Electrical System Maintenance

The electrical system controlling your diesel engine is very important to the reliable operation of your equipment. Unfortunately, it can also be frequently overlooked. Maintaining the engine’s moving parts seems more obvious than maintaining the electrical system. However, you can benefit greatly if you exercise thorough electrical system maintenance procedures and system checks. 

Battery Maintenance

Always check the health of the battery during routine maintenance on your diesel engine. Batteries can have problems at any time of the year. But when the weatherman predicts an Arctic blast, monitoring batteries becomes even more critical.  Are we just more aware of the inconvenience of a bad battery in the winter because we’ll have to do maintenance work out in the cold? Or do batteries really fail more often in the winter?

Cold weather actually is tough on batteries. Essentially, the battery needs to work harder with less power.

• If the battery is warm, the chemical reaction rate inside the battery increases. The battery stores the optimum voltage, and fewer amps are needed to start the engine.
• If the battery is cold, the reaction slows. The battery stores less voltage, more amps are needed to start the engine, and the battery quickly runs out of energy. 

Here is a practical example of this problem:

• The cranking power of a battery at 64°F is twice that of a battery at 0°F.
• A battery will lose 35% of its strength at 32°F and about 60% of its strength at 0°F. 

Other factors can also stress batteries. Cold temperatures thicken engine fluids, resulting in increased engine starting resistance and power demand. Batteries deteriorate and develop internal corrosion with use. This makes it more difficult for a battery to deliver sufficient engine starting power. The battery’s energy output is also reduced when its terminals are corroded. To clean the terminals, disconnect the battery cables and scrape away as much corrosion as you can. Scrub the terminals with battery terminal cleaner spray and a battery terminal brush. The battery terminal cleaner spray removes corrosion and neutralizes harmful acid.  Battery terminal protective spray can be used to prevent the formation of corrosion.

What are some early warning signs that your engine battery is going bad?

1. An unstable voltage reading

• A good battery should have a voltage of 12.6 volts. System voltage under 12 volts when the engine is not running may indicate a failing battery.
• During engine start-up, the voltage should drop about 1 to 1.5 volts and then quickly recover after the engine starts. 
• If the voltage drops to 9 volts or lower when the engine is cranking, your battery is bad and should be replaced.

2. A flickering charge indicator
3. An occasional click but no crank on the first starting attempt
4. A noticeably slow crank

Regular battery checks can help to minimize disruptive equipment failures.

1. Test the battery to be sure it meets the cold cranking amp (CCA) specification of your engine.

• As a rule of thumb, diesel engines require 2 CCA for every cubic inch of engine displacement (1 liter = 61 cubic inches)
• Example – Determine the CCA required for a 6.7-liter diesel engine as follows:
  6.7 liters x 61 cu. in. / liter = 408.7 cu. in.
  408.7 cu. in. x 2 CCA / cu. in. = 817.4 CCA

2. Make sure your battery is corrosion-free.
3. Check your battery cables. Are they secured tightly?

Alternator

Conduct a load test to confirm the alternator amperage output meets the required specification. While the engine is running, check the voltage output on the alternator to ensure the battery is receiving the proper amount of charge. Inspect the wire harnesses. Ensure the connections are secure.

Inspect the drive belt. If it’s worn, cracked, or glazed, replace it. Be sure the drive belt has proper tension. 

Starter

Make sure that the engine cranks over well. Inspect the wire harnesses to be sure the connections are secure. Be sure the wire connections are free of dirt or corrosion. Contaminated connectors restrict the strength of the current that powers the starter.

​​Check the starter mounting bolts. If the bolts are loose, the starter drive and the flywheel will not engage properly and will grind when starting the engine.

Block heater

Remember that engine fluids become more viscous in cold weather, making the engine hard to start. A block heater keeps your engine’s internal fluids warm and prepared for the next start.. Warming the engine before you start it causes less wear and tear and ensures successful ignition. 

Inspect the condition of the block heater electrical cord, and be sure that the block heater actually is heating (if applicable).

Preheat System

Inspect the wiring harness for the glow plugs or intake heater. Confirm the operation of the preheat system (if applicable).

You should also become familiar with the dashboard or operator interface of your machine. Learn to recognize fault indicators and diagnostic codes.

Your equipment’s electrical system seems passive and quiet compared to the main engine, but it is just as important. Don’t neglect it, because its failure can lead to frustrations and headaches. Routine maintenance of your equipment’s electrical system will save you time and keep your machinery running smoothly.