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Discussion Starter #1
G'day :)

I'd love to build an EV but can't afford to go the whole hog - so I'm thinking about a different approach.

I'm thinking of bolting a 24V 2KW motor onto my Nissan Bluebird where an air conditioner compressor would normally go, and using a large relay to simply connect two 12V batteries (charged via mains power) in series.

In theory at least, this should mean that while driving I can press a button to energize the motor, and thereby reduce fuel usage by a small percentage.

I know I'd lose some efficiency since some of the energy would be going into making the ICE spin faster, and because it'd be belt driven, but I'm hoping that since adding a 10A load to the alternator drops the RPM a fair bit in this car (at idle), that adding 16 times that power back in would work well enough to save maybe 20% of fuel?

Does this idea have any merit?
 

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so, to clarify, the electric motor is geared to the ICE and takes some of the load? Ive had a similar idea to that before, but by simply replacing the starter motor with something larger and more powerfull.

give it a shot. I think it would work, if done right. Biggest problem would probably be making sure the electric motor is sharing the load correctly. if you set it up right, you could also get regenerative braking on it.
 

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Discussion Starter #3
so, to clarify, the electric motor is geared to the ICE and takes some of the load?
Yes, that's right - except driven by a fanbelt from the front of the motor instead of the flywheel. If I can find a motor of between say 3000 and 9000 RPM with a suitable pulley diameter attached to suit the motor's 2000-5000 RPM range, then I should be able to forego speed controllers, etc.


give it a shot. I think it would work, if done right. Biggest problem would probably be making sure the electric motor is sharing the load correctly.
Yes - might need to consult torque curves, etc. I'm hoping that a motor that revs free at say 6000RPM will apply a substantial drive at 2000-3000RPM, but without frying itself! (It wouldn't be on when the ICE is idling / off)

if you set it up right, you could also get regenerative braking on it.
Good point. Since this car is unfortunately an Auto, this would probably be ineffective when in top gear, but I'll check the revs next time I'm driving in third (top) to see...

I was originally thinking of converting my HG Kingswood instead but it doesn't have a spare pulley or convenient mounting points, etc and is probably heavier - but it is a Manual and a 161 (smallest available) ICE.

Thanks for the encouraging reply!
 

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I just had a thought. it might be possible with a dc system for it to monitor the motor current drain and voltage actively, and adjust itself (the PWM) so that it gives a constant amount of power to the ICE. You could even have a little dial on the dash for how much motor assist you want to use. It would be like a variable turbo/nitrous :)

on another note, i think it might be best to use sprocket and chains rather then pulleys and belts. Chains should easily be able to handle the power (they have 150bhp+ motorcycles with them) and gearing the motor should also be easier, and more precise. Might be posible to drill some holes in the pulley to bolt the sprocket onto, if your of the lazy persuasion.:p
 

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Discussion Starter #6
on another note, i think it might be best to use sprocket and chains rather then pulleys and belts.

Good idea! Much less likely to slip. Might have to rat some bits of a motorbike...

The Kingswood and the Bluebird turn out to be a similar weight - do you think either one would be best to modify - with a chain drive addition I'll need to modify either one.
The Kingswood is a six cylinder manual, the Bluebird a 4 cylinder auto. Both are in good nick.

The quest for a suitable motor continues - haven't had a response from evparts yet. Perhaps a golf cart motor would suit?

The variable boost option is an interesting idea, but since I'm only looking at an hour or so of battery life, I thought I'd just want to give it all it would take on electric and make up the rest with petrol. Having some form of controller rather than a motor might be useful however - and I imagine I'd need to add a temperature monitor to the electric motor too :)
 

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Im afraid i dont know the HG Kingswood, not sure they ever made them in europe. If both cars are the same weight, might be easier to just choose the one with the most space available in the engine bay?

as for motors:

I've read that a car only requires 10-15hp to cruise (someone please correct me on that if its wrong), so you should probably decide how much of that 10-15hp you want the electric motor to provide. personally, i would want the electric motor to provide ~5hp. In a 48v system, that would be ~80A draw, so that should give a rough idea of battery requirments. You'll also want a serial wound motor for sure. Serial motors are known to 'runaway' and increase speed when theirs no load on them, so this might make it a little easier to match the electric motor and the ICE speeds. speaking of which, you'll probably need a 1:2 gearing as well, as most larger motors ive seen like to run around 3k rpm, and most cars go up to 6k+
 

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Discussion Starter #8 (Edited)
Im afraid i dont know the HG Kingswood, not sure they ever made them in europe.
Fair enough :) The Kingswood is an iconic Australian car from the early '70s - http://en.wikipedia.org/wiki/Holden_Kingswood#HK.2C_HT.2C_HG

Thanks for your ideas re. Motor size, etc. Can you steer me in a direction to find such a motor? I think I must've scared evparts.com away with my email!

I'll do some research on batteries as well, and perhaps a controller. Most of my inspiration is from Gav's EV conversion series on YouTube; and the 200W electric scooter I bought out of curiousity which gave me the EV bug to begin with.
 

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Discussion Starter #10
Progress so far:

I've contacted a number of people and shops to get their opinions, and also called into a radio show on the ABC in Australia. (Radio show presenter was not interested - thinking I was trying to build a prius duplicate, and changed the subject, later getting rather annoyed at further callers suggesting electric cars, saying they were environmentally damaging.) I think that was at http://www.abc.net.au/nightlife/stories/s1664139.htm but I'm on a low bandwidth connection at the moment and can't verify that.

Found another possible motor contender: http://www.baldor.com.au/product_view.php?PROD_ID=27

I'm now waiting for a local mechanic to get back from School Holidays to find out what the registration implications will be. If they are too steep, it may kill the whole project.

Also, Wikipedia states that most car compressors are 5HP http://en.wikipedia.org/wiki/Air_conditioner - with other sites varying wildly in their estimates. So, a fan belt-driven system is still quite possible assuming these stats are true.
 

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I had similar idea, so of course i think it's great.

I was planning on using a larger PM motor and 72 volt battery pack.

The turbo generator would be a great add on.

Only problem I see, is with such a small motor, your gains are only going to be 2-3 mpg.
 

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I assume that's a front wheel drive car. Rather than mounting the EM to the ICE, have you considered changing the rear suspension a bit and mounting the EM to one of the rear tires? This would make the EM push the car along, taking some of the load off the ICE. It would be the equivalent of dropping half the weight of the car off while the EM was running. You could also extend the range of the EM by putting a generator on the ICE as well. When the power runs out, it would be all ICE.
 

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I was thinking the same thing while reading this thread.. Take a FW drive car and add a RW drive axel and differential and attach a electric motor to that. You could put the Front wheel drive in neutral and have a no load situation for all electric driving and try running both at once. The electric motor should provide very little load other then increasing the rotational mass with the rear axle and diff.

You would also get 4WD with this.

Odd thought, looking at that turbine for the exhaust, I wonder if anyone has ever tried putting a Peltier on the Catalytic converter. Not everyone knows this but if you apply heat to a TEC it will generate electricity.

Links regarding peltier power generation:

http://www.realinnovation.com/archives/1997/01/a/index.htm

http://www.fujitaka.com/pub/peltier/english/thermoelectric_power.html

http://www.mne.psu.edu/me415/spring04/mega/
 

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I assume that's a front wheel drive car. Rather than mounting the EM to the ICE, have you considered changing the rear suspension a bit and mounting the EM to one of the rear tires? This would make the EM push the car along, taking some of the load off the ICE. It would be the equivalent of dropping half the weight of the car off while the EM was running. You could also extend the range of the EM by putting a generator on the ICE as well. When the power runs out, it would be all ICE.
adding a rear axle and diff to a car is a hell of a lot of work, unless there already exists a 4wd/rwd version of the car. even then, it would be easier to just buy the 4wd/rwd version in the first place. I would imagine you would also need a more complex controller, as you would want the rear wheels to be rotating at the same speed as the front

Odd thought, looking at that turbine for the exhaust, I wonder if anyone has ever tried putting a Peltier on the Catalytic converter. Not everyone knows this but if you apply heat to a TEC it will generate electricity.
thermocouples are horribly inefficient. you'd probably get more energy by harnessing the power of your farts while driving. :D a sterling engine might be a little better though, but its all extra complexity for a simple project.

I still think your original idea is good. have the motor geared to the ICE crank, and sharing the load. its elegantly simple. It should help the engine rev faster, give a little more torque through the rev range, and require less throttle for engine speed. It would probably be more effective and noticable on a smaller engined car, but i say do it anyway!
 

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adding a rear axle and diff to a car is a hell of a lot of work, unless there already exists a 4wd/rwd version of the car.
I don't think it would be really any more difficult then finding a way to mount a electric motor to the ICE. There are a lot of people doing V8 conversions for the Ford Focus for example. With an electric motor it would be simpler from the standpoint of no drive train to re-route.

I would imagine you would also need a more complex controller, as you would want the rear wheels to be rotating at the same speed as the front
Why? Just use it like a pusher trailer, the rear wheels won't just start spinning wildly. You really don't want to worry about synchronizing wheels, that is why we have differentials in the first place! From the ICE standpoint it would be like going downhill.

Simple and effective, batteries in the back of the vehicle near where the electric motor is. No messy wiring issues around the ICE.
 

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Discussion Starter #16
Thanks all for your ideas and encouragement.

In my case, the two cars available are both rear wheel drive.

I'm not sure that driving one pair of wheels with the ICE and the other with an electric motor would make any practical difference compared to running the electric motor through the ICE drivetrain, except if the electric motor was big enough to be able to carry the car with the ICE transmission in neutral - otherwise the net result would be the same. (Unless it's a modern automatic transmission which disengages the motor when coasting.)

The idea of this project in my case is really to achieve a small fuel saving - maybe 10-20%, and still have the full range the ICE offers as some days I travel much farther than others. (I do on-site computer repairs for homes and businesses, some on rural properties.) I'm also far from wealthy at the moment so can't afford to spend a huge amount on parts to make a fully electric, nor to register a second electric car.

I suppose the more logical alternative on a small budget ($2K say) is to convert to LPG instead - but that wouldn't be as much fun! (I could do both I guess, which would probably wipe out the entire boot space!)

Anyway, as said earlier I need to find out what these changes will mean for registration purposes. There could be too much red tape in Australia - so I'll let you know what I find out soon.

Cheers, Mike.
 

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Well sounds like this idea has been floating around for a while. Do a search for Integrated Starter Generator or "light hybrid vehicle"(keep the quotes). There are even a few patents floating around for this exact configuration.

With either design you can shutoff the engine at idle and basically do a roll start of the ICE, though this is easier with the ISG.

However the advantage in my mind with a Rear Pusher EM(what I am calling the design idea posted above), is that you can run with just the electric motor with the ICE in neutral. That would be impossible with the ISG attached to the Crankshaft of the ICE.


Got a couple of links for your reading pleasure:

http://www.hev.utulsa.edu/trio.html
http://www.sigmaautomotive.com/electrocharger/electrocharger.php (looks like this was vaportech..)
 

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if you have rear wheel drive already existing,check out netgains EMIS system at http://go-ev.com/
they have and interface that will sync up to the vehicles computer to control the electric motor.take a hint from their system and you will have an instant hybrid.:)
 

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if you have rear wheel drive already existing,check out netgains EMIS system at http://go-ev.com/
Interesting system, looks like they have a dealer network setup as well. Looks like it just replaced part of the driveshaft linkup. A major part of their system is the monitoring interface with the car computer so the control is seamless. I would think you could adapt a standard code reader setup to basically give you the parameters you need. Though for DIY typically we want more control over things like that anyway right? :) Notice that their system doesn't support regen currently.
 

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The Texas A&M / sigmautomotive approach seems the best developed - the three modes they suggest cost justify based on the cost of the battery pack and BMS. I like these methods for retrofitting current autos because they present known scenarios to the auto's computer without an electronic interface:
Applying power when accelerating or cruising emulates a downgrade - I've seen 3% as a proposed value (applying constant torque regardless of rpm is simple to do). Conversely, the computer "sees" an upgrade when regenerative braking is happening but it may not be so simple - there's talk of needing some input from sensors to do this right.
Even so, the combination of plug-in power-adding and momentum-recapture from regenerative braking seems to be sufficiently compelling and straightforward to implement that we'll see opportunities to increase fuel efficiency by 50% and more that well cost justify within the remaining life of the majority of used cars. I think I might like to be in the business of installing them by the 100's per day increasingly over the next three years. I wish the sigmaautomotive thing would get real!
 
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