Series hybrid RV chassis

RV_Lee1

Senior Member
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Aug 13, 2012
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199

"The plug-in hybrid platform features a 1.4-liter inline four-cylinder gasoline engine, with a close-coupled 800-volt generator and a 50-gallon fuel tank. The range extender engine is used to recharge the vehicle’s 140,000-watt-hour or 175,000-watt-hour battery system, depending on customer selection.


Harbinger’s electric powertrain delivers up to 1,140 pound-feet of torque and 440 horsepower. The platform’s 800-volt electrical architecture allows rapid charging at DC Fast Charger locations, up to 80% in one hour."

Looks like this is a replacement for a current rig that uses~ a Cummins 360hp / 1250tq. E-axles exist up to 3000lbft so they have lots of room to move up.
 
Hard to argue with those specs. Hybrid makes sense for the vast majority of people. Environmentalists should have pushed for hybrids first. But of course its all EV or nothing with those radicals. All their exaggerated EV hype has made people wary and has probably hurt hybrid sales.
 
Hard to argue with those specs. Hybrid makes sense for the vast majority of people. Environmentalists should have pushed for hybrids first. But of course its all EV or nothing with those radicals. All their exaggerated EV hype has made people wary and has probably hurt hybrid sales.
These make a ton of sense for RVs, I am actually surprised we haven't seen them sooner considering how unreliable the new diesels are when strangled by the emissions controls and DEF.

A little 4cyl gas engine "generator" that keeps the huge battery bank charged that powers the e-axle(s) and the house portion of the RV. Re-gen for brakes.
 
I wonder what the charge rate/time would be from the onboard generator after the battery is depleted and no charge station is at hand.
It'll vary depending on what engine and battery pack it has and then be adjustable from there I assume. There is a sub culture of people that camp in their Toyota prius because you just set the climate control to whatever you want and it runs off the battery and the engine / generator kicks on and off automatically through the night. You can also hook up a cpap machine. The RVs would just be a bigger version

Here's a diesel/electric prototype logging truck being driven

 
Hybrids gain their efficiency through two conditions. One is load leveling, operating the ICE at a peak efficiency. The other is regeneration in stop and go traffic. Highway MPG is lower than city MPG because there's no braking energy to recover and you can't count coasting downhill because for every down there's an up. A series hybrid, where the ICE is strictly a generator has built in conversion losses having to generate electricity that has to be converted and possibly stored, then kinetic energy created in a motor. Each conversion step has a loss. There will be a narrow set of conditions there's an advantage so their effectiveness depends on how much time you spend in the sweet spot. Series and parallel hybrids can offer some efficiencies in torque conversion, witness diesel electric locomotives. In my view an OTR heavy truck (e.g. RV) isn't automatically more efficient because it's a hybrid. Make it a plug in and the numbers shift positive because you're taking the ICE out of the equation. If you have a 16 ton ICE truck that gets 7mpg and carries 100 gallons of fuel, making it a hybrid will not fundamentally transform it's efficiency. If there were efficiency gains to be had with hybrids then the OTR industry would already be all over it. I think it might offer a niche as an all electric RV with a giant house battery that has some grid independence. But unless these things can be built inexpensively I don't think there'd be a market for a niche RV. Like EV's you can make a case for any specialty vehicle as a transportation solution but I wouldn't expect they'd be the universal transportation solution.

Mark B.
Albuquerque, NM
 
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Hybrids gain their efficiency through two conditions. One is load leveling, operating the ICE at a peak efficiency. The other is regeneration in stop and go traffic. Highway MPG is lower than city MPG because there's no braking energy to recover and you can't count coasting downhill because for every down there's an up. A series hybrid, where the ICE is strictly a generator has built in conversion losses having to generate electricity that has to be converted and possibly stored, then kinetic energy created in a motor. Each conversion step has a loss. There will be a narrow set of conditions there's an advantage so their effectiveness depends on how much time you spend in the sweet spot. Series and parallel hybrids can offer some efficiencies in torque conversion, witness diesel electric locomotives. In my view an OTR heavy truck (e.g. RV) isn't automatically more efficient because it's a hybrid. Make it a plug in and the numbers shift positive because you're taking the ICE out of the equation. If you have a 16 ton ICE truck that gets 7mpg and carries 100 gallons of fuel, making it a hybrid will not fundamentally transform it's efficiency. If there were efficiency gains to be had with hybrids then the OTR industry would already be all over it. I think it might offer a niche as an all electric RV with a giant house battery that has some grid independence. But unless these things can be built inexpensively I don't think there'd be a market for a niche RV. Like EV's you can make a case for any specialty vehicle as a transportation solution but I wouldn't expect they'd be the transportation solution.

Mark B.
Albuquerque, NM
In theory you'd think a full EV RV would work, but have you seen what $$$ they charge to charge your EV car? I've seen it as high as $75 for roughly an hour. Now think what the RV park is going to charge for a 1 night stay after installing EV chargers at a bunch of sites.

The normal 50 amp plug would take 2 weeks or more to charge that size battery.

Gas engine as the (actual quiet) generator is still the way to go but at this stage just to replace the emission control strangled trouble prone diesels. At the very least you have instant torque, quieter operation, no diesel smells and a huge dry camping potential right off the bat. We still haven't covered the roof in solar yet either.

The Edison company (video above) is also working on conversion kits, they rip out the old stuff and install the e-axle, battery pack and everything else. I'd like to see what their kit costs versus a new engine in say a newer diesel pusher with a blown motor.
 
I wonder what the charge rate/time would be from the onboard generator after the battery is depleted and no charge station is at hand
Since the genny is ran by a 1.4L engine, I would guess that charges at around 50KW. Into a 140 KWH battery, it would take more than a couple of hours to get to 80% SOC from less than 10%.

For this reason, it makes more sense to look at charging as MPHc (Miles added per hour of charge). And even that would depend on the speed one is driving at after the charge. But you can also charge as you're driving, but the charge rate will not keep up with the battery drain. But it will take longer for the battery to get low, which means better range between charges.

Nevertheless, I like the idea of these "extended range EVs". True EV that can be charged up with anything, even gasoline. Not what I consider a hybrid which uses a real gasoline engine to connect to the wheels mechanically. Extended range EVs simply charge the EV battery and do nothing else. Don't need the engine at all to drive the thing.

-Don- Auburn, CA
 
The normal 50 amp plug would take 2 weeks or more to charge that size battery.
How did you come up with that? A 140 KWH battery, with a typical 12KW AC input charger (240 VAC times 48 amps=11,520 watts). With heat losses, power factor etc., still more than ~10KW DC going to the battery, but let's use that.

140KWH battery charged by 10 KW=14 hours to full not counting the slowdown above 80% SOC. That's far from "two weeks".

I can charge it right here at that rate at this house. Same for my other house.

-Don- Auburn, CA
 
In theory you'd think a full EV RV would work, but have you seen what $$$ they charge to charge your EV car? I've seen it as high as $75 for roughly an hour.
And as low as no cost at all. The price of EV charging varies more than gasoline but is usually a lot less than gasoline for the same distance.

See the several charts shown here for an average comparison per state between gasoline vs. electricity in miles per 100 bucks.

"What state(s) can you travel the furthest in an EV?

The more appropriate answer is “all of them.” At least when comparing an EV vs. an ICE vehicle."

-Don- Auburn, CA
 
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How did you come up with that? A 140 KWH battery, with a typical 12KW AC input charger (240 VAC times 48 amps=11,520 watts). With heat losses, power factor etc., still more than ~10KW DC going to the battery, but let's use that.

140KWH battery charged by 10 KW=14 hours to full not counting the slowdown above 80% SOC. That's far from "two weeks".

I can charge it right here at that rate at this house. Same for my other house.

-Don- Auburn, CA
From my own experience. I have nowhere near that amount of battery and even from 30% it takes nearly 48 hours to charge when at the RV park
 
From my own experience. I have nowhere near that amount of battery and even from 30% it takes nearly 48 hours to charge when at the RV park
Which voltage are you using at the RV park? What type of EV?

There are many other variables too, such as the type of AC input charger inside the vehicle. Old Teslas used 24KW, newer ones use half that, 12KW. This makes sense because many years ago, they didn't have the DCFC networks they have today, so faster AC input charging was needed, especially when on the road. Today, 12 KW or less is standard for home charging and at motels and such. The norm if to be able to fully charge a near dead battery to 100% overnight.

Such as at my homes. For an example, 12KW to an 80 KWH Tesla LR battery. 80KWH (my Tesla M3 LR battery) divided by 12KW=6.66 hours. In reality, more like 8 hours because of the slowdown above 80% SOC and the small losses in heat. But that is from very dead to completely full, which is very rare to be needed these days. So one night when sleeping should give all the charge anybody needs in most cases, by far.

The older Tesla destination charge stations as well as some J-1772 charge stations were often higher than 12KW. I have seen each at 70-amps at 240 VAC, (16.8 KW) but always older units and none of the newer EV cars (AFAIK) can do above 12KW AC input charging anyway.

But sometimes a little lower, as some places use the 208 volts from 3-phase AC industrial power instead of 240 VAC.

And some EVs can only charge at 32 amps @ 240 VAC (~7,680 watts) max.

But the charge times can be figured out with simple math by knowing all the numbers, such as the voltage and current capacity of the AC source as well as the KW of the EV charger located inside the EV.

The "pilot signal" of a J-1772 or Tesla Destination charge station (these are not chargers, but are usually incorrectly called such) will prevent overloads. IOW, you can put a 12KW charger (located inside the EV) on a 3KW charge station (just an AC source like any AC outlet) because the charge station sends a signal to the EV charger to tell the EV charger to reduce to 3KW (or whatever the charge station can handle). But then you charge at 3KW that will take four times longer than 12 KW.

-Don- Auburn, CA
 
from 30% it takes nearly 48 hours to charge when at the RV park

You're obviously using a 120 VAC outlet, such as an RV-30.

If you're using a 16-amp max granny cable, that is correct for when on 120 VAC.

120 VAC times 15 amps (typical max)=1,800 watts. If your EV battery is as large as my Tesla (80 KWH) then it is 80KWH divided by 1.8 KW=44.44 hours.

Get yourself a 40-amp granny cable and use a 14-50R. But unplug your RV when you do.

Then it will charge at 9,600 watts instead of that ridiculously slow ~1.8KWs (probably even a little less).

5.3 times faster charge on 240 VAC with an 40-amp charge cable. Your 48 hours will be reduced to less than 7 hours from 30% SOC.

The only problem there is if your EV is eating up 9,600 watts, you have little left to run other stuff. Maybe 2KW left at the very most for other things.


-Don- Auburn, CA
 

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