Spinning wheels carry a lot of potential to generate power, even as a vehicle is slowing down. But most of the energy used to brake a car's wheels is converted into heat and wasted. At least, that was true until automakers got serious about using regenerative braking systems to capture that waste and convert it into electricity.
Those systems primarily have been relegated to cars, from mild hybrids such as the BMW 3-Series to gasoline-electric hybrids like the Prius to full-blown EVs like the Chevy Bolt. But now it's coming in a big way to trucks. GM may have been first with a very limited run of California-only 2016 and 2017 Silverados and Sierras featuring eAssist braking regen, and then expanded availability for 2018, but introduction of the 2019 Ram 1500's eTorque shows that regen systems are finally hitting full-size pickups on a large scale.
The eTorque system replaces the conventional alternator, which is spun by engine power via accessory belt, with a 48-volt motor/generator that captures braking energy for storage and later uses the energy to boost the engine at low speeds. “Regen operation is mostly the same on hybrid vehicles,” says Brian Spohn, Fiat Chrysler Automobiles' vehicle electrification manager. “What makes the eTorque system unique is its application to full-size trucks.”
The Crankshaft's Helping Hand
That's not to say Ram's eTorque works just like a Prius's regen tech. The Toyota uses electric motors to deliver the conserved energy directly to the wheels. Ram's doesn't directly turn the wheels, nor are there additional components mounted to or near the wheels or axles. Instead, eTorque's point of connection is at the engine's crankshaft.
2019 Ram 1500.
When the Ram 1500 accelerates at low speed, its regenerative capability acts as a motor that delivers power to the engine's crankshaft like a helping hand. When the driver lifts off the throttle to coast, or even lightly touches the brake pedal, the engine's slowing crankshaft reverses the eTorque system and changes it from an electric motor assisting the engine to a generator spun by the engine. The captured energy is passed into a 430 watt-hour, air-cooled, lithium-ion battery pack the size of a small suitcase, which is mounted inside the passenger cabin on the rear wall between seats and pickup bed.
The battery pack converts the 48V juice to a typical 12V that charges the smaller lead-acid battery and powers engine accessories such as the electric engine cooling fan. Freeing up the motor from having to run a cooling fan and alternator means more power makes it to the wheels. In other words, the engine doesn't make more power, but the truck can make better use of its power.
It Comes in Threes
The 2019 Ram 1500’s 5.7-liter V8.
Ram eTorque has three stages of braking regen. When coasting, or when the driver applies just a little brake in a situation such as lumbering down a gentle hill, eTorque operates on pure regen, in which the truck's conventional disc brakes are disabled. The friction of the generator capturing that braking energy is enough to slightly slow the truck.
For a heavier foot on the brake pedal, there's blended regen, in which the conventional disc brakes and regen work simultaneously. The generator is still capturing braking energy, but the brakes are helping out. For hard braking, such as in an emergency, regen is disabled and only the traditional disc brakes are used to stop the truck.
The system powers a conventional start-stop system in which the engine shuts off at traffic stops, and eTorque quickly restarts it when the gas pedal is pushed. This setup saves gas by lessening the time spent idling. For all other starts, such as when you get into a truck that's been off for some time, a traditional starter motor driven by a 12V lead acid car battery fires up the engine, because 12-volt starters are a more efficient way of starting a cold engine.
More Torque, More Towing
RAM 1500 eTorque
Ram 1500s with the 3.6-liter Pentastar V6 will come with eTorque standard, and it'll be available as a $1,450 option on the 5.7L Hemi V8. The V6's eTorque generator is liquid-cooled and mounted on the front of the engine, while the V8's is air-cooled and mounted on the top of the engine. There's no performance difference, Spohn says. The design changes come down to packaging and making space for the components in the engine bay.
The eTorque system gives some assistance with acceleration below 2,000 rpm and is good for an additional 90 foot-pounds of torque on the V6 and 130 on the V8, measured at the crankshaft. Mostly, it's used not to give the Ram a boost of oomph on the highway, but to flatten out gaps in engines' torque bands at low speeds.
2019 Ram 1500
The eTorque Ram 1500's 0-60 mph times are “nearly identical” to non-eTorque models, Spohn says. Adding eTorque to the Hemi boosts the truck's towing capacity from 11,610 o 12,750 lbs. (if you option it out similarly with the tallest 3.92 axle ratio and towing package). The regen tech also boosts fuel efficiency on the Hemi from 17 mph combined city/highway to 19 mph on two- and four-wheel-drive models.
What remains to be seen is whether eTorque will make it to Ram's 3/4-ton and full-ton pickups or vans, or to other Fiat Chrysler trucks. FCA's public relations department won't say. But it's hard to imagine that automakers, as eager as they are to raise the combined MPG of their truck lines, won't expand their braking regeneration systems if buyers love the Ram 1500 eTorque. Electrification makes even more sense on big working trucks because electric motors excel at providing torque from idle, ideal for towing and hauling heavy loads.
Matthew Jancer
Matt Jancer is a Southern-based automotive and outdoors writer.If he isn't outside getting swarmed by things or asking animals to stay still for photos, you'll find him on the side of the road under the hood of an old car, yanking apart emissions equipment and cursing.
