Common Starting Issues in Trucking Applications---Part 3

Alternator

If your batteries were not at full charge, your alternator capacity may not be up to the needs of your rig. How old is it? A standard brushed alternator is good for 100-150,000km, a long brush alternator up to 300,000km and we have seen brushless alternators last for over a million kilometres. You get what you pay for. Also if you’re hauling more than one trailer or have additional lighting or other load on your electrical system, the standard alternator output may not be sufficient to run your truck and adequately charge your batteries. Providing you have a quality brand alternator, you can trust the claimed output, and your auto electrician should be able to work out your requirements. If your alternator is running at or near capacity just to run your truck, there’s a fair chance it’s not getting the chance to charge your batteries between starts. But remember, before you invest in a high output alternator, check the wiring for size. Most truck manufacturer’s use the narrowest cable they can get away with so there’s a chance your new high output alternator may be wasted on undersized cabling.

Wiring

It is amazing how many electrical problems are caused by simple wiring issues. Undersized cable is often at fault, or it can be poor quality or corroded terminals. Remember any voltage drop over half a volt is a problem. Finding voltage drop is easy and fixing it is often just a matter of increasing your cable size.

Battery Switch

Battery master switches are common in many heavy duty applications and intelligent battery switches and rollover devices are mandatory in fuel haul vehicles. The quality of the battery switches in the Australian market varies wildly, and we have seen switches with well over half a volt of voltage drop across the terminals. Look for a quality battery switch with less than 0.1V voltage drop across the main contacts.




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Common Starting Issues in Trucking Applications---Part 2

Slow Cranking: For the starter to be cranking, the control circuit would have to be working. So, if battery and cable checks are within specification and the vehicle still cranks slowly, then it’s a slow cranking problem and it’s time to replace the starter.

Click No-Crank: Check the control circuit. If the starter does not contain an Integrated Magnetic Switch, or IMS, then a voltage drop test will need to be performed on the vehicle control circuit. If the starter does have an IMS switch function, then the technician will have to verify that the vehicle’s control circuit is providing voltage to the starter IMS.

No-Click No-Crank: When this occurs, power is not being sent to the solenoid, making it very unlikely that the issue is related to the starter motor. A diagnostic tool can help you diagnose the complete starting and charging system, including the alternator, batteries, starter motor and wiring. The diagnostic tool can perform a full system check in about 25 minutes, making it a great investment for your workshop. So in a poor starting environment, or when a starter motor has failed, what could be wrong?


Batteries – By now you should have tested your batteries and replaced any that were faulty. Don’t be tempted by the false-economy of leaving one poor quality battery in a bank of four. And you should look at your battery cabling, as this can often be less than optimum from new. In the diagram below, the top illustration shows the original battery cable layout, which results in the two inner batteries working hard and the outermost two never receiving optimum charge. In the diagram below (Pic 1) shows an easy solution to balance the workload of the battery banks.



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