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:
- I've wanted one almost since I heard of the idea.
- I believe that, battery pack notwithstanding, they can be more reliable than an ICE.
- 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.
- I want to take steps toward a cleaner environment.
- 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:
http://www.fuelly.com/car/chevrolet/express_3500/2010 -- 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

), 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.