Explained: EREV, Hybrid (Series vs. Parallel), PHEV in the Scout

[Efthreeoh]

An EREV is a Series-Hybrid. EREV is a marketing name conjured up because most non-technical people don't understand there are two types of hybrid vehicles: Parallell Hybrid (i.e. Prius) and Series Hybrid (i.e. Volt* or BMW i3).

*the Volt was unique in that its transmission could switch to parallel hybrid operation under specific circumstances.

Hybrids are divided into two architectures: (a) Parallel Hybrid and (b) Series Hybrid.

Parallel Hybrid means the gas motor (it can be gasoline or diesel) runs in parallel with the electric drivetrain to power the electric motors and charge the battery and has a mechanical connection to the road wheels. There are several sub-variations of the Parallell hybrid system.

Series Hybrid means the gas engine operates to create electricity that powers the electric drive motors and charge the battery. The gas engine is not mechanically connected to the road wheels. It's called "series" because the engine-powered electric generator has to make electricity first before the car will move. Make electricity first means the generator either supplies the electric drive motors with power or charges the battery, or both.

It appears the Harvester architecture will also be a PHEV (Plug-in Hybrid Electric Vehicle), which means it can be plugged in to a charger to charge the battery in advance of the engine-generator supplying power to the electric drivetrain. Once the battery reaches a predetermined level of energy depletion the engine-generator starts and begins powering the electric drivetrain.

 

[Taghkanic]

Thanks for that detail.

Question: Say theoretically you are out in the wilderness and manage to completely deplete both the batteries and the gas generator.

Could you fill up the engine with gas from a can, and just take off again? Or would the generator have to run a whole to first charge up the batteries a little?

 

[Ehninger1212]

Thanks for that detail.

Question: Say theoretically you are out in the wilderness and manage to completely deplete both the batteries and the gas generator.

Could you fill up the engine with gas from a can, and just take off again? Or would the generator have to run a whole to first charge up the batteries a little?

While we would obviously need to wait for clarifications or independent test once the vehicle is released. I would imagine as long as you have gas for the generator the vehicle will be able to continue to drive. My PHEV has a buffer built in.. So Zero battery charge on the gauge is really 10%

 

[Efthreeoh]

Thanks for that detail.

Question: Say theoretically you are out in the wilderness and manage to completely deplete both the batteries and the gas generator.

Could you fill up the engine with gas from a can, and just take off again? Or would the generator have to run a whole to first charge up the batteries a little?

It depends on how the driveline is configured and how Scout plans on implementing the Harvester system, but in theory such a system just needs gasoline (or diesel) to create electricity and power the electric drivetrain.

 

[Goose]

Thanks for that detail.

Question: Say theoretically you are out in the wilderness and manage to completely deplete both the batteries and the gas generator.

Could you fill up the engine with gas from a can, and just take off again? Or would the generator have to run a whole to first charge up the batteries a little?

TLDR: Check out the Audi RS Q e-tron Hybrid Dakar Race car
https://www.caranddriver.com/reviews/a39851967/audi-rs-q-e-tron-hybrid-race-car-first-drive/

We don't yet know and it depends. What you're asking boils down to the law of thermodynamics. If Scout puts a beefy ICE motor then what you're asking about is perfectly reasonable as long as the battery was not at a dead 0%. If the motor is undersized then performance will be limited until the battery can be charged up enough.

Here's an example. The upcoming Ramcharger is using the 3.6 pentastar for multiple reasons, for this we will ignore the availability and reliability of the engine. The 3.6L has enough power to move the truck at normal speeds if it was connected straight to the wheels. While the truck would not have its normal 663HP capabilities, it would be able to charge the battery while you continue to make progress.

In the end it all comes down to Kilowatts. If you want a 1:1 power comparison, they will need to put in probably a turbo 6 cylinder at the very least in order to get the power required to never have a dip in performance.

Here is the most likely scenario based on cost and size. They will probably put a 4 cylinder engine in these trucks, then the engine will kick on when the battery dips to a certain percentage to charge it up. If the electric motor is not working hard, say on the highway when driving at a constant rate, then the little 4 banger will be able to outperform the electric demands. If you're pushing it REALLY hard then you will need to charge up first, then slow down.

 

[JesseS]

With a four banger in this case and you run the battery down to safety shutoff then I would think you would have to gas up and let the generator run for awhile to get back on the move, how long would depend on several things, generator output, battery charge rate, and DOC needed to resume
Traveling. I wouldn’t think the generator would be more than a 4-6 KWh.

 

[RMK!]

This is a good discussion about the Harvester.

 

[Stumpy]

This is a good discussion about the Harvester.

Good discussion on EREV / Series Hybrid but realize that BMW was chasing additional CARB ZEV credits in CA with the i3. If your EREV had more EV range than gas range, then the Range Extender couldn't get kick in until there was 6-7% battery charge left (in order to qualify as a "BEVx" and gain extra CARB credits).

 

[4sallypat]

Honda Clarity PHEV is also a parallel hybrid w/ eCVT.

2018 with 70K miles has been solid - no issues - very little cost to own.

Small 7 gallon gas tank will extend range from 45 miles pure EV to 350 miles of hybrid driving.

2 factory extended warranty / recalls: A/C evap and low pressure fuel pump.

 

[NukeDukem]

I put a reservation down for the model with the Harvester. Now I'm a bit worried. I thought that the non-hybrid model would get approx 300 miles range on batteries and the Harvester option would just boost that range. Now it seems the hybrid model will have a substantially shorter EV range and then run on gas like any other ICE vehicle. I was naively assuming the hybrid model would have the same EV range and the Harvester option would just add another 200 miles to that range when you really need it.

 

[NYR]

I thought that the non-hybrid model would get approx 300 miles range on batteries and the Harvester option would just boost that range. Now it seems the hybrid model will have a substantially shorter EV range and then run on gas like any other ICE vehicle. I was naively assuming the hybrid model would have the same EV range and the Harvester option would just add another 200 miles to that range when you really need it.

That'd be a difficult/impossible package to accomplish because the Harvester would need about the same size battery pack as the full-EV model, but also fit the gas range extender engine.

 

[NukeDukem]

That'd be a difficult/impossible package to accomplish because the Harvester would need about the same size battery pack as the full-EV model, but also fit the gas range extender engine.

What are the experts thinking? 75% of the normal size? Half? Too early to say>

 

[GarageMahal]

I put a reservation down for the model with the Harvester. Now I'm a bit worried. I thought that the non-hybrid model would get approx 300 miles range on batteries and the Harvester option would just boost that range. Now it seems the hybrid model will have a substantially shorter EV range and then run on gas like any other ICE vehicle. I was naively assuming the hybrid model would have the same EV range and the Harvester option would just add another 200 miles to that range when you really need it.

Dont worry about it at this point. We don't have many details and you can order something completely different from your reservation.

 

[Efthreeoh]

TLDR: Check out the Audi RS Q e-tron Hybrid Dakar Race car
https://www.caranddriver.com/reviews/a39851967/audi-rs-q-e-tron-hybrid-race-car-first-drive/

We don't yet know and it depends. What you're asking boils down to the law of thermodynamics. If Scout puts a beefy ICE motor then what you're asking about is perfectly reasonable as long as the battery was not at a dead 0%. If the motor is undersized then performance will be limited until the battery can be charged up enough.

Here's an example. The upcoming Ramcharger is using the 3.6 pentastar for multiple reasons, for this we will ignore the availability and reliability of the engine. The 3.6L has enough power to move the truck at normal speeds if it was connected straight to the wheels. While the truck would not have its normal 663HP capabilities, it would be able to charge the battery while you continue to make progress.

In the end it all comes down to Kilowatts. If you want a 1:1 power comparison, they will need to put in probably a turbo 6 cylinder at the very least in order to get the power required to never have a dip in performance.

Here is the most likely scenario based on cost and size. They will probably put a 4 cylinder engine in these trucks, then the engine will kick on when the battery dips to a certain percentage to charge it up. If the electric motor is not working hard, say on the highway when driving at a constant rate, then the little 4 banger will be able to outperform the electric demands. If you're pushing it REALLY hard then you will need to charge up first, then slow down.

But the truck doesn't need a 1:1 ratio of ICE to electric motor horsepower. That is the engineering beauty of an ICE-hybrid drivetrain, a smaller-consuming-energy internal combustion engine is assisted by a higher available horsepower EV drivetrain to move the vehicle. The battery size (available kilowatts) is what dictates the power delivery of the system, not the engine horsepower alone. The hybrid drivetrain is advantageous because any vehicle does not need all of the maximum available power of the engine (or electric motors) all of the time, so the power developed by the ICE-generator can be split to power the electric motors and at the same time recharge the battery.

For (a simple) example, if a 4,500-pound pickup requires just 60 horsepower (approx. 45kW) to push through the air, power various vehicle systems (i.e. HVAC, lights, computer modules) and overcome road friction to travel down the highway. If the engine's maximum power is 260 HP (194kW), 200 HP (149kW) is left over to recharge the battery. If the vehicle's total EV motor horsepower is 360 HP and needs all 360 HP to climb a grade while towing, the extra 100 HP comes from the energy stored in the battery (until the battery charge is depleted). Again, just a simplistic example of how a series hybrid drivetrain can operate to consume the energy available to it. A simple example that ignores heat loss of the engine and battery conversions of the stored energy sources.

 

[Efthreeoh]

I put a reservation down for the model with the Harvester. Now I'm a bit worried. I thought that the non-hybrid model would get approx 300 miles range on batteries and the Harvester option would just boost that range. Now it seems the hybrid model will have a substantially shorter EV range and then run on gas like any other ICE vehicle. I was naively assuming the hybrid model would have the same EV range and the Harvester option would just add another 200 miles to that range when you really need it.

The Harvester hybrid has more total range at 500 miles than the BEV version at 350 miles between recharging events. The difference to you will be in the MPGe efficiency. MPGe is the EV equivalent of MPG for an ICE-powered only vehicle. The 500 mile range rating is based on a fully charged battery and a full tank of gasoline (assuming the engine is not a diesel). So, it is just a matter of cost-per-mile you will spend to travel in the Scout depending on how you use the Scout. If most of your trips will be within the 150-mile range of the EV-only mode and you recharge at home, then your cost will be nearly as low as the battery-only version. Nearly as low because the engine will consume the fuel in the tank over time to (a) prevent stale fuel build up and (b) to keep the engine operating at peak efficiency (i.e. not letting it sit in a non-running state). If you frequently drive your Scout long distances and only refuel at a gas station (vs. recharging the battery) your cost will be higher because of the less efficient conversion of the energy stored in the gasoline by the engine combustion process.