F-150 Lightning BEV to EREV Strategy - Hank Green

[eringer]

I'm a Terra reservation holder still waffling between the EREV and BEV. I started with an EREV reservation, switched to BEV, and am leaning back in the EREV direction again. I just watched Hank Green's video on the Ford F-150 Lightning strategy adjustment from BEV to EREV and while he's a big advocate for EVs, he was complimentary of the truck manufacturer trend to lean into EREVs.

• BEV: I like the idea of BEV for simplicity of maintenance and full divorce from fossil fuels.
• EREV: On the EREV side, I like the idea of NOT lugging around the massive battery for my typical sub 50 miles per day use, and then leaning on the generator when range needs to be extended (yes I know the Scout EREV battery range is expected to be around 150 miles). I also don't plan on getting a package that is optimized for fuel efficiency, so lightening the vehicle a bit is advantageous.

Does anyone know what the weight difference is likely to be between the BEV and EREV versions?

Here's the video for the other nerds on the forum.

 

[SpaceEVDriver]

Everyone assumes the EREV will have a lower curb weight, but I don’t understand that assumption. People must think Lithium batteries are made of solid lead. I don’t think that there will be a significant difference between the mass of the Harvester vs the BEV.

Yes, the battery will be smaller on the EREV. But the EREV will still be lugging around an engine attached to a generator motor with an extra cooling loop, a heavy fuel tank and associated fuel lines and emissions equipment, and the fuel and its tank itself.


Facts:
The NCMA Lithium battery likely to be used by Scout for their BEV carries about 270 to 300 Wh/kg.
The engine for the Scout Harvester will be a custom engine, not something that is coming off the shelf from VWAG. The suggestions are that it will be a 4-cyl, NA engine. Regardless of the specifics, a 4-cyl NA engine is going to weigh about 130-140 kg (287-308 lbs) wet.
The generator motor attached to the engine will weigh about the same as the motors in the
Scout said 350 miles of range for the BEV.
Scout said 150 miles of range for the battery-only Harvester and 500 miles of range for with both.
Scout has said that the engine can produce enough power to keep the vehicle driving on gasoline only.

Assumptions:
Assume the battery in the Harvester is the same chemistry as the battery in the BEV. I tend to think it’ll be LFP and not NMCA, but we don’t know for certain.
Assume the Terra gets about the same efficiency as the Lightning or Silverado; they’re about the same physical dimensions.

The Silverado’s and Lightning’s EPA efficiencies range from about 2.37 miles/kWh to 2.44 miles/kWh. Assume the top for the Terra.

Some part of efficiency has to do with mass, which depends on how much battery, which depends on what efficiency they want to achieve, which...which means we’ll end up with a calculus problem if try to solve it at too high precision. But we can calculate it directly for the BEV and then assume for the moment that the efficiency is the same for the Harvester.

We also need to assume something about the efficiency of the gasoline engine that’s charging the battery just enough to power the wheels when there’s no battery. This will tell us how big of a gas tank is needed to go those 350 miles of gasoline-only range. The numbers bandied around arrive at 15 to 20 gallons of gasoline. Let’s use 15 gallons. 15 gallons of gasoline has a mass of about 42 kg.

The extra cooling loop for the Harvester is probably going to have to be a full separate cooling system, with maybe a few shared parts, but almost certainly a separate compressor and condenser, separate fluids, and separate lines. The total mass could be between 50 and 150 kg, depending on how seriously they need to deal with heat buildup beneath the passenger compartment in the Traveler Harvester. Assume 75 kg.


Calculations:
350 miles range, 2.44 miles/kWh means 143 kWh.
150 miles / 2.44 miles/kWh = 61.5 kWh.

143 kWh / 270 Wh/kg = 530 kg.
61.5 kWh / 270 Wh/kg = 228 kg.

530 - 228 kg approx. = 300 kg.

Assuming the above are accurate, Scout has about 300 kg to play with before the Harvester is as massive as the BEV.
They could easily run over that mass if they aren’t shaving every possible mm of aluminum off the parts.

Part	Mass estimate (kg)	Running total
Genset (includes engine, generator, and inverter/converter)	220	220
Fuel	42	262
Fuel tank	10	272
Extra cooling loop for the Harvester	75 kg	347

If the battery is LFP or NMC, there will be a few differences, but they won’t be so much that the Harvester is wildly different in curb weight.

The only existing EREV in the US that we can use for comparison is the BMW i3 and its REx model; it had a 2-cylinder engine with a 2.4 gallon tank.

Battery & Model Year	BMW i3 (All-Electric)	BMW i3 REx (Range Extender)	Weight Added by REx System
22 kWh (2014–2016)	2,635 lbs (1,195 kg)	2,899 lbs (1,315 kg)	+264 lbs (120 kg)
33 kWh (2017–2018)	2,965 lbs (1,345 kg)	3,234 lbs (1,467 kg)	+269 lbs (122 kg)
42 kWh (2019–2021)	3,045 lbs (1,381 kg)	3,276 lbs (1,486 kg)	+231 lbs (105 kg)

 

[maynard]

Everyone assumes the EREV will have a lower curb weight, but I don’t understand that assumption. People must think Lithium batteries are made of solid lead. I don’t think that there will be a significant difference between the mass of the Harvester vs the BEV.

Yes, the battery will be smaller on the EREV. But the EREV will still be lugging around an engine attached to a generator motor with an extra cooling loop, a heavy fuel tank and associated fuel lines and emissions equipment, and the fuel and its tank itself.


Facts:
The NCMA Lithium battery likely to be used by Scout for their BEV carries about 270 to 300 Wh/kg.
The engine for the Scout Harvester will be a custom engine, not something that is coming off the shelf from VWAG. The suggestions are that it will be a 4-cyl, NA engine. Regardless of the specifics, a 4-cyl NA engine is going to weigh about 130-140 kg (287-308 lbs) wet.
The generator motor attached to the engine will weigh about the same as the motors in the
Scout said 350 miles of range for the BEV.
Scout said 150 miles of range for the battery-only Harvester and 500 miles of range for with both.
Scout has said that the engine can produce enough power to keep the vehicle driving on gasoline only.

Assumptions:
Assume the battery in the Harvester is the same chemistry as the battery in the BEV. I tend to think it’ll be LFP and not NMCA, but we don’t know for certain.
Assume the Terra gets about the same efficiency as the Lightning or Silverado; they’re about the same physical dimensions.

The Silverado’s and Lightning’s EPA efficiencies range from about 2.37 miles/kWh to 2.44 miles/kWh. Assume the top for the Terra.

Some part of efficiency has to do with mass, which depends on how much battery, which depends on what efficiency they want to achieve, which...which means we’ll end up with a calculus problem if try to solve it at too high precision. But we can calculate it directly for the BEV and then assume for the moment that the efficiency is the same for the Harvester.

We also need to assume something about the efficiency of the gasoline engine that’s charging the battery just enough to power the wheels when there’s no battery. This will tell us how big of a gas tank is needed to go those 350 miles of gasoline-only range. The numbers bandied around arrive at 15 to 20 gallons of gasoline. Let’s use 15 gallons. 15 gallons of gasoline has a mass of about 42 kg.

The extra cooling loop for the Harvester is probably going to have to be a full separate cooling system, with maybe a few shared parts, but almost certainly a separate compressor and condenser, separate fluids, and separate lines. The total mass could be between 50 and 150 kg, depending on how seriously they need to deal with heat buildup beneath the passenger compartment in the Traveler Harvester. Assume 75 kg.


Calculations:
350 miles range, 2.44 miles/kWh means 143 kWh.
150 miles / 2.44 miles/kWh = 61.5 kWh.

143 kWh * 270 Wh/kg = 530 kg.
61.5 kWh * 270 Wh/kg = 228 kg.

530 - 228 kg approx. = 300 kg.

Assuming the above are accurate, Scout has about 300 kg to play with before the Harvester is as massive as the BEV.
They could easily run over that mass if they aren’t shaving every possible mm of aluminum off the parts.

Part	Mass estimate (kg)	Running total
Genset (includes engine, generator, and inverter/converter)	220	220
Fuel	42	262
Fuel tank	10	272
Extra cooling loop for the Harvester	75 kg	347

If the battery is LFP or NMC, there will be a few differences, but they won’t be so much that the Harvester is wildly different in curb weight.

The only existing EREV in the US that we can use for comparison is the BMW i3 and its REx model; it had a 2-cylinder engine with a 2.4 gallon tank.

Battery & Model Year	BMW i3 (All-Electric)	BMW i3 REx (Range Extender)	Weight Added by REx System
22 kWh (2014–2016)	2,635 lbs (1,195 kg)	2,899 lbs (1,315 kg)	+264 lbs (120 kg)
33 kWh (2017–2018)	2,965 lbs (1,345 kg)	3,234 lbs (1,467 kg)	+269 lbs (122 kg)
42 kWh (2019–2021)	3,045 lbs (1,381 kg)	3,276 lbs (1,486 kg)	+231 lbs (105 kg)

Sounds like you are leaning towards a 7000 pound Terra Harvester…

 

[eringer]

Everyone assumes the EREV will have a lower curb weight, but I don’t understand that assumption. People must think Lithium batteries are made of solid lead. I don’t think that there will be a significant difference between the mass of the Harvester vs the BEV.

Yes, the battery will be smaller on the EREV. But the EREV will still be lugging around an engine attached to a generator motor with an extra cooling loop, a heavy fuel tank and associated fuel lines and emissions equipment, and the fuel and its tank itself.


Facts:
The NCMA Lithium battery likely to be used by Scout for their BEV carries about 270 to 300 Wh/kg.
The engine for the Scout Harvester will be a custom engine, not something that is coming off the shelf from VWAG. The suggestions are that it will be a 4-cyl, NA engine. Regardless of the specifics, a 4-cyl NA engine is going to weigh about 130-140 kg (287-308 lbs) wet.
The generator motor attached to the engine will weigh about the same as the motors in the
Scout said 350 miles of range for the BEV.
Scout said 150 miles of range for the battery-only Harvester and 500 miles of range for with both.
Scout has said that the engine can produce enough power to keep the vehicle driving on gasoline only.

Assumptions:
Assume the battery in the Harvester is the same chemistry as the battery in the BEV. I tend to think it’ll be LFP and not NMCA, but we don’t know for certain.
Assume the Terra gets about the same efficiency as the Lightning or Silverado; they’re about the same physical dimensions.

The Silverado’s and Lightning’s EPA efficiencies range from about 2.37 miles/kWh to 2.44 miles/kWh. Assume the top for the Terra.

Some part of efficiency has to do with mass, which depends on how much battery, which depends on what efficiency they want to achieve, which...which means we’ll end up with a calculus problem if try to solve it at too high precision. But we can calculate it directly for the BEV and then assume for the moment that the efficiency is the same for the Harvester.

We also need to assume something about the efficiency of the gasoline engine that’s charging the battery just enough to power the wheels when there’s no battery. This will tell us how big of a gas tank is needed to go those 350 miles of gasoline-only range. The numbers bandied around arrive at 15 to 20 gallons of gasoline. Let’s use 15 gallons. 15 gallons of gasoline has a mass of about 42 kg.

The extra cooling loop for the Harvester is probably going to have to be a full separate cooling system, with maybe a few shared parts, but almost certainly a separate compressor and condenser, separate fluids, and separate lines. The total mass could be between 50 and 150 kg, depending on how seriously they need to deal with heat buildup beneath the passenger compartment in the Traveler Harvester. Assume 75 kg.


Calculations:
350 miles range, 2.44 miles/kWh means 143 kWh.
150 miles / 2.44 miles/kWh = 61.5 kWh.

143 kWh * 270 Wh/kg = 530 kg.
61.5 kWh * 270 Wh/kg = 228 kg.

530 - 228 kg approx. = 300 kg.

Assuming the above are accurate, Scout has about 300 kg to play with before the Harvester is as massive as the BEV.
They could easily run over that mass if they aren’t shaving every possible mm of aluminum off the parts.

Part	Mass estimate (kg)	Running total
Genset (includes engine, generator, and inverter/converter)	220	220
Fuel	42	262
Fuel tank	10	272
Extra cooling loop for the Harvester	75 kg	347

If the battery is LFP or NMC, there will be a few differences, but they won’t be so much that the Harvester is wildly different in curb weight.

The only existing EREV in the US that we can use for comparison is the BMW i3 and its REx model; it had a 2-cylinder engine with a 2.4 gallon tank.

Battery & Model Year	BMW i3 (All-Electric)	BMW i3 REx (Range Extender)	Weight Added by REx System
22 kWh (2014–2016)	2,635 lbs (1,195 kg)	2,899 lbs (1,315 kg)	+264 lbs (120 kg)
33 kWh (2017–2018)	2,965 lbs (1,345 kg)	3,234 lbs (1,467 kg)	+269 lbs (122 kg)
42 kWh (2019–2021)	3,045 lbs (1,381 kg)	3,276 lbs (1,486 kg)	+231 lbs (105 kg)

Excellent details @SpaceEVDriver, thanks for taking the time to write it all out.

My biggest takeaway is that in either vehicle, you’re hauling around weight you don’t need if you’re only driving 50 miles or so a day.

My assumption that the EREV weighs less than the BEV wasn’t based on nothing.

F-150 Lightning curb weight: ~6,500 lbs
F-150 Gas Powered curb weight: ~5,200 lbs

With a 50kWh battery added to the weight of the gas powered vehicle (for simplicity’s sake), that puts the F-150 E-REV curb weight around 6,000 lbs.

 

[Broverlander]

Sounds like you are leaning towards a 7000 pound Terra Harvester…

@SpaceEVDriver , you lost me at "math!" So glad to have you here for the hard stuff!

I'm with you though, I think the weight will be about the same between the two. I think the generator, gas tank, exhaust, etc., will make up for the weight of the larger battery. My R1 weighs about 7,500 lbs. I'd guess the Traveler will be around 7,000.

 

[Broverlander]

Excellent details @SpaceEVDriver, thanks for taking the time to write it all out.

My biggest takeaway is that in either vehicle, you’re hauling around weight you don’t need if you’re only driving 50 miles or so a day.

My assumption that the EREV weighs less than the BEV wasn’t based on nothing.

F-150 Lightning curb weight: ~6,500 lbs
F-150 Gas Powered curb weight: ~5,200 lbs

With a 50kWh battery added to the weight of the gas powered vehicle (for simplicity’s sake), that puts the F-150 E-REV curb weight around 6,000 lbs.

I think you've identified the "problem" many of us have. I'm in the same boat as you. My daily commute, which is about 99% of my driving, is about 60-70 miles. For that, I'll only be using the battery on the Harvester. I'm more worried about the gas getting stale than anything. But I need that harvester for the other 1%. Trips to the in laws, trips to the lake cabin, trips where EV charging isn't as readily available. Having a BEV right now, I don't want anything with gas, but legit there are places I can't go with it here. For example, living in Minneapolis, my favorite football team is about 4.5 hours east of here. I can't take my BEV there because they legit don't have any fast charging along the way without going out of the way. I'll put up with the hassle of having a gas Harvester so I don't have to worry about that. Maybe when I'm ready to trade my Scout in for Gen 2, the infrastructure/battery tech will be better. Hopefully.

 

[6-ScoutFamily]

I don’t understand the angst with the gas going stale. If you get a Harvester, run the harvester for a week or two every few months, or on whatever schedule you think appropriate.

 

[SpaceEVDriver]

Excellent details @SpaceEVDriver, thanks for taking the time to write it all out.

My biggest takeaway is that in either vehicle, you’re hauling around weight you don’t need if you’re only driving 50 miles or so a day.

I think this is the key. If someone buys a big V8 dually they use to commute to work every day and only use the full capabilities of once a month to haul a horse trailer to an event, there’s no argument that they don’t have a use for the dually. But most of the time they are hauling around a lot of unnecessary mass and size.

I have a Silverado EV. I use its capabilities about once a week to once a month, depending on the season. I use its range extremes about twice a month. Its electrical outlets are used once a week to once a month. Its 205 kWh battery is a LOT of extra mass to haul around for a daily driver, and it’s really too big for a daily driver. In short, I’m not one to argue that rare use cases can’t be used to justify extreme capabilities.

My assumption that the EREV weighs less than the BEV wasn’t based on nothing.

F-150 Lightning curb weight: ~6,500 lbs
F-150 Gas Powered curb weight: ~5,200 lbs

With a 50kWh battery added to the weight of the gas powered vehicle (for simplicity’s sake), that puts the F-150 E-REV curb weight around 6,000 lbs.

This is a totally fair way of looking at it too. A 50 kWh battery is probably too small, and we don’t know the chemistry, but it’s still a reasonable assumption. I would have used the hybrid’s curb weight and added the 61 kWh battery to that: 5500 pounds + 500 pounds = 6000 pounds. But if it’s an LFP battery, it might be more like 750 pounds, giving 6250 pounds curb weight. And I didn’t include the protective cage we think they’re building the Harvester into so it can be dropped from the vehicle in a (mostly) single package.

The reality is that we just don’t know enough yet, but I don’t expect things will be so different that the curb weight will make a strong argument for the Harvester.

 

[speedrye]

I think this is the key. If someone buys a big V8 dually they use to commute to work every day and only use the full capabilities of once a month to haul a horse trailer to an event, there’s no argument that they don’t have a use for the dually. But most of the time they are hauling around a lot of unnecessary mass and size.

I have a Silverado EV. I use its capabilities about once a week to once a month, depending on the season. I use its range extremes about twice a month. Its electrical outlets are used once a week to once a month. Its 205 kWh battery is a LOT of extra mass to haul around for a daily driver, and it’s really too big for a daily driver. In short, I’m not one to argue that rare use cases can’t be used to justify extreme capabilities.



This is a totally fair way of looking at it too. A 50 kWh battery is probably too small, and we don’t know the chemistry, but it’s still a reasonable assumption. I would have used the hybrid’s curb weight and added the 61 kWh battery to that: 5500 pounds + 500 pounds = 6000 pounds. But if it’s an LFP battery, it might be more like 750 pounds, giving 6250 pounds curb weight. And I didn’t include the protective cage we think they’re building the Harvester into so it can be dropped from the vehicle in a (mostly) single package.

The reality is that we just don’t know enough yet, but I don’t expect things will be so different that the curb weight will make a strong argument for the Harvester.

From an engineering perspective, I'd think it'd make more sense to build the EREV as close to the same weight as the BEV to utilize common suspension components, etc. With the tow rating issue, I suspect we'll see some upgraded components in the rear frame to raise the towing capacity, but I might be backwards in that and they're trying to save every pound of sprung mass out back. Spring rates, shock valving and vehicle dynamics' tuning will be different between the two since you've got a different weight distribution, but they should be able to use the same suspension arms and such at least. Definitely looking forward to comparing parts numbers between the two drivetrain choices later on.

 

[SpaceEVDriver]

From an engineering perspective, I'd think it'd make more sense to build the EREV as close to the same weight as the BEV to utilize common suspension components, etc. With the tow rating issue, I suspect we'll see some upgraded components in the rear frame to raise the towing capacity, but I might be backwards in that and they're trying to save every pound of sprung mass out back. Spring rates, shock valving and vehicle dynamics' tuning will be different between the two since you've got a different weight distribution, but they should be able to use the same suspension arms and such at least. Definitely looking forward to comparing parts numbers between the two drivetrain choices later on.

I suspect one of the reasons they put the Harvester genset over the rear axle was to try to have as close to the same distribution of mass as the BEV. They probably could have done something similar with moving the genset to the front, but I think they would have had to give up the frunk and I think marketing told them that would not go over well with the most likely first-round buyers or reviewers.

 

[speedrye]

I suspect one of the reasons they put the Harvester genset over the rear axle was to try to have as close to the same distribution of mass as the BEV. They probably could have done something similar with moving the genset to the front, but I think they would have had to give up the frunk and I think marketing told them that would not go over well with the most likely first-round buyers or reviewers.

Under the rear cargo area is probably the most under-utilized space on any modern vehicle. I'm happy to see engineers using that space, even if they're cramming a bit too much in there.

 

[Gottesacker]

I suspect one of the reasons they put the Harvester genset over the rear axle was to try to have as close to the same distribution of mass as the BEV. They probably could have done something similar with moving the genset to the front, but I think they would have had to give up the frunk and I think marketing told them that would not go over well with the most likely first-round buyers or reviewers.

I'll say that the frunk remaining on the EREV was one of my deciding factors to put in a reservation. I'm leaning more BEV these days (even changed the reservation) but if the EREV hadn't been said to keep the frunk I'm not sure if I would have made that reservation.

I've been in the camp of thinking the EREV would be less weight, though nothing super crazy, but it is illuminating also putting the BMW i3 side-by-side too.

 

[cyure]

I'll say that the frunk remaining on the EREV was one of my deciding factors to put in a reservation. I'm leaning more BEV these days (even changed the reservation) but if the EREV hadn't been said to keep the frunk I'm not sure if I would have made that reservation.

I've been in the camp of thinking the EREV would be less weight, though nothing super crazy, but it is illuminating also putting the BMW i3 side-by-side too.

If SM hadn't launched the EREV as well I probably would not have put in my reservation. I also have switched my reservation to the BEV at this point.

 

[J Alynn]

Everyone assumes the EREV will have a lower curb weight, but I don’t understand that assumption. People must think Lithium batteries are made of solid lead. I don’t think that there will be a significant difference between the mass of the Harvester vs the BEV.

Yes, the battery will be smaller on the EREV. But the EREV will still be lugging around an engine attached to a generator motor with an extra cooling loop, a heavy fuel tank and associated fuel lines and emissions equipment, and the fuel and its tank itself.


Facts:
The NCMA Lithium battery likely to be used by Scout for their BEV carries about 270 to 300 Wh/kg.
The engine for the Scout Harvester will be a custom engine, not something that is coming off the shelf from VWAG. The suggestions are that it will be a 4-cyl, NA engine. Regardless of the specifics, a 4-cyl NA engine is going to weigh about 130-140 kg (287-308 lbs) wet.
The generator motor attached to the engine will weigh about the same as the motors in the
Scout said 350 miles of range for the BEV.
Scout said 150 miles of range for the battery-only Harvester and 500 miles of range for with both.
Scout has said that the engine can produce enough power to keep the vehicle driving on gasoline only.

Assumptions:
Assume the battery in the Harvester is the same chemistry as the battery in the BEV. I tend to think it’ll be LFP and not NMCA, but we don’t know for certain.
Assume the Terra gets about the same efficiency as the Lightning or Silverado; they’re about the same physical dimensions.

The Silverado’s and Lightning’s EPA efficiencies range from about 2.37 miles/kWh to 2.44 miles/kWh. Assume the top for the Terra.

Some part of efficiency has to do with mass, which depends on how much battery, which depends on what efficiency they want to achieve, which...which means we’ll end up with a calculus problem if try to solve it at too high precision. But we can calculate it directly for the BEV and then assume for the moment that the efficiency is the same for the Harvester.

We also need to assume something about the efficiency of the gasoline engine that’s charging the battery just enough to power the wheels when there’s no battery. This will tell us how big of a gas tank is needed to go those 350 miles of gasoline-only range. The numbers bandied around arrive at 15 to 20 gallons of gasoline. Let’s use 15 gallons. 15 gallons of gasoline has a mass of about 42 kg.

The extra cooling loop for the Harvester is probably going to have to be a full separate cooling system, with maybe a few shared parts, but almost certainly a separate compressor and condenser, separate fluids, and separate lines. The total mass could be between 50 and 150 kg, depending on how seriously they need to deal with heat buildup beneath the passenger compartment in the Traveler Harvester. Assume 75 kg.


Calculations:
350 miles range, 2.44 miles/kWh means 143 kWh.
150 miles / 2.44 miles/kWh = 61.5 kWh.

143 kWh / 270 Wh/kg = 530 kg.
61.5 kWh / 270 Wh/kg = 228 kg.

530 - 228 kg approx. = 300 kg.

Assuming the above are accurate, Scout has about 300 kg to play with before the Harvester is as massive as the BEV.
They could easily run over that mass if they aren’t shaving every possible mm of aluminum off the parts.

Part	Mass estimate (kg)	Running total
Genset (includes engine, generator, and inverter/converter)	220	220
Fuel	42	262
Fuel tank	10	272
Extra cooling loop for the Harvester	75 kg	347

If the battery is LFP or NMC, there will be a few differences, but they won’t be so much that the Harvester is wildly different in curb weight.

The only existing EREV in the US that we can use for comparison is the BMW i3 and its REx model; it had a 2-cylinder engine with a 2.4 gallon tank.

Battery & Model Year	BMW i3 (All-Electric)	BMW i3 REx (Range Extender)	Weight Added by REx System
22 kWh (2014–2016)	2,635 lbs (1,195 kg)	2,899 lbs (1,315 kg)	+264 lbs (120 kg)
33 kWh (2017–2018)	2,965 lbs (1,345 kg)	3,234 lbs (1,467 kg)	+269 lbs (122 kg)
42 kWh (2019–2021)	3,045 lbs (1,381 kg)	3,276 lbs (1,486 kg)	+231 lbs (105 kg)

I SCIENCE!!!

 

[Reinvent]

Everyone assumes the EREV will have a lower curb weight, but I don’t understand that assumption. People must think Lithium batteries are made of solid lead. I don’t think that there will be a significant difference between the mass of the Harvester vs the BEV.

Yes, the battery will be smaller on the EREV. But the EREV will still be lugging around an engine attached to a generator motor with an extra cooling loop, a heavy fuel tank and associated fuel lines and emissions equipment, and the fuel and its tank itself.


Facts:
The NCMA Lithium battery likely to be used by Scout for their BEV carries about 270 to 300 Wh/kg.
The engine for the Scout Harvester will be a custom engine, not something that is coming off the shelf from VWAG. The suggestions are that it will be a 4-cyl, NA engine. Regardless of the specifics, a 4-cyl NA engine is going to weigh about 130-140 kg (287-308 lbs) wet.
The generator motor attached to the engine will weigh about the same as the motors in the
Scout said 350 miles of range for the BEV.
Scout said 150 miles of range for the battery-only Harvester and 500 miles of range for with both.
Scout has said that the engine can produce enough power to keep the vehicle driving on gasoline only.

Assumptions:
Assume the battery in the Harvester is the same chemistry as the battery in the BEV. I tend to think it’ll be LFP and not NMCA, but we don’t know for certain.
Assume the Terra gets about the same efficiency as the Lightning or Silverado; they’re about the same physical dimensions.

The Silverado’s and Lightning’s EPA efficiencies range from about 2.37 miles/kWh to 2.44 miles/kWh. Assume the top for the Terra.

Some part of efficiency has to do with mass, which depends on how much battery, which depends on what efficiency they want to achieve, which...which means we’ll end up with a calculus problem if try to solve it at too high precision. But we can calculate it directly for the BEV and then assume for the moment that the efficiency is the same for the Harvester.

We also need to assume something about the efficiency of the gasoline engine that’s charging the battery just enough to power the wheels when there’s no battery. This will tell us how big of a gas tank is needed to go those 350 miles of gasoline-only range. The numbers bandied around arrive at 15 to 20 gallons of gasoline. Let’s use 15 gallons. 15 gallons of gasoline has a mass of about 42 kg.

The extra cooling loop for the Harvester is probably going to have to be a full separate cooling system, with maybe a few shared parts, but almost certainly a separate compressor and condenser, separate fluids, and separate lines. The total mass could be between 50 and 150 kg, depending on how seriously they need to deal with heat buildup beneath the passenger compartment in the Traveler Harvester. Assume 75 kg.


Calculations:
350 miles range, 2.44 miles/kWh means 143 kWh.
150 miles / 2.44 miles/kWh = 61.5 kWh.

143 kWh / 270 Wh/kg = 530 kg.
61.5 kWh / 270 Wh/kg = 228 kg.

530 - 228 kg approx. = 300 kg.

Assuming the above are accurate, Scout has about 300 kg to play with before the Harvester is as massive as the BEV.
They could easily run over that mass if they aren’t shaving every possible mm of aluminum off the parts.

Part	Mass estimate (kg)	Running total
Genset (includes engine, generator, and inverter/converter)	220	220
Fuel	42	262
Fuel tank	10	272
Extra cooling loop for the Harvester	75 kg	347

If the battery is LFP or NMC, there will be a few differences, but they won’t be so much that the Harvester is wildly different in curb weight.

The only existing EREV in the US that we can use for comparison is the BMW i3 and its REx model; it had a 2-cylinder engine with a 2.4 gallon tank.

Battery & Model Year	BMW i3 (All-Electric)	BMW i3 REx (Range Extender)	Weight Added by REx System
22 kWh (2014–2016)	2,635 lbs (1,195 kg)	2,899 lbs (1,315 kg)	+264 lbs (120 kg)
33 kWh (2017–2018)	2,965 lbs (1,345 kg)	3,234 lbs (1,467 kg)	+269 lbs (122 kg)
42 kWh (2019–2021)	3,045 lbs (1,381 kg)	3,276 lbs (1,486 kg)	+231 lbs (105 kg)

I was looking to this and crunching some basic numbers. But I see you did most of the work. I think it is a strong probability Scout will use a EREV motor from the Horse Powertrain company. Specifically the C15 powertrain. It weighs 375 lbs. The entire compact package (engine, generator, inverter, and cooling system) measures roughly 50 × 55 × 27.5 cm (about the size of a cabin suitcase).
The Naturally Aspirated Version: Produces up to 70 kW (94 hp / 95 PS) of electrical power.
Turbocharged Version: Produces up to 120 kW (161 hp / 163 PS) of electrical power.
Horse Powertrain is a well established company with lots of R&D and manufacturing capability. .

https://www.automotivemanufacturing...train-banks-on-combustions-second-act/2621511

 

[SpaceEVDriver]

I was looking to this and crunching some basic numbers. But I see you did most of the work. I think it is a strong probability Scout will use a EREV motor from the Horse Powertrain company. Specifically the C15 powertrain. It weighs 375 lbs. The entire compact package (engine, generator, inverter, and cooling system) measures roughly 50 × 55 × 27.5 cm (about the size of a cabin suitcase).
The Naturally Aspirated Version: Produces up to 70 kW (94 hp / 95 PS) of electrical power.
Turbocharged Version: Produces up to 120 kW (161 hp / 163 PS) of electrical power.
Horse Powertrain is a well established company with lots of R&D and manufacturing capability. .

https://www.automotivemanufacturing...train-banks-on-combustions-second-act/2621511

They've stated it will be built by VWAG, customized for their purposes.

 

[Reinvent]

They've stated it will be built by VWAG, customized for their purposes.

I should have guessed that. Hopefully VWAG can meet of beat the specs of the Horse Powertrain.