[85bmw528edude]

I have always been interested in new technology. I am a soon to be 48 y.o. who likes the idea of an battery powered vehicle. I have an old BMW 528e that I would love to convert to a total battery/electric vehicle. I am not in love with the idea of a DC car. I am an electrician by trade and I know how dangerous an DC electric system can be. I have read some of the stuff on the web about Metric Minds AC powered cars. I realise that the AC projects cost more to build. So to those of you with experience in this field. here are some requirements I would have from an electric commuter car.
1) I need a vehicle with a range of about 75 miles off 1 charge as I do not have yet a place to plug in during the day while I am at work.
2) I need to be able to reach 70-75mph on the freeways as my commute is mostly Interstate driving on mostly flat, but some slightly hilly roads.
3) I need a practical heating system for the winters.
4)I need to be able to run the AC system in the summer due to high humidity in my local.
5) I need to maintain my power steering.
6) The candidate for conversion, I have has a 5 speed transmission.
7)I really love the car and its ride and its looks.

So my ?,s are
a)Is this a reasonable project?
b)What AC equipment is neccesary to obtain my requirements?
c)What equipment(manufacturers, models, etc)should I be looking at?
d)what books should I be looking at?
e)Anyone I should be picking their brain?

I am looking to start this project in about 18 months and I want to have a plan in place of equipment to purchase. I will have to do it in stages, The purchases, that is.
BTW I have another car, so that will allow me to have this vehicle apart for a while, without any time constraints/deadlines.
I really would appreciate any comments, suggestions. I am a newbie, so please don't flame me to bad. Thanks! Shanno

 

[85bmw528edude]

Well, I guess no one thinks much of my ideas for an AC drive system. Anyone have anything to say or suggest?

 

[TheSGC]

What you are asking for with the 75 mile range at 70-75 MPH is really out of the range of affordable EVs. But it is very possible, with the AC system you suggested and a lot of money. Here is a break down of what would be required:

AC Motor/Controller/Inverter -(which is usually a package deal)
Direct Drive- since I believe the Metric Mind kits have direct drive couplings and have no need for a transmission.
Vacuum Pump for brakes
DC/DC converter for accesories
4/0 gauge wiring (Highway speeds = lots of amps)

And lithium batteries. I would say 288 volts of 160Ah batteries should do it, but they are expensive.

Now some good quality AGMs might be up to the task of 75 miles, but it would be under 40 MPH and getting a lot of help from regen breaking. Lithium would be the way to go. We have Solectria Geos at my college and they get about 60 miles at highway speeds on lead acid, 80 miles on NiMH and an estimated 160 miles on the 160Ah lithiums, but they haven't been installed yet because we don't have the BMS systems in. (And these are about 300 volt cars.)

 

[85bmw528edude]

In the next 2 years I could see spending about $3000.00 the first year, spending $5000, the next year and spending upto another $5000 the 3rd year. Unfortunately I have bills to pay so that limits the cash outlay at 1 time. I can do the work. I was just hoping that their were cheaper places than Metric Mind to source some of the parts. I have seen the EVALBUMS and they have some nice projects on that website. I just liked the idea of an water cooled system mostly and that AC power doesn't have the same inherent dangers that DC power has. Well anyway I was hoping for suggestions on what to do. I have also thought about waiting on the car project and doing an electric dirtbike project and then doing the BMW. I have an old Kawasaki KX 250 with a bad engine that would make a nice bike something like the bikes that Quantya makes but without an $11,000 price tag of a new one. Well anyway, no matter what I like the idea of an electric powered vehicle and no emmissions and no gasoline.

 

[saab96]

Time to go through the stages of grief because cheap EVs have lots of compromises. You get what you pay for.

 

[LeTank]

I would read thru this first to see what you may like for your options in an AC motor or DC if you change your mind.
http://www.diyelectriccar.com/forums/forumdisplay.php/electric-motors-37.html?

Then as an electrician, I would use what you currently know and apply it to the vehicle as much as possible for any AC project.

Now, you have research ahead of you, but I went cheap, i mean dirt cheap in making my EV with AC equipment. Such as just using a 10,000 watt inverter (with my own makeshift three phase box and controller) and 12 Volt batteries to run my 15 hp AC motor. I cannot say it was any more efficient than a DC motor, in fact my mileage was abour 45 miles and I had a top speed of 57 miles per hour with my AC motor.

I wouldn't take anything I have done as a good project, but as I said I went cheap. I would do my second one right to have more miles and more speed.

I would read through this forum in any areas dealing with AC powered EV's before making a real choice. I would not want to give you any wrong advice and I surely would not want anyone to follow my footsteps in going "dirt" cheap and have to redo it again later. (As I am revamping the whole project now for 2009.) I hope others who have converted theirs to AC will give you more options as well.

I can't see what you mean about DC being more dangerous, in fact, DC is safer than AC. Or was it a typo on your part?

Good luck and the choice of vehicle sounds great.

 

[1clue]

I saw your post earlier, when there were no responses yet. I didn't post because I have all research, no experience.

My reaction was pretty much what everyone has said so far, which means my research has put me in the right frame of mind. That's good for me, but not so good for you.

I too think that AC is the only way to go. I'm just not interested in a DC car, I looked into them at first and then decided on AC. I also don't have a lot of spare cash.

What I intend to do is build an AC bicycle conversion, or maybe a trike. FWIW, most of my trips could be easily done if I had a trike with a rain shield of some sort, and think of the economy you could get! Miles per penny I would guess. If I use the same design criteria I would for a car, it should be a good training exercise.

By all the standard calculators, you would be pushing the limits with the 70 mile limit, and that would be slow. So you're stuck with modern expensive batteries. Your BMW is certainly not an econobox, so the rolling resistance will not give you any breaks there.


If you have a car handy and don't need to get it done right away, then it would be reasonable to start your conversion now, get it all cleaned up and painted and the parts removed. Then get the motor and controller and put that stuff in, and then start saving for batteries. It's possible that the battery technology will get cheaper in the time it takes you to finish your car. They should be bought last anyway, because they age even if you don't use them.

 

[Guest]

What inherient dangers does DC have that makes it safer than AC? A hundred years ago, Rural electrification was bringing electricity to rural communities. Two competing companies, Edison Electric was a promoter of DC systems. Westinghouse Inc was a proponent of AC power systems. The two companies sent teams of salesmen to rural communities to get the contract to build the power plant and wire the town. Edison's electric sales team caried a portable power unit with both DC and AC generators. They would stop at the dog pound and get a few strays and take them into the town square. There they would set up a demonstration and try to ELECTROCUTE the dogs. DC only caused a burn mark where the wires were connected, because DC ionises the moisture in the skin, making gas bubbles which then insulate the living tissue from further damage. (At voltages of less than 300 volts DC) On the other hand the dog electrocuted by AC was killed. AC passes into the living tissue and interfiers with nerve activity, if the current passes thru the heart or brain the subject dies! ( and it only takes 35 volts AC or more! ) And AC causes muscle immobility but DC does not. It is the skin that protects us from electricity, so do not cut yourself on a live wire for only three volts AC or DC can kill you if there is internal blood contact! Your body is not comfortable acting as a live wire, so insulate yourself.

 

[1clue]

What inherient dangers does DC have that makes it safer than AC? A hundred years ago, Rural electrification was bringing electricity to rural communities. Two competing companies, Edison Electric was a promoter of DC systems. Westinghouse Inc was a proponent of AC power systems. The two companies sent teams of salesmen to rural communities to get the contract to build the power plant and wire the town. Edison's electric sales team caried a portable power unit with both DC and AC generators. They would stop at the dog pound and get a few strays and take them into the town square. There they would set up a demonstration and try to ELECTROCUTE the dogs. DC only caused a burn mark where the wires were connected, because DC ionises the moisture in the skin, making gas bubbles which then insulate the living tissue from further damage. (At voltages of less than 300 volts DC) On the other hand the dog electrocuted by AC was killed. AC passes into the living tissue and interfiers with nerve activity, if the current passes thru the heart or brain the subject dies! ( and it only takes 35 volts AC or more! ) And AC causes muscle immobility but DC does not. It is the skin that protects us from electricity, so do not cut yourself on a live wire for only three volts AC or DC can kill you if there is internal blood contact! Your body is not comfortable acting as a live wire, so insulate yourself.

And to combat that FUD, Tesla used to do demonstrations of his gadgets and used his own body to complete the circuit.

The increased danger is only in the range of 50-60 HZ. At different frequencies, the danger is similar to DC. Considering that the only AC thing in the whole care is the motor, which changes frequency depending on speed, the risk doesn't seem to be all that high to me.

And the way I read the book, Edison didn't get all of his critters from the pound. He would nail dead electrocuted animals to light poles with a sign that said, "Westinghoused." It was not uncommon for someone to find their pet on that light pole. He also tried to make AC current illegal by petitioning state legislatures with these demonstrations. Very little of it had any substance behind it, it was pure marketing.

If someone used Edison's techniques today, they'd wind up going bankrupt because all the animal rights activists AND pet owners AND just about everyone else would go ballistic.

What I never figured out is why Tesla/Westinghouse didn't just change the frequency to something dramatically different. 1 khz would be much easier to make transformers, motors and DC power supplies for if my limited understanding of electronics is anything close to right.

 

[gmijackso]

60 Hz humm is annoying, but a 1kHz squeel would drive you nuts. It's also (mostly) about wavelength. If the transmission lines are a wavelenth of the frequency or a proper fraction thereof, that transmission line becomes an antenna and you start radiating power. That's bad.

This (from what I understand) is the reason the supergrid is DC instead of AC. It just happened that the length of transmission was problematic for 60Hz.

AC won the Westinghouse/Edison debate/war because it is woefully inefficient to carry DC. The "safety" factors they both employed didn't really mean much. The main difference in safety is that a high ammount of DC will effectivly blow off any part of you that touches it. The moisture vaporizes so quickly that it explodes. AC forces the muscles to contract and if you've touched it with the palm of your hands, you'll not let go and grab tighter.

Another thing that should be noted, it that almost everyone is kinda using AC in their EV. Even if you're running a DC motor. If you're using PWM, it's not much different than running AC. Think about what AC looks like (sine wave), then think about what your PWM signal looks like at 50% (50% square wave). As far as most equipment cares, they're the same (providing they're at the same frequency). The difference is that the PWM never falls to a negative voltage, therefore technically not alternating current. But if you were to DC offset an AC signal enough that the negative peak were at 0V then you'd be back at 50% PWM. The other difference is how you control the speed of the motor.

BUT to remain on topic for a bit of the post. I agree with eveybody else. Your goals are pretty lofty for somebody with "not much money" unless your definition of "not much money" is significantly different than mine.

 

[85bmw528edude]

Thanks All, for the advice. I am going to start with an electric dirtbike. I have found a decent Kawasaki KX250 rolling chassis. Not sure yet on all the components yet, but leaning toward the Perm132,Alltrax 7234,not sure on batterys yet, probably sealed lead acid. I will appreciate any suggestions advicegiven, thanks!

 

[85bmw528edude]

Thanks, I think that I am on the right track. I am a big fan of the Quantya bikes from Switzerland and the Blade. I have also seen a couple of bikes that were homebuilt with an old rolling chassis that I really like. This project would probably be a good test bed for a first time builder/converter. I have bought an 92 KX250 rolling chassis and will piece by piece aquire the parts and then the batterys last. I am not sure if I can do 72 volt battery pack, I am sure I can fit 48 volt pack, though. Any thoughts. I would like to be able to get up to 50 mph and 15-20mile range to start.