For 1990-2009 cars

Caution: Batteries produce explosive gases. Batteries contain corrosive acid. Batteries supply levels of electrical current high enough to cause burns. Therefore, in order to reduce the risk of personal injury while working near a battery, observe the following guidelines:

• | Always shield your eyes.

• | Avoid leaning over the battery whenever possible.

• | Do not expose the battery to open flames or sparks.

• | Do not allow battery acid to contact the eyes or the skin.

- | Flush any contacted areas with water immediately and thoroughly.

- | Get medical help.

Molded into the top of the maintenance-free battery is a built-in temperature compensated hydrometer (1). The built-in temperature compensated hydrometer is also known as test indicator, state of charge indicator, dot, or eye. Built-in hydrometers provide a go/no go indication of the battery state of charge, based on the specific gravity of the electrolyte. Use the hydrometer in the following diagnostic procedure:

1. Make sure the vehicle is relatively level.
2. Make sure the top of the hydrometer is clean.
3. Use a light in poorly-lit areas.
4. Tap the hydrometer on the top to dislodge any air bubbles. Air bubbles will give a false indication.

Under normal operation, one of the following three indications will be observed:

1. The green dot is visible (A).

• | Any green appearance in the hydrometer is interpreted as a green dot.

• | The green dot means the battery is at least 65 percent charged and is ready for testing.

2. The dot is black or dark (B). This indicates the charging rate is below 65 percent and the battery needs to be charged before testing.

• | If there is a cranking complaint, refer to Starting System Check .

• | Check the charging system. Refer to Charging System Check .

3. The dot appears clear or light yellow (C).

• | A diagnosis cannot be made at this fluid level.

• | A clear or light yellow dot means that the fluid level is below the bottom of the hydrometer.

• | Do not charge or test the battery when a clear or light yellow dot is visible.

The following can cause a low fluid condition:

• | Overcharging

• | A cracked battery case

• | Tipping the battery

• | Normal battery wearout.

Do not charge or test the battery when a clear or light yellow dot is visible. Replace the battery when there is a clear or light yellow hydrometer and a cranking complaint.

Built-in hydrometers are subject to the following operating characteristics:

• | There is a time delay in having the hydrometer indication change at about a 65 percent state of charge during both charge and discharge. This is due to the slow mixing of the electrolyte. The lower the charge or discharge current, the longer the time delay. Therefore, when working with batteries that have been in use, tested or discharged within the last 24 hours, remember that the built-in hydrometer may not be giving a stabilized indication. Check the built-in hydrometer again after 24 hours to be sure the indication has not changed.

• | When recharging a battery that had a dark indicator, the time delay of the green dots appearance actually helps the technician do a better job. The plates will be around 90 percent charged by the time the green dot appears.

• | When battery power is used during vehicle repair (such as repeated engine starts, lamps and accessories left on, etc.), remember the hydrometer indication is delayed. A green dot indication right after such vehicle repair may not always mean the battery is still adequately charged. To ensure customer satisfaction, charge the battery to replace the power that was used. A 15-20 ampere charge for an hour will normally be enough to restore a slightly discharged battery.

• | Use a battery charger that is capable of charging the battery at a level of at least 16 V. This helps to recharge in a reasonable amount of time and promotes mixing of the electrolyte in the battery. This minimizes the delay in the hydrometer indication.

• | Remember that the built-in hydrometer only indicates the condition of one battery cell. In a normally functioning battery, all the cells will have nearly equal specific gravity and electrolyte levels. The hydrometer should not be used as the only indication of a fully charged battery.