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EV/hybrid conversion from ICE

2241 Views 22 Replies 7 Participants Last post by  tommyhp2
Hello everyone,

4th gen styling looks very unattractive to me in addition to no 8 passenger beyond LE trim. So I'm thinking of keeping our 3rd gen and doing EV/hybrid conversion. While my question is specific to gen 3 but I think it's applicable to older gen too. I'm looking for some input from DIYers (whom do more than just oil change) or mechanics regarding space and technicality of converting a (gen 3) 2015 FWD to quad EV motors, battery pack, and 600 CC motorcycle engine with gearbox to drive a few alternators. I realize venturing into unexplored territory will have unknown costs (for parts and labor). But seeing options out there, I don't really have much choice unfortunately. With all this (urgent) drive to go green, it seems none of the current manufacturers design their vehicles to be upgradable, within reason, like computers. How much carbon foot print is needed into a vehicle that could be upgradable [1] ... not to mention that styling is very subjective.
  • Space: removing the engine, transmission, exhaust, gas tank should leave plenty of room for 2 rear and 2 front motors for hybrid 4x4 (hoping to implement pseudo locking differential). The battery pack will be installed underneath between the axles and a small pack where the gas tank was. The motorcycle engine driving a few alternators will be in the front where the engine was. There should be half engine bay left for the "frunk".
  • Motor control: I'll probably inquire with AEM if they have or could possibly come up with a solution to control the EV motors.
  • Battery control: I'll probably need to check for CoTS or other means for a reliable BCM/BMS.
  • Vehicle functions: power steering, AC, etc are either done by the motorcycle engine with modifications or converted to electronic counterpart.
  • Ride height: Probably lifted a couple of inches for battery pack, ground clearance for snow and, possibly, off road.
The attached image is the approximate dimensions of the Tesla motor in case I want to use Tesla's instead of other generics. (Courtesy of Tesla Large Drive Unit Dimensions)


[1] "The vehicles are shredded and the metal content is recovered for recycling, while in many areas, the rest is further sorted by machine for recycling of additional materials such as glass and plastics. The remainder, known as automotive shredder residue, is put into a landfill."
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This is an interesting idea and I really look forward to seeing any results but I have to ask - what is the motivation for this? Are you actually looking to save money overall on gas or is this more of a fun engineering project?
All of it. I don't like:
  • Gen 4 styling is too aggressive, IMO. It's a minivan (or rather swagger wagon) and not sports/race car.
  • Non removable 2nd row seats limiting my cargo space from 150 cu ft (up to 1st row).
  • Gas prices and environment reasons such as wasted energy during braking in addition to maintenance costs of ICE after high mileage ownership/usage due to too many moving parts.
  • Even the largest SUV Toyota has to offer, the Sequoia at about 120 cu ft (up to 1st row), still pales in cargo space to gen 3.
  • Being able to lift the vehicle for off road for the ultimate cross over and one bad ass look :)
This looks like fun. Are you doing this for environmental or economical reasons?

A “few” alternators aren’t going to cut it, if you’re talking about automotive alternators. Say you have a 130 A alternator. At 15 volts, that’s 1950 watts. 750 watts per HP, so that’s 2.6 HP. So four of these alternators would generate 10 HP of electrical energy. A quick search also shows alternators are anywhere from 55-75% efficient, so you’d need some 13-18 HP from the engine to get 10 HP of electrical output. Most alternators don’t like running at max output continuously either.

To be practical, you’re going to need a high efficiency (90+%) generator sized appropriately to the engine, not a few car alternators.

What about pulling the engine and drive from a crashed hybrid car? May have to look for a suitable vehicle or two and piece it together, but it would probably be a lot less work. The Toyota hybrid drive may be the most difficult, since it maintains a mechanical linkage from the engine to the wheels, and it sounds like you don’t want that anyway. But from what I’ve read the Honda hybrid system and some others use the engine to run a generator which powers the electric motors and charges the battery, with no mechanical linkage. So that’s more along the lines of what you’re looking to do.
I haven't quite work out the math for the alternators yet but I figured that if an alternator is able to charge the battery or drive the rear wheels in gen 4, what if you have 3+ alternators? In the event that hybrid does not work, I have backup of using Toyota's fuel cell module(s). Just need to figure out the dimensions and placement.

My reasons for going quad motors, each driving the wheel directly via the axle (maybe a gear or 2 involved similar to Tesla ?):
  • Smaller motors for easier placement instead of 2 large motors (1 front and 1 rear)
  • If a motor died (up to 3), I could still get somewhere in limp mode.
  • Get all the benefits of 4WD's locking differentials without its drawback
  • Get all the benefits of LSD on turns by reducing power appropriately on the inner wheels via mathematical calculations
  • No transmission, transfer case, LSD to worry about (less weight, mechanical complications, and maintenance of moving parts) if I can get 4 exact motors or at least 2 matching pairs
  • In eco mode, I could use FWD or RWD. In sport mode, all 4 are used. If I have larger rear motors, I can also enjoy drift .. lol. I can also "shift on the fly" from eco to sport and vice versa unlike most of the current 4WD system.
In short, I can drive in any manner in any weather conditions, depending on tire size, pressure, and type of course. I guess you could call it the real "MPV" (multi purpose vehicle) and not Mazda's old wimpy version... hehe.
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The Toyota HSD does not use "alternators" in the colloquial use of the word. They use expensive, high power density, permanent magnet motor-generators. Yes, the output in generator mode is 3-phase alternating current, which is what an alternator outputs, but that's the only similarities they have. Standard car alternators simply won't cut it. Period. They simply don't have the power output to do what you want.

There are high power, high efficiency 3-phase generators out there (such as the ones used in the HSD), but you're talking thousands of dollars or more. They need to be sized appropriately to match the engine. You'll only need one...but you're going to pay a pretty penny for it.

On a related note now that I'm thinking of it. I read the 4-cylinder atkinson cycle engine in the Sienna hybrid has a whopping 40% thermal efficiency. I would guess a typical 600 cc motorcycle engine may be something like 30% efficient, if even that. This is a massive difference. All else the same (same vehicle/weight/tires/generator efficiency/motor efficiency), at steady state speeds the Sienna can get 36 MPG. The same vehicle with a 30% thermal efficient engine will get...27 MPG. It's doubtful you'd even get that, as the HSD uses a direct connection from the engine to the wheels which helps increase it's drivechain efficiency.

Also since you mentioned environmental reasons, in addition to burning more gas (so more CO2, etc), most motorcycles don't have catalytic converters, so they release much higher amounts of nitrous oxides and unburnt hydrocarbons than a typical automotive engine with a catalytic converter. Obviously you could have a catalytic converter, but your original post mentioned removing the exhaust system, so...

On a related note, you original post also said remove the gasoline tank? How are you going to run your van without a gas tank!?

More and more I think the only way to remotely economically get something that's efficient is going to be to cannibalize an existing drivetrain on a similar hybrid vehicle and use that. It's going to be extremely difficult to get anything remotely as efficient as a DIY build compared to what's already there for anything short of the amount of money that would just allow just buy a 4th gen Sienna and pay someone to custom modify the body to your desired style and add limited-slip or locking differentials.
The general idea of hybrid that I had was to use motorcycle engine to drive the alternators via gear(s) not belt. For fuel storage, I was thinking of using 2 military grade 5 gallon tanks. For exhaust, I was thinking of using catalytic from small vehicles like Corolla/Civic or smaller. Even though I haven't put the idea in the 3D modeling software, thinking about it there's still too many moving parts so this wouldn't work.

For the fuel cell route, if Toyota's module(s) doesn't work similarly the same way as Murai's, I'll have to check with Plug Power or perhaps somewhere else.

I haven't thoroughly thought out my power source yet since I have not able to find the motors of satisfying my need of 300+ hp and 400+ torque combined (75+ hp and 100+ torque per motor) for decent price. I have found a few AC induction motors of similar spec with max ~5k RPM. For highway cruising of 2k RPM (70 MPH in the sienna):

2000 rpmTireDiameterWidthSidewallCircumferenceRev/MileGear RatioMPH
2015 Sienna235601728.19.35.688.27180.583.56545961
2008 Sequoia275552030.810.85.496.86550.591.60305344

This is calculated for direct drive mating to 0.5 reduction gear ratio. I used the 2008 Sequoia for comparison in case I also want to do the same to the Sequoia or lift the Sienna for off road to use similar tires. After getting reliable source for the motors, I'd need to test how much power is consumed at that speed with load of about 1500 lb per wheel since I think Sienna's GW is almost 6k lb. Once I have the power consumption, I can then plan how much 'fuel' is needed to achieve at least 500 range since the current Sienna can drive 450 miles following a semi before needing to look for gas station.

As for 4th gen, my main like of our 3rd gen XLE Premium:
  • 7+1 seating (only available in 4th gen LE)
  • 150 cu ft cargo room up to 1st row (100 cu ft in 4th gen since 2nd row is non removable as quickly and conveniently)
  • Sleek sporty style not aggressive like 4th gen, IMO, or other brands
One of our friends is modifying a Ford diesel van to go off road. His estimates is about 50K total. I'll see about uploading some pictures of the undercarriage he has done so far. He wanted to use Sienna's 2nd row captain's chair for his van.
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Your not alone. But instead of spending $500,000 transforming an older Sienna maybe just a facelift would do. If enough complain maybe Toyota could offer an option of a different front bumper without the gaping mouth.🐘
Actually a lot of newer cars could benefit from that option.
On the positive side, no desire to upgrade will save me money.
Even though I'm venturing into explored territory, I don't think it would cost me more than 50K to convert. Thinking about either spend that money or more to get an EV and be at mercy to that manufacturer, especially Tesla, or convert and be free. Not to mention that I could start the business to convert others' vehicles with similar needs. At that point, the economy of scale would reduce the costs drastically. :)

Just for the record, the day I'd trust any AI, especially overhyped Tesla's, to drive for me is the day that AI has to be in top 5 professional races: 24 hour Le Mans, Indy, or WRC.
Gear/belt doesn't matter. When you said "a few alternators" I figured you were talking about standard car alternators, and I was pointing out that standard car alternators won't cut it by any means. Nearly all generators output 3-phase AC, so they can be called an "alternator" but nobody does, they simply call them generators.

Alternator came into the car vernacular because early cars (till like the 1970's) used DC generators. It was pulsed DC, but DC nonetheless. When they switched to generators that outputted alternating current they became known as alternators to differentiate them.
Based upon my understanding of physics, gears have less energy loss. But as I have said, converting to a hybrid still has too many moving parts. So, this would no longer apply.
I don't think an induction motor is suitable. Have you looked into the size and weight of induction motors? We use a 20 HP induction motor at work, and that thing is as big as my 100 HP motorcycle engine, and probably heavier.

Doing a quick search, a NEMA 360 frame, 75 HP motor is going to be on the order of 771 lbs, with length not including shaft of 24 inches. There's just no way you could fit 4 induction motors into any sort of passenger vehicle, nor carry the 3000 lbs of said motors.

You'll have to use 3-phase permanent magnet motors for size and weight reasons. This is what everybody uses for electric and hybrid vehicles, and for good reason.

My point was for the money you are likely to spend, you could buy a 4th gen Sienna, and modify the Sienna body panels, add an 8th seat if you'd like, modify the 2nd row seats to be quick release. If you don't care about airbags in the 2nd row, then you could just fake out the airbag connectors and weld in the track mounts from a 3rd gen Sienna to get the 3rd gen removable, 8 passenger seating.

Modding can be great fun. And people have been making electric cars since forever. I've seen pictures of an electric pickup truck mod from the 70's, with the bed full of lead acid batteries. But trying to build something that someone else has already mass produced on a one-off, hobby scale? There's simple no way to make it on any reasonable economic level.

If this is just a project you want to do, go nuts! Please note I'm not trying to say you shouldn't do what you want. But you seem to be very unaware of what is actually needed, from a technical, time, and money perspective, to get what you want for performance specs.

I'm saying this as someone who has wanted to do all sorts of stuff, and found that in nearly all cases, if something is available off the shelf, there's almost no chance you can make an equivalent product for the same cost, even if all your time is of no account. In many cases, even putting together the parts you need costs more than the off the shelf component.

That said, since your main "sticking points" with a pre-made vehicle seem to revolve around styling and seat arrangement (both of which can be changed), have you considered other options? The Chrysler Pacifica hybrid has more of the traditional "minivan" look, less aggressive than the Sienna. And it maintains removable seats on the 2nd row. The hybrid is not available in an 8 passenger model though (though in the context of this thread, figuring out how to add an 8th seat is one of the easiest things of all those proposed here).
Our 2015 has 2GR-FE which weights 359 lb. If you add that to weight of transmission, intake + exhaust, and 20 gallon fuel tank, I think there should be some weight gain to convert to EV motor, battery, fuel cell, and hydrogen tank since the AC-34 and AC-50 weights at 115 lb each for a total of 470 lb total which is way less than what you've mentioned.

As for upgrading to a new hybrid and then do mods you've mentioned, IMO, it's not worth it because the of the cost of modifications, aesthetic appeal, and I still have to deal with too many moving parts.
How much do you anticipate spending, budget, etc.?
Financial cost (rough estimate shouldn't be more than 50k) and DIY hours are hard to say right now since I have not yet find all the parts and put my ideas into 3D modeling for fitness and financial practicality.
Looks like someone beat me to my idea of hybrid.
  • Haha
  • Wow
Reactions: 2
I was bored, and wanted to see what my Sienna gets at 45 MPH.
This test of getting the best MPG isn't practical, IMO, because there are 2 practical uses: local and highway. On the highway, best MPG for our XLE FWD (gen 3) is 30 MPG (for a range of 450 miles before looking for gas station) following a semi truck or big commercial vehicle for that major wind resistance reduction. As for local, if you can drive it in 6th gear at the slightly above the lowest possible RPM, that's your best MPG using the best gear ratio and still decent on the HP/torque power band to handle small incline.
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