electric motorcycle project

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jyracing
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Hi all, Chas and Link,
The trike was a success but it was too slow and had very little suspension. So now I'm on to my next electric project. A street legal electric dirt bike based on a 1985 Honda CR250 rolling chassis. The EleCtRic 250! To start the bike project I scavaged some of the parts from my electric trike. I'm using the two 24V/22A/2600RPM motors and the two 12V/125AH batteries from the trike. I first tried to use the 24V/30A controller like on the trike but it wouldn't work. When the 25-1/2" diameter rear dirt bike wheel and a 144 link #520 chain (versus the trike's little 10" wheels and 2' #25 chain) is off the ground with no drag, everything was doing what it supposed to do.
But on the ground the bike wouldn't move at all. Even when I ran beside it pushing it and applying full throttle the bike wouldn't sustain movement on its own. The huge rear drive wheel was just too much for the small scooter controller. I needed more amp availabilty. So I removed the 30A controller and wired the motors through a 50A switch to the batteries. That made a big difference. Lots more power/torque without the amp limiting controller. I can walk beside it flicking the switch on and off so it wouldn't move to fast.
Now I have a new problem... Without the controller to limit the amps the wires are getting too hot just from walking beside it as it moves slowly under its own power. I haven't tried to ride it because I'm sure the wires would melt. I going to solve the wire problem and try to ride it. But then I will most likely fry the little motors, if I dont limit the amps they can draw from the 125AH batteries.
Any idea on what size controller I should move up to? 50A? 100A for this bike?
And, I thinking of a single 4 to 8HP motor next?

Thanks,
James

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LinkOfHyrule
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Re: electric motorcycle project

WB. ;)

First: You need a bigger motor. For sure. IMO, the minimum for a "motorcycle" is around 72V and 100A. To give you an idea of the power some have, if I end up with the money and time in the near future, my motorcycle will be something like 96V 1,000A, which should be comparable to a racing bike.

I'd suggest something like this as a minimum:

\

It seems to be a little overpriced there, so you might want to check out other places.

Second: Few motors that large run on 24V, unless we're talking about R/C motors (but then there's a whole host of other technical issues). So, you're going to need at least 48V, preferrably 72V. Since that many 125Ah batteries would weigh a ton, something like 50Ah would be more suitable.

Third: How's your budget this time around?

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jyracing
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Re: electric motorcycle project

Hi Link,
Thank you. Nice to be back. I bought two IE street legal dual sport bikes in the last few months so EVs went on the back burner. Then I came across the rolling CR and the light bulbs started going off in my head again.
Wow! 96V and 1000A??? 96,000 watts? 128HP? Can I ride it??? I just want to cruise around at 30 MPH, not break the land speed record :)
First, I agree. A bigger motor(s) is a must in Phase Two. The two little motors are only held on by two bolts. That 1000W motor you suggested doesnt seem like much of an upgrade from my 700 combined watters? Is it?

Second, I have already mounted the big batteries (lots of welding, although I could bank a bunch of small batteries in the ~15"x15" box I built too) and I want to run them for now
cr250side.jpg
cr250batts.jpg
cr250motors.jpg

so right now I am limited to a 24 volt motor(s). I'm looking hard at this 24V/4HP motor
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=230284755625
What do you think of it in staying with my 24V parameters? The 8000 RPM seems like a bit much.

The prices for 150 to 200A controllers are ridiculous so I am leaning towards a 150A solenoid setup
cr250electrical.jpg
(dont tell Gramps).

Third, Unlimited, but as cheap as possible in the experimental stage. And, I have to at least try it my way first. You know me, I try to reinvent the square wheel.

JY

reikiman
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Re: electric motorcycle project

JY, Hunt around the motorcycles at evalbum.com .. it should give you lots of ideas. My motorcycle runs at 60v and cruises at between 100A-200A. It gets up to 48 miles/hr though I'm not sure but think there may be a friction problem somewhere. It's a very nice ride.

You describe high powered controllers as 'ridiculously overpriced' .. uh .. yeah, sure. I kinda agree. But they do work really well.

As for your design ... it's almost exactly the same as a design in a booklet I have.. this booklet was printed in 1967 and shows how to build an electric motorcycle. Using 1967 technology. No MOSFET's so for speed control it has a 100 watt rheostat and some relays. (reinventing square wheels, indeed!)

Where you're heading is to use the relays to switch between 12v and 24v and I suppose with enough relays you could go to 36v or 48v the same way.

I can't imagine speed control using relays would be very .. uh .. smooth. Um. With these modern MOSFET based controllers you can incrementally change the speed from very slow to very fast and it's smooth as silk.

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deronmoped
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Re: electric motorcycle project

Is that a O-ring chain you have on the bike? That and the knobby tires are probably robbing gobs of power.

I have always though a motorcycle was just overkill for a EV. Now if it was for the freeway, the extra weight would make for a nice stable bike. For the city streets I would look into a much lighter bike, like a scooter or a moped. Actually I would just find a heavy duty full suspension bike that could handle 35 to 40 MPH. Starting off light makes everything so much easier. In fact I surprised that someone is not manufacturing a bicycle like a crossover electric bike. Full suspension, heavy duty tires and wheels, heavy duty frame, a real seat, a full set of lights... Not sure if I would bother with pedals or not. A electric bike has to live within the limits of a small battery pack, it needs a whole new design and category, not trying to be a blend of motorcycle or scooter and bicycle.

40 MPH top speed, 40 mile range, I think it could make a killer bike.

Have you guys seen anything like a purpose build electric two wheel style transportation?

Deron.

Brutus361
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Re: electric motorcycle project

Hi Jyracing,

I made my electric motocross, for a CR-250 you need at least an ETEK-R or an ETEK-RT. With an Etek-R for this motocross you can use it everywhere, at slower speed. On a paved road the top speed is 45 Mph, but with SLA batteries your motocross will be really heavier. You need a lot of amps for a good range. For motocross trails 72 volt is better, no doubt about it(my next upgrade).

I use an Etek-R at 58.8 volt, 45 Ah Li-Mn, Alltrax 4834 (300 Amps) and it weight 150 pound. I use it on quad trail with a lot of sand or mud, I have a range of about 50 Km but the average speed is around 35 to 45 km/h. I can go faster but the ride is shorter as the speed goes up.

So if you want an electric motocross for this kind of trail. I strongly recommend a great LifePO pack 40 amps and more, 72 volt, Etek-RT now you have a "real" motocross with a great range!.

http://www.evalbum.com/1709

Good day!
Brutus361

LinkOfHyrule
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Re: electric motorcycle project

Now that I think about it, what's the gearing on that thing? Might be a little high.

jyracing wrote:

Wow! 96V and 1000A??? 96,000 watts? 128HP? Can I ride it??? I just want to cruise around at 30 MPH, not break the land speed record

Heh. It'll be a long way off yet. I don't even have a motorcycle license yet (hopefully get one in a few months...)

And I haven't specced out the FETs in the controller I'm planning on using, yet. For all I know, they could be only rated for 50A or something and I could get away with 2,000A. If they really were rated for 50A, then I could actually get away with 3,000A if I replaced them with 4110s, but that'd be pushing even A123s, and I'm pretty sure no motor of a suitable physical dimension yet exists that could handle that kind of power.

Quote:

First, I agree. A bigger motor(s) is a must in Phase Two. The two little motors are only held on by two bolts. That 1000W motor you suggested doesnt seem like much of an upgrade from my 700 combined watters? Is it?

It's only RATED for 1,000W. In reality, it's going to want something like 60A or more. Plus, I'd bet it'd be okay on 60 or even 72V, giving it that much more power. It's possible to find motors about that size for relatively cheap, and, since it's brushed, a simple modded controller will also allow to to handle that power for cheap. I pointed it out because there's a huge power gap between similar motors and something like an Etek.

Quote:

Second, I have already mounted the big batteries (lots of welding, although I could bank a bunch of small batteries in the ~15"x15" box I built too) and I want to run them for now

so right now I am limited to a 24 volt motor(s). I'm looking hard at this 24V/4HP motor
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=230284755625
What do you think of it in staying with my 24V parameters? The 8000 RPM seems like a bit much.

The specs are comparable to to motor I linked to, actually, but the 8,000RPM would require a reduction for it to be usable. Otherwise, it might be okay...

Quote:

The prices for 150 to 200A controllers are ridiculous so I am leaning towards a 150A solenoid setup

Mod one. A normal brushed controller with some 4110s and new schottkys in it will take some serious power. My YiYun will handle 100V already, would handle around 100A if the schottkys were replaced, and it's only got two FETs. One with four would be perfect, assuming you could find one. There's also the option of putting the FETs on another PCB to add more, but that also might entail replacing gate drivers and a fair bit of rewiring. Not recommended unless you have a good idea of what you're doing.

Quote:

Third, Unlimited, but as cheap as possible in the experimental stage. And, I have to at least try it my way first. You know me, I try to reinvent the square wheel.

Fair enough. ;) Incedentally, what do you plan on using this for? Recreation? Commuting?

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jyracing
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Re: electric motorcycle project

Hi David,
Spent a couple of hours browsing Evalbum. Great site! Thanks. I have read several of your blogs. I especially enjoyed your Strange ride home and thought provoking Lectra fairing blogs. Did you get the fairing mounted? Would love to see a pic of it. Would love to see that '67 book of yours too. Especially the pics and diagrams of the electrical setup and the solenoid(s). For now, I want to ride as smooth as burlap in phase one. Motocross riding is somewhat seat of you pants WOT or hard braking anyway. In phase seven when I want a Cadilliac EV I will pop into the 7gen store and buy an EV rider :)
I like that multiple solenoid idea though. 12V then 24V. Sounds good. If I can split the voltage of two batteries with solenoids, I wish I could double the voltage with just solenoids. Its like trying make a half full (or half empty) glass of water into a full glass of water without adding any water. How about pouring the water into a smaller glass so the new glass is full, i.e. overvolt a 12V motor at 24V since doubling volts quadruples HP and doubles RPM. In effect a 1/2HP 12V motor becomes a 2HP motor with 24V batteries? Two 1/2HP 12V motors in parallel put out 4HP? 4HP is my phase two target goal.

sawracer
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Re: electric motorcycle project

"The specs are comparable to to motor I linked to, actually, but the 8,000RPM would require a reduction for it to be usable. Otherwise, it might be okay..."

I don't understand the 8000rpm issue. Does that mean it operates at 8000 rpm at max efficiency, thus wanting to gear it so it spends the most time there? I have been watching those motors too. My motorcycle project worked but the motor is gutless so I got my ears on for a replacement. I hope this isn't considered a hijack.

jyracing
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Re: electric motorcycle project

Hey Deron,
Does the O-ring chain have more or less friction? It's a new cheap 144 link heavy non-Oring chain. It has lots of stiff slack warpage under RPM too. Hopefully it will loosen up some when it breaks in. I found an aluminum Oring chain.
Gotta have the knobbies for off-road. Thats where it will spend 99% of the time.
Great Idea... A EV mountain bike. Blend away. I dont see much difference in motorcycles and scooters anyway. Just weight and power categories for Capitalistic marketing? Dont forget mopeds, with peddles that are never used so the government will leave us alone. Bicycles are in a whole different category... Peddles. So lets make a 8HP full suspension mountain bike? I will add peddles to my CR250 and make a moped? :)

jyracing
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Re: electric motorcycle project

Wow, nice bike Brutus. Looks like a Zero X too. 140 pounds? My batteries weigh more than your whole bike. Zero to 45 in 3 seconds? That's a rocket! You must weigh 60 pounds? Have you jumped it much? How does it work on doubles or on the whoops? Put the peddles back on and we have Deron's mountain bike.
I will keep the Etek and lifePO info. I will be in Quebec next month. Should I bring my helmet? I would love to thrash on your 8 grand EV :) Come to SoCal and you can thrash on mine.

jyracing
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Re: electric motorcycle project

Link, Gearing (right now) is 10/51. I can go any size on the motor sprocket from 10 to 18 when I use a bigger motor(s). And, there are several size 85 XR250 rear sprockets available. I will know which motor I am going with for phase two in 1d 2h 39m. Most likely the 24V/4-8HP/45-150A motor I mentioned above. If so, I need to do something about the 8000RPMs.
Okay, you build your rocket now and I will ride it until you get your license?
I will find out what the heck FETs, 4110s, schottkys, PCBs, gate drivers, and A123s are and get back to you on them.
My little motors are only rated at 22A, but I was blowing 40A fuses just starting it up off the ground with only one motor hooked up. So I bypassed the fuse. Straight thru 125A to the motors. Haven't fried the 50A switch yet. You people and your damn controllers. Controllers are in phase 4. I want to at least try a solenoid before I give up and bow down to a controller.
Use is going to be 99% recreation (off-road) and a fun street legal 30 mile round trip grocery getter... hopefully
JY

BTW, whomever moved my blog to Custom builds or home-built, thanks. I didn't know it existed. This category doesnt appear when I go to forums, electric rides, motorcycles and large scooters. It just says E Max after that

LinkOfHyrule
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Re: electric motorcycle project

Quote:

i.e. overvolt a 12V motor at 24V since doubling volts quadruples HP and doubles RPM. In effect a 1/2HP 12V motor becomes a 2HP motor with 24V batteries? Two 1/2HP 12V motors in parallel put out 4HP? 4HP is my phase two target goal.

That might help. You'd have to drop the gearing to half of what it already is, though.

One thing you have to remember is that motor ratings are basically complete and utter crap. For example, the 125A you're drawing? At 24V, that's 3kW, which is already 4hp.

Thing is, you're only doing it in the motor's low-rpm range, where it's getting that much power in, but, mechanically speaking, it's not putting near that much out. A lot of it is just heating up the motors.

Quote:

I don't understand the 8000rpm issue. Does that mean it operates at 8000 rpm at max efficiency, thus wanting to gear it so it spends the most time there? I have been watching those motors too. My motorcycle project worked but the motor is gutless so I got my ears on for a replacement. I hope this isn't considered a hijack.

That's probably how fast it should be spinning at 24V under a normal load. I'm guessing that it's also quite high in it's RPM band, so efficiency is likely pretty good, too. Gearing a motor is a very subjective process. It will determine your top speed for a given voltage, but too high and you'll have terrible takeoff or even fry the motor. You have to either find the right balance of top speed and acceleration/efficiency, or find a bigger motor.

Quote:

Okay, you build your rocket now and I will ride it until you get your license?

Got around $15-20,000 for batteries? I'll make you your own rocket. :P

Quote:

You people and your damn controllers. Controllers are in phase 4. I want to at least try a solenoid before I give up and bow down to a controller.

Yes, us and our controllers, brushless motors, lithium batteries...Freakin' technology...

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deronmoped
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Re: electric motorcycle project

Yeah,

I would think that you would want the lightest non O-ring chain you could get away with. The O-rings are to keep the dirt out, but I'm sure they add a lot of friction.

Reminds me a flywheel powered bike I tried to build as a kid. Put a huge 25 lb flywheel on a bike and reduced it through a bunch of pulleys. I could get the flywheel spinning like crazy, but the multiple pulleys would eat up all the power before it got to the wheel.

Deron.

Brutus361
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Re: electric motorcycle project

Hi Jyracing,

Thank's but my bike weight 150 pounds, I have steel swing arm and frame. I fact this motocross accelerate from 0-30 Mph in 3 second, I correct it on evalbum. I made many mistake's, when I made this motocross and I will modifiy this motocross again. Until now the cost of my motocross is higher than a brand new Zero X.

But my motocross as a bigger batteries pack (2.3 KW/h) Zero X (2 KW/H), Quantya (1.9 KW/h). With the torque I have now, this motocross is able to climb any sand hill's on a quad trail. I'm in the north of Quebec is 800 km from Quebec City. If you drive my motocross one day, is better to bring a helmet this motocrcycle can really kick you out!

My batteries pack is able to give 10C and 16C peak. Do the math:

58.8 volt x 300 Amps = 17640 / 746 = 23 HP is more than a CRF-230 for a lighter motocross but the top speed is lower.

Good day!
Brutus361

jyracing
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Re: electric motorcycle project Phase Two

Well guys, phase two is in full swing now... I hope. I picked up a new Western Golf Car golf cart motor tonight. Its a GE 48v/7hp cont/133A/4200RPM series wound motor, model 5BC49JB1127. Did I buy a monster motor or a 60 pound boat anchor? Be gentle.
You guys said to go with more voltage and technology. Link, I dont think I will be able to control this beast with solenoids. I have been looking at the wiring diagrams for 48v golf carts and I am really confused now. There are 4 connectors. Forward and reverse? 19 splines and no protruding shaft. Gonna be tough to mount a 520 chain sprocket on it.
What now?
JY

Brutus361
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Re: electric motorcycle project Phase Two

Hi Jyracing,

Is hard for us to tell you what you need, because we didn’t' know exactly the project you have in mind.

What is the purpose of this motorcycle, motocross use or street use or both?
What kind of top speed you expect?
The average cruising speed you expect is?
What kind of range you expect?
The weight of this motorcycle is important or not?

With all of those questions is easy, for us to help you much better.

For 48 Volt set up:

With the GE motor you have enough torque and power to reach 50 Mph on that kind of road with (4) 12 Volt 125 amp battery, downside Is quite heavy. To ride this motocross on quad trail this motocross have bad handling, is to heavier to do this job correctly.

For 24 Volt set up:

With the GE motor you have enough torque and power to reach 30 Mph on that kind of road with (2) 12 Volt 125 amp battery, better in term of weight, but half the range. The most important factor for any EV is Watts/hours. More Watts/hours more running time you have.To ride this motocross on quad trail this motocross have a much better handling than the 48 Volt version but still not funny to use on that kind of trail.

When you build an electric motocross you have always to deal with compromise, or you go with top technology at higher cost to meet your goals.

Have a nice day!
Bikeraider

LinkOfHyrule
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Re: electric motorcycle project Phase Two

jyracing wrote:

Did I buy a monster motor or a 60 pound boat anchor? Be gentle.

Oy, golf cart motor...Does it have a faceplate? Most of the ones I've seen don't have faceplates. They bolt up directly to the transmission of he cart, so they can't be used unless they have one machined for them.

jyracing wrote:

Link, I dont think I will be able to control this beast with solenoids.

Golf cart motor? No. No you won't. Those things draw hundreds of amps even WITH the controller. I don't even know how many they would draw with none. :O

jyracing wrote:

There are 4 connectors. Forward and reverse?

Field and armature, I'm guessing. Some golf-cart motors have separate connections for their field windings. This way, they can be run as series or sepex motors.

jyracing wrote:

19 splines and no protruding shaft.

Reason #2 I haven't got a golf cart motor myself. There's no getting around the fact that some machine work is going to be required here.

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Re: electric motorcycle project Phase Two

Quote:

Field and armature, I'm guessing. Some golf-cart motors have separate connections for their field windings. This way, they can be run as series or sepex motors.

a SEPEX controller won't drive a series wound motor as a sepex. most of the field windings on sepex are ~30V for golf carts/smaller controllers.

The 4 posts are because on a series motor, to change direction, you have to switch polarity on the field windings.

Series are for series applications. Sepex is a more complex type of motor, because you can overspeed it, and reverse it on the fly. There are curves that interract between the field and armature to get it working.

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jyracing
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Re: electric motorcycle project Phase Two

Oy is right Link. At least you didnt say boat anchor. No faceplate.
5BC49JB1127a.jpg
I'm thinking of making an aluminum faceplate mount with a 19 spline male adapter and pillow block(s).
I'm assuming that it is 133A continuous. How many amps will this draw at max? 600A?
Actually, the early 36 volt golf carts came with 4 solenoids... before the fabulous age of technology.
198536vs.jpg

Hey Frodus. Field and armature? It looks like A1 is the battery positive. Is A2 the battery negative?
Can I ignore S1 and S2 or do I need one of them (or both) to control the direction the motor spins?
Say S1 for CW and S2 for CCW?
Thanks Guys
JY

reikiman
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Re: electric motorcycle project Phase Two

You need all four A1/A2/S1/S2 ... Oh, A1/A2 is both ends of the armature, S1/S2 is both ends of the shunt? Anyway what I would suggest is head over to the alltrax site and look for their documentation. Some of their wiring manuals describe how to set up Forward/Reverse wiring of this kind of motor. If you study the arrangement it will come clear to you how to do this right. Obviously a motorcycle doesn't need F/R except where I had to work this out was with my three-wheeler which clearly does need F/R support. Anyway the two-wheeler motorcycle only needs F and so you can hardware the A1/A2/S1/S2 in one direction only, and the alltrax manuals will show you how to set it up. I suggest looking at these even if you're not gonna use an alltrax controller.

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LinkOfHyrule
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Re: electric motorcycle project Phase Two

frodus wrote:
Quote:

Field and armature, I'm guessing. Some golf-cart motors have separate connections for their field windings. This way, they can be run as series or sepex motors.

a SEPEX controller won't drive a series wound motor as a sepex. most of the field windings on sepex are ~30V for golf carts/smaller controllers.

The 4 posts are because on a series motor, to change direction, you have to switch polarity on the field windings.

Series are for series applications. Sepex is a more complex type of motor, because you can overspeed it, and reverse it on the fly. There are curves that interract between the field and armature to get it working.

Hmm, now that I think about it, that makes sense. But why can't you separate the field on series and drive it as a sepex? Not enough flux in the field coils? Would a rewind fix that?

Not to thread-jack. :P

jyracing wrote:

Oy is right Link. At least you didnt say boat anchor. No faceplate.
5BC49JB1127a.jpg
I'm thinking of making an aluminum faceplate mount with a 19 spline male adapter and pillow block(s).
I'm assuming that it is 133A continuous. How many amps will this draw at max? 600A?
Actually, the early 36 volt golf carts came with 4 solenoids... before the fabulous age of technology.
198536vs.jpg

Check the resistance of the motor. I'm guessing it could draw over 1,000, voltage depending.

Damn, those must have been some big solenoids. :O

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bermurray
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Re: electric motorcycle project Phase Two

Although the VECTRIX does have reverse due to the weight of the bike (+-500lbs?). You twist the throttle the other way, and it gives a slow speed reverse.

I had a Honda 750 with almost the same weight, and I don't remember ever missing "reverse"...

Bernie

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jyracing
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Re: electric motorcycle project Phase Two

Okay, so when I use a controller I will avoid a SEPEX controller. Will checkout Alltrexo David. Since Link said, "No, No." I am more determined than ever to use solenoids :)
I just spent a hour with my local golf cart repair guru. He didnt like my 12v batteries and said "for test purposes ONLY I can jump the A1 and A2. I think this is an opposite shunt, David?. Then hook the battery +/- to both of the F or S terminals, as the case may be. Swap the battery cables to spin the motor in the other direction." I asked, "Why for test purposes only?" He said, "It will launch like a rocket if I hook it up the way and ride it." I said, "That's what I want! I will add a wheelie bar." He laughed and said, "Okay, this is what you have to do without a controller...solenoids... resistors...etc." I asked, "How bout 24v then 48v?"
I drew up this diagram trying to remember what he said. Not sure about the resistors and I guessed on the solenoids. Does this look right so far?
24v48v2solenoids3.jpg
Anyway, as I was digging around in his used parts I found two 19 spline input drive shafts. Seems like I can pop off the bearings and use two pillow blocks for radial force support?
Then I saw the rack full of golf cart rear axles that "mate" right up to my motor. Another light bulb went off...Skip phase two and move on to phase three...
Hell with the input shafts, pillow blocks, chain, sprockets, rear wheel, etc. What about a trike? Just U-bolt the golf cart axle (with motor mounted) right to the motorcycle's monoshock swingarm and boddabing, the drivetrain is finished? He's gonna ask his boss how much he wants for the axle tomorrow. If its under $200 complete with hubs and tires I'm buying it.
So, if I make a trike I might as well use forward and reverse, right? Just need the F/R switch and make a couple more cables. It may go too fast in reverse without a controller though.
I am going to take the bike over to his shop with a 6 pack of beer when the motor gets here.
If I do use a hitech controller can I still hook up my little 300w scooter throttle to it or do these hitech controllers need hitech throttles too?
Go ahead and threadjack, I have no clue what you are talking about. I might learn something.
I dont think I like the idea of reverse on the throttle. Too much of a chance of throwing it in reverse while going forward and frying the brushes?
How do I check the max resistance Link?
Here's all I know
5BC49JB1127j.jpg
Thanks for all your help guys, you too threadjacker :P
JY

LinkOfHyrule
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Re: electric motorcycle project Phase Two

jyracing wrote:

Okay, so when I use a controller I will avoid a SEPEX controller. Will checkout Alltrexo David. Since Link said, "No, No." I am more determined than ever to use solenoids :)

At least do me a favor and only try it on 12V first, plz?

Quote:

I drew up this diagram trying to remember what he said. Not sure about the resistors and I guessed on the solenoids. Does this look right so far?

Hmm, I'm having a bit of a hard time reading that with all the crossed wires, but my initial assessment tells me I don't like it. It looks like it'll switch from 24V to 48V well enough, but the problem is, the second set of batteries aren't being used in 24V. So, if you ride in 24V mode for a while and then switch to 48V mode, you run the risk of overdraining the first set of batts.

Might want to rework that with different solenoids to make it switch from series to parallel instead of just swapping one pack in and out.

Quote:

If I do use a hitech controller can I still hook up my little 300w scooter throttle to it or do these hitech controllers need hitech throttles too?

Doubtful. Most scooter throttles use hall sensors and a magnet to vary the output signal. Most controllers suitable for a golf cart motor take a 0-5k pot throttle, which are basically just a variable resistor in a fancy housing. They're also more expensive. The Maguras are like $50, but they're good quality.

Quote:

I dont think I like the idea of reverse on the throttle. Too much of a chance of throwing it in reverse while going forward and frying the brushes?

It shouldn't fry the brushes, and it may even survive this multiple times, but it's not a good thing by a long shot. Reverse full throttle when going all out basically adds the motor's BEMF to the batteries voltage, not to mention all the amps that would be generated...

Prolly a good idea to have a separate switch out of the way.

Quote:

How do I check the max resistance Link?

DVM. Check the resistance between S1 and S2 when A1 and A2 are connected. Dividing 24V or 48V by the resistance you get will tell you how many amps you'll (theoretically) draw at stall, eg 48V / 0.1Ω = 480A. Not that I think you could actually stall a shorted out golf cart motor on 48V for long...

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jyracing
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Re: electric motorcycle project Phase Two

Okay, I promise lol So just hook up one 12V battery to the 48V motor? I thought undervolting might hurt the motor somehow? That will suck. No wheelies? For that matter, can I run it on 12V and 24V max, rather than 24V and 48V? I would just as soon run it at 12V and 24V if I can, I really dont want the extra weight of two more monster batteries, nor do I really have the room for two more. If I run a 48V/7HP motor at 24V doesn't it divide the HP by 4 then, 1.75HP? Since doubling voltage quadruples HP the opposite should hold true?

I dont like my drawing either but I wanted to get my thoughts down quick before I forgot them.

I didn't think about draining one bank before the other bank in 24V. I thought that the fully charged bank would equalize with the low side somehow when I switched to 48V. So that's why there are more solenoids, to make 4 batteries into 24V and the same 4 batteries into 48V. Technology is looking better by the minute :) Would I have the same problem if I ran two big batteries and two small batteries?

When A1 and A2 are jumped to each other? My drawing might be wrong. I took David's advice, thanks David, and found this diagram at alltrax. It doesn't use A1 and A2. I think I misunderstood my new best friend today. It uses A2 and S2...
norev3.jpg

Regen braking... throw it in reverse at top speed :)

LinkOfHyrule
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Re: electric motorcycle project Phase Two

jyracing wrote:

Okay, I promise lol So just hook up one 12V battery to the 48V motor? I thought undervolting might hurt the motor somehow? That will suck. No wheelies? For that matter, can I run it on 12V and 24V max, rather than 24V and 48V? I would just as soon run it at 12V and 24V if I can, I really dont want the extra weight of two more monster batteries, nor do I really have the room for two more. If I run a 48V/7HP motor at 24V doesn't it divide the HP by 4 then, 1.75HP? Since doubling voltage quadruples HP the opposite should hold true?

No, it won't. But it will dramatically increase brush life. And yeah, 12V and 24V will be fine.

It's pretty difficult to figure out actual hp, especially since ratings are just confusing. I'll take a wild guess that this thing was meant to be run at 48V and around 400A peak, so that would sort of make it a 25hp motor.

And, since you're running it through solenoids, even that goes out the window, since there's no controller to limit amperage.

Quote:

I didn't think about draining one bank before the other bank in 24V. I thought that the fully charged bank would equalize with the low side somehow when I switched to 48V. So that's why there are more solenoids, to make 4 batteries into 24V and the same 4 batteries into 48V. Technology is looking better by the minute Would I have the same problem if I ran two big batteries and two small batteries?

Yeah. Only then you run the risk of EITHER side dropping too low, since you can now run the higher voltage setup too much and drain the smaller batteries.

Quote:

When A1 and A2 are jumped to each other? My drawing might be wrong. I took David's advice, thanks David, and found this diagram at alltrax. It doesn't use A1 and A2. I think I misunderstood my new best friend today. It uses A2 and S2...

With a series motor, I don't think it really matters how the thing is connected up so long as current flows through the armature and field coils.

Quote:

Regen braking... throw it in reverse at top speed

Er, not quite. It's pretty hard to get regen out of a series wound, since you can't take advantage of the magnetic field that magnets or a separate field coil supplies. I'm not sure how you actually get regen out of a series, but I think full reverse at top speed just throws a crapload of current through the system...

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jyracing
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Re: electric motorcycle project Phase Two

Good, Brushlife is a good thing.
So if V*A=W
48V*~400A=19200W/780=24.6HP
24V*400A=9600W/780=12.3HP
Cool! That should make it move
Since I am cutting the volts in half am I cutting the ~amps down too 200 too or do the peak amps stay at 400?
24V*200A=4800/780=6.15HP???

reikiman
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Re: electric motorcycle project Phase Two

As for U-bolting a golf cart axle to a motorcycle ...

http://visforvoltage.org/blog/reikiman/2871

The motor on that bike is very similar, similar color, similar ratings on the face plate, etc, to the one you have.

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- Charger bike (rebuilt), Electrified Electra Townie, 1971 Karmann Ghia

Brutus361
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Points: 25
Re: electric motorcycle project Phase Two

Hi Jyracing,

First 746 Watt = 1 HP, the power (Amps) that goes to the motor is determine by the controller for a 300 amps controller at 24 Volt x 300 = 7200 /746 = 9.65 HP.

A 400 amps controller at 24 Volt 9600/746 =12.8 HP for the same voltage. But it also drains your batteries pack faster.

Any SLA 125 amps battery with the peurkert effect give you around 70 Amps as is best and 60 Amps in "real" life and is about the maximum you can expect from them.

Other consideration are very important on electric vehicle, bigger tire drain your energy faster meaning a 4" motocross tire vs. 3" motocross tire. Like I says before more Watt/hour gives you more running time. When you cut the voltage by two you also cut the RPM of your motor by two (RPM/Volt) don't forget it!

Have nice day
Brutus361

LinkOfHyrule
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Re: electric motorcycle project Phase Two

jyracing wrote:

Good, Brushlife is a good thing.
So if V*A=W
48V*~400A=19200W/780=24.6HP
24V*400A=9600W/780=12.3HP
Cool! That should make it move
Since I am cutting the volts in half am I cutting the ~amps down too 200 too or do the peak amps stay at 400?
24V*200A=4800/780=6.15HP???

Since you're using contactors, the amperage will be related to voltage, too. So, yeah, if it drew 400A at 48V, it'll only draw 200A at 24V.

However, it'll only draw max amps at stall, where it's not making any power. So, while you may be getting a certain hp into the motor, you're not getting that hp out. Still, with that kind of power, it'll move.

Plus, we don't even know if 400A is the max it will draw. From what I've seen from golf cart motors and controllers and their ratings, I'm inclined to think that particular motor would draw a fair bit more...

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