Idle Limiters: the Good, the Bad, and the Compromise

July 9th, 2010

Aaron Turpen

Image via Wikipedia

A popular innovation for “greening” a truck fleet is to install idle limiters. These little electronic gadgets cost only about $200-$500 per truck and can save big on fuel. They work by tying into the electronics of the truck’s engine and basically putting it on a timer.

Like the lamp in your window while you’re on vacation, the timer waits for a specific amount of time and then shuts the engine off. So if your driver stops the truck and is idling for more than, say, 4 minutes, the idle limiter will automatically shut the engine off.

From the fleet’s perspective, this is a great idea. Idling costs about a gallon of diesel an hour and adds to the wear-and-tear on the truck. By limiting idle, trucks become compliant with California anti-idling laws, save fuel, and lower emissions.

From the driver’s perspective, idle limiters are a source of annoyance and an object of derision. Many drivers innovate interesting ways to get around the limiter, so they can idle the truck as they wish. This usually involves tricking the gadget into thinking the truck is not idling – such as by raising RPMs. Higher RPMs means more fuel being used, which is exactly opposite of the idea behind the limiter.

As an example, the company I drove for in Salt Lake City, Utah did not have idle limiters (despite their being built into the engines from Caterpillar, requiring only software activation). They did have alternative power units (APU) on each truck and paid a bonus to the driver, based on idle time percentage, for not idling. This worked out great and most drivers worked hard to get that bonus (which equated to up to .03/mile). That could mean several hundred a month sometimes.

Later on, the company started activating those idle timers thanks to California law. This was a pain in the neck since the APUs being used would often break down on the road. This meant the driver was stuck without any way to heat or cool the cab easily. Most of us got innovative..

Despite the California mandate, I think the answer is in the middle rather than on either end.

Allowing the driver to make the decision or have an override should his alternative to idling be unavailable empowers the driver. Using the idle timer means saving a lot of fuel, but giving a little power to the driver saves a some driver turnover as well.

The idle timers we had could be overridden (I later found out) through the Qualcomm communications unit in the truck. All the dispatcher (or shop) had to do was log in and turn it off. This has the added incentive of saving motel costs when a driver has no APU and can’t sleep in a truck without freezing or boiling to death.

It’s something that fleet managers should consider, as merely enforcing blanket no-idle rules always means a lot of unhappy drivers. The job is hard enough and good drivers are hard enough to keep without adding more strain. Most drivers are an independent lot and taking away some of their self-reliance is rarely good.