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Proper Battery Testing and Maintenance Maximizes Service Life and Cost Savings

Electrical systems for today’s trucks and other commercial vehicles now must support numerous onboard systems, such as fuel control, the Global Positioning System (GPS), surrounding traffic surveillance, climate control and the Anti-lock Brake System (ABS).

Unlike consumer automotive battery systems, commercial vehicle battery systems commonly use multiple 12-volt (V) batteries connected together in parallel. This configuration increases the Amp-hour (Ah) capacity and CCA for more cranking power and energy to meet the increased power demands of onboard accessories and power significantly larger engines.

Additionally, commercial vehicle batteries are expected to withstand harsh operating conditions, while being ready to start high-compression diesel engines and provide power for hotel loads. Trucks used for urban delivery with non-idle restrictions and sleeper trucks with DC-to-AC power inverters can deeply discharge batteries due to the energy consumption. On a regular basis, batteries used in these applications can experience numerous charge/discharge cycles annually.

In order to maintain overall fleet uptime and profitability, it is important to properly test and maintain a vehicle’s battery system. Here are some tips to help you maximize your fleet’s battery systems.

Know the Battery Type

There are three types of lead acid batteries used in commercial vehicle applications today: the maintenance-free flooded electrolyte battery, the Absorbed Glass Mat (AGM) battery and the Thin Plate Pure Lead (TPPL) AGM battery. Unlike maintenance-free flooded lead acid batteries that have liquid electrolyte, an AGM battery contains fiberglass mat separators to absorb the electrolyte. This makes the battery spill-proof with no additional water ever needed.

Plates made of pure lead that are found in premium TPPL AGM batteries, like ODYSSEY® batteries by EnerSys®, can be thinner. More plates can be used when they are thinner to increase the surface area exposed to the electrolyte. This generates more power in the same amount of space as a comparable flooded or AGM battery.

Identifying Proper Battery State of Charge

When a truck comes in for periodic maintenance, technicians should test each battery, looking for consistent values. This can help spot a potential problem battery before it causes a no-start condition on the road.

A voltmeter on the battery terminals will determine the voltage which also indicates its’ State of Charge (SOC), as they are directly related. Initially, the voltage may be low if the SOC of the battery is low, but the voltage will increase as the battery SOC increases. Battery charging is done by the alternator which should provide a regulated charge no lower than 14.00V and no higher than 14.70V to prevent premature failure of the battery.

Charging systems on all vehicles usually operate at 14.20V; the charging system output amperage is what differs. Output amperage on small vehicles can be less than 100 amps and go up to 300 amps on large HD trucks. Some applications like transit buses can have more than 500 amps of output.

Battery Testing

The testing methods for different types of batteries are identical. Whether using a carbon pile load tester or a conductance tester with settings for various types of lead acid batteries, the test results enable the technician to make an informed decision. It is important that the battery be at least 75% SOC, which for TPPL batteries is 12.60V, before testing for the most reliable results. If the battery voltage is below 12.60V, complete the following steps.

  • One of the most common service mistakes is using the incorrect method of charging for the battery type. Modern, “smart” battery chargers have the ability to determine the battery condition and adjust the charging rate accordingly. They also have been programmed with a charging algorithm to adjust the charge voltage and amperage during the charging process. Charging should always be conducted in a ventilated area.
  • Be sure to choose the proper battery type charge setting for the battery being charged (Flooded vs. AGM). Charge the battery until the charger indicates the charge is complete. Unplug the charger and disconnect the battery from the charger. For best results on AGM/TPPL batteries, let the battery sit 10-12 hours to let the surface charge dissipate to obtain a proper voltage reading.  For flooded batteries let the battery sit 30 minutes. If the voltage is ≥12.60V, proceed to the the testing below; otherwise, reject the battery.

½ CCA Load Test Procedure

This procedure should help determine whether the battery has sufficient cranking power or is reaching end of life. The load test should be performed on each battery separately.

  • Connect the load tester cables and the voltage leads of a separate digital voltmeter (if the tester does not have a built-in digital voltmeter) to the battery terminals.
  • Adjust the tester load current to load the battery to half its rated CCA and apply the load for 15 seconds.
  • At the end of 15 seconds note the battery voltage on the voltmeter and discontinue the test. If the temperature is 70°F (21°C) or higher, the battery voltage should be at or above 9.60V. If so, the battery can be returned to service. If below 9.60V, the battery should be rejected.

Handheld Conductance Tester

This procedure should help determine whether the battery has sufficient cranking power and capacity.

  • Connect the tester cables to the battery terminals. Be sure to choose the proper battery type selection for the battery being tested (Flooded vs. AGM vs. TPPL (Pure Lead)) and input the full CCA rating in the tester.
  • Start the tester and read the results when the test is complete (15-30 seconds). If the tester says, “Good battery”, it can be used. If it says “Bad” battery or “Replace”, it should be taken out of service.  

Avoiding Failure with Premium AGM Batteries

The best and most effective defense against high cycling with deep discharging is to incorporate large amperage alternators. This provides the fastest recharge to fully charge on the batteries. Take rested voltage values of each individual battery to look for voltage value consistency. This will help identify any battery with a lower voltage value that might be failing.

Fleet managers are increasingly willing to pay more to include a long-life TPPL AGM battery in their new trucks. They have found that these batteries usually last the life of the trucks’ first owner. In addition to this net cost saving, TPPL AGM batteries help reduce costs associated with an unexpected failure to start. The TPPL AGM batteries also offer significantly longer service life: generally, 30 months to 60 months. The use of pure lead significantly reduces plate corrosion, while a TPPL battery with tin-plated brass terminals requires no terminal maintenance.

Please refer to your owner’s manual or consult a battery professional for more details about your specific application.

Learn More About How ODYSSEY® Batteries Deliver Greater Reliability and Value:

Technicians may refer to the ODYSSEY® Battery Technical Manual as a good source of information about how ODYSSEY® batteries work, and their proper testing and maintenance. A copy may be downloaded here.





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