Idle reduction is about cost savings and driver comfort.
Battery-powered heating, ventilation, and air conditioning (HVAC) systems help fleets deal with cab climate control, by providing climate control to the truck cabin while the truck is parked. Fleet users benefit because the systems are quiet and produce no emissions, but they may not provide enough cooling capacity for long rest periods or when operating in very hot temperatures.
They can be powered by a set of batteries on the tractor or come with a plug-in capability for battery charging and/or operation while connected to an electrical power source. They are also called battery APUs and battery EPUs.
No emissions produced during operation
Fuel Cost Reduction
Since they do not burn fuel there is no fuel cost while they are in use
Lower Purchase Price
Less expensive than some other anti-idling options
Quieter than diesel APUs
Fewer moving parts so less opportunity for malfunction and less maintenance training than diesel APUs
Integrate with Off-board AC Power Connection
This will increase the operating time of the unit and will also recharge the batteries more cheaply than doing so with the engine alternator
Easy to Operate
Digital or rotational automotive-style controls provide automatic temperature control. The driver simply turns the switch to heating or air conditioning, and selects a fan speed and a desired temperature
Limited Run Time
Not a viable solution for the 34 consecutive hours of rest without restarting the truck’s main engine and running it from time to time. In most cases, however, the batteries of the battery HVAC system will simply be recharged while the truck is driving
Issues in Hot Temperatures
Concern that in extremely hot conditions there will not be enough battery power to keep the sleeper/cab cool enough for the driver to be comfortable
The AGM batteries in these units do not last forever and will have to be replaced. Two years seems to be the typical life expectancy of these batteries
Including the required four deep-cycle AGM batteries and a fuel-fired bunk heater, battery HVACs will add 500 to 600 lbs. to the weight of the vehicle. This may become less of an issue in the future if other battery technology is developed. However the Energy Policy Act of 2005 allowed for a national 400-pound exemption for the additional weight of idling reduction technologies on heavy-duty vehicles. In 2012 the Moving Ahead for Progress in the 21st Century Act increased the weight allowance to 550 lbs. However, each state can adopt the exemption at its own discretion and not all states have. The Office of Energy Efficiency & Renewable Energy has a map showing states that recognize the APU weight exception
Need for Large Capacity Alternator
The increased load battery HVACs place on the charging system means a large capacity alternator is needed. Cables of the proper size also must be used, and it is important that all connections be tightened properly for the system to operate
Adds Load to the Engine
The alternator for a battery HVAC system puts twice the load on the engine of a normal sleeper tractor’s alternator. These higher capacity alternators take up to an additional 7 hp from the engine. Therefore, their use does cause a truck to consume slightly more diesel fuel while driving, but lowers fuel use overall as they can eliminate significant amounts of idling
Can Consume Fuel
Systems equipped with fuel-operated heaters will consume diesel fuel during heater operation as well as battery or AC power to run the heater fan
Fleet Survey Results
- If a fleet does not use APUs, their idle percent tends to be in the 30% to 50% range
- If a fleet uses APUs, idle percent is in the single digits to 20%
- Fleets seem to be split on diesel APUs vs. battery HVAC systems with some fleets using both (but not on a single vehicle)
- Use of auto start-stop systems is increasing
- Almost everyone uses diesel fired heaters
- Most fleets are looking for positive ROI, but most of them also think there is significant value in driver retention and hiring
Our team produced top-line tools to assist fleets in making their idle-reduction technology choice:
- The confidence matrix summarizes the study findings and indicates NACFE’s confidence in the various idle-reduction technology solutions.
- The Payback Calculator allows fleets to estimate the payback in months for various idle-technology solutions. Fleets input data into the form and the calculator uses the data along with the information gathered by the study team to quantify and benefits and consequences likely to be experienced by the fleet in terms of upfront costs and year-over-year costs.
In addition the report contains challenges and changes charts for each of the anchor technologies. The charts can be found in section 9 of the report.
- Carrier Transicold
- Hammonds/Arctic Breeze
- Phillips & Temro
- Thermo King
Each truck OEM offers a battery HVAC solution under its own brand name:
- Kenworth: Kenworth Idle Management System (KIMS)
- Peterbilt: Smartair
- Navistar: Navistar No-Idle Solution
- Volvo: Volvo Parking Cooler
- Freightliner: Battery Powered HVAC System (BPHS)
- Western Star: Rest Star
As a result of research and interviews the study team reached the following conclusions concerning idle reduction in the sleeper cab market:
- Reducing idle is good for the environment, saves fuel and improves a fleet’s “green image.
- A 10% reduction in annualized idle percentage is worth about 1% in fuel economy that results in a $500 to $700 annual savings assuming 100,000 miles a year and diesel at $3 a gallon.
- Driver hiring, comfort and retention are mentioned in almost every conversation about idle-reduction technologies. Some have said that offering a good solution is a requirement for hiring and retaining drivers.
- There is no “one size fits all” solution to idle reduction.
- Drivers are still a very important part (If not the most important part) of successful management of idle times.
- Depending on “shore power” (outside electrical connection) to be available is not a reasonable idle-reduction solution for most fleets as the number of electrified parking spaces is extremely small compared to the number of trucks that need to be parked at any given time.
- Most suppliers of idle-reduction technologies mention that their solution helps minimize maintenance costs, particularly in the vehicle’s aftertreatment system. However, we have been unable to uncover any data that actually substantiates those claims.
- The answer to the question of the resale value of trucks equipped with idle-reduction technology is unclear.
- Maintenance of the vehicle’s battery connections and electrical systems is critical to getting the best performance out of idle-reduction technologies.