Maytag's GT gets a BMC

[maytag]

Couldnt find color matched connectors locally for the high current motor connectors. 6-pin mini DIN connectors work great for the motor hall sensor connections, thats only if you can solder the little tiny wires and pins while keeping things from melting or shorting together.

 

[maytag]

And here's the other side.

 

[maytag]

This is how I will be charging until I get side covers on. The 2 Milwaukee chargers completes a full charge in roughly 3.5hrs. Another project will be to remove both charger's internals and placing it all in a single enclosure. I'll start another thread for that project.

 

[maytag]

Ahhh the satisfaction of putting it all together and making it work.

 

[knoxie]

Great Work!!

Loving the way you have got that battery pack squeezed in to the frame, nice nice job, you have put a lot of work in to this so I hope it all holds up well for you!!

Id be interested to know what top speed you get, the puma I have does 23mph at 37V and 37mph at 72V this is for the rear, the front BMX motors are geared higher and will do 42mph, both with good acceleration at 72v the acceleration is very good, the new modified controller should hold up a lot better now at 72V.

These little pumas do have good torque, I have been telling people this for a while now, its great that we can do side by side comparisons with an X5. The X5 is still a fantastic motor, I now have one! I am going to put it on my proflex full suss MTB and try it at 72V, it should be a lot of fun, I can then do comparisons.

Thanks for posting the pictures as well, I am a big fan of GT bikes as well so its nice to see, I have been offered an Idrive GT to modify as well but havent got space in my e-garage!! ha ha its like an electric vehicle showroom!! just need a speed boat and a helicopter and I would have it all!!

Thanks again, looking forward to your ride report with speed and amp info, also be interested to see if the cable on the motor or the axle is getting warm after you have been riding, at 72V the axle does run a little warm.

Catch you later

Knoxie 8)

 

[maytag]

I'm very interested to see how everything gets installed in the frame. The mounting of the batteries and bracket design is where I see the challenges and where Maytag is going to be able to show off his engineering prowess.

Sorry John,

No rocket science involved in this one, just quick and dirty. Although I plan on replacing the zip ties with the same type of straps I used for my electric pocketbike racer, a crash proven system (actually crashed many times and the batteries never budged)

 

[Mathurin]

Lookin good, what's the total bike weight so far?

 

[Lowell]

Excellent work! I love the custom shaped battery pack, and I know how much work those are as I did three of them for my own bike. Looking forward to a full review on how it performs. Handling wise it should be excellent with that battery pack location. 8)

 

[maytag]

Lookin good, what's the total bike weight so far?

Only 54.6lbs 8)

I really havent put the Puma through much testing yet but if it holds up well I'd have to say that it's gotta be the best overall performer of the hub motor bunch. Some key features to like about the Puma: 1) Strongest torque that I've experienced in a hub motor 2) It freewheels like a regular bike 3) Small, less likely for people to come up and say "What the hell is that in your back wheel?" 4) At only 8lbs, it has to be the best pound for pound Power to Weight ratio king.

 

[maytag]

Excellent work! I love the custom shaped battery pack, and I know how much work those are as I did three of them for my own bike. Looking forward to a full review on how it performs. Handling wise it should be excellent with that battery pack location. 8)

Thanks I held off for an extra 2-3 days before ripping apart all of the V28 packs, at $100 a piece it wasnt an easy decision since I've never built a battery pack before. Very glad I did and am very proud of the results. It rides and feels like I'm riding a regular bike. Nice thing about the geared BMC is that it has a freewheel built in.

 

[maytag]

Great Work!!

Loving the way you have got that battery pack squeezed in to the frame, nice nice job, you have put a lot of work in to this so I hope it all holds up well for you!!

Id be interested to know what top speed you get, the puma I have does 23mph at 37V and 37mph at 72V this is for the rear, the front BMX motors are geared higher and will do 42mph, both with good acceleration at 72v the acceleration is very good, the new modified controller should hold up a lot better now at 72V.

These little pumas do have good torque, I have been telling people this for a while now, its great that we can do side by side comparisons with an X5. The X5 is still a fantastic motor, I now have one! I am going to put it on my proflex full suss MTB and try it at 72V, it should be a lot of fun, I can then do comparisons.

Thanks for posting the pictures as well, I am a big fan of GT bikes as well so its nice to see, I have been offered an Idrive GT to modify as well but havent got space in my e-garage!! ha ha its like an electric vehicle showroom!! just need a speed boat and a helicopter and I would have it all!!

Thanks again, looking forward to your ride report with speed and amp info, also be interested to see if the cable on the motor or the axle is getting warm after you have been riding, at 72V the axle does run a little warm.

Catch you later

Knoxie 8)

Hiya Knox,

Thanks for the compliments. I gave it a brief but pretty good test run last night. It was pretty chilly last night but I got a GPS measurement of 31.5mph, it gets to top speed pretty darn fast. Then I rode it up a street thats about 3/4 mile straight up hill. I didnt have it on the GPS at that time but I'd say it was running in the low to mid 20's and still pulling stronger but backed off to proceed any faster fearful of smoking anything. When I got home the motor, wires, batteries weren't even warm. Its raining today but a ride is in for tomorrow (sunny skies) with my bro (joystix) and jondoh. Stay tuned.

 

[maytag]

Just like before, I'm still able to hang up the GT when not in use. Another goal accomplished

 

[maytag]

I tugged on the back wheel and tugged some more before parking the wife's car underneath it. Its all good 8)

 

[BiGH]

I'm tremendously impressed! congrats! and its light enough to hang! wow VERY impressive.

I'll be very interested to hear what kind of range you get out of it

 

[xyster]

Wow...couldn't do that with mine!

 

[fechter]

2 torque arms were shipped with the Puma from EVTech. I only have room for one of the arms. Its mounted with a stainless steel pipe clamp. I'm leaning towards installing another pipe clamp connected near the middle portion of the torque arm. Does anyone think its necessary?

No, I think the weak point will be right at the axle. It looks good the way you have it.

Nice Job! That will be a real stealth bike once you get the side covers on. You should have no problems riding on bike trails etc. especially with the freewheel, you can just cut the throttle and be totally silent.

 

[knoxie]

Hi

Yes was running my Puma today, they are very quiet indeed and the freewheel works like a charm, great low down torque and super light! let us know how it goes

Knoxie

 

[maytag]

Took out the GT to meet up with Joystix for a range test and X5 vs Puma comparison testing. Turned out to be an upsetting day for the Puma. Before everybody jumps to a conclusion that the X5 had a Puma sandwich for lunch, the Puma just never made it to the brawl. On my way to Joystix's house the GT came to a sputtering halt about 3 miles into the ride. I knew we were going to do some range testing and this was actually going to be the GTs 1st full test run so I was taking it very easy on the ride. I came to a very long road with about a 1.5mile stretch into a 10-15mph headwind. I set the cruise control at about 16-18mph and peddle assisted the whole stretch when suddenly I felt a loss of power with a vibrating sound/feel coming from the motor and I now needed to peddle harder to keep pace. I then shut off the cruise control and gave it more throttle and got what felt like about 1/4 the torque that it was putting out earlier and more vibration. I stepped off the bike to check if any of the connections came loose, everything looked good and the battery gauges still showed a full 4-bars. Lifted up the rear tire and gave it throttle, the Puma spun normally without any vibration but soon as I put the tire back down on the pavement and apply throttle I can actually hold the bike (not sitting) and stall the motor. I can feel the motor try to spin as its vibrating then stall and lose complete power. I decided to peddle the rest of the way(~3mi) to Joystix's house. After more troubleshooting in his garage it turns out that the Crystalyte controller died. Knowing that Joystix was anxious to see how the Puma performs we disconnected my dead controller and strapped on his for a quick whirl. I'll let Ric post his thoughts but I believe he was impressed. We did a quick comparison run up a nearby street with a mediocre grade and we both agreed the Puma pulled just a tad bit harder than his X5. For some reason, my comparison between his controller and mine the Puma felt like it had even a little bit more torque when my controller was working properly and both 36-72v/35A controllers were bought from the same supplier. I sent an email to the PoweRidestore regarding warranty/exchanges but havent heard back from them. I'm concerned that I've replaced the original hall sensors connector with a 6-pin Mini DIN and cut the extra long red/blk power leads to length, I'm wondering if this will jeopardize my warrant/exchange claim. If the PoweRidestore gives me $hit I guess I'll have to do the FETs upgrade sooner than planned.

 

[xyster]

Seems there's an unfortunate run of bad crystalyte controllers going around...

Am I right in remembering that you're running the Puma in a 26" wheel at ~56volts (14-S emoli) and that joystix is running an X5 5304 in a 26" wheel with ~48 volts (40-S) NiMH, and both controllers are the 72V35A model?

 

[maytag]

Seems there's an unfortunate run of bad crystalyte controllers going around...

Am I right in remembering that you're running the Puma in a 26" wheel at ~56volts (14-S emoli) and that joystix is running an X5 5304 in a 26" wheel with ~48 volts (40-S) NiMH, and both controllers are the 72V35A model?

more like 54v and yes same controllers (but his works )

 

[Ypedal]

wow... all these controller failures are insane... my batch better not be this bad or i'm screwed.....

Was this a 36-72v 20amp or 35 or 40 amp rated ?

 

[maytag]

wow... all these controller failures are insane... my batch better not be this bad or i'm screwed.....

Was this a 36-72v 20amp or 35 or 40 amp rated ?

36-72v/35A model. I bought mine from PoweRidestore.com about a month after Joystix bought his from the same place. His is still working fine with his X5 and 48v of NiMh and I'm using(or was using) mine with a 54v lithium pack. I was not stressing the controller at all when it happened. Hope yours works out better.

 

[xyster]

I got my 72V35A controller from the poweridestore too. 1300 miles, 84 volts and no problems.

 

[Ypedal]

I have not personally had a cotroller failure either.. yet. I have used about 8 different one's from 36 to 100v.

I got one 36/72v 20 amp dual speed from Poweridestore.. all others from Justin at ebikes.ca.

Well.. there was one incicent... but that was my fault. Lesson: Dont' work on electrical anything when completely drunk...

 

[knoxie]

Hi

Yes I think we are starting to see a pattern, my controller on my Trek is the 24-48V one sold by Tim at powerpack, it has the same fets in as the 36-72V controller and 160V caps, this controller has been working fine at 48V for about a year and used daily, it has also ran fine at 72V.

I have seen failures on the 36-72V controllers on BMC, Kol motors, Pumas and Crystalyte, there may be many reasons why they have been failing, cheap or poor quality batch of fets etc etc, I think I have ironed a few of the problems out, the shitty plastic tubes and the fibre washers holding the fets down and the voltage rating on the fets.

Maytag, check with a DVM resistance between the screw and the tab of the fet, push down hard on both of them, I have had so many that short through here test each one pushing down hard on each of them, it could possibly lead to false triggering on the gates of the fets, very bad news especially on higher voltages, It is technically possible for 2 or 3 phases to fire together, this could cause possibly twice the voltage to appear at one of the fets? or maybe fet shoot though I am only surmising here, but it may be the reason the failure doesn't occur until you take the voltage higher nearer to half the 100V limit of the fets if you like, Richard should be able to confirm if this is correct.

After fitting the proper TO220 fitting kits there is no reading what so ever as you would expect, this is just a guess but it may be why the controller has been less than reliable on higher voltages, I used brand name quality fets and fitted the TO220 kits, its working great and runs cool as ice even under full load so I am pleased, of course it may fail again at 72V, if it does I will start to suspect the Puma is maybe struggling however the old motor that was connected when this controller blew is working fine now I have fixed up the controller to 150V.

Its up to you Maytag but I think I would modify the controller, there is every chance that your next one will blow again, Kenny has been told about this by Mark, they should not be fitting those rubber tubes and fibre washers to the new controllers, we are also going to specify 150V fets but still only run them as 72V controllers, this should give some leeway on reliability, the on resistance of the fets is still lower than the stock fets.

Let me know how you get on, you may not want to take it apart, I would however and If you need any help myself and I am sure Richard Fechter will be able to answer any questions that you have.

Good Luck

Knoxie