--Wayne's Mac Giant DH to mid drive--

[crossbreak]

Sounds like a moot point but this was bugging me trying to figure out what was with the lag time.

Did you set your controller for fast throttle response? I had this issue a lot when using softstart ramping BMSbattery controllers (KU123). Got a lot better with a Greentime 15Fet. Still it does not feel like a direct drive. My solution would be:
Use a torque throttle, always apply a little throttle to keep the chain rolling. Does't consume much energy. When using an Arduino, there could be a "sport mode" and an "eco mode" with this function disabled. Already wrote that on my list a year ago. Yet we are still working on the BMS register reads and did not have much time for throttle logic. The BMS story is almost done, my friend will write an Android interface for displaying cell voltages, battery cycles, total AH charged and discharged etc... after that, I'll try to write a program that exactly does the above described.

 

[waynebergman]

Sounds like a moot point but this was bugging me trying to figure out what was with the lag time.

Did you set your controller for fast throttle response? I had this issue a lot when using softstart ramping BMSbattery controllers (KU123). Got a lot better with a Greentime 15Fet. Still it does not feel like a direct drive. My solution would be:
Use a torque throttle, always apply a little throttle to keep the chain rolling.

I have not to date looked at any of the controller settings because I feel the CA is overriding and controlling the controller pretty much as I would like. Also I can tell by how the bike responds on the bike stand the power is in fact delivered instantly so my CA and controller settings are working for me. The work around for the lag issues I feel can be dealt with as you describe above. I find just leaving a bit of power to the wheel before hitting the throttle or else by tensioning up the chain by pedal assist will do the trick.


Thanks crossbreak for the tips.

 

[jackjetful]

waynebergman,

Your build is amazing! ... looks very compact, (light?) and reliable. I realy like the idea of converting a geared hub motor to an internally running motor. So on the advantage of your drive is defenitly also the mounting of the motor.

I think you have to live with the issue that the motor is not responding immediatly. That is one issue of middrives that could hardly be solved.


.. Jakob

 

[jk1]

Waynebergman "I will admit the motor conversion is a bit noisy but not offensive."

How noisy is it? do you have a video of the noise in a ride ? i thought the mac motors with plastic gears were supposed to be super quiet ?

Is it noisier then when it was used as a hub motor ? Does using it mid drive put more load on the motor/gears and hence make the gears noisier ?

 

[waynebergman]

JK1.....
No I am sorry no video as of yet. It is for sure more noisy than a stock mac used as it is intended as a hub for the wheel. I am not sure why it is more noisy. One day I should take it apart and see if anything is rubbing. I do not feel the plastic gears are making noise but maybe some thing else is. I am not noticing any heat and it has lots of snap for a 50volt bike. For now I will just ride it and enjoy it and maybe after the summer is over I will take it apart and see how it looks inside.

Thanks Jakob for the comments.

 

[crossbreak]

I have two converted hubs an swxh and swxb. I have also a non converted swxh in the bike of my girlfriend. The reason why the converted ones are loader: i run them faster rpm with more voltage at lower speeds mph/kmh. the noise for the same conditions stays the same. If i have time i can post sth. On youtube.

 

[jk1]

Cross break " i run them faster rpm with more voltage at lower speeds mph/kmh. "

Ahh yes that would make sense, since that is the purpose a mid drive to allow the motor to run at a higher more efficient RPM band, but has the side effect that their is more noise.

So I guess this is the case for any hub motor conversion to mid drive, that it will be louder then it was as a wheel motor, which is a surprise no one considered before ?

Being a mid drive I guess you still have the choice of any gear at any time, so if you really need it to be quiet you can run it in the hardest gears to slow it down and quieten as well. Steel gears maybe better if you want to run it very slow speed and high torque to keep it quiet.

ALso with the crank drive gear ratios, you can adjust them to allow higher top speed then when the motor was in a wheel motor, wouldn't that also mean that their is more load on the motor then 1:1 in a wheel ? i.e overdrive ratio and hence louder and also the risk the plastic gear teeth breaking ? Whereas originally the plastic teeth could never break even with the same motor power in both cases ?

 

[crossbreak]

i'd like to answer your questions but plz dont highjack this build thread, I'll answer your question in the Original Conversion thread, here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=45245

 

[waynebergman]

Good news today at getting the motor to run a bit quieter. The photos show some rubbing that was happening between the pins that house the planet gears and the outbound side of the magnet bowl. I had built into the conversion an allowance for the clutch and its planets to be pulled outbound from the magnet bowl by side loads from the right side drive sprocket adapter. The conversion worked well but it was a bit noisy and my idea to pull the clutch assembly outbound from the magnet bowl did not really work as planned because the cir-clip shown in the other photo was seating itself against the motor shell bearing and stopping the outbound travel of the clutch assembly. The solution was to remove the circlip totally which let me pull the clutch assembly far enough away from the mag bowl so it no longer scrapes. . There is now just one cir-clip inbound of the clutch assembly and that is all that is needed for the way my axle and spacing is. Since I made a new axle for this project I placed my own cir-clip grooves as I wanted but each builder may have different spacing and work arounds etc to stop things from making noise and heat. My solution my not be yours but this has worked well for me today. I have noticed it runs very quiet compared to before and I have a better feeling for the conversions staying power.

I only have 50 or so miles on the bike to date so its a bit early to make any real conclusions I guess but it was a good feeling to sort out this little bug.

 

[waynebergman]

[youtube]dJJFZmB2oR8[/youtube]

http://www.youtube.com/watch?v=dJJFZmB2oR8&feature=youtu.be

This video is pretty slow moving, hope it does not put you to sleep. This is not meant to be a thriller. I wanted to share the sound of the bike for those interested in the converted mac and to show how the FW and drive sprockets etc interact. The motor is pretty quiet but I think the video just makes it sound louder than it is. When you are going 30mph all that you can hear is wind if this helps anyone relate to the sound the converted motor makes.

Bike has 100 miles on it now and is running smooth. I plan to do a big hill climb next week to see how it sheds the heat. So far not even warm to the touch but I have been taking it easy on it for its break in. Not that it needs a break in period like a new car or something, I just don't want to have anything fail on me yet.

 

[rodgah]

remove the & at the end of your youtube tag and it will embed

thats brilliant, thats the first midmac I have seen running and it looks like a fun little bike. Might need a chain guard or rollers for the rear wheel chain but other than that very good.

Rodger

 

[spinningmagnets]

Thanks for posting that video. I knew you lived in BC, but I didn't realize it was so beautiful where you live...

 

[jackjetful]

It sounds very qiet! Not much louder than a non geared hub. ... whats about frame stability ... does the frame hold the tourque so far?

greetings
Jakob

 

[waynebergman]

Thanks Rodger for the tips. Got it to embed, awesome. Jakob to answer your question regarding the frame stability, the frame is very sturdy and if there was going to be any weakness it would be at my handy man efforts with my motor mounts. The way the motor and battery is mounted I have used hose clamps loading up the external aluminum tubing clamped around my bike frame tubing and aliminum plates with rivets to the motor shell so nothing on the bike has been damaged or changed so the frame itself with stay as original and I am confident the frame itself will survive anything I will ever throw at it. As far as the motor mounts themselves I am surprised how stiff they appear to be. I see zero side to side movement under power. The way I figure it if the rivets fail and I don't think they will for a long time, I can always take the time to re drill slightly bigger mounting holes and go machine screws and nuts to replace the rivets. The rivets were super quick however and I would recommend this so far.

I am now going to start on a new battery box for the Giant. I think it was a good idea to test this conversion out on the hardtail as it is a bit more tricky on a full suspension and I also want to see how it works. I have a new battery from cellman coming the same as this battery in the hardtail. For the summer I will go with the one new battery placement in the Giant for the second bike and then in the fall give the Giant the same treatment as the little hardtail if the motor conversion holds up over the next couple of months. With this new battery to replace the other two packs I had in the Giant I can have much better weight distribution and also lighter. I will have slightly less range at 14.3ah but I can still run 35amps or so I figure.

Wayne

 

[jackjetful]

As far as the motor mounts themselves I am surprised how stiff they appear to be. I see zero side to side movement under power. The way I figure it if the rivets fail and I don't think they will for a long time, I can always take the time to re drill slightly bigger mounting holes and go machine screws and nuts to replace the rivets. The rivets were super quick however and I would recommend this so far.

Your motor mount looks very stable! I tried several times to build a mid driven e bike with a hub motor. Every version failed. Not because of stability of the motor mounting rather because the frame was flexing.
I think the big advantage is your internal running hub which allowes you to mount it on the motor housing. So you don't need those long mounting plates or whatever which mostly cause the big tourque force on the frame.

The other thing is that you can only use this type of hub motors which probably arn't as powerful as non geared hubs.


... Jakob

 

[crossbreak]

The other thing is that you can only use this type of hub motors which probably arn't as powerful as non geared hubs.

If you compare our converted hubs that weight around 4kg with DD-Hubs that weight 4kg this is big false estimation. Hubs that are converted the way I invented http://endless-sphere.com/forums/viewtopic.php?f=28&t=45245&sid=a492768463f9e893a50050add8f80c8d are capable of at least 3 times the continuous power of a DD hub with the same size and weight. I already wrote thermodynamics degrees 1-3 and the electric motor & power electronics classes during my mechanical engineering degree at university, believe me I know what I'm talking about

 

[waynebergman]

[youtube]1HGr7bAl2V8[/youtube]
Awesome ride today. Short but sweet. I wanted to compare this short climb with the mid drive compared to the old Giant that had the mac in the hub. No comparison at all. This mid drive bike climbed up this trail with no heat and lots of pep. From the water shown in the background up to where the photo is taken and video is .8 of a mile. I used only 1 AH to climb this hill. Most of it was easily done at 800 watts and for some of the steeper stuff I would pin it going for the full 1800 watts. I am so happy with this conversion.

Google earth picture shows starting point at the lake and the purple oval shows the lookout at the .8 mile mark. Most of this trail was pretty tame but I can not see why I could not climb for a steady 5 miles no problem. Even 3000' vertical......why not?

 

[spinningmagnets]

This mid drive bike climbed up this trail with no heat and lots of pep. From the water shown in the background up to where the photo is taken and video is .8 of a mile. I used only 1-Ah to climb this hill

I want to emphasize that this was done with an affordable and easier-to-fit 48V battery. Christerljung is also getting great performance from a GNG-Gen1...using 72V. The 6.5-inch MAC is an outrunner, and the 4.5-inch GNG is an inrunner. This means that the MAC (or even the BPM) has so much more leverage than the GNG from the magnets being much farther out that they make more torque from the same watts (or the same torque from fewer watts).

You could probably get some pretty great performance from an even smaller motor that has the heat-bridge installed with the shaft-drive conversion, but...by using the largest motor that will fit there, it will run cooler under all loads compared to the smaller motor.

Nothing wrong with LiPo (if you are experienced with them), but the low amp-draw of this configuration and limiting the pack to 48V means that a non-LiPo pack is actually an option (I like cell_mans NMC triangle pack, and Migueralliarts 20R cell-pack)

http://em3ev.com/store/index.php?route=product/product&path=35&product_id=123
http://endless-sphere.com/forums/viewtopic.php?f=14&t=50538

 

[crossbreak]

. This means that the MAC (or even the BPM) has so much more leverage than the GNG from the magnets being much farther out that they make more torque from the same watts (or the same torque from fewer watts).

This is not true. For a GNG drive that is geared for the same Nm/amp, efficiency should be almost equal. Sadly the GNG is geared badly, wasting most of it's potential. The MAC/BPM just have an advantage since they have more power and can run more efficiently at the same power. Inrunners are fine if geared right!

When you go for LiPo i can advise to use a BMS, since it's likely to loose a cell one day if LVC isn't monitored for every single cell. I use the OZ890 SmartBMS with great success. It's easy to use, programmable and very affordable. It's only rated for 40amps, i use it with 100amps peak @ 12s Lipo with additional heatsinc. Short circuit protection, overcharge protection and bleeding ability (no more need for RC chargers ) are additional features worth buying.

 

[rodgah]

Still missing something on embedding the video

unfortunately youtube has a few links that will navigate you to the same video so it gets confusing if you dont know what the rest of the link means ie....

http://www.youtube.com/watch?v=1HGr7bAl2V8&feature=youtu.be
or
http://www.youtube.com/watch?v=1HGr7bAl2V8

the &feature part is a variable passed in the url....the only need the bit you need is the bit after the = which is 1HGr7bAl2V8

 

[spinningmagnets]

For a GNG drive that is geared for the same Nm/amp, efficiency should be almost equal

I see what you mean...perhaps it would be more accurate to say that a larger diameter magnetic gap on the MAC means that a 6-inch outrunner requires much less reduction to achieve the same output shaft power as a small diameter inrunner.

If the GNG motor was a larger diameter and was available in a dozen kV's, I might not have experimented with shaft-drive converted MACs

 

[jateureka]

Great build thread and nice video. Thanks for posting.

 

[waynebergman]

View attachment 1
Starting to chip away at the battery box for my new pack to go on the Giant. The new battery pack for the Giant is the same 14.3ah from cellman that I have on the mid-drive hard tail. This 14.3ah lith mang has worked so well on the hard tail and such a nice size pack I feel I will have a much better handling bike putting the weight here in the triangle instead of the twin 10ah placements. The old seat post mount is no more and the mount for the old pack that was under the down tube will also be removed. I will have plenty of range and be much lighter overall than my old twin 10ah packs. The new pack that will be installed on the Giant will also have the new version 3 ca and eb3 controller c/w temp sensor and the pre charge feature for the battery pack. I will keep the mac 10t in the wheel for now even though I know I will convert it like the hard tail, but I want to have the bike ready to ride for taking out friends etc to share the e-experience with for the summer. Come fall I plan do the mid drive treatment on the Giant as well. The little hard tail is running like a charm! I am feeling the geared system is the way to go if you can, and especially if you are trying to keeping the weight down with a 48v battery.

 

[waynebergman]

A report on mileage per ah on today's ride. Its obvious you will get better mileage per AH if you ride slower providing your motor is still working in its happy zone but I was just curious today to slow the ride down to 20mph instead of 30 to 35mph on my 6 mile round trip to town. This is kind of an up and down ride all on paved roads. It is a round trip so no overall elevation gain or loss. Normally if I have the throttle pretty much pinned for such a ride I will get about 2 miles per 1 AH. Today slowing things down and still using the gears to keep the motor in its happy zone I was able to get very close to 3 miles per 1 AH. This is a 50% extension on my range if I was needing to conserve battery power. I am sure this obvious to most but I was curious to see how much more range I could get slowing the over all speed down. Its nice to know if I take it easy like this I should be able to get pretty close to 40 miles on a full charge.

 

[rodgah]

yep that is why spinning a larger motor in its happy zone is sometimes more efficient than spinning a small motor in its unhappy zone to keep the same speed. Good luck with the dh comp, I have been looking at mine for a while, it is a good candidate for middrive with its wide BB.