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Ask HN: How feasible is it to convert a petrol car to an electric car?

10 points by kagamine ↗ HN
EDIT: The link below from the BBC clearly posits the question of converting classic cars to electric drivetrains. If you are unhappy with that or found a link where 1 guy once made an electric Metro from a petrol Metro and you think no more can possibly be said on the subject, please move along. I can't downvote yet, clearly many of you can, it's like reddit rebooted in here.

still editing: for all the people focussed purely on "now", think ahead 5-7 years. 2nd hand parts are common, development costs recovered, manufacturing costs in decline. Petrol harder to come by making a lot a of classic cars too expensive for the average car guy - now a conversion might be worth it in both time and bank.

Original post: From engineering and economic perspectives. Given that all existing cars have passed crash-tests etc and that the only real reason to go electric is environmental, does conversion make sense for many existing vehicles?

Inspiration for the question from here:

http://www.bbc.com/autos/story/20150521-vintage-gas-guzzlers-ripe-for-a-battery-powered-reboot

27 comments

[ 3.2 ms ] story [ 71.5 ms ] thread
valarauca1
Unless you have a lot of experience with power train engineering it will be very difficult. The primary reason for this is that Electrical Motors have different torque curves then Petrol. Petrol have their peak power/torque at a non-zero RPM (dependent on fuel type, air temp, moving speed, etc.). Electrical Motors have their max torque at stall, zero RPM, just starting.

Engineering an automotive transmission is normally a $1Bil+ over 10yr+ project. Normally automotive companies coolbrate on new transmission designs (currently GM/Fiat are, and Ford/BMW kinda).

:.:.:

If you just want a hobbityst project not start a company, then its fairly straight forward with basic Mech Eng/Mechanical experience.

kagamine
So it would be possible to produce a mass-produced replacement part targeted at specific models, at least at first, using for example the Leaf drive train and a conversion kit? I assume electric cars have standard axles++.
valarauca1
There is no standardization between manufacturers in the automotive industry.

When there is, its often because two models were developed as an collaboration between companies, or a licensing deal between manufacturers.

Between model lines you'll see some part repeat, and some drive train components repeated. But for cross manufacturers production it'd likely be very impossible, this is done intentionally by manufacturers.

:.:.:

While some companies do manufacturer aftermarket drive train components. They have licensing deals to get early dyes while production is under way. Often partnering to lower the cost of the dye production ($10Mil +).

Often these specialize on high performance model lines, and the performance company is very often a sub-division of the parent company. If you buy a high performance transmission, drive shaft, etc. Your just buying an alternative part designed by the same parent company, sold via a shell performance company, which is part of the parent company, but exists largely as advertisement for the high end market.

kagamine
By standard axles I meant that there are really only 2 types on production cars in the last century, fully floating and not. Many of these parts may not be "standardized" but they are interchangeable. Want Land Cruiser axles on a Land Rover or Jeep? Not a problem.

Anyway, I wanted to discuss the feasibility of it now and in the future, not explain-away any possibility of it because it's too hard to do. The automotive industry is full of small and large manufacturers willing to fill a niche. I have a car with a replacement carb that requires conversion kit, and a lead-free head on the engine. There are also disk-brake kits, engine & gearbox conversions, suspension conversions... the list goes on.

nl
Want Land Cruiser axles on a Land Rover or Jeep? Not a problem.

Err.

Well, it's not a problem in the sense that yes, it is possible. But it take choosing the exactly correct parts, custom machining and a fair bit of bodging stuff together (eg[1]).

And that's just axles, which aren't exactly the most difficult part of the drive train.

Having said that.. yes, it's quite possible to convert conventional cars to electric ones. See[2] for a place to start.

[1] http://www.pirate4x4.com/forum/jeep-non-hardcore/622698-toyo...

[2] http://www.evmotors.com.au/services/quickguide.html

kagamine
It's far more common among off-roaders than you know.
valarauca1
Okay fine then. Producing a hardware prototype will run ~15mil since steel dye work is expensive.

You'll also need a team, and office space. Good luck.

bluedino
>> So it would be possible to produce a mass-produced replacement part targeted at specific models

It wouldn't be a big deal to design an electric motor that would be a bolt-on replacement to a gas engine - especially for the most popular vehicles like a Honda Civic or Toyota Camry.

The problem is where do you put a big enough battery?

kozak
One of the main reasons why we consider electric vehicles to be so cool is their low center of gravity, thanks to the batteries being located near the very bottom (good to have them there, and also batteries are better not to be damaged in a crash). Can we find such a place in existing cars? Maybe we can use space under seats and in place of the fuel tank and the spare tire. But in this case batteries need to come in small modules.
kagamine
You just described the location of most fuel tanks and exhaust/catalyst systems. A conversion would not be a perfect fit, but an extension of the vehicle's life, like the classics with replacement lead-free heads and an LPG tank in the boot area.
dalke
What does "feasible" mean to you, and how are sites like http://www.instructables.com/id/Build-your-own-Electric-Car/ and http://www.hybridcars.com/top-7-issues-electric-car-conversi... insufficient for resolving your questions?

What does "make sense" mean to you? It does not make sense to convert a heavy vehicle to electric because you won't get much range from the result.

In general though, no, it does not make sense. Otherwise more people would be doing it. It's not like the idea is new either. I recall as a kid reading a Donald Duck comic where Donald converts his car to electric then goes for a ride with Daisy. Problems ensue, of course, as this is Donald we're talking about.

kagamine
Given that there was a link in the question, what does "feasible" mean and what does "make sense" mean? What does "pedantic" mean? What does anything mean?

I am so sorry for having troubled you and for wanting to discuss something on the Internet. To think that I made you type all of those words. I truly am a monster.

je_bailey
The questions he posed are legitimate given his final statement. Converting legacy cars to electric is a waste of time and money. Unless of course, your definition of "feasible" and "make sense" is different than mine. Or maybe there is a different question you're trying to get too. Like, is it feasible to start a start up producing kits to convert cars, or a boutique conversion company. Which in my opinion would be the best option.
kagamine
What, using Donald Duck cartoons as evidence?
dalke
The example is evidence that the idea of a gas-to-electric conversion is not new, yes. Such evidence is trivial to find, so I didn't think it worth pointing out a specific example.

If you want a concrete example, here's a newspaper article from 1993: https://news.google.com/newspapers?nid=2457&dat=19930921&id=... .

Looking over it now, very little has changed about the overall procedure.

dalke
"Feasible" here means things like "are you a hobbyist car mechanic", "do you have access to a car shop", "how much time are you willing to spend working on it"? There are people who can easily say "yes" and "lots". For those it's feasible.

Indeed, it's been done for decades. Six years ago I drove a borrowed converted pickup running on lead-acid batteries, with a solar panel in the back. The owner had acquired it used, and he had several other electric vehicles. He lived in the high desert, running 12 large solar panels, which he also used to power his house and his recording studio. He loved that he didn't have any 60 Hz noise on his recordings.

For him it made sense.

In Norway, which has a government policy to switch from oil to local hydropower, an all-electric car gets an exemption from car taxes, tolls, public parking, etc. and can drive in the bus lane. For someone in Oslo, a conversion can make sense.

Since "feasible" and "make sense" depend on the person asking the question, neither I nor anyone else can really answer effectively, other than to point out that if the economics were really good then a lot of people would be doing it.

johngalt
No from both perspectives. Engineering wise there isnt much cross over between electric motors and ICEs. Think of all the systems that would need replacement, removal or modifications. You would end up with an electric car with exceptionally poor characteristics or an absurdly high cost to modify. Crash test performance is also heavily dependent on overall design.
seynb
Thinkin' the same thing. Actually, it is very feasible and affordable for a low-range city car. The major factors are the cost of batteries, and range anxiety. You can do conversions with in some cheap lead-acid batteries generally for a total build cost <$3-4k. Cons: limited recharge cycle, weight, not practical for >30km range (~18mi).

Lithium batteries are the best (either LiOn or LiFePo), super expensive though. Tesla Model S 85kWh uses 7104 3.1mAh Panasonic 18650 cells. They probably have a special purchase agreement ala Apple with Samsung NAND. If you wanted to buy enough for 100mi range I crudely estimated the retail cost at $15167.58 (vendor Orbtronic).

But there are people who spend $20k+ on conversions. Check out http://www.evalbum.com

Also at http://www.forkenswift.com they did a conversion for $672CAD on a Geo Metro

raihansaputra
Some conversion kits have been around for quite some time, but targeted towards hobbyists. Some kits from EVWest [0] even retains the transmission and the rest of the drivetrain, only replacing the internal combustion engine with an electric motor and supporting devices (chargers and coolers), and a place to put the battery in. They even have braking regeneration and replacement heaters for the passenger compartment. Maybe the space to put the battery in is the main hurdle in converting the car.

[0]: http://www.evwest.com/catalog/index.php?cPath=40

louithethrid
Not interesting.. You could add a generator and electric motors, but then you basically have a bad double conversion and extra weight.

You can strip out the motor, but then you basically are near building a new car anyway.

Everything engineered is a series of well-weighted compromises towards a optimum. Adding as a after thought a electric option to a gasoline car, is going to be a bad compromise. Always. If you want a good compromise, build one from scratch (just reusing chassis and gears) or buy one that is designed with this in mind.

jodoherty
Wayne Bickley did a pretty cool electric conversion on his C4 Corvette:

http://www.ndneyes.com/

I originally read about it on Corvette forum (I used to be a C4 vette owner and was always looking for interesting tips or projects).

If you're mechanically and electrically inclined, it's more than feasible.

dalke
Responding to the edited question, see this article from 1993 on converting a car from gas to electric: https://news.google.com/newspapers?nid=2457&dat=19930921&id=... .

Every point you made about thinking ahead 5-7 years from now could have been said in 1993. Second-hand electric parts became more common, petrol became more expensive, etc.

Your edits come across as if you are chastising people for not thinking about the future when, at least in my case, I'm pointing out that nothing about your evaluation of the future has changed for decades.

Nothing really new can be said about your question because your question itself is probably older than you are. It's certainly older than I am.