EV with onboard generator

[redpoint5]

An EV with range extending ICE is probably not a good solution for most these days.

Plenty of hybrids get 50+ MPG nowadays, and that's extremely good.

EVs recharge quickly and infrastructure is mostly adequate these days.

Here's my comment on another forum-

On my recent 600 mile trip to Monte Rio I made the following stops, which worked out to exactly 1 hour spent charging.

10:30am Depart Silverton
2:00pm - Medford - 28min - 55 kWh (ate lunch)
5:00pm - Cottonwood - 15min - 35 kWh (bought groceries)
6:20pm - Williams - 17min - 39 kWh (stayed longer than the suggested 7min to arrive with a higher state of charge.
9:00pm - Arrive Monte Rio

Driving an EV set me back about 10min, and only because I decided to spend an extra 10min at my last stop to arrive with much more range. I was either getting food, using the restroom, or buying groceries at the other stops, and spent no time just sitting in the car. I averaged 130 kW and 400 miles per hour at the DCFC.

Considering series hybrid is the solution on trains, it follows that other very large machinery would most benefit from such a solution. I could see semis benefiting from a series hybrid system.

Asking AI, I got the following info-

A diesel engine consuming 8.5 gallons of diesel per hour generates approximately 170–180 horsepower.

According to a widely used rule of thumb, 1 gallon of diesel per hour produces about 20 horsepower, so 8.5 gallons/hour × 20 hp/gallon = 170 horsepower

I asked that because a fully loaded semi gets about 7 MPG cruising at 60MPH.

My back of the envelope figuring suggests we need a diesel engine capable of ~300 horsepower; enough to maintain speed, slowly charge the battery, and account for losses.

Based on Hummer EV specs, the semi motors should output 1,000 horsepower and requires a 205 kWh battery, which weighs 3,000lbs.

The upside is the ability to recapture energy during braking, hopefully massively reducing runaway truck incidents in the process.

The other upside is not needing to idle the truck to provide AC/electricity when drivers rest.

[freebeard]

Originally Posted by redpoint5

If I were forced to add a genset to a car not designed for it, I would mount it to a 2" hitch external to the vehicle instead of ruining it.

Would you put wheels under it?

[redpoint5]

Originally Posted by freebeard

Would you put wheels under it?

Not for a genset. Engineering suspension on a 5th wheel is outside of my area, especially adding in the complexity of varying power output based on demand.

[freebeard]

Do you like oversteer, because that's how you get oversteer.

[RustyLugNut]

Originally Posted by redpoint5

An EV with range extending ICE is probably not a good solution for most these days.

****

Considering series hybrid is the solution on trains, it follows that other very large machinery would most benefit from such a solution. I could see semis benefiting from a series hybrid system.

****

My back of the envelope figuring suggests we need a diesel engine capable of ~300 horsepower; enough to maintain speed, slowly charge the battery, and account for losses.

****

The upside is the ability to recapture energy during braking, hopefully massively reducing runaway truck incidents in the process.

The other upside is not needing to idle the truck to provide AC/electricity when drivers rest.

This is the real market for strong hybrid drivetrains. And this is where a redesign of the internal combustion engine is needed. There is a lot still left on the table.

[JSH]

Extended Range EVs don't really make a lot of sense of small vehicles as demonstrated by Redpoint. EVs work fine there as long as you have chargers available.

Also an PHEV or EREV (call it want you want - I personally think Plug-in Hybrid will sell better than Extended Range EV). will cost more than either a simply hybrid or an EV.


PHEVs do make a lot more sense for larger vehicles and especially ones that need to tow.

Ram is doing an EREV for their 2026 Ramcharger. Details here:

https://www.motortrend.com/news/2026...tech-deep-dive

[freebeard]

That's a lot of parts!

A through-the-road hybrid would be ICE at one end and electric at the other. Let the road mediate the two.

[JSH]

Originally Posted by freebeard

That's a lot of parts!

A through-the-road hybrid would be ICE at one end and electric at the other. Let the road mediate the two.

This has no more parts that a through the road hybrid but has the benefit of allowing AWD in EV mode.

[Logic]

IIRC the power needed to cruise at 60 to 75 mph is 20 to 30 kw for a small to medium sized car with decent aero.
That's a 200cc to 250cc engine at max power, but probably slightly bigger for max efficiency.

As the engine would run at constant rpm and load, tuning the intake and exhaust tract lengths etc is much more worth doing than in an engine that is 'never' at the same rpm all the time.

Other advantages are IC engines are over 80% efficient if/when you can use the normally wasted heat. (See Combined Heat and Power: CHP)
So in cold weather, heating the battery and interior become more efficient than pure EV solutions.
The genset can also directly add the amps that aren't accessible when the battery is cold.
In fact directly using those amps in high load situations would make the expensive batteries last longer.

The other thing about constant rpm is that you can go with a cheap carburetor and ignition system without losing efficiency.

Even better: With constant rpm vapour or gassified, pyrolysed fuel becomes easy.
I know-I know; "All the fuel is burned so hot vapour etc is pointless" is the mantra here. But I'm not arguing that.
It's not how little is left in exhaust, it's about WHEN is the fuel burned..!
ie: Is it 'all' burned at the optimal crank angle..?
The various Geet etc systems online are all just science and industry proven Pyrolysis and Steam Reformation systems, using normally waste exhaust heat, when you strip away the 'Magic-Smagick' BS.

In Summary:
Tuning an engine; cam, intake, exhaust, jetting, timing etc is cheap, easy and worthwhile with constant rpm.

Force = Mass X Acceleration, so the lighter the vehicle; the less fuel it takes for the same acceleration. That's why small engined motorbikes can out drag much more powerful cars and trucks..
So saying that weight reduction hardly matters does not make sense to me redpoint5?

As liquid fuel is around 80X lighter and smaller than batteries there is a lot of room here for making a lighter EV with less, expensive batteries and without range anxiety and long stops.

The rotation to electricity to chemical to electricity to rotational efficiency thing sucks, so yes; some means to get engine rotation to the wheels for constant speed/rpm highway cruising still seems to be worthwhile, despite the added weight and complexity.

IIRC the world average car trip is only 15 miles, so lugging around more batteries than that seems a waste.
Lugging around an engine for these short trips is also a waste, so a genset trailer, with extra packing space that you hook behind your EV for long trips makes the most sense.
This has been tried by trailer rental companies etc, but met with little success for some reason?
Probably because most people are incapable of reversing a trailer!??

[Logic]

Originally Posted by Gasoline Fumes

BMW did that.
https://en.wikipedia.org/wiki/BMW_i3

The American spec BMW i3 Rex was seriously borked so as to pass some or other silly rule or some-such, turning it into a much less capable and desirable vehicle!
It can be modded back to European spec easily, making it a much more desirable and capable car!

Google AI Overview:

Modding a US-spec BMW i3 REx to match European specifications involves enabling the "hold state of charge" feature, which allows the range extender to be activated manually when the battery is at or below 75% charge.
This gives drivers more control over when the gasoline engine/generator kicks in, allowing them to conserve electric range for city driving or lower speeds and use the range extender for highway driving or when extra power is needed.
Additionally, the full fuel capacity (2.4 gallons) can be unlocked, as it's software limited to 1.9 gallons in the US