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this post was submitted on 01 Jan 2024
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Serious Question: Why can't we just have towable generators so EVs can go from an electric car to a Plugin Hybrid for road trips?
Generators aren't very expensive relatively speaking.
Yet I've never heard not seen this anywhere, and seems like a very easy solution to range anxiety.
What if the generator was inside the front of the car - and only turned on when the battery was low? Wait, I've just re-invented the hybrid.
Yeah okay but almost nobody is making Plug-in Hybrids and they cost an absolute fuck ton of money.
You also don't need the generator for 99% of rides so you can remove it to reduce costs.
Look at the new "Ram Charger" that works like you describe. It's 60k and for whatever reason needs a 600hp engine and a full electric engine.
The 2024 Prius prime starts at $33k, is a PHEV https://www.kbb.com/phev/best-phev-cars/2024/
BMW, Volvo, Mercedes are also making PHEVs for 2024 model year So are Chrysler, Mazda, Hyundai, Kia, Porsche, Land Rover https://www.autoweek.com/rankings/g45455983/best-plug-in-hybrids/
There are some really expensive ones on that list, but a half-dozen under $45k
Yeah a lot of the hybrid offerings in the truck market are really not targeting the budget market at all- some of them seem to reflect automaker bets that truck buyers want more power and don't want to compromise on towing or range. Other hybrid trucks (looking at you, Toyota) aren't using their hybrid systems to improve fuel economy, they're using them to juice performance.
I didn't know the Prius was a Plug-in now. Last time I looked at them. The Prius only ran the battery under 15 and only a very short distance. Didn't think they changed that.
$45,000 is still a lot of money. That's a $750 Monthly payment
An average EV consumes .32 kilowatt hours of electricity per mile. If you are driving 60 miles per hour, that means you are spending 19.2 kilowatt hours of electricity every hour. So you need a generator that's at least 19.2 kilowatt. Tack on some more because you are now towing the extra weight of a generator and because you are probably wanting to go 70mph and let's just say you need 25 kilowatts. This is what a towable 25kw generator looks like. It costs $22k. I'm sure cheaper ones could be made, but even at $10k, is it worth it? Just buy some plane tickets or rent a gas car for a week or take a train.
https://herogenerators.com/products/25-kw-caterpillar-towable-diesel-generator
Buy? No thanks I don’t even have a good place to store it, never mind maintenance.
But I’d rent it.
Only wrinkle: backing up. I’ve owned/used trailers many times so I have no problem with backing up, but many would. Can’t think of a way around this that would be even “almost” idiot proof.
Could use a trailer that stays directly behind the car. Like instead of just a ball hitch, have several mount points on the rear of the car, then it won't swing freely. Maybe rig it to only use one wheel when the vehicle turns (otherwise I think it would cause a bit of understeer).
Though people do learn how to use trailers. Some truck drivers even know the black magic of backing up with multiple trailers.
I think it's because someone who takes enough Road trips to use something like that would properly just get a regular plug in hybrid. That being said, this might be coming soon for ev trucks actually. The dodge ram ev is going to have a gas powered range extender, and I believe ford has patented a bed mounted version for its ev truck.
Safety as well. Generators are not built for all the regulations the DOT has. It's a different thing to transport a generator and then actually having it fixed to a vehicle as a usable entity.
Probably be more efficient to just have a towable battery you charge ahead of time.
It's a massive waste of energy. What does a good diesel generator have, like 20% energy efficiency? Not taking into account that you're wasting a lot energy for towing it.
It would also have to be massive.
Why would It be diesel?
Besides what exactly is the alternative if there is no charging location on the way?
Just spend $150/day to rent a car in addition to all other travel expenses?
Lets work through some back-of-the-napkin math here.
Lets say the average speed you're looking to take on your road trip is 50MPH. For that discharge rate you'd need to be able to charge at 50MPH to keep up. That would put you at a charging requirement of 50kw.
Here is a picture of a 50kw towable generator:
This isn't even any of the additional gear needed for DC rectification and power management needed to interface with NACS or CCS.
You can see why this idea doesn't really work then.
I'm going to need to see your work for the 50mph to 50kw conversion.
Googling a rough average returned 0.346 kwh/mile for electric cars between 2000 and 2022 (wide range, im aware). Traveling at 50MPH, you go 50 miles in 1 hour (assume you're already going 50, and stay at that speed). So you'd use [0.346KWh/mile] *[50 miles/hour] = [17.3 KW] per hour @ 50 MPH
One of the problems is that air resistance increases at a squared rate vs velocity, so that average is only really accurate at one specific speed (which tbf might actually be 50mph). But this is a lot more accurate than just replacing "mph" with "kw" lol.
My biggest red flag was the picture of a commercial-grade-looking generator when plug in hybrids can fit the generator plus electric motor, battery, AC, and all the other stuff needed under the hood.
1 Kw per mph sounds pretty bad. I would've thought electric cars are more efficient than that.
Also one is a force while the other is a speed. You'd need a lot of assumptions to go from one number to another single number.