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Discussion Starter · #1 ·

I live in a small city in a low-population area in the central USA.

I've been interested in electric vehicles since before auto makers started releasing them a few years back. (Don't talk about the early days of autos, I'm talking like Chevy Volt)

My problem with typical EV projects is that they focus on some econobox car, which is impractical for me. I'm 6'4" (193 cm) and those cars just don't hold somebody my size. Not only that, I'm a foster parent and we have some variable number of kids, and then the people in my real family, and then a couple dogs, and whatever fishing/camping gear I want to take with me.

My current vehicle is a 15 passenger van. It's a 2010 Chevy Econoline 3500, extended. There are 4 bench seats and 2 buckets up front. 3 of the bench seats hold 3 people, the last one holds 4. Usually the back seat is out to make room for dogs, but I have literally had every other seat used. The van has a V8 in it, and it's adequate for acceleration but nothing to write home about. The most economic speed is 55-60 mph. My area generally has 2-lane blacktop roads at about 65 mph, and interstate speeds of 80 mph. The existing ICE gets terrible fuel economy in town, usually less than 10 mpg. On the highway it can get close to 20 mph depending on the wind and such.

My normal day involves driving around town a few miles, easy for an EV project. Most days the van just doesn't move at all. But when we take a trip, we use the van. When we take a trip, we WILL go more than 300 miles round trip.

So here's my question finally:
Consider a van conversion, set up for in-town driving. I can't sacrifice a whole lot of weight to batteries as I use the van to carry a lot of people. But they're little people usually, maybe as many as 5 adults but the rest are miniatures. I figure this is a do-able EV conversion and probably straightforward.

The van has an OEM trailer hitch, something like 7500 lbs weight rating.

What I'm thinking of is a trailer for trips. Probably double-axle. It would have:
1. An internal combustion engine, possibly the same one that's in the van now.
2. A big fuel tank.
3. A storage area for luggage.
4. More batteries.
5. Possibly motors to assist with driving force.

My idea is that, in town, the van is a pure EV. When I go on a trip, I hook up the trailer which converts it into a hybrid. I would obviously need a big high-voltage umbilical going up to the van, and a pretty good control unit.

Is this a feasible idea, or are there too many safety or legality concerns? AFAIK there are no laws forbidding a running engine on a trailer, but I haven't really researched it.

Thanks for your time.

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Discussion Starter · #3 ·
I have serious doubts as to whether a 25hp engine could move this thing fully loaded (per my description above, plus trailer) at 65 mph for hours, and if I'm traveling from town to town it would be hours. Even if you're using the on-board electric drive to even out the high-power stretches. I'd go so far as to doubt that a 4-cylinder auto engine could do it without really stressing. I wouldn't mind a little 5L Cummins diesel though. I'm pretty sure you can get those buckled up to an appropriate generator already on a trailer, but the trailer would not be what I had in mind. And it might be expensive.

We have a second vehicle, but it's a little Toyota Corolla. My wife commutes with it. Usually if we travel we have more people than the Toyota can hold, and the van is much more comfortable for everyone anyway. Clearly if the Toyota is adequate for the job it's the vehicle we take, but usually it's not.

This is a more-than-one-ton capacity vehicle. It's not a minivan, it's at least two minivans in one. I figure It's frequently loaded to more than half weight capacity during trips, the way we do it right now. Limiting myself to less than 65 mph top speed would be counter-productive, I don't think I want extra nights in motels with 8 or more people just to accommodate a lower top speed. State law says no more than 4 people in a hotel room per night. If I'm going to do the conversion at all, it will need to perform like it does now. I will accept a 65 or 70 mph top speed, even though it does much better than that right now. But hill climbing and acceleration I would not want to sacrifice.

I could consider having the van's motors capable of pulling the loaded van and trailer combined at highway speed continuously, I can see where this might simplify things a bit and may even save money on build cost. But the pure push trailer idea does not have appeal for me. I'd like to arrive at the destination city fully charged, possibly find a place to drop the trailer off, drive around doing my business and then come back for the trailer. Possibly the trailer would run at night and charge the batteries, unless the place I drop the trailer has EV charging as a service. I haven't seen this at all in my area, at least at motels. At any rate I'd be looking at a pretty good (quiet) exhaust system for the trailer.

I know that typical DIY EV projects use DC motors, and that absolutely every commercial offering uses AC motors. I know that the DC motors can be had cheaper, especially if you look at an old forklift or something. While I can't say what I will actually choose to do at this point, I can say right now that an ACIM appeals much more to me than any DC option. The final decision would have to be left to a price estimate comparison on both options, and a comparison of features possible on each system.

There are lots of hills where the van coasts higher than the cruise speed, both in and out of town. Regenerative braking would be an appealing feature. I currently ride the brakes to keep the speed in check. I know that regen only gets about 10% of the energy back.

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Discussion Starter · #7 ·
If I'll need another engine for this, I think I'd rather get something designed for a generator than something designed for an automobile. Given a diesel's maintenance cycle and overall simplicity, I'd rather go that route than with gasoline.

I can see your point about average power. And I was thinking of the inline v6 diesel found in 90s Dodge trucks. My father had one, it would pull like a mule. You're probably right about it being bigger than the original van engine in terms of power and torque, but it was pretty small in terms of physical size per unit power. If there's a 4-liter version of that, or even 3-liter I'd be interested. Not sure if I want to design something that has to run flat out when being operated in the typical use case though, equipment wears out faster when you do that. And of course it would need a matching 3-phase generator on it.

I was thinking that I could replace the rear suspension with independent suspension, run a shaft to the centerline to a gear box mounted on the frame of the van, and then power each wheel from a motor with a fixed gear ratio. Motors sticking out in front or behind the drive shaft. By my guess the van wheel will be turning about 780 rpm at 65 mph, so probably 4.6:1 or so ratio if I'm using 3600 rpm motors. I'd like to avoid shifting gears and clutches or any of that nonsense if possible. I was thinking 3-phase induction motors with a separate controller for each wheel, and some sort of sensor and controller to provide traction control to avoid spinning one wheel on slick roads. We get ice here, and snow.

It would be interesting to have 4wd, but I'm not sure I can find an adequate suspension and drive train for that size vehicle. And I don't want to sacrifice turning radius, it's already bad enough as it is.

I know most DIYers take off the engine and keep the transmission, putting the motor right where the engine was, but I think that will likely just add a lot of weight and complexity to the drive train and take up a lot of room. I see most people here seem to use just one gear most of the time anyway. I can see how it would be a much simpler conversion that way, just saying I don't like the compromise.

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Discussion Starter · #8 ·
It has been done, but a lot of unsound things have been done - that doesn't make it advisable. "Sketchy" is the nicest word that I can think of for this scheme.

There are actually articulated buses (essentially a bus towing a passenger-carrying trailer) with the engine in the back (so, the trailer) pushing the whole thing... but they are not nearly as crude as those "push trailers".

By the way, powering one axle with an engine while charging with a generator driven by another axle is called "through the road" hybrid charging. It is a bad idea with both axles on the same vehicle, but with the driver on the trailer and the drag on the tow vehicle it's really bad.

I don't like any of these ideas. The only "through the road" charging I was thinking of is regenerative braking.

I had originally thought to power the trailer wheels only because I was thinking that the van motors would be smaller and aimed at just carrying the van's weight. I've already been convinced not to do that. I have fairly extensive experience with trailers, they can get in enough trouble when they're not pushing anything. The more you guys talk about push trailers the more the hair on the back of my neck tickles me. Enough said on that.

Right now I'm focused on a generator on a trailer, with storage and power cables. And general ideas about driving the van itself.

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Discussion Starter · #11 ·
That tesla powered mercedes build looks like what I was thinking, only I don't think both of those sides are motors. Not sure what the other can is. But I thought I overbuilt when I weld crap together, this guy is outrageous.

Those are both much smaller vans than I have. I have seen another maxi van project here a couple years back, but it's not an extended van, and it was only built for a small amount of local driving. Small battery pack, small motors for only in-town driving.

I've read enough though to know that the bigger the vehicle the more it's worthwhile to convert it to an EV, even though the conversion cost is higher.

The main point of my query seems to hold water though, the idea of a generator on a trailer that converts a pure EV into a hybrid. Especially attractive is the idea of storing luggage on the trailer too. We always end up with 3 coolers, baby supplies, a couple pack-and-plays and pretty much an entire daycare in the van all folded up.

I'm thinking that the first step is to get a plan to convert the van itself, and price that out. There's a ton of room under the floor of the van, still protected by the frame. Not sure if I could swing actual EV battery packs, but there's lots of room for them if I can. I'd probably need some sort of cover under them to prevent damage from rocks and dirt though. Things have changed a bit since I first started researching this years back.

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Discussion Starter · #13 ·
Re: Engine options

Any modern diesel is certainly more complex than a gasoline engine. If you want an engine designed for optimal efficiency at the desired power level, that would be a gasoline engine from a Toyota hybrid.

Inline and V are opposite things; I assume that you mean the Cummins B-series inline 6, originally called the 6B (then 6BT when turbocharged). The current version (called the ISB for commercial applications) is still used in 2500 and larger Ram trucks, but it is now much more complex and powerful. The B-series started as a 5.9 litre and has grown (to 6.7 litres). It is not small for its power, by comparison with anything other than an even larger diesel.

There is a 4-cylinder version of the B-series, called the 4B. With the same bore and stroke, it is a 4-litre. It is an enormous and heavy paint-shaker, used in many delivery vans and similar commercial vehicles. There is no version which meets modern emissions standards, but it might be suitable in power output.

I don't know where that v came from. Inline 6 is what I was talking about, from a 90s Dodge Ram truck.

I can't say I've looked at a modern diesel, but the ones from the 90s are much simpler than a gas engine if you discount the mechanical injectors. I know that the newer injectors are computerized, with some sort of actuator instead of a mechanical pump. To me, that means simpler.

With respect to efficiency I'm going to have to ask for proof. My dad's truck frequently pulled a 40 foot trailer with 20+ tons on it, and it still got 15 to 17 mpg. He drove it until it had 300k miles on it with minimal maintenance.

If your claims about gas engines being more efficient were true, or even if the efficiency were close to true, the commercial haulers (big trucks and trains) would be switching over.

I don't mean to get into a pissing match here. If you show me real-world proof that your gas engine is more efficient and more reliable than a diesel generator then I'll pay attention.

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Discussion Starter · #14 ·
One challenge is weight distribution, with the big fixed weight of the engine and variable cargo load. Where do you put things so that the weight distribution is suitable under all conditions?

Put the engine at the desired center of gravity. Put the fuel roughly the same place, just like a commercial trailer generator. Luggage goes around the outside.

Correctly loading a trailer is not complicated, just necessary. The only post-loading variable here is fuel. You pack the trailer with the correct hitch weight, and if the fuel tank COG is right in front of the axle then the trailer maintains correct balance the whole trip.

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Discussion Starter · #18 · (Edited)
If the fuel tank is at the centre of gravity, then the engine can't be behind the fuel tank (the trailer would have negative tongue weight without cargo), so it must be ahead of the fuel tank. That's pretty front-heavy. A more practical configuration would put the fuel at the axle, and the engine and generator immediately in front of that.

Of course the fuel could be on top or under the genset, but that's not reasonable for a large tank. It could also go in saddle tanks on each side, I suppose.

Even then, the cargo is all going in front and rear trunks on the trailer. That can work, but doesn't sound like a convenient thing to use, and requires attention to distribution between front and rear. On the other hand, if this is a simple build, the front and rear cargo compartments can just be off-the-shelf cargo boxes.

The axle has two wheels. Side-to-side balance is not incredibly critical on a trailer but important enough you don't want it too far off. Mount the engine such that with no cargo and no fuel the trailer is correctly balanced. Tanks are either to either side of the engine or higher, is usually how mobile generators work. Mount them so that empty or full, the trailer is balanced properly. Hitch weight should be 10% of total loaded trailer weight. Actually usually the tank goes above the engine, but that would put the gas tank in the rear window of the van; commercial mobile generators for commercial construction tend to be pretty high.

Luggage goes where it fits. The van currently has a 25 gallon tank. I can't imagine needing more than 50 gallons, but probably a pair of tanks with a combined capacity of 40 would be most practical. Once the generator (and I'm thinking of buying a commercial built-to-spec motor/generator already on a trailer for this, whether new or used) is mounted and the tanks are mounted, you can look at your trailer to determine the best place for luggage.

No matter what the trailer, balancing and securing the load is critical. This goes for 18-wheelers as well as the one you put behind your lawn mower. So loading the trailer will ALWAYS require more attention than loading your car, and loading your car when it's going to pull a loaded trailer will ALWAYS require more attention than if you just had the car. It's not complicated, it's just important to pay attention. Good tire pressure, good grease in the bearings, good brakes, proper hitch weight for the trailer weight. Proper load balance front-to-back on the tow vehicle. Good lights. There's a check list just like on an airplane.

The problem is that a mechanical injection pump is more complex than a complete gasoline injection system plus a complete ignition system. Modern diesels use electronic injection systems which are similar to gasoline injection systems but at much higher pressure; modern ignition systems have no moving parts and routinely go for the life of the vehicle without failure or repair... and a couple hundred thousand kilometres without even changing the plugs.

On top of that, modern diesels have both diesel particulate filter (DPF) and selective catalytic reduction (SCR) emissions control systems which are far more complex and less reliable than the catalytic converter on a gasoline engine. The problems of making a diesel to meet current emissions regulations are so extreme that Caterpillar dropped out of the business of manufacturing these engines for heavy trucks in response to the regulation changes - they just couldn't make it work economically and reliably. And of course most people have heard of Volkswagen's "dieselgate" nightmare. If you use an old engine you avoid all of that, but it's strange to promote EV conversion (which is often chosen for environmental reasons) then run a filthy engine. If you do, a pre-2007 common-rail electronic injection engine from a light commercial application (not something intended only for cars) is probably the most efficient and reliable choice... although I would want to avoid the parts prices of Mercedes engines.

A good diesel run as intended is more fuel-efficient than a gasoline engine under similar conditions. I was just pointing out that the engines which are available in light vehicles which are optimized for hybrid operation (nearly constant power at an engine speed unrelated to road speed) are those gasoline engines.

Modern gas engines in cars light trucks are more reliable than diesel engines in the same vehicles, due to the problems with current diesel emission controls. Of course heavy diesels are reliable (other than the emission controls), and there is no gasoline comparison (although they would be just as reliable) because diesels are cheaper to fuel - due to both fuel consumption and fuel pricing - so no one builds large commercial gasoline engines.

OK what you're saying is at least plausible. I'll look into that, the emissions specs did ping on my brain a few years back, and I remember the dieselgate thing. As I said I had planned to use a diesel generator set, not mate a generator I found to a motor I found somewhere else. Don't particularly want a stinky engine around though either, so it may be that a gasoline or e85 engine may be a more viable alternative. The hovercraft I built awhile back had a VW inline 4 in it, and I kept the computer and the catalytic on it.

If the van has suitable battery capacity for local use as a pure battery EV (running on battery power only), that capacity will be lots for series hybrid operation with the trailer. A plug-in hybrid car typically has about 16 kWh of capacity; the much bigger van with trailer would be a reasonable plug-in hybrid with about three times that capacity, and you'll want that for routine operation without the trailer anyway. Unless you want long battery-only range with the trailer, I don't see any need to make things complicated (and expensive) by putting more battery in the trailer.

The trailer could be treated as a mobile charging station for the van, but the van will need to accept a charge while driving, which is not normal for EVs. You do need the connection, but there are off-the-shelf connectors for high-rate DC charging of EVs at up to 400 volts and a couple hundred amps.

The space under the floor is at least 8 or 9 inches top to bottom and there's a ton of room between the frame members, especially if you can remove the drive shaft. If rear-mounting the motor(s) pans out, then there is easily enough room between the frame rails to put 5x the battery pack of a plugin hybrid in there. Not saying I'll need it, just saying there's room. There would also be all that room under the hood and in the doghouse.

I was thinking of putting raw 3-phase AC through the trailer connector. Thinking now on it that probably won't work so well, a generator set will probably be either 240 or 480, or maybe 400. There's probably no reason to route around that circuitry, and the EV charging circuitry will be set up for one of those too most likely.

What sort of voltage does a highway-capable (65mph) EV run these days? It would be good to avoid unnecessary voltage conversions through all this, which is why I was thinking of 3-phase through the trailer connector.

I was also thinking of gadget power in the vehicle, we have a ton of phone chargers and tablets and whatever crap we need for baby food. How many people run an AC wall outlet in the car? It's either that or a whole crapload of 12v or USB plugs. Or maybe all of the above.

Back in the day, EV builders had a high voltage battery pack and then a 12v battery for the automotive systems. Is this still the practice or do you run an inverter-pwm regulator for that sort of thing?

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Discussion Starter · #20 ·
Go look at a construction site where they're putting up an apartment building, a hotel or some commercial building especially in a remote location. They have generators on wheels that have 4 cylinder automotive-sized engines or even bigger. Most of the ones I've seen are diesels, but the key here is that they are designed to run as a generator: constant speed, reasonably constant load, day in and day out. They'll be there until the power is hooked up to the site.

The trailers they are on are set up to be hauled onto a site when the dirt work is not done yet. So the COG is very high, ground clearance is high too.

If the site has a crane they tend to hook onto the generator and pick it up for the night to prevent theft, so you'll see a louvered box on a trailer 40 feet in the air after hours.

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Discussion Starter · #21 ·
Another thing to keep in mind here is that I rarely travel more than once a month. So this trailer, it's likely to go a long time between uses. My daily driver as it were will be a really big plug-in pure EV that I plug into the wall outlet when I get home. When I get range anxiety, I hook up to the evil ICE trailer and do what I need to do.

I don't see a diesel as a necessarily bad thing here, if they can be as reliable and efficient as I'm thinking. If the pollution regulations are too tight then I'll clearly need to do something else.

I've recently seen articles about opposed cylinder diesels with a common combustion chamber instead of a common crankshaft. They're reaching thermal efficiencies near 60%. I think if diesel were ridiculously over-regulated then there would be less research on improving them right?

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Discussion Starter · #23 ·
Interesting stuff I didn't know there.

The generators I've seen run output higher than the official output and then are regulated down to something standard. A 480v generator may well have a raw output of 600v but then get regulated down to something reasonable. I know that the output of these things has gotten much cleaner over the years, so it's possible that there are some pretty sophisticated electronics in there to give clean power.

No matter what the van will need to accept 240v because that's what is likely to be in the garage when I charge it, and that's what is supplied to homes in the USA. But as you mentioned there are reasons to want to send over the raw 3-phase too, if it gets away from an unnecessary conversion.

The regulation and conversion circuitry to go from 3-phase to single-phase needs to be somewhere, and the circuitry to adapt to the charger's raw input voltage needs to be somewhere. Unlike most EVs I don't think space is going to be a problem here, and having the most direct voltage conversion seems to be a good thing.

But I can also say from experience that trailer electrical connections can be problematic, just because they're flexible connections being bounced around, bent, twisted, rained on and sprayed with gravel and mud and part of a racoon. While it would clearly be necessary to put 240v through that connector, it may not be advisable to double it for safety reasons. Either that or I'll need some pretty amazing safety circuitry.

It's my understanding that a commercially built generator will very possibly have 400-600v circuitry somewhere, and it seems like such a shame to not just send it over to charge the pack. But I'm not sure what sort of noise will be on that line, and whether the charger can handle filtering it. Lots more questions than I started with now.

Then there's a distinct possibility that the generators I'm thinking of may be unsatisfactory for some reason and that I would need to build something from scratch. Which is a drag to me.

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Discussion Starter · #24 ·
You know, almost every time I do something nonstandard when there's a standard, I regret it later. You're saying there's a charging standard voltage, so I think the generator needs to supply that voltage. This opinion will be final until I change my mind yet again.

Somebody said something about satisfactory motors being hard to find? AC induction motors is what I'd prefer. Was that with respect to a dual motor system, or a single motor system?

I made a comment about 4 wheel drive earlier, it would be handy but I didn't think it would be workable. Maybe it would be an advantage to try to find some front suspension parts that would work with 4wd? A separate motor for each wheel? Maybe a suburban's front suspension might be adequate?

I've looked into the mechanics of 4-link custom suspension, and I was thinking of either building or buying something for the rear (prefer buying!). Maybe I should consider the front as well? 4-link is incredibly better than stock suspension when it's done right. Typically used with drag racing and with off-road vehicles. This would be neither, but I could seriously benefit from 4wd in this area. I think with ACIM motors all I would need to do is turn off the front wheels when driving slowly. I doubt that spinning the motors would be a huge drain on power at low speed.

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Discussion Starter · #27 ·
New engine designs always have enthusiastic marketing. If third-party test results support it though it's not just marketing. Unfortunately I can't find the article I read the other day, so I can't tell who did the tests.

Emissions checks on a trailer:

A few years ago I went to Colombia. The country in South America, not one of the cities in the USA. (those are spelled Columbia anyway)

There are no pollution laws to speak of there. There are way fewer cars per capita, but not a single one of them has a catalytic converter or any other type of emission control. You could be out on a mountain with only one car for a mile around, and when you turn that car on your eyes burn. But go to Bogota, a city the size of NYC, and you think somebody dropped tear gas on you.

FWIW I think the emission controls are a good thing. They're pretty much unregulated in my state, but I think if this thing goes through I'll actually have what emission controls I can get on the trailer regardless of regulations.

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Discussion Starter · #33 ·
I kinda want to back up to the start with a couple key questions....
Fair enough, and they're good questions.

- Why do you want an electric vehicle?
A number of reasons. In the order I think of them:

  1. I've wanted one almost since I heard of the idea.
  2. I believe that, battery pack notwithstanding, they can be more reliable than an ICE.
  3. I want better fuel economy in town. I love to just get in and drive for awhile, and with my current living situation (foster kids) it's difficult because I'm either leaving my wife to take care of kids, or I'm in a big van that gets ~10mpg in town on a good day.
  4. I want to take steps toward a cleaner environment.
  5. I'm sure I can come up with more answers that are still honest. Those are the big ones.
I'd like to point out that while EVs are almost certainly cleaner while operating, it's clear that the manufacturing environmental cost of a converted vehicle is much higher than a standard one, because you manufactured everything in the standard vehicle, took some of the stuff out and then put more stuff in.

I also realize that an EV means a longer tailpipe. I'd like to get some sort of green power at my home, and that will likely need to happen first. What seems to be most practical would be solar with saltwater batteries.

- What is your budget/what are you thinking you'll spend?
I'm not sure. I know that converting an EV will easily spend all the money you would have spent on gas buying the electric components. I can't imagine a van project (without trailer) to be less than $30k USD. I'm not rich, and this would be a big chunk of cash for me.

That said, vans have been the same thing for decades. Other cars change shape, the van is just a big box going down the road. Mine is in good shape. No rust I can find, no significant dings. If I maintain it I think could keep it as an EV for a long time and not wish for something else.

I've researched DIY cars before. I was looking at small cars back then, but I know that people spend a ton of cash on them and have a lot of problems getting things right. I've also talked to a few DIY EV owners and looked at their cars in person, and I know that once they get them done the guys are usually happy with them.

You have basically described the worst case scenario for an EV....

You gas milage: -- Something in the range of 10-15mpg.
Yes. Only it's hilly terrain, not mountainous. I live in the Missouri River valley. Once I'm on top it's the Great Plains. Mostly flat-ish but lots of rivers and occasional relatively sharp altitude adjustments in the in the altitude which are probably on the order of 1000 feet or more. going down any one of these hills on cruise control in this van at 65 mph will overspeed the cruise and I'll be going 75 or 80 by the time I reach the bottom. Probably 7%-8% grade I'm guessing.

Winter in-town mileage is more like 8, 10 in summer. When I drive a distance I choose my route and my speed to get best economy. I have had it as high as 21 mpg round trip economy over about 6 hours total, and it's usually above 18 in summer.

Occasional use: Most of our driving is in town. We both work. I don't need to drive to work. If at all possible we engineer our trips so that one or two adults takes one or two kids in the Toyota to do what we need to do. If we need more people then we take the van.

We like taking everyone if we can, and if the kids are all behaving. If the van would be more economic to drive in town, we would probably take everyone when we go shopping or running around town. It would certainly see much more use than it does right now.

EVs make the most sense when you want to save money on gas, with frequent daily use, short range.

You need the frequent use to justify the investment in batteries
You need the short range so that you don't need an outrageously-sized, expense, and heavy battery pack.
I guess part of what I'm hoping for is for the van to be more frequently used. I don't see us spending a lot less money driving it, because in my past I tend to have a budget for transportation and I use all of it whether I actually had someplace to go or not.

The van costs $80 to fill up, give or take depending on gas prices. Usually every other week unless we travel. If we're going out of town that gets us almost 500 miles. Per ton mile of people/cargo (not including vehicle weight), loaded full of kids, the van is actually much more economic to drive than the Toyota.

The short range part is why I'm talking about a trailer, so I don't need a literal extra ton of batteries. The trailer is for the infrequently used edge case. Normally a 30 mile daily range for the van is great, and a 60 mile range would be fantastic. So 30 days a month it would be charged from the wall outlet.

You have huge power requirements because...
True as far as it goes. Again, I'm not looking at pure numbers here comparing economy of a van to economy of a Toyota Corolla. The Toyota gets 35 mpg at 60 mph fully loaded. The van gets almost 20 at the same speed fully loaded. 4 people at 35 or 12 people, 2 dogs, 3 coolers and fishing gear at 20. I'll take the latter. Drop a bit if I have the (existing) trailer pulling kayaks.
... I would actually suggest "Why not remove the motors and batteries and put that engine under the hood of the van instead?".

I think your current situation is actually the best solution to your circumstances. If you need a cargo trailer, just go buy a simple, cheap cargo trailer, done.
I hear you. I really do. "I want to" is a huge part of this, and ever since I was in my 20s that has been an adequate reason to do most of my stupid projects. Many of them have been exactly that--stupid. I don't feel the need to justify projects that satisfy my curiosity to any naysayer. That's not defensive, I'm just saying that somebody else's opinion doesn't matter nearly as much to me as walking my own path or learning something. I'm not a teenager anymore. I'm 53. I have some bit of experience with building things and with having successes and failures, both of which tend to cost much more than I'd anticipated.

I don't feel that "saving money" is an adequate excuse to buy or build any EV or hybrid. So far as I can tell, the statistical numbers don't support saving money when considering the total cost of ownership. Even commercially built EVs don't likely pay back the additional cost. So zero that out of my equation.

That said, the cost of tooling around town or the local countryside DOES matter. I see turning this van into an EV which, ideally, would double the "money economy" of driving (miles per unit cost) as a big deal, and I would still spend at least as much money driving it as I do now.

Another thought, yeah you've got a big family now but when the kids become teenagers they'll drive their own cars (and you can force them to chauffeur their younger sibblings, a time-honored family practice :p ), and you won't be making as many family trips. So that means the time before you have to pay off this expensive conversion is narrower that you might imagine.

Just peeing on the parade a little, as a sober-second-thought.
Last statement first. I ask this sort of question to people in other forums. You are NOT peeing on the parade, you're asking questions that need to be asked BEFORE the n00b spends a shit-ton of money on something that won't get them what they're after.

Teenagers: We're foster parents. My wife and I don't have kids of our own. We tend to stick to the under-4 set as far as preferred placements. The number of kids varies from month to month, and is usually somewhere between 2 and 7. There are 3 adults in the house, and will be until somebody dies most likely. It's possible and hopeful that we might be able to adopt a couple of the kids, but I'm not counting on it.

Kids come here, they stay a few days or a few months, and one of them has been here 2 years and is likely to stay longer. Then they go somewhere else, either back with their family or to a new foster home that can better care for their needs. We feel that kids should have a safe place to grow up, and a happy place to live. We hope that their families can pull it together and get through whatever trouble they're having, but sometimes it just doesn't happen that way.

I've had dozens of hobbies over the years. None of them has been as fulfilling as fostering kids. If a kid comes into your house, you can't help but love them. If you don't then you're not doing them any good at all. When they leave they take a piece of me with them every time. We get money for caring for the kids, but if I don't have the kids we make more money by ourselves. We spend our own money on top of what we get to make their lives better.

Those of you reading this, if your life is empty of meaning maybe you should consider being a foster parent. Every part of the world is short of people who will step up and help out. Every kid is worth the time you spend putting a smile on their face. Kids come to you scared and hurting, and sometimes a little thin, and you feed them and make them happy. There is no better feeling.

Sorry for the shameless foster care plug. At any rate our situation is different. We may see a couple of these guys grow up -- we hope to have some over for holidays when they have their own families -- but in general I think we'll have baby seats in the van for many years to come. And if not, the seats come out and there's always a use for a big van.

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Discussion Starter · #34 · (Edited)
Since the EV with generator trailer thing is difficult to do well, there is another option... two vans:
  1. one converted to EV for local use (maybe buy one which is cheap because it has a dead engine and/or transmission)
  2. one left stock for longer trips - no trailer required

I'm not convinced that the generator trailer is difficult to do well. The EV itself would be aimed at 30-60 mile range and I'd use battery packs from a hybrid or commercial EV for it if I can find them. So lighter weight, leaving more of my full capacity for cargo.

The generator trailer, we've had some discussion about how to implement it but the balancing is extremely straightforward. The generator trailer makes the EV itself much easier. While I have been talking about a commercially built genset, I'm not married to the idea. If it's cheaper or significantly lighter to get a reliable generator which is more appropriate for my use case then I'm open to the idea.

The idea of the trailer is to have it kick on when the battery gets low, run full blast until it's charged and then shut off again. Or, near the end of the programmed trip, have the trailer top off the battery just as I arrive, letting me drop the trailer off somewhere if it's practical so I can park in normal slots found in malls or whatever.

Or a "Battery Trailer" - and use it for your house to load shift to get cheap (night rate) power when it's not needed as a range extender

Some of the trips I take are 14 hours each direction. Maybe twice a year. I don't think a battery trailer is adequate for that. But if it were only a few hundred miles, that might be a neat idea.

I don't see long trips as viable for a pure EV. Not in my area. Part of all this is that the vast majority of my driving either vehicle is in town. I see two (or three) projects here:

  1. A short-range EV with big motors because it's a big vehicle.
  2. A generator trailer for trips, to mitigate the fact of a short range EV.
  3. A house installation for solar. (not related to this forum)
The way I see it, I stand to gain miles-per-dollar for short range driving, which is what I really want, and almost certainly will lose a bit of miles-per-dollar when going a distance. If I'm lucky I may break even on that, but an extra axle really bites into fuel economy.

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Discussion Starter · #35 · (Edited)
Having done some calculations on the van's cost per mile right now:

  • Winter in-town driving, fuel costs generally are up in winter for reason, I've had an actual cost per mile of $0.46 USD, probably higher. Based on highest gas prices in the area over the past 3 years I can see $0.50 per mile.
  • Summer driving in town, with current fuel costs, $0.35.
  • Best-case economy highway mileage, current gas prices: $0.13
  • Average case economy highway mileage, current gas prices: $0.15.
If I can double the miles per unit cost in town in pure EV mode, I would consider this a successful project in that respect. There are of course other considerations, but just getting that aspect of it out there.

Edit: And in the past year, with the minimalist use of the vehicle I described above, I estimate having spent more than USD $2000.00 on gas for in-town driving.

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Discussion Starter · #37 ·
1 - I had a feeling that this was a "because I want to" project. I'm all aboard.

2 - Ehn. You're driving a 2010. It'll last you another 20 years with very minimal work. You'll be 73 by then. You will put more work into your EV than it will ever redeem in bonus reliability.

3 - That you'll get.

4 - 50% of the carbon/energy/whatever footprint of a vehicle is in manufacturing it. All the gas you burn in the vehicle's 20-30-year life only makes up the other half. You're driving a newer vehicle. So be rebuilding it, you're wasting huge amounts of the energy of its life. Roughly speaking, energy use scales with cost. Things have cost proportional to the resources they took to make them, if they didn't take that amount of resources, they would be cheaper. Cost effective is generally environmentally effective, and you're probably net negative on the environment.

Agreed, more or less.


I'm going to piggyback on Brian's suggestion from earlier and it's where I was kind of leaning with my questions. I think you need two vans.

At least, temporarily.

Quite possible. I'm investigating if it's worth my effort at this point.

In terms of effort, 2 vans is easier. In terms of conversions, not having to worry about a generator and second fuel tanks and all that is way faster and cheaper. Motor and batteries and you're good. Maybe cheap enough to buy the second van carcass. You should be able to get a 15-year-old one for, what, $2k? If you're looking to spend $30k, that's pretty small in comparison. That's what a used genny is going to cost you, minimum.

For long trips you just eat the cost of gas 100% of the time, whether trailer is parked or not. But around town, your 90% use case is electrical.

I don't see the trailer as the expensive part here. Probably right though that 2 vans might be easier.


Another option you might like even less...

Don't buy a second van. Don't build a generator trailer. Build an EV push trailer.

Nope. Nope. Nope. Nope.

No push trailer, period. I've pulled trailers for a lot of miles. Enough crap goes wrong with them that I will absolutely not make a push trailer. we discussed it earlier in the thread.

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Discussion Starter · #40 ·
Well, that was a gasoline push trailer that you'd use to recharge batteries by regen braking on the lead vehicle.

This is just an electric push trailer. No braking, no charging. Unless you want to charge the batteries from the engine, in which case it's just like pulling a slightly heavier trailer.

But, I get it. You want an EV. Not a trailer :p

I never contemplated a push trailer of any kind.

The closest I came was in my first post, where I pondered powering the trailer wheels to reduce force on the van's motors. In my mind it would be operated the same as hydraulic trailer brakes: The hitch has a slide which, when the van moves forward, the trailer motor would accelerate to match. The van ball would have zero force for acceleration and stopping. Only turning and the tongue weight would affect the ball.

By my second post I realized just how much of a cluster-fuck that would be if the controls got messed up, possibly killing someone. I also realized by then that it would be simpler and cheaper to put motors on the van adequate for pulling the trailer.

Using a push trailer to regenerate from the van... Let's see how well that works. By rule of thumb one can expect regen to recoup about 10% of the energy. So we have all the losses associated to get power to the wheels, and then you push the van forward. And from there you lose 90% of whatever's actually "on the road" by using regen.

Or you could just run a wire forward from the generator on the trailer and lose maybe 1% max. I see absolutely no reason to throw away 90% of the energy of fuel just so I can use a push trailer, which is a profound safety hazard at best.

Alternately, I could just leave my van as it is, buy a trailer, put a big open drum of diesel fuel on it, light that on fire and drive around town hoping no burning fuel spills out on the streets, the trailer, the van or nearby cars. That would actually be much much cheaper than the push trailer and every bit as effective.

Sorry about the sarcasm. I would actually rather haul around the burning barrel of diesel fuel than use a push trailer.

Hopefully that's settled.

If somebody still thinks it's worth discussion, please post links to at least 20 commercially available push trailers sold in the USA.

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Discussion Starter · #41 · (Edited)
...Pushing the van with a trailer to keep the van moving is not much different from pushing the van with a trailer for through-the-road battery charging (which is not regenerative braking). Pushing the van with a trailer hard enough to accelerate the van is downright scary. :eek:

I'm with Ken on this one!

Sorry for the major edit. I'm cleaning it up but not really changing the meaning.

Pushing the van with a trailer is worse than if you are pulling a trailer and the trailer gets away from you while stopping. Youtube has plenty of examples of that.

  1. You have two wheels forming a triangle with the ball. The ball not only allows turning left to right but also up and down or twisting motions.
  2. You have two wheels driving the trailer, which when everything works and the van is going straight, would push the van down the road.
  3. If you're taking a highway-style turn, the trailer pushes straight forward for it, which means toward the outside of the curve for the van. It's not pushing the front of the van that direction, it's pushing the rear of it.
  4. The sharper the turn the more the trailer tries to push the rear of the fan off-course.
  5. If you're in a sharp turn with the trailer at 90 degrees to the van, the trailer uses all its force to push the rear of the van toward the outside of the turn. If you're on ice, you have vehicle damage right there no matter what.
  6. If you have one trailer wheel with good traction and the other on slippery or lose material, then the ball experiences a force to the left or right, torquing the van's rear again to one side or the other, but you don't know which side until it happens and in 2 feet it might be pushing in the opposite direction. If the van does NOT have good traction on all wheels you're likely to have vehicle damage again.
  7. Even using trailer brakes strongly on questionable traction is sometimes difficult to control. Most trailer stopping accidents happen because the trailer pushes the rear of the vehicle off course and to one side or the other. Which means trailers are prone to this type of physics already, just because they have mass.

Most of this occurred to me shortly after I posted my original post here. That's why I backpedaled on it in my second post.

I don't think a generator on a trailer is an inherently bad idea, but any sort trailer with power to the wheels is absolutely positively not going to happen if I'm involved.

Just having a high voltage high current line running between the trailer and the car is going to require some amazing safety gear.
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