Workhorse W-15 Truck will use the i3 REx engine to get 310 miles...how?

[EVBob]

It looks like Workhorse will indeed use the 3 cylinder i3 REx engine/generator for the pickup
s (w-15) range extender. : https://www.trucks.com/2018/03/12/workhorse-production-w15-electric-truck/

Workhorse mentioned they were testing other (bigger) gas engine generators - I am kinda surprised they decided to stick with the i3 REx engine...I found it just barely covers slightly slower than average highway driving in Eco-Pro - I wouldn't think it would have enough output for a much heavier/larger pickup truck (it has two larger traction motors vs the single in the i3) that will be hauling around more cargo....For it to get 310 miles with the 40kwh available battery that will get 80 miles by itself (they will use a 60kwh passive cooled battery - but only allow 40kwh to be utilized) , unless the REx was set to start running at 90% battery and its Rev speed wasn't tied to speed of the vehicle...

Though I will say I am very interested in the power export option (7.2kw initially, but 14.4kw may be offered later) http://workhorse.com/pickup/ -- this could be a very interesting option to have during Hurricane/Severe Storm seasons where power could be knocked out for days....

Magazine snippet from their prototype:
http://workhorse.com/storage/app/media/uploaded-files/ChargedEVsMay-June2017.pdf

Brochure:
http://workhorse.com/storage/app/media/uploaded-files/Workhorse_W15_Brochure_2017.pdf


Your thoughts?

 

[alohart]

It looks like Workhorse will indeed use the 3 cylinder i3 REx engine/generator for the pickup
s (w-15) range extender. : https://www.trucks.com/2018/03/12/workhorse-production-w15-electric-truck/

Minor nit: the 3-cylinder description is incorrect; this engine has only 2 cylinders.

Workhorse mentioned they were testing other (bigger) gas engine generators - I am kinda surprised they decided to stick with the i3 REx engine...I found it just barely covers slightly slower than average highway driving in Eco-Pro - I wouldn't think it would have enough output for a much heavier/larger pickup truck (it has two larger traction motors vs the single in the i3) that will be hauling around more cargo....For it to get 310 miles with the 40kwh available battery that will get 80 miles by itself (they will use a 60kwh passive cooled battery - but only allow 40kwh to be utilized) , unless the REx was set to start running at 90% battery and its Rev speed wasn't tied to speed of the vehicle...

I think Workhorse envisions this truck being used at moderate city and suburban speeds rather than long distances at highway speeds. I'm sure that the REx engine will be able to be started manually in situations where its output is less than the power being consumed which would slow the discharge of the battery pack. Maybe it would turn on automatically when the power being consumed exceeds the REx engine's maximum output.

We'll have to wait until a production version of the truck can be tested to learn more.

 

[EVMan]

With proper use of software , the Rex can in-deeded provide lot of power.

It can start be started at 90/95%. If fact the 2017 Rex should also do the same , but BMW choose not to optimize it . The 2017 car can charge to 85% in max rate on DC charge.

It can keep charging the car , when not in motion. It can in theory pre charge the car. U do need a larger gas tank.

A smaller durable engine can do the job, with proper software and settings.

The i3 is missing the setting to run the rex at optimum rpm , for better fuel economy, for longer journeys.
Why the 2017 rex model will run at higher inefficient rpm , to decrease fuel economy , if started at 75% is just poor thinking.

 

[viking79]

Running the Rex above 75 or 85% could damage the battery. Also, I think the C650 scooter makes about twice the power with the same engine?

Limitation is most likely in the charge rate of the battery and generator output. If the genset put out 44 kW, that would be like a 2C charge rate for 22 kWh pack.

However, it seems like they could program the engine to only run at those RPMs when electric motor has demands above a certain level to not damage the battery.

 

[EVMan]

Running the Rex above 75 or 85% could damage the battery. Also, I think the C650 scooter makes about twice the power with the same engine?

Limitation is most likely in the charge rate of the battery and generator output. If the genset put out 44 kW, that would be like a 2C charge rate for 22 kWh pack.

However, it seems like they could program the engine to only run at those RPMs when electric motor has demands above a certain level to not damage the battery.

Yes.
We are not talking about charging the battery at max rate above 75%. , but to use rex to buffer the consumption at optimum rpm
Also The battery size increased form 22 to 33 KWh in 2017 and will further increase in 2019
Also the generation is variable, based on rpm , so this 75% hard stop is artificial , when for 2017 the battery charges upto 44 KWH at 85 percent.

I would guess the limiting of power of the C650 is for efficiency, as the drive train consumption peaks upto 125 KW.

 

[viking79]

How do we know this is the i3 engine? I find that highly unlikely, the statement says 1.5 L 3 cylinder.

This is almost certainly the i8 1.5L 3 cyl that makes 220 hp. The i3 rex engine would explode trying to power such a large truck, 220 hp would probably keep it moving 80 mph down the highway with a dead battery. The i3 engine barely keeps my i3 going 65 mph, long hills are almost nogo. And the i3 is like half the size and way more aerodynamic.

 

[viking79]

PS I would expect a de-tuned version, but the 1.5 liter 3 cylinder definitely sounds more like the i8 range extender. Even 120 hp would be fine to move that truck at highway speeds up to 100 mph on flat ground.

 

[EVMan]

How do we know this is the i3 engine? I find that highly unlikely, the statement says 1.5 L 3 cylinder.

This is almost certainly the i8 1.5L 3 cyl that makes 220 hp. The i3 rex engine would explode trying to power such a large truck, 220 hp would probably keep it moving 80 mph down the highway with a dead battery. The i3 engine barely keeps my i3 going 65 mph, long hills are almost nogo. And the i3 is like half the size and way more aerodynamic.

I am not following this truck,
As you correctly said , powering on just rex alone is not sufficient even for i3. That is why , we need a rather large battery buffer or a larger engine .
If you need the capability to run on a dead battery then , those vehicles are called plug-in-hybrids and not electrics. Volt , Prius are correct examples , and not the i3 rex.

They called the truck electric and not hybrid, so it needs more than a dead battery as buffer.

The marketing department does spin things out incorrectly some times.

 

[alohart]

How do we know this is the i3 engine? I find that highly unlikely, the statement says 1.5 L 3 cylinder.

The REx engine used is confusing. Workhorse's own Website doesn't specify the W-15 Pickup's REx engine, but it does specify the BMW i3's W20 REx engine in its larger e-Gen step van (UPS delivery van). It seems likely that Workhorse would use the same REx engine in all of its vehicles, especially the i3's W20 that is already mated to a generator unlike the i8's engine.

However, Motor Trend's May, 2017 W-15 prototype test article states that the REx engine has 3 cylinders and its generator produces 50 kW. The i3's REx engine's output is only 25 kW, so its generator could not produce 50 kW of electricity. In the specs section of this same Motor Trend article, the REx engine is described as a "0.7L/38-hp (est)/41-lb-ft DOHC 8-valve I-3". Hmm, 0.7 liters is the size of the i3's REx engine. Even though it is described as a 3-cylinder engine, only a 2-cylinder engine can have 8 valves. Something's not correct.

 

[jadnashuanh]

One of the issues with the REx and the 75% turn-on threshold is that it is programmed to run at least 10-minutes once on. If it got triggered, and then you stopped or were now gliding down a long incline, 10-minutes might come close to reaching a point on the SOC that could become problematic. The 75% provides a buffer to prevent any worst case issues about overcharging the batteries.