Calcium Battery Charging Requirements

This bulletin is to advise dealers of the required battery charging equipment to successfully charge lead calcium batteries as found in 2007 and 2008 model year Lumina and Caprice models.

Important: Investigations into warranty returned batteries have determined that the majority of these batteries have successfully recharged when charged on the correct equipment.

Lead Calcium Batteries -- Lead Calcium batteries have different characteristics to lead antimony (conventional) batteries and therefore have different charging requirements. Charging a lead calcium battery with conventional battery charging equipment may lead to a battery that is only 60-70% charged.

Battery Condition -- When battery voltage drops low, two conditions (stratification & sulfation) can occur within the battery.

Stratification: This is a condition where the acid separates from the water in the battery cells, giving a layered effect. The acid concentrates at the top of the cell and the water at the bottom. When carrying out a hydrometer test, the high acid concentration at the top of the cell gives a false high specific gravity reading as only the acid is drawn up into the hydrometer.

Charging at a controlled higher voltage has the effect of removing the stratification from the acid and allowing complete charging of the battery.

Should a calcium battery that is suffering from stratification be charged with a conventional charger that does not charge at the higher voltage (15.0 to 15.5 volts), the acid stratification is not removed and the battery is not fully charged.

Sulfation: This condition is the formation of a crust on the battery plates which prevents the battery from functioning correctly. Sulfation occurs when battery drops below a nominal value (refer to Dealer Letter 10/07). This can result in a battery that does not recharge fully, has excessive charging time, fails to hold charge or fails in service.

When testing with a voltmeter, the battery voltage reading may appear higher than what it actually is. A battery charger may switch off prematurely, believing the battery is charged when in fact it is not.

Some battery chargers "pulse" at the start of the charging process if sulfation is detected within the battery. Pulsing is believed to help break down the sulfation.

Calcium Battery Chargers

The following is the recommended charger specifications for calcium batteries.

Some battery charger manufacturers have developed chargers that are specifically for use on calcium batteries. These include low amperage output chargers, 4.5 - 6 amps, and higher amperage chargers of around 14 amps. Typically these chargers are referred to as 4 stage chargers.

The 4 stages are listed below.

Chargers suitable for lead calcium batteries may not be suitable for conventional lead antimony batteries. Refer to battery charger manufacturers’ specifications and operating instructions.

There may be chargers on the market where manufacturers claim they are suitable for calcium batteries. Please ensure that any charger you use on calcium batteries meets the specifications listed in this bulletin.

GM recommends that all dealers review their battery charging equipment to ensure it is capable of fully charging calcium batteries. Dealers MUST ensure new vehicles delivered to customers have fully charged batteries that have been maintained in accordance with the battery maintenance procedure.