Scout Deal Breakers

[R1TVT]

I already watched that one.

TLDR: A lot of details remain to be finalized.

Right, but not sure why you are ignoring what Scout stated, which was that the EREV / Harvester WILL power the battery.

 

[AlanL]

Thats a heavy read.


We still dont know the "Steady State" of the charging system, and we also dont know if they will use an architecture like some other EREVs that bypass battery charging and directly power the motors with the generator.

Yes we don’t know for sure. But I do have faith that SM has great engineers. The simple and obvious approach is to have a common high power DC bus. Power comes onto this bus from the battery, generator when running, or drive units with regen braking. Power comes off this bus to charge the battery or to the drive units for propulsion.

Also yes, we don’t know the output of the generator and how that will compare with propulsion needs. But it does not take a very big ICE to provide power for flat highway driving. Then software to keep the battery charged enough to get up grades and recover after. I think we need to have a trust but verify approach. Trust SM to do a decent job and wait for real specs and tests.

 

[AlanL]

BTW this also illustrates that if you plan to tow you can’t be too close to 100% SOC at the start of a downgrade. Regen braking is your “engine brake”, the power generated by the drive units can only go to the battery. If the battery is too full, no regen braking. Think of the old high school experiment of spinning a generator by hand. Easy with no load, hard with a load. There will be some kind of fall off curve of course that we won’t know until real world testing, and that will differ depending on load, speed, road, temperature.

 

[Jamie@ScoutMotors]

I think we will all learn a lot more about every use case where an EREV could have a limitation now that other EREV vehicles are hitting the marketing. Dodge is using the big hammer approach with a large V6 engine in their RAM EREV. Once these hit the market, people will undoubtedly do a lot of different tests. While EREV has been available in other markets, it is newer in this market, particularly in heavier duty applications like full-size pickup trucks and towing. Like any new technology, there will be a learning curve.

 

[AlanL]

I think we will all learn a lot more about every use case where an EREV could have a limitation now that other EREV vehicles are hitting the marketing. Dodge is using the big hammer approach with a large V6 engine in their RAM EREV. Once these hit the market, people will undoubtedly do a lot of different tests. While EREV has been available in other markets, it is newer in this market, particularly in heavier duty applications like full-size pickup trucks and towing. Like any new technology, there will be a learning curve.

Indeed. I think those of us on the outside need to chill a bit and realize the tough job the SM engineers have to find the right compromise. More tow capacity means a smaller genset to allow more rear axle payload. More Harvester battery range means a smaller gas tank and/or smaller genset, or more expensive NMC battery. More ability to drive on genset with less battery input means less towing and possibly less battery to keep the curb weight down.

 

[sgtK]

For me most of these are any car but I was looking at Scout to replace my Wife's current car, so want what she has now and then some:

• No heads up display (she has that now and its a must for both of us)
• Too much functionality in screen (have a Maverick pickup 2025, and too much has moved to screen, hating the UI more every day)
• Tow Rating (GX 550 tows 9000 lbs we like to be around there in an SUV)
• Range 350 for full EV is ok today but not in 2 years (We want to drive from St George Utah to Vegas alot, but sometimes CA so stopping every 2 hours is annoying)
• Range Extender sound cool but 150 EV and hit to towing have thrown water on it for me

Those are main ones for me. Every cars has a few issues, hoping this list can get shorter by time car is in production?

Also no assisted-driving ft. (like SuperCruise) is a deal-breaker to a current GM EV owner looking to go Scout.

 

[Scout4x4]

Please explain (using science) how there is a misunderstanding. I can simplify this (again) as much as possible, because Scout has stated that the Harvester EREV will be a generator used to charge the battery, and that the Scout will NOT be a HYBRID.

1. The motors are driven by electricity
2. Electricity can come from 2 sources: a) The Harvester b) A EVSE, DCFC or other compatible charger

So why is this important and why can't the truck just keep driving forever? Because consumption of power will exceed production of power from the EREV under many normal driving conditions, and of course when towing. When power consumption exceeds production, and depletes a stored power source (aka a large battery pack on a truck or SUV), you must re-fuel / re-charge.

When you have fully depleted the battery, the battery needs to re-charge to a minimally viable level (using 1 of the above 2 sources) BEFORE it contains enough energy to propel the vehicle forward. This is quite simple, since the EREV/Harvester is not connected directly to a drive shaft or axle. People interested in the Harvester have not considered that there is also time requirement to charge if / when the battery is fully depleted.
Using more science, charging a battery is not an instantaneous process - it takes some time for the energy that is produced to be converted and stored. Battery chemistry, temperature, and modularity all factor into charging. And you cannot simultaneously charge and deplete energy from a cell (at least using current technologies). The EREV (and BMS) will theoretically need to send energy to an "open" module for charging. Once a module is charged, the BMS can tell the vehicle that that module can be used for consumption. How much time will be required for this process will be determined based on how fast you are charging (using the Harvester or a charger), how big the battery is (we are awaiting spec's), and where Scout sets the bottom threshold for SOC before driving away (also TBD).

In reality most people won't drive their truck until the battery is fully depleted or drops much below 10% SOC... They will charge along their route and refill gas on longer trips or when towing. For some people, this may be viewed as an inconvenience, but Scout has not developed a perpetual motion machine. The amount of energy required to move the truck (based on what we know now of similarly shaped and sized SUV's and Trucks) will be approximately 470-480 Wh/mi (WITHOUT TOWING). We can make assumptions on the energy produced from the Harvester looking at small (non-turbo) engines or generators, but we also must take into account energy losses, conversion of energy via the inverter, the aerodynamics of the vehicle, the weight of the vehicle, the speed of the vehicle, ambient temperature, trailering, etc.

Here is a video explaining how the Ram Charger is solving the issue of towing when its battery gets depleted. This is a very different approach than how the BMW i3 behaved when its battery was depleted. When that car's battery was depleted it severely limited the speed it could drive while it's gas engine slowly charged the batteries - and it didn't need to worry about the extra load of towing!

The Ram has a realitive big engine to support this continual state of electrical generation. While the BMW had only a small 3 cylinder engine. Scout hasn't announced their engine choice yet but all rumors point to an I4 engine that is smaller than the Ram's (my personal bet is the H-4 from the Cayman line). But at this point we just don't know how Scout is planning on managing this part of the performance envelope.

 

[AlanL]

So why is this important and why can't the truck just keep driving forever? Because consumption of power will exceed production of power from the EREV under many normal driving conditions, and of course when towing. When power consumption exceeds production, and depletes a stored power source (aka a large battery pack on a truck or SUV), you must re-fuel / re-charge.

You’re asking good questions but I disagree with your conclusions. In the Motor Trend interview Scott Keogh said 60 to 70-ish kWh for the Harvester battery, with 150 miles estimated non towing range. Let’s say that is at a steady 65 mph on level ground no head wind. You do 150 miles in 2.3 hours. To get 65 kWh in 2.3 hours you need a steady 28 kW generator. And that keeps the SOC constant. At a straight energy conversion that is 38 hp. Double that for towing and call it 80 hp. Not too hard to achieve.

They need to have enough extra power to recover from high demand losses, which don’t last that long over a full days drive. Not to mention less demand going downhill or with regen braking. And extra to cover conversion and mechanical losses. Seems doable within reason.

 

[AlanL]

And you cannot simultaneously charge and deplete energy from a cell (at least using current technologies). The EREV (and BMS) will theoretically need to send energy to an "open" module for charging. Once a module is charged, the BMS can tell the vehicle that that module can be used for consumption.

I think you’re misunderstanding how it will probably work. Genset power will not literally go into and back out of the battery at the same time. It will go onto a common high power bus. If it is more than needed for propulsion the excess will go into the battery, nothing coming out of the battery. If the genset power is less than needed for propulsion the extra will come out of the battery. Slowing the discharge of the battery, not simultaneously discharging and charging.

 

[AlanL]

The Ram has a realitive big engine to support this continual state of electrical generation. While the BMW had only a small 3 cylinder engine. Scout hasn't announced their engine choice yet but all rumors point to an I4 engine that is smaller than the Ram's (my personal bet is the H-4 from the Cayman line). But at this point we just don't know how Scout is planning on managing this part of the performance envelope.

Yes, this is the big hammer approach that Jamie mentioned. The Ramcharger has a very specific target market, much different from Scout’s. They have explicitly said it is a solid work truck and can be used with (almost?) full capability with a truly dead (broken) battery. Hence the Pentastar engine. Scout can go for a much broader compromise. Should you really demand full performance with a depleated or broken battery? Your ICE vehicle goes nowhere with an empty gas tank and poorly with a bad fuel injector or spark plug.