Recommendations for Battery Charging and Temperatures for Machines and Generator Sets{1401, 751B} Caterpillar

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Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.

Problem

New recommendations are now used when cleaning the battery to prevent any ruptures. New information is now available about the proper operating temperatures that are recommended for the battery.

Solution

Cleaning the Battery

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Rapid air movement from compressed air that is combined with dust, dirt, or other debris could create static electricity. When the static electricity is discharged in the vicinity of a battery, an explosion which could result in personal injury or death could occur. Never use compressed air for cleaning in a vicinity of a battery.

Recommended Operating Temperatures

Maximum operating temperature for Caterpillar batteries is 52 °C (126 °F). The ideal operating temperature range for Caterpillar batteries is 20 °C (68 °F) to 25 °C (77 °F). For every 9.4 °C (15 °F) degrees over 25 °C (77 °F) the battery life is cut in half. This is true for any type of lead acid battery, whether sealed, accessible, gelled, AGM, or industrial. The battery temperature should not exceed 52 °C (126 °F) during normal use. If the battery is exposed to extreme heat, electrolyte is converted into hydrogen and oxygen gases, resulting in loss of performance, shorter service life, and the potential for an explosion.

Batteries used in colder or moderate conditions can last between twice and three times as long as batteries used in hot climates. In colder climates the life expectancy of a battery is between 48 and 54 months. In the warmer locations the life expectancy of standard batteries is about 18 to 23 months. This data is based on normal usage and very good charge and discharge conditions.

Battery Charging and Effects of Temperature

If battery chemistry type is changed from the Orginal Equippment (OE) specified battery type, then refer to Table 2 or Table 3 under "Caterpillar Battery Charging Parameters" to ensure optimum battery life.

The charge voltage should be compensated for the battery temperature in high or extreme ambient temperatures. The following reasons are why the temperature compensation of the charging voltage are recommended.

• Prevent thermal runaway of the batteries when the batteries are used in high temperature conditions

• Prevent excessive water loss and shortening of battery life

A battery will emit hydrogen and oxygen gases when the battery is being charged due to the decomposition of water. The decomposition of water because it is being charged at a higher rate than the battery can accept. Generally, a battery will emit gases when the battery reaches a full state of charge. This happens because the charge rate is too high for the battery to accept all of the charge energy. A battery charger, which automatically reduces the charge rate as the battery approaches the fully charged state, eliminates most of the gases that are emitting. Do not charge sealed Caterpillar Maintenance Free (low water loss) batteries for extended periods of time, at rates that will cause the battery to emit gases. The reason for this is because the water cannot be replaced and the gas pressures can build up internally. Of course, no battery should be overcharged for a long period of time.

When a battery has reached a full state of charge, any additional charging will result in wasted heat and the loss of water. This produces hydrogen and oxygen gasses. The excess heat will cause damage to the plates and separators. The loss of water lowers the electrolyte level and increases the specific gravity of the electrolyte. All of these factors contribute to shorter battery life and the potential for an explosion.

Temperature compensation of the charging voltage can prolong the life of batteries as follows:

• Approximately 5 percent compared with no compensation at 30 °C (86 °F)

• Approximately 10 percent compared with no compensation at 35 °C (95 °F)

• Approximately 15 percent compared with no compensation at 40 °C (104 °F)

Note: Thermal runaway is a state of operation where heat generation increases faster than heat dissipation. If this condition continues, permanent battery damage will occur.

Machine Charging System Recommendations

In order to limit the alternator voltage to a safe value a voltage regulator is included in the charging circuit. The primary function of the regulator is to provide control of the output voltage to maintain the battery at a proper state of charge.

Many voltage regulators are temperature compensated. The system voltage is decreased as the temperature increases and conversely increases as the temperature decreases. Normal settings are adjusted for approximately 25 °C (77 °F) temperature. The purpose of this adjustment is to compensate for the charge acceptance characteristics of the battery, which varies with temperature.

The voltage regulator setting can influence the service life and performance of the battery.

Settings that are too high result in overcharge and reduced battery life. Settings that are too low result in undercharging, reduced performance and eventually a discharged battery.

The voltage regulator should be checked every 10,000 miles, or 2,000 hours, or every time the oil is changed. The battery should be checked immediately if the battery is hot to the touch, or if the electrolyte is bubbling or spewing from the battery vents. This is evidence of the battery being overcharged.

Caterpillar Battery Charging Parameters

Maximum charging volts for a 12-volt battery vs. temperature for lead acid batteries, utilizing an alternator.

Maximum charging volts for 12-volt battery vs. temperature for lead acid batteries, utilizing a charger.

Note: Use Caterpillar Data SheetPEHJ-0073 to identify chemical construction of Caterpillar batteries to determine recommended charging voltages in previous tables.

Battery Composition and Charging

Caterpillar currently has a variety of battery compositions on the market.

Maintenance Free (Lead calcium)

The maintenance free batteries use lead calcium grids for both positive and negative plates, and has a lower charge acceptance than other batteries. This means the battery accepts a charge more slowly, but the battery will tolerate an overcharge more than the lead antimony, hybrid, AGM or gel batteries.

Low Antimony (Lead antimony)

The low antimony batteries use lead antimony grids for both positive and negative plates, and has a higher charge acceptance than lead calcium batteries. The low antimony batteries are prone to overcharge.

Hybrid

Hybrid batteries uses lead antimony for the positive grid and lead calcium for the negative grid and has a charge acceptance between lead antimony and full lead calcium batteries. The hybrid batteries are still somewhat prone to overcharge.

Note: Lead antimony and some hybrid batteries require periodic additions of water. Lead calcium batteries generally do not. Battery types should never be mixed on a vehicle, If the battery types are mixed, some batteries may be overcharged, while other batteries are not charged sufficiently. This happens because the alternator responds to the average load and voltage. Also if a battery system has a battery pack of more than one battery and one of the batteries in the battery pack needs to be replaced, the best practice should be to replace all the batteries.