# Motor Controller Combo, need advice.



## Mastiff (Jan 11, 2008)

I'm planning on building an electric two-seater Quadricycle out of mountain bikes and square steel tubing for the frame.

I plan on using a "used" Alltrax AXE 4855 500 Amp Motor Controller:
http://www.alltraxinc.com/Products_AXE.html

This controller has a 1-hour amp rating of 250 amps.

I plan on using it with a motor such as this one:
http://cgi.ebay.com/48-volt-CLUB-CA...ryZ64662QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


I want at least 200 amps worth of continuous power because I plan on moving a 600 pound(fully loaded) vehicle to 50mph and keeping it at that speed.

My question is for the motor and controller experts out there, will running this motor at 250 amps and around 2500 RPM(I'll have probably a 4:1 drive ratio) for 1-hour burn it out or be in any way stressful to it?


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## Mastiff (Jan 11, 2008)

Hmm, I re-did my calculations with an EV power spreadsheet and used the frontal area of a Honda Insight (0.5m^2) and a Coefficient of drag of 0.50 (Hummer H2=0.57) with a gradient of 3 degrees.

According to this spreadsheet it tells me to maintain 50 MPH I'd need 5100 watts of power (4500/48volts = 106.25 amps) this seems almost too good to be true.

The spreadsheet I used is available here:
http://www.cameronsoftware.com/ev/EV_EstimatingPowerNeeds.html

This means I could get away with an Alltrax AXE 4845 controller with a 1-hour rating of 175 Amps and have power to spare 

That certainly makes things cheaper.

I used this calculator to back up these results:
http://www.wemoco.com/pages/calculator/specs2.html

I used a frontal Area of 5.1 square feet (the Honda Insight)
Coefficient of drag of 0.5 (Hummer like)
Motor nominal voltage of 48 volts
Weight of 630 pounds
Percent grade of 3 degrees
Finally a Velocity of 50MPH
(tire size and gear ratio aren't needed they just effect the RPM's)

This calculator tells me I need a motor with a diameter of 7.2 inches and pulling 135.3 amps.

So I'd pull 110-140 amps to do 50MPH with the vehicle fully loaded up a 3 degree grade 

Assuming I used 4 50AH 12 volt batteries in a series string I would be pretty well off too under the 1C rate.

I'm not sure how to calculate my own frontal area but I plan on my vehicles frame and body being ~5 feet wide and 3-3.5 feet tall (you lay down inside it)
I'll design it with a gentle curve from the front going up to the passenger's heads then a steeper curve going in the back, this would give me a reverse airfoil shape creating down force instead of lift.


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## BenNelson (Jul 27, 2007)

I am using the 48 volt Alltrax 300 amp controller on my motorcycle.

I still haven't got an ammeter on it yet, but it is running at 36 volts, and weighs around 5 or 6 hundred lbs.

It has great acceleration, but limited to about 38 mph top speed. It is just a single gear to a rear sprocket 14 tooth to 72 tooth.

I haven't had any problems with anythiing getting to hot or not working yet.

If anyone has a spare ammeter to donate, let me know!

My cycle page for more info


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## Mastiff (Jan 11, 2008)

Thanks for that, I think I could go with a 300 amp Alltrax controller then, that will cut the costs by about $100 

It seems to me that if you added that 4th Optima battery you'd be able to do 45mph on your motorcycle.

One thing about a motorcycle is that you've got a high drag coefficient.

Check out this Wikipedia article on Drag Coefficient:
http://en.wikipedia.org/wiki/Drag_coefficient

0.9 Cd is a typical bicycle plus cyclist

So humans aren't very aerodynamic.

I plan on putting a smooth plastic shell body around this whole vehicle and I'm planning on a Cd of 0.5 or less. (a Hummer H2 is 0.57 Cd )

Also looking at having a Frontal Area of around 3.5 square feet.

I'm looking at a cost of $1600-$1900 to build the whole thing.

Most of that is the ~$800 worth of Optima batteries 

Perhaps I could go with lower end batteries?

Or maybe I should order a Honda Insight sized pack from LionEV for $1,125.00:
http://www.lionev.com/upgrade_to_Lithium.html

Hmm but the charging equipment makes it even more expensive sigh.


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## BenNelson (Jul 27, 2007)

Yeah, those Optima batteries are expensive.

I used them because they are sealed and therefore don't need to be accessable for watering.

I figured if I ever didn't want them for the motorcycle, they would make kick-butt car batteries, or lots of other great uses.

For the electric car I am working on, I am looking for some batteries replaced from a telecom system or somthing similar. If that doesn't work, then I will shell out the money for flooded golf cart type batteries.


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## mattW (Sep 14, 2007)

Just quietly this project sounds incredibly dangerous, 50 mph on a bicycle lead sled to me is just asking for trouble. In any sort of collision you would be stuffed as there is no safety measures whatsoever. I realise it would have a good novelty/uniqueness factor but its not worth killing yourself when you can buy a cheap car with things like seatbelts and crumple-zones. Not to mention it would be much more aerodynamic (less power required) and have much better handling. I don't like discouraging uniqueness but I just don't think its a good idea from a practical or safety perspective. Obviously its your life and you can decide what risks you want to take with it, just hoping its an informed decision.


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## Mastiff (Jan 11, 2008)

I wouldn't be driving it in any traffic, otherwise I'd convert a gasser.

Btw, I don't get in anything that goes over 25mph without seat belts

You do have a point though, perhaps I should just save up my money and build a full size conversion...


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## mattW (Sep 14, 2007)

Or you could make it a low speed town car, limit the top speed to something closer to a bicycle like 20mph then you can get cheaper parts this time and save the money for a full size conversion. You would learn a lot doing a smaller conversion first, my only problem with it was the 50mph stat (if you want to get anywhere that fast then use a real car). Were you planning on have two people upright on the bike seats or suspending reclined seats between the two frames?


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## BenNelson (Jul 27, 2007)

I agree about things that go really fast without seatbelts.

My motorcycle is just for local, in-town use.

I don't think I would ever want to ride a motorcycle on the freeway.

I saw a two-car collision a couple Thanksgivings ago while I was shoveling my driveway. Two cars hit each other, each going about 45 miles an hour.

The car start ended up almost hitting MY car parked in MY driveway after hitting the car on the road, had an airbag and the driver was really shaken, but ok otherwise.

The other car was crushed in on its side.

Now this was winter driving, I think both drivers were going a little too fast for conditions.

I only ride my motorcycle during the day on dry pavement.

Life is all about risk vs reward and the choices we make.

I think for an EV, range tends to be more important than speed. My next project is a low-speed electric car. Keep the costs down, has seat-belts, and is street legal


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## Mastiff (Jan 11, 2008)

I was planning on designing the frame so that you actually lay in a reclined position inside the vehicle, not sitting up.

A sitting up position would increase the frontal area of the vehicle too much to reach 50mph.

It's not going to be two linked bicycles that's for sure I wouldn't even go 30mph on something that top heavy or awkward, I'd ride a roller coaster for that kind of thrill 

The frame and the people riding would be sitting at the same level as the axles on the bicycle wheels, only about 6"-8" off the ground.

The frame was to be just over 5 foot wide and around 9-10 feet long so that I can get the correct sloped shape on the body to reduce drag.

I was going to build the whole thing out of 1" square steel tube and build a curved and reinforced roll cage over the top.

I plan on fully building the frame in a 3D CAD program I now have before starting the project.

Btw the 50MPH "top" speed was a goal because I'd like to impress people and show them what some simple aerodynamics can do to really improve speed and get them interested in EV's, I wasn't planning on driving it on the highway.

I'd drive it on 25mph back streets if I where to drive it into town, people drive their ATV's around here on back streets all the time and those are noisy, so no one would even know I went by with my silent EV 

Plus if I where to go anywhere else but town I couldn't use an EV, I live in the middle of nowhere, it's 40 miles to get to a Wal-Mart, over mountains with 5+ degree slopes on the roads.

Check out this google map of where I live:
http://maps.google.com/maps?q=Talihina,+OK,+United+States+of+America&sa=X&oi=map&ct=title
Click the "Terrain" button in the top right and zoom out.


So I guess this will basically be a NEV to beat all NEVs 

Thanks for the advice though everyone, I now know what I'll need to build this.


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## Bugzuki (Jan 15, 2008)

What CAD system do you have? I have Pro/Engineer WF3.


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## Mastiff (Jan 11, 2008)

I'll have Solidworks soon hopefully, if not I'll try to get Autodesk Inventor or Pro/Engineer.

I learned about Solidworks from this:
http://youtube.com/watch?v=UyMciBk5nco

From this video, I was hooked, a James bond car made in Solidworks:
http://www.youtube.com/watch?v=3cai9MOkJ6s&feature=related

Just Youtube Solidworks and you get a ton of videos.


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## Hi Torque Electric (Dec 23, 2007)

Hey Mastiff

That motor you linked to may not be the motor you're looking for as it's got a number of issues that make it ill suited. I saw it's bought but thought I'd throw some insite toward this motor.

There is no DE plate (which is obvious) but that shaft isn'ta bearing match and will need to be machined to take a bearing on top of needing to make a DE plate for it as well (which people have done). This motor is a short comm whos brush leads are a single 1/8 in diameter wire, and the brush ring holders are made from sheet metal (curls when heated, grabing the brush) rivited to an 1/8 thick fiberboard (tends to fry easier, plus warps easy as well). If you cook those field coils, there isn't an easy replacement for them as they're wound into that insert and then pressed into that thin outer housing. As there are no vent holes for the brushes it'd be hard to blower cool as well which would really really need.

Sorry I didn't see this post earlier but I hope late is better than never 8^)

Jim Husted
Hi-Torque Electric


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## Mastiff (Jan 11, 2008)

I'm not sure what your referring to by "DE plate" I assume you mean the (non existent) plate on the front of the motor near the shaft?

Also, your saying that this motor would need a bearing set on the shaft? I didn't realize this.

This is another example of what I was looking to buy:
http://cgi.ebay.com/48-volt-CLUB-CA...ryZ64662QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

From my understanding of the rest of your post if I where to put too much power into this type of motor basically it would be damaged beyond repair?

What type of motor would you suggest then?

Also forgive my ignorance with electric motors, I'm a computer guy, never built anything mechanical, thus why I'm asking advice here.


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## BenNelson (Jul 27, 2007)

Mastiff,

Jim is referring to the fact that the motor doesn't have an end plate on the Drive End.

Those are designed to go directly into the differential on a golf cart. I believe that the shaft itself is supported and stabilized by the differential.

This picture should give you an idea.









Note that this is a double-ended golf cart motor. The driveshaft sticks directly into the differential it is attached to. The other tailshaft had a parking brake attached to it


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## Mastiff (Jan 11, 2008)

I understand, so basically I'd have to build a custom faceplate with bearings to support the shaft.

Sigh, more and more problems.

Thanks for the reply.


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## Hi Torque Electric (Dec 23, 2007)

Hey Mastiff

That's another short comm / no drive end plate (DE) motor. Of course you can machine a plate for it, and machine the shaft to fit a bearing, and modify that shaft so you could mount something to it. But at what cost in materials and effort. I couldn't find exactly comparable, but this 12 volt motor has the DE plate, has a shaft that would be way more user friendly, is a long comm, ect, and for an extra 60 to 70 bucks is well worth it. Ebay number 160119949871 in case the link doen't work.
http://cgi.ebay.com/Clark-electric-...ZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem

This just a 12 volt but they do make 24 and 36 volt versions although Father Time does use a 12 volt motor much like this on 120 volts on FrankenDragon 8^o
Hope this helps
Cya 
Jim Husted


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## Mastiff (Jan 11, 2008)

Perhaps I should go forklift hunting huh?

Thanks for the help, I'm glad you pointed that out before I bought anything.

Now I need to re-evaluate my plan.


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