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What is eTorque in a Jeep or Ram Truck?

Getting something for free is typically very nice. Getting something you can really use, like more power for towing and hauling, is even better. And that is just what the eTorque system in a Jeep or Ram truck does. With eTorque, a vehicle collects, stores, and uses energy that otherwise would have gone to waste.
This results in advantages all-around:

Improved fuel economy
More towing capability
Better hauling ability
Enhanced drivability

What is eTorque?

The eTorque technology used in Jeep models and the Ram 1500 full-size pickup truck is a "mild hybrid" system. Unlike a conventional hybrid powertrain, like the one used in the Toyota Prius and scores of other vehicles these days, the eTorque system is a simpler and much less-expensive technology. But, as outlined above, it offers a substantial list of benefits.

How Does eTorque Work?

In a powertrain fitted with eTorque, a belt-driven motor-generator unit replaces the conventional alternator on the engine. This motor-generator unit performs several functions in addition to the standard operation of the alternator, which is to provide electricity to keep the vehicle's battery charged. But in an eTorque-equipped vehicle, the electrical system is significantly different than in a conventional vehicle.

With the eTorque system, the motor-generator supplies electricity to a dedicated battery pack used to gain several advantages. The motor-generator unit delivers a 48-volt current to a 430 watt-hour lithium-ion nickel manganese cobalt-graphite battery whenever the engine is running. The battery pack array includes a 3-kilowatt direct current-to-direct current (DC-to-DC) converter that changes 48-volt current to 12 volts. This enables it to power the vehicle's accessories, which run on a typical automotive 12-volt current. Also, it allows it to charge the vehicle's conventional 12-volt lead-acid battery.

The motor-generator also creates electricity during deceleration and braking through brake regeneration. This process captures energy that otherwise would dissipate as waste heat. That energy flows to the 48-volt battery pack for storage and keeps the battery pack at a proper charge level.

A compact module that is easy for auto engineers to package within a vehicle, the air-cooled battery pack is mounted in various places in the Jeep and Ram vehicles that offer eTorque. For example, in Ram 1500, the battery is mounted at the cabin's rear wall and insulated to quiet the potential hum of the cooling fans. The system leverages the cooled interior air of the air-conditioned cab.

What Does eTorque Do?

The combination of the motor-generator and the 48-volt battery pack offers a laundry list of benefits that include improved fuel economy, better towing and hauling capability, and quieter, smoother operation. The electronically controlled "smart" system has six separate modes of operation. Perhaps the most important of them is the automatic engine stop-start function.

Maligned when first introduced to the public, engine stop-start systems save fuel by turning off the engine when it would otherwise be idling and using fuel, such as when waiting at stoplights and in bumper-to-bumper traffic. The first systems were not well-liked because they were often clumsy and slow. But in the eTorque system with 48-volt power, engine stop-start operation is smooth and almost undetectable.

The reason it works so well is its added power versus that of a typical starting battery. For engine restarts, eTorque sends up to 90 lb.-ft. of supplemental torque to the engine crankshaft to fire up the engine again. Torque to the wheels travels within 400 milliseconds, more than twice as fast as in the typical engine stop-start systems that use a conventional starter battery.

While one might wonder why the 48-volt battery pack does not replace the 12-volt battery, there are two reasons:

The traditional 12-volt battery offers greater efficiency in extreme temperatures for cold starts and the day's initial engine start.
It also simplifies the electrical system that powers the 12-volt vehicle accessories.
In addition to spinning the engine's crankshaft for restarts to help launch the vehicle from a standstill, eTorque also recaptures energy during deceleration and braking to charge the battery pack. The system uses the recaptured energy to aid fuel economy and improve overall drivability.

For example, the eTorque system uses the motor-generator's motor function to add extra torque to the crankshaft during gear changes to minimize noise, vibration, and harshness. Similarly, the motor-generator can draw on the 48-volt battery pack to provide added torque to aid acceleration on the highway and in situations like towing a boat trailer up a ramp at a launch site.

Jeep and Ram Vehicles That Offer eTorque

The eTorque systems available in Jeep and Ram vehicles differ slightly in their details depending upon the individual vehicle's powertrain. The Jeep Wrangler uses eTorque technology on its optional turbocharged 2.0-liter 4-cylinder engine and its 3.6-liter V6. In Ram trucks, eTorque is used in conjunction with the standard 3.6-liter V6 engine and is optionally available on the 5.7-liter Hemi V8 engine.

Written by Jack R. Nerad | Mar 17, 2021