What would be involved in converting an old SUV into an electric vehicle
January 2, 2014 3:29 PM   Subscribe

This is just a thought experiment at this point, and probably will remain so. In the back of my mind I have the idea that when my old SUV finally gives up the ghost I might rip out the internal combustion drivetrain and convert it to an electric vehicle, possibly with a removable range-extender generator. Setting practicality aside for the moment, can you help me envision what this would involve?

So I'm already pretty sure that this idea is something that will never be practical to actually do, but nevertheless it's been itching at the back of my mind and I wanted to query the hivemind so that I could get a fuller picture of what all would be entailed and what the end result might look like.

I have an old SUV, a '94 4Runner, much beloved. It has lots of good points but fuel efficiency is not one of them, so I am often thinking about ways to make it into a more efficient and environmentally-friendly vehicle. The nuclear option, obviously, would be to tear out everything related to the internal combustion engine and retrofit the truck as an electric vehicle. I realize that this is the sort of thing that is more of a hobby activity for people with advanced mechanical and fabrication skills than a practical transportation option, but it's fun to think about.

In my mind, this is something I would do after some important and expensive component (i.e. the engine or transmission) finally dies and a retrofit is therefore a little bit more practical (assuming the rest of the car is still in good shape). I'm curious as to what would be involved as far as time, expense, equipment, parts, design, etc. The whole deal. I know only the vaguest stuff about this sort of thing, which is why I'm tapping AskMe's collective expertise.

The rough plan, as I envision it, would be to remove the engine and possibly the transmission, along with the gas tank and all the associated support hardware for same. I would then drop in a big ol' electric motor (not sure whether it would make sense to attach it to the existing automatic transmission, or put in a new one, or go direct drive or what) and install a big bank of lithium ion batteries under the carpet of the cargo area and/or in the area under the car previously occupied by the gas tank. It would charge from a 240v house line. I have no idea whether trying to implement a regenerative braking system would be at all sensible.

I also have the idea of putting an insulated box in the cargo area, with exhaust and intake ports, into which I could place a generator if I wanted to extend the vehicle's range and/or have portable charging capability. The normal (un-assisted) range for the vehicle would only need to be maybe 30 miles a day (mostly city driving, short bursts on the highway) with an 8-10 hour overnight charge, but the goal would be to extend it to maybe 100-200 miles with the generator installed.

So, setting aside the fact that this is probably not something that it will ever make sense for me to attempt, how would you go about doing something like this? What do you envision as the major hurdles? What gaping holes are there in my plan, and what haven't I thought of? I'd love to hear your thoughts about this.
posted by Scientist to Travel & Transportation (10 answers total) 6 users marked this as a favorite
The biggest hole I see is that enough batteries to get that range will cost a fortune. Next to that, everything is just details.
posted by wotsac at 3:40 PM on January 2, 2014

You could just rip out the battery/drivetrain/electronics from a Chevrolet Volt, which would meet all of your requirements.

The 4Runner would probably handle a little funny with the additional weight (the batteries alone would be ~400 pounds), so you'd probably end up having to modify the suspension and maybe brakes.
posted by shihchiun at 3:45 PM on January 2, 2014

These folks might be a good place to start, looks like they make adapter setups for 4Runners with the 22R (4-cyl) engine, not clear if they make one for the V6: http://www.ev-propulsion.com

I've not seen it done with a 4Runner, but there are a few Jeep Cherokee EV conversions out there. This guy went through such a project and his detailed site will give you a good overview of what you're potentially getting into (and manage your expectations a bit): http://driveev.com/jeepev/home.php
posted by M.C. Lo-Carb! at 3:48 PM on January 2, 2014

Dunstan, a guy that formerly worked at Flickr, has been converting an old Japanese jeep into an all-electric drivetrain for the last year or two. His flickr set of photos covers much of the assembly. He's probably still months from it driving and it seems to be a long process of cleaning and fitting parts.
posted by mathowie at 4:03 PM on January 2, 2014 [1 favorite]

Yea, this isn't anything new with the major (read:minor, because others have done it but google is your friend here) twist being the generator to make your EV into a pseudo-hybrid monstrosity.

Here's a site that I toss around when someone asks me about this sort of thing as the prices/parts listed give a baseline of what you might want to plan for for a given conversion. Looks like they do hybrid stuff via generators as well but no prices listed.

All that said, picking a car/truck model that someone else (or better yet multiple someone elses) have converted before is a good starting point rather than blazing your own trail, not that it can't be done. That's one of the reasons we got a '62 Beetle for example, because one day in the next few years that engine, rebuilt heads and all, is coming out and being replaced by an electric motor.
posted by RolandOfEld at 4:14 PM on January 2, 2014

This will be a very costly and time consuming endeavor. I think the 4Runner is a questionable platform as its a very heavy vehicle, but it's definitely big enough to do what you're thinking.

Finding a suitable motor will probably the most difficult part of the project. Mating the electric motor to the stock drivetrain will be the simplest, most efficient option (versus direct drive). You might consider having a motor custom made, or making one yourself. The former will be very costly, the latter time consuming. Most forklifts use large electric motors that might work.

Here are a few thoughts...

- Machine flywheel (or pressure plate) to mate to electric motor
- Machine custom adapter plate to mate electric motor to transmission bellhousing
- Fab/machine custom motor mounts, reinforce frame where needed
- Secondary motor output shaft (and gearbox?) to power accessories, i.e. power steering pump, A/C compressor, etc
- Vacuum pump for the brake booster
- Cooling system for motor and/or batteries (may not be needed)
- Manual transmission will be MUCH easier to integrate
- For automatic transmission, program custom ECU and relocate brazillian sensors
- Battery charge controller
- Electric "throttle" controller
- Need a lot of batteries, will probably have to beef up suspension and reinforce frame

General tools for the job...

- SolidWorks to design parts
- Mill (CNC would be best)
- Lathe (hope you don't need to broach shafts)
- Welder (for frame reinforcements)
- Wad of cash

If you decide to do this, definitely make a web site and document every step!!
posted by mrrisotto at 4:19 PM on January 2, 2014

I've seen at least one mention of a Ford Ranger pickup converted to EV. Googling suggests that there is more than one. Here is one of them. Looks like he sank about $13K into it.
posted by Good Brain at 5:55 PM on January 2, 2014

Secondary motor output shaft (and gearbox?) to power accessories, i.e. power steering pump, A/C compressor, etc

Just as a little note on this bit, people who do this tend to scavenge electric PS pumps from vehicles that had those, and now electric AC bits from hybrid cars, etc. No one runs that stuff off the motor since the motor stops every time you come to a halt, and runs at very low RPMs when you're driving at stop and go/non-arterial speeds.

Also, no one does this with an automatic because of all the programming issues and power loss. With a manual though, you just never shift besides into reverse.

In addition, in a lot of modern conversions there's just a general "power controller" used. It controls the throttle, charging/discharge, the motor in general, etc. It's all just one ECU/drivetrain controller at this point.

I'd need to contact a friend on facebook and wait to hear back for a link to the info, but he briefly had plans to start up a company locally that converted cars and i was going to work on that project with him. This is relevant because there's a chinese corporation selling complete kits for about $10k. Motor+batteries+controllers+other hardware to link up with existing throttle and run the brakes and tons of other bits and bobs like blanks of metal for converter plates ready to be drilled out.

Note that if you're really serious about doing this, only look at the AC motor kits that use PWM VFD/inverter drive. Anything else is outdated old stuff that companies are just trying to offload and is inferior. It's a bit more expensive, but the performance and efficiency is WAY better. Everything from the prius to the tesla use VFD motors.

This is my favorite conversion, and the site is a wonderful read. It's a few years old but the technology used is still very up to date. Also, that car is completely bonkers and awesome.

Really read and absorb what he's saying about picking a car that you really want to keep for a while that's in good shape, and generally worth converting. You're essentially getting married to this car once you do this and pour a bunch of money into it. It's very much worth noting that you can buy a good used 2nd gen prius for ~$10k now, or maybe even less(crap, i've seen them for like 7). Then slap in a plug-in mod kit which isn't all that expensive and run on electric except when you need the extra range, without any weird generator mods. Think long and hard about whether that's a better plan when you're really going to have to spend probably close to 10k including batteries and such to do this right, and actually have a meaningfully useful vehicle with decent range. 30 miles is super easy to achieve, but i've never seen a charge controller that wanted to accept input power while driving. It's generally charge mode or drive mode, and the cars that can do otherwise(IE: the volt) are completely custom jobs.

Also, mrrisotto i don't want to come off as crapping on your post. It's a good and for the most part realistic estimate of the materials/skills required. A lot of people use forklift motors as well since they're very durable and have lots of torque, and just generally work well for this. A lot of the electric drag cars use forklift motors.
posted by emptythought at 6:17 PM on January 2, 2014

I think you are spot on in your assessment of how difficult this would be, and agree that it's not the platform for your project.

If you REALLY want to do something like this, it makes more sense to get rid of the thing and find an old hybrid. Ideally, a Prius, since it will run battery-only with some firmware mods and more batteries. A Honda Insight (good because they have been around since 2000) MIGHT be good, because it's easier to move an 1800 pound box around than a 3500 pound unit. Regen is something they already support, etc. (I own one. It is an electrically ASSISTED vehicle, which is different than a Prius. It might be modifiable, with some major effort and someone has probably already done it. )

On a 1..10 scale, for a well equipped, inexperienced maker, this is a 9, and maybe a 10. Not a good level to start. If I were doing it alone, with 45 years of creating things under my belt, it would be a year or two project. There is a LOT to learn, from basic physics and materials and electronics, machining, handling heavy objects, assembly, precision measuring, software, systems integration, chemistry, and then the vehicle/safety angle. Big, big, big project. Big.

I'm already tired. Good luck, amigo.

(No kidding.... check the prius hacks.)
posted by FauxScot at 6:23 PM on January 2, 2014

Keep it simple, install the e-traction motion system to existing suspension.
posted by hortense at 6:30 PM on January 2, 2014

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