# AC engine for a 4000 lbs EV



## Benjamin515 (Apr 12, 2012)

Hi,

My calculations indicate that after my 1997 Saab 900 Coupe is converted, including batteries, engine etc with 2 passengers on board, the car will weigh just under 4000 lbs.

What AC engine will be up for the job to at least reach 70 mph?

Benjamin


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## dubelt (Sep 27, 2011)

minimum 20kW


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## Benjamin515 (Apr 12, 2012)

Do you have an example of a proven model AC engine that is used by more EV builders?


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## dubelt (Sep 27, 2011)

no. this is power needed to move with speed of ~70mph and weight of 4000lbs.
pure mathematical equation result.


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## Nathan219 (May 18, 2010)

Our MES-DEA TIM600 and 40kw motor move our 3000lb car to over 130mph, it is expensive, hard to work with, but it does what it claims and then some.


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## bjfreeman (Dec 7, 2011)

do the calculations and the actual vehicle take Grades into account or are they just for flat land?


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## dladd (Jun 1, 2011)

power requirements for a certain speed on flat land based on a vehicle weight seem a little nonsensical to me...

weight is acceleration. Speed is aero.


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## Benjamin515 (Apr 12, 2012)

Yes it will be on flat land.

The car actually needs to go 62mph (100km/h) on flat lands to go on the highway's in Holland. But to constantly ask a peak voltage from the engine does not seem healthy so that's why I think it's better to choose an engine with a bit more power.

I don't need to drive that far per day, it will be somewhere around 19 miles but I want the car not to be a snail. And I don't care if the engine takes a lot of power and have to recharge her every night. Gas in the Netherlands costs 8.82 a gallon and rising quick. 

So, I need a somewhat powerful AC engine that takes a 4000lbs car to around 70mph. 

Anyone here with experience on AC engines for that weight, please respond.


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## Yabert (Feb 7, 2010)

Why that much weight. Lead acid battery?


Why do you need AC systems?

Cost wise? No!
Higher efficiency? No!
Regenerative braking? Well, yes, but.....


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## Benjamin515 (Apr 12, 2012)

Because I'm converting a 1997 Saab 900 Coupe and want an engine that has regenerative braking.


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## Duncan (Dec 8, 2008)

Benjamin515 said:


> Because I'm converting a 1997 Saab 900 Coupe and want an engine that has regenerative braking.


I would ask - Why?

Re-gen is OK but not worth a lot - 

if you drive nicely you won't get much benefit

If you drive like a hooligan ... then re-gen gives a good benefit

But if you want to drive like a hooligan an AC motor will be a bit sluggish- a DC series motor will give a lot more oomph for your money


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## Benjamin515 (Apr 12, 2012)

Why? Because I truly love the Saab.

So it is too enthusiastic to say that on average regen-braking extends your traveling distance with 20% to 30% with normal driving?


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## PThompson509 (Jul 9, 2009)

20-30% is a bit high. Highest I've seen is 15%. However, another big benefit of regen is that you don't use your brakes anywhere near as much. 

I've got a 80kw BLDC motor from China - despite the lack of customer support, it seems to be a decent setup. I hope to have the regen working soon.

http://en.glelec.com/cps/&productId=77cb016d-c8a4-431d-8ae6-fecb317ee74b.html

If you could find a company local that would deal with the factory, that would be ideal.

I'm sure there are other BLDC motors out there that you could find.


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## PThompson509 (Jul 9, 2009)

Sparky is running ok - no regen yet. Will play with that some more tomorrow. The motor/controller was through Dave Kois (no longer in biz) for $5.9K. I used to have a link to a person in NJ, but can't find it now. 

I'll look around some more - it may be that you'd have to import it either through a 3rd party or contact the factory direct. From my experience, it would be better to use a 3rd party - so try to convince your favorite EV parts supplier to do it. 

Cheers, Peter


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## Duncan (Dec 8, 2008)

Benjamin515 said:


> Why? Because I truly love the Saab.
> 
> So it is too enthusiastic to say that on average regen-braking extends your traveling distance with 20% to 30% with normal driving?



from what I have heard 
15% in city or very hilly driving
5% or less if its moderately flat.


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## Jesse67 (May 12, 2009)

Where do you get 4000lbs? 
http://www.vehix.com/car-reviews/1997/saab/900/vehicle-specifications

Base curb weight shows 2940lbs for a 2 door, 2980 for a 4 door, even with a lot of options it shouldn't be that much heavier. Even with a lead acid conversion I doubt you would add 1000lbs of weight on top of removing the engine and all its associated extras. You should lose at least 500lbs taking that out. Say 600lbs for 48 x 160Ah TS cells 23+ KWhs, 200lbs for motor and accessories, -500lbs for stripping the car out gives ~3300lbs. Unless you have five people in the car all the time? 

Good luck!

Jesse


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## Benjamin515 (Apr 12, 2012)

The weight of my Saab now is even lighter, it’s 2550lbs. But the engine is not 500lbs. It’s a 2.0 liter, it’s almost 200lbs. So when I take the engine out the car will weigh 2350lbs. 

I don’t know how you strip cars but I’m not stripping out 500 pounds when the engine is already out. 

So, 2350lbs the car weighs when the conversion starts. Let’s say your conversion weight is correct and have a total weight of 800lbs. That’ll make the car weigh 3150lbs. Three passengers of 85kg weigh 510lbs pounds. That’ll make the car weigh 3660 pounds.

The maximum recommended vehicle weight for the warp 9 engine is 3600lbs. But according to most conversions in my class of weight the total conversion comes down to 1000lbs added when the engine is taken out. So that’s an extra 200lbs on top of your estimate of weight and that will make the car 3800lbs. 

My line of thought is to choose an engine that can pull the weight instead of putting in an engine that is not designed for the weight or to constantly have a maximum work-load all his life to pull the car. Even your guess of the weight of the conversion comes very close to the maximum advised vehicle weight when not carrying any passengers. My guess of weight even go’s over the maximum vehicle weight of the Warp 9. That’s why I choose the Warp 11 engine.

Benjamin


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## Jesse67 (May 12, 2009)

I'm not making any motor recomendations, just talking about the weight. Remember you also get to remove the gas tank, exhaust system, cooling system, tubing, and any brakets and extra stuff that goes with them. That with the engine will weigh more than 200 lbs. I looked on EV album for an example but no one has any weight numbers for a Saab, there are quite a few conversions though and check out the pile of stuff this guy took out!

http://www.evalbum.com/3271

The 1000lbs conversions are most likely using lead acid batteries, lithium weigh 1/3 of that for the same capacity. What type of batteries were you thinking? What sort of range are you looking for? From my estimates based on the weight of the stuff put back into my mini truck conversion it should weigh at most 200lbs more than stock or under 1700lbs. That said I still need to actually weigh it but the weight of all the components you pick is easily available, piece together a hypothetical system, add up the weights and add 100 lbs for wiring, brackets and extras and you should be pretty close. 

Good Luck!


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## Ryan800 (Apr 15, 2010)

I agree that you're unlikely to end up with 4,000 pounds of car without really a lot of batteries. For one more example, my Saturn SW had over 500 pounds of engine-related crap that didn't go back in. Like your car, it is a 2.0L but it has an aluminum block and head so if anything you will remove more weight. Still, it doesn't hurt to over design things as long as it doesn't keep you from overlooking acceptable parts.

I also agree that DC will be cheaper for the same performance and range- about $3,000 for average performance and $5,000 for a fast car. But if you really want AC anyway (I did too), I've seen a few options. I went with Tritium, an Australian company that makes a nice controller for $6,000, or $7,000 if you include shipping and a few other gadgets that you will probably want to buy. It works with just about any AC motor, so depending on how resourceful you are, you could find one for as little as $1,000 or as much as you want.

There is also the Curtis/AC50 for about $4,500 plus shipping, which makes about 60hp. This would definitely be under-powering your car and I doubt you would be happy with it in the long run, but you could probably make it work.

Other AC options that offer good performance will start at $15k for motor/controller only and go up from there.

To answer your first post, use a Tritium controller with whatever motor they recommend for your application and expect to pay about $10,000, or try electro vehicles europe, which I think will have something with good power in about the same price range but I don't have any experience with them.


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## zafh15a (Mar 13, 2012)

I have looked for a powerful a/c motor/controller pair for a similar project. I desired a/c for the same reason (regen). I came to the conclusion that a power rich, plug and play a/c system for the *hobbyist* does not exist, or I can't find it. Maybe it will someday soon, but not now. It seems as a non-oem my choice was between the ac/50(not powerful) or one of the Siemens traction motor products (stupid expensive). Modified VFD's may hold some promise, but that solution is currently far from plug and play. 

let me restate my impression of your goals
1) ice replacement with a power level similar to original
2) regen braking
assuming these are your goals.....

O.K. I am going to write something that will make most people on this site freak out. There will be moaning and groaning and gnashing of teeth. Ready, drum roll.

Automotive alternators.....

Now when you get done cursing at the screen, wondering how can it be that yet another fool could be spewing forth this free energy nonsense, proving his ignorance of the most basic laws of nature and science. Relax no free energy here, for that you need to mount a wind turbine to the hood. (joke)

You can effectively utilize a series of pulse width modulated automotive alternators to provide a smooth natural "engine braking" feel thru modest hard braking. At the same time you can reap the rewards of converting the cars kinetic energy to a galvanic potential. The biggest issue is not the conversion of energy, or effective braking, but the utilization of the large amounts of energy converted in a small amount of time. 4,000 lb @ 65 m/h = 652,533 joules /?time? even after subtraction of all the the other drags (rolling resistance / aero ect.) which are quite large, that is still a lot of energy fast.

I know that 98% of the viewers are lighting their flame throwers now. I hate watching threads run off the rails. So I will leave it at that. If you would like more info on what I have done shoot me a message I will be happy share with you what I can.

Don't bother flaming me, I promise I will never write the word "alternator" on this site again. flaming me only serves to move the discussion away from the original question posed (not fair to original poster)

If you just have to flame me or want conversation on this topic go here so we dont hijack this thread http://www.diyelectriccar.com/forums/showthread.php?p=296247#post296247


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## Ryan800 (Apr 15, 2010)

If you're going to design custom electronics, why not just do a sep-ex motor controller? I think you're overcomplicating the problem.

As to the lack of availability of AC drives, did you check the links above? They are available at about 10k dollars/ 8k euros (I guess the EVE stuff would be about 10k euros). They're not common yet, but there are a few:

My Saturn

Z3

Miata

That's still quite a bit more than top of the line DC systems, which I think is why they are somewhat discouraged and less popular for DIY.


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## major (Apr 4, 2008)

zafh15a said:


> ....the utilization of the large amounts of energy converted in a small amount of time. 4,000 lb @ 65 m/h = 652,533 joules /?time?


Hi zaf,

I don't think we have a problem with alternators here  Just with people trying to use them for impossible purpose. And what you propose is not impossible. But I think impractical. 

So you have 650,000 joules /?time? Let's say you accomplish that stop in 10 seconds (not unreasonable). Then 650,000 Ws / 10 s = 65,000 W = 65 kW. And that is average power. As the vehicle slows, the torque would have to increase to maintain a constant power over the 10 seconds. So the peak power could be twice the average, 130 kW. That's a big alternator 

The basic problem with an additional machine and associated hardware solely devoted to regeneration is that the benefit realized in range can be more easily accomplished by increasing the battery by an equal mass, volume or cost. And that will be more efficient and reliable. Regenerative braking makes sense when done with the traction motor. It takes an unusual application to warrant a separate regen system IMO.

Regards,

major


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## Jesse67 (May 12, 2009)

I believe your average alternator can provide about 1kw, they certainly have more powerful ones (maybe 300A @ 12v?) but they are still not very efficient, I've heard on the order of 60%? The other thing you need to take into acount is braking control, if you have a rear wheel drive vehicle and you try applying full regen torque even with just a little AC50 system, you will spin some nice circles on the hiway. You will need front wheel drive to really take advantage and even then you need a way to dial it down for slippery conditions or gravel to avoid any unplesantness. 

I've personally driven this vehicle and worked with the guy who built it,
http://www.nappepin.com/LithiumHawk.htm
This thing uses an AC31 running at 126V, it weighs 900lbs and the gearding is such that he has full torque up to 100km/hr, 196km at 6500rpm. You get the same punch from 70-90km as you do off the line! It is scary fast and he's really had to dial down the regen to make it drivable. Trust me, you don't need a more powerful motor, you need a lighter car!


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## Arlo (Dec 27, 2009)

Are you looking for AC or PMAC?? I think the two are getting confused on this thread. Tesla used induction AC and there is a bigger version of the AC50 coming although I think you might find the AC 50 not bad for your build.


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## mizlplix (May 1, 2011)

B: Welcome to the forums.

First, The terminology "engine" is usually describing a gasoline fueled power plant. We in the EV community use the term "motor" to mean an electric powered unit.

OK,Then.You almost have the same requirement as a friend of mine. He is building an S10 pick up. It will probably weigh in at 3,500-3,800 Lbs when done with Lithium Batteries.

He was planning to use an HPEV AC50 and a 4 speed transmission for it.

It would have been slow in acceleration and freeway speeds would have required plenty of amps to maintain.

He is now investigating the conversion of an existing 3 phase motor to work in an EV. 


You might look there in Europe for an AC drive system. 

We have no"ready made" *affordable* systems that I know of, at this time...

Miz


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