Building HXT 80-100-B 130Kv bike

[VRdublove]

Hey guys, my buddy is using the HXT 80-100-B 130Kv Brushless RC motor to build an ebike.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5142

We're using the Turnigy 100A HV ESC :http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6550&Product_Name=TURNIGY_Sentilon100A_HV_5-12S_(USA_Warehouse)

I'm new to this RC stuff, but as far as I know, we also need a BEC and a Servo tester, is this correct? The ESC's page says "BEC: N/A (No BEC)". Does this mean that one is not needed for this controller, or it is not included in the controller? Also, where can I order a servo tester and BEC (if I need one) in the states?

We are planning on using 4 Zippy 22.2V, 5Ah packs connected 2S2P for 44.4V, 10Ah. I appreciate any help you guys can give!

 

[Miles]

Tommy,

That controller doesn't have a built-in BEC. The BEC is only needed to power the servo tester.

You should consider waiting for fechter's circuit board, which combines the functions of servo tester, BEC and current control:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8160

Otherwise:
http://www.dimensionengineering.com/VHVBEC.htm
http://www.astroflight.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=servo+tester

 

[recumpence]

That motor should work OK. But, the controller concerns me. Right now, there are only a few controllers that work for e-bike use. Please be sure to post your results with that controller. It would be fantastic to know of a decent innexpensive controller we can use.

Matt

 

[etard]

Can you post some more details about your setup, aka... how this motor is applied to the bike, mounting, battery placement, etc.....
thanks

 

[safe]

Your selections look pretty good based on what I've been picking up so far. Those Zippy packs seem to be a very good value. So far so good as far as I can tell.

You will need to get one of Fechters circuits.

 

[VRdublove]

Thanks for the quick responses guys!

Would this servo tester work as well:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8373

It is much cheaper and a little more compact.

And how about this BEC?
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6320

Or do I need the HV BEC recommended earlier since we are running 44.4+ volts?


I appreciate all the help already.

We are doing this project in an independent study course that we created named "Custom EV Fabrication" at Appalachian State University in Boone, NC. The build will be well documented since we need to prepare a final report, laden with plenty of pictures. We plan on using a synchronous belt reduction of 10.5:1 for a top speed of around 45mph. I'll put up much more info in a bit.

 

[Miles]

Some of the ultra cheap servo testers have been problematic, but for $6 I guess it's worth a punt

44.4 Volts is your nominal voltage - charged voltage would be around 51 Volts, which may be too much for that BEC.

 

[liveforphysics]

I'm using a pair of the same motors on my bike build. You might want to change the bearings. The motors come apart very easily, and you can feel that the bearings seem to have quite a lot of non-rotational motion between the races.

The shaft is also made of a non-hardened very soft and easily bent metal. I'm having some custom shafts made, and if you would like, I could have an extra made for you too. I'm going to use either tool-steel or titanium.

It would just be much nicer to change them in advance, than to wait until failure, which would likely destroy the motor and possibly cause injury if it were to lock the rear wheel at a bad time.

From playing with these motors at only 10s, they seem to be SHOCKINGLY torquey. You still need to find a way to gear them at about 10-12:1.

Good luck with your build!

 

[VRdublove]

Thanks for the great info!

What is one of those shafts going to run you?

I did notice some slop in those bearings, do you have the dimensions on them so we could order up some new ones? I'm looking for a slightly more affordable alternative to the bearings that you ordered

These have the potential to be some pretty sweet little motors.

 

[Dirt-E-Dan]

Miles,

Do you know if the 105 servo tester that you suggested can be operated by a 5k potentiometer? Also, will the BEC need a battery?

Thanks,

Daniel

 

[sockman]

hey, i'm also building one using the same motor (vers A)
currently looking for a better motor controller, wondering if anyone building or modifying a standard ESC to higher amps..

 

[Miles]

Daniel,

I'm not sure what value pot. is used in the Astro-Flight servo tester.

The BEC is needed to power the servo tester - it reduces the voltage of your main battery pack down to the 5V/6V required to do this.

 

[Dirt-E-Dan]

I'm building up this bike with the HXT motor on my 1992 trek 830 that I upgraded to accept an eight inch disc rotor on the front. This is my first build and I will be assisted by Tommy (VRdubluv). Thanks for the advice on the BEC and the Servotester, Miles , because we got the motor set up for a little test and are more than pleased. This motor is ridiculous. If anyone is interested, I would love to post a video of it being tested using one of my four Zippy 5000mah 6s1p 15-25c batteries and the equipment that miles suggested. I'll go ahead and post some pictures of my bike as well as the motor, because the different platforms seem to be a definite point of interest. I've been learning a ton from reading all of the previous and current builds, and can't wait to get this finished! Feel free to ask about our plans for the bike!

Thanks,

Daniel

 

[recumpence]

You still need to find a way to gear them at about 10-12:1.

Hmm, I wonder how you could do that? :wink:

Matt

 

[Dirt-E-Dan]

We'll be gearing it to 10.29 :1, using the belt drive as our first reduction and #35 chain drive for the second. This should put me around 40 miles per hour . I'm waiting on the material to get here to start the reduction box, then the project will hopefully be finished by mid march. For now, I'm just trying to figure out how to integrate a freewheel into the design. Does anyone know about single direction bearings, and how much torque they can handle?

Daniel

 

[Miles]

Daniel,

The motor drive goes to the wheel (not the cranks)?

You might need to gear it down a tad more than that...

You'll need to look up the individual spec. for one-way clutch bearings. The peak they will handle is usually twice their nominal rating. Where they are in the transmission determines the capacity needed, of course.

 

[Dirt-E-Dan]

Miles,

The rear sprocket will be bolted to a centerlock brake adapter on the rear hub, so as of now the plan excludes a freewheel design, but at least I'll have some additional stopping power! I did the calculations and my ratio calculated a top speed of 48.45 mph, which is unfortunately excluding external forces. I assume with the loss of efficiency through the drive train, air resistance, rolling resistance, etc., I 'll be right around 40 mph. I plan on assisting a good deal from the start to save power and limit strain on the drive train as well, so it can be geared for more top speed.

Do you have any suggestions on bearing types? I'm running a 1/2 inch jack shaft with a 15 tooth cog to the 60 tooth rear sprocket. I've done a rough design on AutoCAD that I'll be sure to upload soon so you guys can check it out and critique a first timer! :wink:

Thanks for the help!

Daniel

 

[Miles]

One way clutch-bearings are bulkier than bicycle freewheels. You might get away with using one of these, outboard of the 15t sprocket: http://www.vxb.com/page/bearings/PROD/Kit8179

Have you considered using #219 chain?

 

[lawsonuw]

A bicycle freewheel will have a bit less drag while freewheeling than a sprag or roller ramp clutch. Furthermore, a 15 tooth freewheel exists for "standard" hub threads, and freewheels down to 13 tooth are available for the smaller BMX metric hub thread.

Heh, just had a brain-storm. If a freewheel adapter keys into the removal slots on the front face of the freewheel there would be no need to thread the adapter.

Lawson

 

[Miles]

Heh, just had a brain-storm. If a freewheel adapter keys into the removal slots on the front face of the freewheel there would be no need to thread the adapter.

Yes, I used this trick on the first build of my bike The freewheel I used had recessed slots.

In my experience, bike freewheels vary quite a bit in their drag - my CSK35 Sprag clutch bearing feels to be well within that variation (0.06 Nm resistance according to the spec.). I think it's probably true that the freest freewheels win, though... I've no experience of the roller-ramp type clutch.

 

[steelefist]

On the scooter I'm building I acheived an 80:11 reduction gear ratio using a 25# chain and sprockets. I am only running my HXT motor with 5 Li-polys in series (18.5 - 21V) giving a quite useable aprrox 4000rpm at the motor reduced to 550ish rpm at the wheel flat out. Can't wait to get all the final components I've ordered from hobby city to see what these motors can do with li-polys behind them.

 

[dontsendbubbamail]

Is this the correct way to determine the clutch rating?

Shaft Speed1352 RPM
Power Input 4000 watts = 4000/746 = 5.36 HP

HP = Torque * RPM / 5252

Torque = 5.36 / 1352 * 5252 = 20.82 ft-lb
20.82 ft-lb = 249.87 in-lb

So this clutch should be close enough to work?



Bubba

 

[mechanix]

Dan, where did you get that pulley, and is it hardened steel? I'm using the same motor as you and looking for some replacement bearings for mine as well. I'm doing a very similar build to yours and will hopefully be posting my build pretty soon once I get all the parts and start making some progress. good luck!

Joel

 

[Dirt-E-Dan]

Hey Joel,

Sorry for the late response. It was the week before spring break, which means too much work! I ordered the pulley from SDP-SI.com and it is aluminum. It is the 5mm pitch GT2 pulley, for a 15mm synchronous belt. I'm about to start the machine work today with my 60t aluminum rear sprocket, so I'm pretty excited! Also, I'm not replacing the bearings in my motor for now, so hopefully I won't have any problems. Let me know if you have anymore questions.

Also, are there any recommendations on rear rack designs? I looked at Bubba's and I think that is what I will base mine on.

Thanks,

Daniel

 

[mechanix]

hey dan thanks for the reply. I actually ended up ordering the same pulley from sdp si, haven't got it in the mail yet. I actually ended up welding my own frame, as I couldn't find a frame that was strong enough and had the right dimensions for my project. I'm planning on posting my own build thread tomorrow with pics. I've heard the hxt's can have problems with their bearings, but if the bearings are bad,they usually start out bad from the beginning. I decided to order some sealed ceramic bearings from vbx.com just to be on the safe side, as this is my primary source of transportation.

Joel