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Mack Introduces Battery-Operated Anti-Idling System

Mack Trucks has introduced a battery-operated anti-idling system to replace engine idling as a power source for heating and cooling and amenity loads for stationary trucks.

The environmental and financial benefits of reducing idling are significant. The US Environmental Protection Agency estimates heavy-duty truck idling in the US consumes 960 million gallons of diesel fuel annually, and the average heavy-duty truck burns 0.8 gallons per hour. According to the EPA, truck idling results in annual emissions of 11 million tons of CO2, 180,000 tons of NOx and 5,000 tons of particulates.

The Idle Free system uses a bank of high-efficiency absorbed glass mat (AGM) lead-acid batteries to provide stored electrical power for heating, air conditioning and amenities, such as TV or microwave. The bank of five AGM batteries is stored under the sleeper’s bunk.

The batteries can be recharged three different ways: by the truck’s alternator when the engine is running; through a shore power connection when the vehicle is stopped; or through an available connection to the reefer unit for tractors hauling refrigerated trailers. When the truck is not moving, the driver can use battery power or shore power to run heating, air conditioning and amenities. The system provides either 12- or 120-volt power.

Idle Free uses a Xantrex Prosine 2000W inverter/charger to control and regulate electrical power, as well as to charge both the Idle Free batteries and the truck’s batteries. Mack'’s complete climate control package includes a Webasto diesel-fired heater and a Dometic HVAC unit. The Odyssey AGM 31 batteries have the ability to run the AC for 10 hours with an outside air temperature of 90 degrees.

The total weight of the system, with five batteries, inverter, HVAC and controls is 370 pounds—less than many APUs




Eliminating truck idling seems like low hanging fruit. And saving a billion gallons of diesel is nothing to sneeze at.

Bob H

It has to be balanced against the added weight of the batteries.


Sounds like it would be a good implementation of the firefly batteries.



On long-haul routes, most of the driving will be at freeway speeds, so I expect the weight of batteries will have only a minor impact on mileage, since aerodynamic drag will be the biggest influence. Not that lighter wouldn't be better, of course. In any event, I think the biggest benefit will be from improved air quality at truck stops, etc.


Definitely nothing sneeze at. Refinements of enery usage like this and on tankers, boats, etc., docked can eliminate tons of waste.


wonder why it wasn't done in all trucks 25 years ago. It's such an obvious thing to do.

Sid Hoffman

370 pounds on a 60-80,000 pound truck isn't much. Granted, any weight that can be lost is a benefit, but the fact that it's lighter than most auxiliary power units seems to indicate that as long as it's priced such that it pays for itself in fuel savings, it should be popular.

If it's true about being able to go 10 hours on one charge, that means it can run an entire night, thus saving 8 gallons, or about $24 in fuel. Multiply that by 250 work nights a year and that's $6000/year in savings. If the batteries can do 1000 deep discharge cycles, it would be $24k or so in fuel savings and likely costs less than $10k to purchase.


Shoot, assuming the A/C uses ~20kwh per night, and the $24k in fuel savings over four years figure is correct, these will be a sure fire hit. If they're similar to other AGMs 1000 cycles at 50% dod is np, so in this case $12k in fuel savings over the same time period, and w/ a 20kwh AGM pack being ~$3500 over the long run the savings are huge. This is all assuming diesel stays at $3/gal and doesn't run back to ~$1/gal or something. Almost makes EVs look nice too, cept that a 20kwh pack would weigh over half a ton, so unless we have some seriously low CdA/Crr passenger cars it wouldn't fly.


"reefer unit" ... that explains some of the truck driving I see on the Pennsylvania Turnpike ;-)


Why are the not using flooded lead acid batteries? At the slow drain conditions that these systems are run under, you could get the same amount of useable energy storage for about half the battery cost. The battery bank would also weigh less.


I'm guessing because of the range of conditions AGMs will operate compared to flooded lead acids.


Flooded Pb-acid batteries are a little heavier and bigger than glass absorbed ones and you have a little consume of water but as "coal burner" says for that drain conditions (daily deep discharges) liquid electrolyte batteries are better (with tubular positive electrodes ,the best) , they cost less than half, they would last longer and have less temperature sensitivity.


Using commercial grade Li ion batteries packaged in the Matrix configuration developed by Quallion would address the weight concerns posed by Lead Acid batteries. You would also get much better run times.


Using commercial grade Li ion batteries packaged in the Matrix configuration developed by Quallion would address the weight concerns posed by Lead Acid batteries. You would also get much better run times.

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