Maytag's GT gets a BMC

[maytag]

Well I couldnt wait any longer and picked up a BMC "Puma" rear hub motor from EVTech. Let me explain something that I found out about these motors after the fact and what I've done to hopefully break it through to higher grounds. I can only speak for the current crop of rear BMC's coming out of EVTech in the US, I believe the same motors that Team Hybrid is selling have already been modded by Team Hybrid to relieve the so called problem. It's only a problem for modders like myself running them at higher voltages than its rated 36v 540W. Run it at its advertised 36v and it runs like a champ and outperforms most non-geared hub motors at the same voltage so EVTech cant be blamed for my madness (I want to run it at 52v, then maybe 60v, 72v?). Once I first inspected my new motor it was clearly apparent what could possibly be holding it back, the hi-current phase wires are only 18ga (see comparison pic next to an X5's phase wires). I knew I'd have to beef up these wires if I want to run this motor at higher voltages but before I can get started I 1st needed to make sure I was sent a working unit. Well I quickly found out that this motor is not a straight plug-in match with the Crystalyte controllers. Thanks to the help provided by Knoxie and Mark at Team Hybrid I was able to get it running correctly. Now that I was comfortable knowing the motor does work, I can go ahead and rip apart my brand new $500 motor (what the heck its only money, right?) I never hesitate to tare into something if I truely feel I can make it better. So here are some pics of the mod, I replaced the 18ga phase wires with 16ga and used a 6-wire shielded cable for the hall sensors. All the wires feed through a bored out axle, not much space for running anything larger othewise I would have. This motor's build quality is nothing close to the BMC front hub motor in Knoxie's test video. In the photos you can actually see evidence of some rework, only thing missing is the "Made In China" sticker.

*** VIDEO UPDATES ***

BMC vs X5 Dragrace (04/29/07)- http://www.youtube.com/watch?v=jdY-WJiCyno

Range Test (05/01/07)- http://video.google.com/videoplay?docid=2729231669468479851&hl=en

Burning in the new FETs (05/05/07)- http://video.google.com/videoplay?docid=3724591204990101488&hl=en

 

[maytag]

Stock , notice the rework tracks in back epoxy *click on image for larger view

 

[maytag]

Cant return it now *click on image for larger view

 

[maytag]

Just need to epoxy down the wires and its all done. Only needed 5 of the 6 leads for the halls, one left over for future use maybe I'll add a motor temp sensor. *click on image for larger view

 

[maytag]

Here's a shot of the gears on the back side. This is what seperates it from the rest and is how an 8lbs motor can have more torque than a 24lbs X5. I hope all the hype is for real, I guess we'll soon see cause I have Joystix sitting on his X5 waiting to pounce on the Puma.

Ebike Plans:
-GT full suspension w/I-Drive
-Modded BMC rear geared hub motor in 26" rim
-Crystalyte 36-72v/ 35A controller
-2s3p of Milwaukee v28 packs (51.8v/9Ah)

Keep checking back, more to come

 

[Lowell]

How much torque does that motor make?

 

[maytag]

How much torque does that motor make?

Dont know exactly but Doug at texaselectricbikes (EVTech) says that it out accelerates a TidalForce when both are running stock 36v. I believe the TidalForce has a X5 motor in it. These BMC geared motors are still relatively new to market but thought I'd be one of the early pioneers. Check out Knoxie's videos of the Puma.

 

[xyster]

gears on the back side. This is what seperates it from the rest and is how an 8lbs motor can have more torque than a 24lbs X5. I hope all the hype is for real, I guess we'll soon see cause I have Joystix sitting on his X5 waiting to pounce on the Puma.

Oh this should be good... my popcorn's popping....the lighter weight should favor the Puma off-the-line. But with 3X less thermal mass, at powers 72 volts 35 amps or more, my money is on the X5, particularly on long hills. Knoxie wrote here somewhere that his modded Puma gets hot at 72v, so he thought 60v a "sweet spot" for it. At 80v35a my X5 has never even gotten more than a tiny bit warmer than its surroundings.

I believe the TidalForce has a X5 motor in it.

The TF/Wavecrest hubmotors are different. They come in 750w and 1000w versions:
http://www.electricrider.com/wavecrest/diy.htm
http://www.greenspeed.us/tidalforce_electric_motor.htm
Because their company's out of business, some TF owners have replaced their TF motor with the crystalyte. On the TF forums, there used to be posted race results showing a 5304 handily thumping a stock TF under the same conditions.

Well I quickly found out that this motor is not a straight plug-in match with the Crystalyte controllers. Thanks to the help provided by Knoxie and Mark at Team Hybrid I was able to get it running correctly.

Interesting. What exactly had to be changed for them to mate OK?

 

[maytag]

Well I quickly found out that this motor is not a straight plug-in match with the Crystalyte controllers. Thanks to the help provided by Knoxie and Mark at Team Hybrid I was able to get it running correctly.

Interesting. What exactly had to be changed for them to mate OK?[/quote]

When I 1st ran a functionality test I jimmy-rigged all the connections to my bro's Xlyte controller. A bad connection within the hall wires (my fault) sent me spinning in circles for a couple of hours. After all the smoke cleared up and a few PM's to Knoxie and Marc, all is running fine. The hall sensors connector was actually a straight color-color match with the Xlyte controller's wires. The hi-current phase wires were all different, here's a pic of the wiring layout.

 

[joystix2]

Heres a couple of Videos we shot in the garage for testing.

http://www.youtube.com/watch?v=_4_kjHAwjWg

http://www.youtube.com/watch?v=OPptcfufap4

 

[deecanio]

YEAHHHHH,

Go guys get that baby running!!!!
chances are you guys are far less lazy than me and we might see some more puma vids soon can't wait to see her running.

D

 

[fechter]

That's cool how you can run it with the cover off.

Now, how to figure out a forced air cooling system. :wink:

 

[knoxie]

Hi Dave

Nice work on the motor, good to see that you have got the thicker cables in, it should be better with less axle heating, still keep them short though, it may be an idea to earth one end of the screen cable to the frame of the bike somewhere, only one end though.

These motors as you point out are nowhere near the build quality of the BMX motor. There are some new versions coming out apparently. One thing I noticed on your motor was the lack of grease on the gears? I havent checked my ones other than the BMX which has a good dollop of black lithium grease, you may have white or clear grease on yours I cant tell though.

Be careful running the motor with the lid off, esp on the vertical, tighten up the lower nut to stop the casing falling away otherwise it may drop out and screw you gears if it is spinning.

I think I am going to upgrade the cables as well, I have new motor coming and an X5 motor as a direct comparison. Oh and I also have 150V 80A fets to put in the controller should make the controller a lot more hard wearing.

Cheers

Knoxie

 

[xyster]

One thing I noticed on your motor was the lack of grease on the gears? I havent checked my ones other than the BMX which has a good dollop of black lithium grease, you may have white or clear grease on yours I cant tell though.

I was under the impression nylon gears don't require extra lubrication because they're somewhat slipper already.

 

[Toorbough ULL-Zeveigh]

I've heard the term 'self-lubricating' attached to nylon gears. Perhaps they're not really the true DuPont stuf but chinese 'nighlon'.

Named after its 'inventor', Nigh-Lon.

 

[maytag]

Hi Dave

These motors as you point out are nowhere near the build quality of the BMX motor. There are some new versions coming out apparently. One thing I noticed on your motor was the lack of grease on the gears? I havent checked my ones other than the BMX which has a good dollop of black lithium grease, you may have white or clear grease on yours I cant tell though. * There is grease on the plastic gears just cant see it in the video, seems to some pretty thick/sticky white stuff.

Be careful running the motor with the lid off, esp on the vertical, tighten up the lower nut to stop the casing falling away otherwise it may drop out and screw you gears if it is spinning. * I've already closed it up no need to worry, hopefully I wont have to open it up again for many many miles.


Cheers

Knoxie

 

[knoxie]

Hi Dave

Yes good stuff, is the insulation good on the wire that you have put it, the stock wire has very thin insulation, so the actual wire is a lot thicker than you may think at first, its still to thin to cope though so what you have done is a very good move.

The BMX motor is little more powerful than these ones, however there isnt much in it at all, please keep us all up to date with the motor and how you get on with it when you test it, be interesting to see how it holds up to higher volts.

My modified controller shoould be sorted sometime this week and I hope to have it running with a newer Puma motor in a 26 inch wheel, I want to make sure that it hold up well at 72V.

If you run it at 72V you should see 35-37mph on the flat with very good hill climbing ability, make sure you fit the torque arm though thats important.

Cheers

Knoxie

 

[maytag]

Hi Dave

Yes good stuff, is the insulation good on the wire that you have put it, the stock wire has very thin insulation, so the actual wire is a lot thicker than you may think at first, its still to thin to cope though so what you have done is a very good move. *I found 2 different versions of 16AWG wires at my local electronics surplus store, I picked up the version that visually appeared to have more strands w/less insulation and physically thinner in diameter. Good thing because if I were to use a set of the other 16AWG wires, it all wouldnt have fit through the axle bore.

The BMX motor is little more powerful than these ones, however there isnt much in it at all, please keep us all up to date with the motor and how you get on with it when you test it, be interesting to see how it holds up to higher volts.

My modified controller shoould be sorted sometime this week and I hope to have it running with a newer Puma motor in a 26 inch wheel, I want to make sure that it hold up well at 72V.

If you run it at 72V you should see 35-37mph on the flat with very good hill climbing ability, make sure you fit the torque arm though thats important. * Using your review #'s for this motor of 23mph@37v, I'm expecting 32mph@52v. I'm hoping the mods I've done allows me to run the motor reliably at 52v then later maybe add a 1s3p pack of Milwaukee v18 batteries in series (~70v nom.) for a quick registration into the 40+mph club (43.8mph est.)

Cheers

Knoxie

 

[maytag]

I've been searching for a source who can lace the motor up for me. The 3 bicycle shops I checked with all said they could and it would only take an hour BUT only if I brought it in with the rim and spokes with the proper length. So far I havent had any luck finding reliable information on a known working rim&spoke length combination for this motor. One bike shop had some 12ga 183mm spokes on hand and started to lace it up on a nice double wall Mavic downhill rim, after about 6 spokes were on he knew it wasnt going to work. He said with this rim the proper spoke length was guestimating somewhere around 210-215mm, a different rim(but same 26in) will also change the spoke length so it pretty much has to be custom built. There is some hope tho, Jondoh knows a guy who can custom cut to length 12ga spokes build up the wheel for me but might take up to 2 weeks to get it done. I'm still hoping Mark at Team Hybrid gets back to me with a known good rim/spoke combo then I can just order the parts and drop it off for a quick 1hr lacing. So for now I'm just working on my custom emoli pack solution. I'd like it all to fit in the tiny triangle of the GT frame with custom side covers for a stealthy look. I'm also conjuring up a plan to charge the entire 2s3p pack of Milwaukee v28 batteries using 2 Milwaukee v28 chargers and 2 of the v28 BMS modules through a single plug. Guess I'll have to put on my MacGyver hat for this one.

 

[Ypedal]

Can you please tell me who can custom cut 12 gauge spokes in north america ?... I'd really like to know as it could come in very handy !!!..

I had to order mine from Crystalyte ( all 60 sets of them !!! )

 

[maytag]

I've been tied up with work (hate when that happens) so progress on the GT has been slow. Got a call from the bike shop saying the BMC is all laced up and ready to go. Picked it up along with some new Serfas tires, Chuck (the bike dude) said these were really good rolling tires with enough traction for hard packed bike trails. Thought I'd wait till tomorrow to mount the newly laced wheel since we were eating out tonight but soon as we got home I just had to start working on it. Here's a few pics to share. More to come

 

[maytag]

A shot of the 12ga stainless steel spokes and torque arm. Up close the spokes almost look like motorcycle or moped spokes.

 

[maytag]

I think a 7-speed cassette may have fit, not really planning on using many gears anyway.

 

[maytag]

Lets take a closer look at that sticker.... "250W@36v" WHAT THE HECK???

After dishing out 5 bills for the Puma and then seeing this sticker on it, I almost puked. I was assured that this particular version of the Puma is more like a 400-450W motor. Well with the mods I've done to it, I'm hoping it can handle 52v@25A which will be around 1300W. We'll have to wait and see.

 

[maytag]

Here's a shot of the actual emoli pack and bms from a Milwaukee v28. I placed a C alkaline in the photo for comparison.