequently, measurements should either be taken at a standard temperature or calculations should be performed using the measurement result to find the corresponding specific gravity at the standard temperature. For more details, refer to the instructions provided with the hydrometer.

Upon completion of the specific-gravity check:

If the specific gravity was found to be normal, it will indicate that the battery is in a satisfactory condition.
If the specific gravity was found to be high, distilled water should be added.
If the specific gravity was found to be low, a load test should be performed.

Battery Load Test

The “Battery Test” as detailed in shop manual is actually a load test; furthermore, this test is also often referred to as the capacity test. Note that this test simply involves the measurement of voltage between the battery terminals and that it does not enable estimation of battery performance when a large load such as the starter motor is connected. Nevertheless, this is the most accurate and widely used test for determining the battery’s state of charge.

As described in shop manual, apply a load of three times the battery ampere-hour rating (or 50% of the cold cranking rating), and measure the battery voltage.

For details regarding usage of battery tester and battery charger, please refer to the relevant instructions.

Precautions for Battery Inspection

Both hydrogen and oxygen are produced by a battery during, and immediately after, charging. Accordingly, the use of naked flames or items which may generate sparks is strictly prohibited in the vicinity of batteries. Furthermore, when disconnecting devices such as a charger or battery tester, be sure to first of all turn off the power switch to prevent sparks from being generated at the clips.
Do not short circuit the battery’s positive and negative terminals with metal tools or fixtures.
Ensure that the battery cables are disconnected and reconnected in the correct order. Specifically, the negative-side cable should be disconnected first of all, followed by the positive-side cable. The reverse order is to be implemented for reconnection-i.e., connect the positive-side cable before the negative-side cable.
The vehicle’s engine should be tuned off during maintenance, inspection, and replacement of the battery; furthermore, all other electrical loads such as the lights and audio components should also be turned off.
Do not allow the battery’s electrolyte to come into contact with skin or eyes. This liquid is actually a dilute sulfuric acid; consequently, blindness could result from contact with the eyes, and burns could result from contact with skin. Note also that electrolyte can also damage clothing and machinery.
The battery must not be tilted or turned upside-down; in addition, it must not be exposed to strong blows. Failure to observe these precautions could result in the leakage of electrolyte.

Precautions for Battery Charging

All caps should be removed from a standard battery for charging.
Charging should be carried out in a well-ventilated area.
Always replenish insufficient fluid as failure to do so can result in the battery’s service life being shortened.