Hi Ben, I'm a little surprised at the light response you've gotten to your question. I would have thought there'd be more folks here who at least have put some thought into homebrewing a hybrid this way, if not done it themselves.
So, even though I'm about the worst person to do so since I'm a EE dropout and have never built a hybrid, I'll post a few random ideas about them that have popped into my head over the years. First, some thoughts on why or why not. ICEVs' efficiency has improved immensely from microprocessor engine control, but it's still pretty abysmal on short trips. For some folks, short trips can amount to a lot of driving - take the kids to school, come home, run to the store, come home, pick the kids up, come home ... repeat to 40 or 50 significant digits. That kind of use is also hard on an ICE, because it never gets properly warmed up. OTOH, EVs excel at short trips. They don't need to warm up, they don't idle, and many have regen to claw back some kinetic energy normally wasted as heat in the brakes.. For folks who need to make both short and long trips, intuitively the true hybrid seems like an ideal compromise. However, the devil is in that little word, "compromise." It's because you have two vehicles in one. To stick with conversions here, you're in effect doing a full EV conversion, but still leaving the engine and all its supporting hardware in place. You have to find a place to mount the EV drive components and the battery; but unlike a BEV conversion, you don't have nice big chunks of space where the ICE and gas tank used to be. So you have a packaging challenge. Your vehicle also gains a fair bit of weight. And there are other little places where you miss out on efficiency. For example, with the exhaust still there, you probably can't add a belly pan to smooth out the underbody aerodynamics, as you could with a BEV. The result is that your hybrid isn't going to be optimized as either an ICEV or an EV. It's likely that its EV range will be less than a similar BEV's, and its fuel efficiency less than a similar ICEV's. So after thinking all this over, I've decided that I'm more in favor of having multiple vehicles. Each can be optimized for different needs - an EV for local trips, and an ICEV for long trips, for example. This is a great solution where you have two drivers and two cars. With just one driver, I guess it depends partly on what it costs to license and insure two vehicles in your area. I also really like the station car concept, where you commute using mass transit, and lease an EV for daily use between your house and the train station. In the best of these proposals, you can also swap your EV for an ICEV car or van or truck, when you need that instead (you want to go on vacation with the kids, or to fetch a load of lumber). Alas, I don't see many of these on the horizon. Not that I'm trying to talk you out of this project, just presenting some things to consider. Now, again, I'm not really the right person to advise you. But maybe if I cast out some ideas here, someone else will pop up and disagree with me ;-) First a little of my somewhat quirky nomenclature. I'm an old guy, so "hybrid" still means to me what it meant in 1969. To me, a hybrid is a vehicle that can use multiple energy sources. The cars most folks call hybrids today get all their energy from gasoline. Others here disagree with me on this point, which is fine, but I don't consider a car like a non-plug-in Prius a true hybrid. In my book, most of the factory "hybrids" are really ICEVs with electric superchargers and/or sophisticated transmissions. The Prius power splitting device is a really clever gadget that amounts to an electomechanical torque converter, for example. So let me use the term "true hybrid" here for the real stuff. You may already know this, but true hybrids come in two flavors, series and parallel. A series hybrid has its motor (only) permanently linked to the driveline. The ICE drives a generator or alternator that supplements or replaces the battery's energy. Diesel-electric locomotives are series hybrids. The downside of the series hybrid is that you lose some efficiency in the conversion of mechanical energy to electrical energy. Back in the 1960s and 1970s, before the days of microprocessor ICE control, you gained ICE efficiency by running the ICE at a constant speed and load. This helped to make up for the conversion losses. With today's computer engine control, that's not true any more. ICEs are now much more efficient over a wider range of speeds and loads. So there are fewer situations where a series hybrid is apt to give you improved efficiency. This is where the parallel hybrid comes in. A parallel hybrid can mechanically link either the motor or the ICE to the driveline - sometimes both. This is the system you're proposing. In theory, you should get the best of both systems this way, with (theoretically) fewer conversion losses. As I said above, though, I don't see any way for a hybrid of any flavor to ever be as efficient an EV as a pure EV, nor as efficient an ICEV as a pure ICEV. >From what I can see, it's (not surprisingly) any hybrid is tougher and more expensive than a straight BEV conversion. I think this is especially true of a parallel hybrid, because you have somewhat less flexibility in positioning components. (One possibly more flexible parallel hybrid variant is the "through the road" hybrid, where you drive the front wheels with one fuel and the rear wheels with another.) To get a final result that's as efficient and as seamless as one where a team of automotive engineers designed it (Volt or Plug-in Prius), you probably need to have some automotive engineer chops yourself. But I do think you can build something that will work, to one degree or another. After all, hobbyists homebrewed hybrids back in the 1960s and 1970s; they can still do it today. That reminds me to mention that maybe in some ways you might indeed be better off converting a 1960s car than a later one; certainly you don't have to worry about fooling the body computer into thinking the engine's running. Just remember that you have to provide all the patches that you'd have to do in a BEV - power brake vacuum, power steering pressure, and aircon drive. You need a DC:DC converter (or, somewhat cruder and less efficient, a motor- driven alternator) to provide 12v house power. You need an electric heat source for cold weather driving. (It occurs to me that in a homebrew hybrid you might be able to dispense with some or all of those items burdening the ICE. Just remember that the energy to run them has to come from somewhere.) You have to fit all this stuff in - and a motor, controller, and battery - without emptying out the engine bay or removing the gas tank or exhaust system, as is done in BEV conversions. So, again, packaging is more of a challenge than with a straight BEV. Now, if you decide that you just want to make your car a "mild hybrid" - where the motor boosts acceleration and recaptures energy when you slow down, but the ICE still runs all the time - then that's likely to be easier and cheaper. You can even make it a "charge depleting" hybrid. In this case, the motor assists the ICE all the time to at least somewhat improve its MPG. When the battery runs flat, the ICE takes over full motive duties. I've seen mention of a few "hybrid kits" for light trucks. I think we've talked about a them here, so a look in the archives might be worth it. I just did a web search for pickup truck hybrid kit" and turned up a couple of them, but I don't know what their production status is. In the kits I've seen mentioned, a motor unit goes between the trans and the driveshaft. As above, it's like an electric supercharger, and it usually also captures some kinetic energy when the vehicle slows down. Whether you could adapt one of these kits for a car, I don't know. However, it looks like you'd have a better shot at it with an older front engine / rear drive car such as yours, than with a modern FWD car where the whole business is in the nose. Kits aside, if you're a good hacker (in the positive sense) with lots of spare time, a machine shop and the expertise to use it at your disposal, and nice deep pockets, what you describe would be a fascinating project. I hope a few more EVDLers who've done something similar will hop on board here, and give you an idea of what they went through. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. 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