Electric free ride build from scratch

in retrospect i'd have to say that i should not have put the motor in the swingarm :lol: i did it in an effort to simplify things but i can see now that mounting it in the frame doesn't really add more complexity and it's definitely still possible to have the motor coaxial w/ the pivot to avoid "chain growth" issues.
 
Finally even after my request to cancel order for the flipsky 6374 and vesc controller both items arrived after 70 days . Now I have them with me . But like I posted earlier I do not intend to use them on this build. I'll use it for a side project of making an electric skateboard for my son sometimes later

<a href="http://s1378.photobucket.com/user/atulsdharan/media/IMG_20190410_104519_zpsikvmm4vk.jpg.html" target="_blank"><img src="https://oi1378.photobucket.com/albums/ah119/atulsdharan/IMG_20190410_104519_zpsikvmm4vk.jpg" border="0" alt=" photo IMG_20190410_104519_zpsikvmm4vk.jpg"/></a>

<a href="http://s1378.photobucket.com/user/atulsdharan/media/IMG_20190410_104539_zpswqq8gcla.jpg.html" target="_blank"><img src="https://oi1378.photobucket.com/albums/ah119/atulsdharan/IMG_20190410_104539_zpswqq8gcla.jpg" border="0" alt=" photo IMG_20190410_104539_zpswqq8gcla.jpg"/></a>

In the mean time I also got some sample lithium ion cells for testing from a local supplier
He just gave me 5 cells of 2400 mah and a claimed 7.5 amp discharge capacity to check

I charged the cells to 4.2 vusing an rc charger and left them for almost 15 days and then the voltage of all cells were around 4.17v

Then I did a discharge test of all cells at 2 amps which is slightly below 1c . Two of the cells only showed in the range of 2100/ 2200 which is something I don't know if I need to be worried about

Is it ok to have 200/ 300 Milli amp hour variation in cells making a battery pack


<a href="http://s1378.photobucket.com/user/atulsdharan/media/IMG_20190410_104440_zpsn8ks1gdm.jpg.html" target="_blank"><img src="https://oi1378.photobucket.com/albums/ah119/atulsdharan/IMG_20190410_104440_zpsn8ks1gdm.jpg" border="0" alt=" photo IMG_20190410_104440_zpsn8ks1gdm.jpg"/></a>
 
I haven't yet checked the max discharge capabilities of the cell. Frankly I don't know how to check. Planning to run an rc motor with a propeller at high speed and check how much the cell is discharging

Kindly give me some pointers regarding the capacity I saw I'm the sample cells . Is 2166 / 2200 ish acceptable
For a 2400 mah cell?

I won't be building the pack myself since I don't have a spot welder

Intend to make 3 packs of 6s15p and connect them in series
 
For the motors I ordered a ds4500 from eastgem and also a Kelly controller from the same site

I saw a video of skeetab burning the phase wires of a d7500 motor

Can I know what led to such a failure?

How much power was he running when the wires smoked ?

Any reliable figure of how much power can the d4500 take without burning ?

As of now my battery pack if it delivers the claimed 7.5 amps will give a peak of 15x7.5= 112 .5 amps
The Kelly controller I bought has a limit of 120 amps max

The pack is 18 s so nominal of 66 ish volts

That gives a 7.3 kW max to my motor. Will the d4500 be able to this ??
What's the max someone has run this motor on

Any suggestions would be incredible

Thanks in advance
 
https://secondlifestorage.com/repackr.php

this tool should help you group your cells to have the least capacity differences across parallel groups

denzel d4500 is a 5kg motor, in the same class as my BHT. i got a thermal sensor directly on the windings and i'm getting up to 90C in difficult terrain. controller battery amps: 55A. i don't think i want to increase this any more :lol:
 
The local battery seller says that he ll do grouping . Guess I'll have to go and monitor that when the pack is being made
 
yeah it climbs pretty much everything around here. btw i'm also planning on using a smaller motor sprocket to sacrifice top speed for more torque.

since you ordered a Kelly just start conservatively then start upping the amps if you see that the motor isn't getting hot

as for the cells since you'll be using used cells i recommend you do the vetting yourself, with high rejection rate. buy more than you need and use only the best cells
 
Ok. I guess I'll have to buy some equipment which allows discharging of multiple cells together
 
<a href="http://s1378.photobucket.com/user/atulsdharan/media/IMG_20190417_193505_zpsyplz0bbv.jpg.html" target="_blank"><img src="https://oi1378.photobucket.com/albums/ah119/atulsdharan/IMG_20190417_193505_zpsyplz0bbv.jpg" border="0" alt=" photo IMG_20190417_193505_zpsyplz0bbv.jpg"/></a>

Finally the Denzel 4500 and controller delivered
 
Chain is an area im most confused on. I understand the dimensions but in local market I can only buy chains for motorcycle models launched in India. The sellers don't have much idea of specs of the chain. I wanted a low pitch chain so that I can make a sprocket with large teeth count and yet be smaller in diameter

What reduction should I run ? I took 4500 rpm as the no load rpm and thinking of coming down to 1000 rpm on wheels. With 18 " motorcycle tyres ( oh yes I'll update on that I bought an 18 inch rim and semi off road tyres of an Indian brand. Slightly on heavier side ) will 1000 rpm be exiting ? The calculations show interesting results . I reduced another 20 % for the sake of realism and still the speed value looks good. The tyre needs 533 rev/ km. So in getting 90 KMPH even after reducing 20 percent for all kinds of losses . Seems a little unlikely.

What would be the onload speed of a motor that spins 4500 rpm no load ? Is there a way to determine that ?

Also I calculated the torque based on 4500 rpm and 4500 watts and it's about 9.5 NM. Is that the actual torque of this motor ? I had to depend on calculations because I did not find the torque value in any of the speck sheets

Also I went through your build but could not understand how u charged your batteries. Where did you connect your balance wires on that charger which you showed
 
Fk0qecO.png


i used this calculator but i ended up having an actual speed of about 50kph (or 55kph using this controller's "overspeed" mode). so use a value of about 80% in the "percentage of speed when loaded" for more realistic results. get a cheap laser tach very useful.

use as much reduction as needed to get your desired speed. check w/ your local industrial chain supplier for availability of those big sprockets in the 80t range. common motorcycle sprockets only go up to around 52t. you probably don't want smaller than 11t for the motor sprocket

as for chain size i'm already having chain "stretch" (wear) issues w/ 420 chain so you probably don't want anything smaller especially for riding off-road. #35 or T8F chain will probably wear out too quickly. BTW #41 industrial size is compatible w/ #420 sprockets. i just purchased some 41 chain, should be a lightweight alternative to 420 chain. this also means that you could use #41 industrial sprockets i.e. these are probably your only option since you probably need a rear sprocket in the 80t range

as for charger i'm using the Minghe BST900W. no BMS

R52zGES.jpg
 
Hey Bonneville, Welcome!

I've make my own e-motos too and all sources are free. Check some project links:

https://endless-sphere.com/forums/viewtopic.php?t=92563
https://www.youtube.com/channel/UCxQhyZTLAw3pfvJFZXAff8w
https://github.com/eroldan/OpenEMoto

About motors, I'm very happy with the Denzel D4500, it is really powerfull. Hub motors are easier to install and any MXUS3000 clone will be nice to ride.
 
Bonneville said:
Chain is an area im most confused on. I understand the dimensions but in local market I can only buy chains for motorcycle models launched in India. The sellers don't have much idea of specs of the chain. I wanted a low pitch chain so that I can make a sprocket with large teeth count and yet be smaller in diameter

What reduction should I run ? I took 4500 rpm as the no load rpm and thinking of coming down to 1000 rpm on wheels. With 18 " motorcycle tyres ( oh yes I'll update on that I bought an 18 inch rim and semi off road tyres of an Indian brand. Slightly on heavier side ) will 1000 rpm be exiting ? The calculations show interesting results . I reduced another 20 % for the sake of realism and still the speed value looks good. The tyre needs 533 rev/ km. So in getting 90 KMPH even after reducing 20 percent for all kinds of losses . Seems a little unlikely.

What would be the onload speed of a motor that spins 4500 rpm no load ? Is there a way to determine that ?

Also I calculated the torque based on 4500 rpm and 4500 watts and it's about 9.5 NM. Is that the actual torque of this motor ? I had to depend on calculations because I did not find the torque value in any of the speck sheets

Also I went through your build but could not understand how u charged your batteries. Where did you connect your balance wires on that charger which you showed
Click to expand...

Hey thanks for the pointer. Finally I was able to contact a chap who supplies spares for go-kart who has agreed to provide chain as well as the front sprocket. May have to make an adaptor to fix it to the motor .

The transmission calculator from recumbent bike is quite useful thanks

Designing the motor mount and swing arm attachment to frame

Will post the pics once done

Cheers
 
trazor said:
Hey Bonneville, Welcome!

I've make my own e-motos too and all sources are free. Check some project links:

https://endless-sphere.com/forums/viewtopic.php?t=92563
https://www.youtube.com/channel/UCxQhyZTLAw3pfvJFZXAff8w
https://github.com/eroldan/OpenEMoto

About motors, I'm very happy with the Denzel D4500, it is really powerfull. Hub motors are easier to install and any MXUS3000 clone will be nice to ride.
Click to expand...


Hey trazor thanks a lot
I had already gone through your posts and was impressed and inspired by your frame welding. Very clean notches on the joints. I could never manage to get it that clean while cutting

Cheers
 
Finally after a long period of inactivity i got some time to work on the designing of motor mounts this weekend.

i finally decided not to mount the motor on the swing arm. though its easy implementation i realised that for the shape of my frame the motor mounted swing arm wasnt looking good. it had an odd look so i decided to mount the motor inside the frame cradle in the more conventional fashion. though it may be a little difficult to impliment ill still attempt to make the bushes of the swing arm concentric with the motor shaft to avoid chain slacking issues during shock compression.

i designed the motor mount in onshape. it has a removable back plate design to dismount the motor when the mount is attacted to the frame.

the mount itself can be moved laterally ina slot on the bed plate for correct sprocket to drive alignment



the mount and the base plate which has slots for lateral movement of the bolts of the mount
 
decided not to hand cut the plates for the parts for the mount and went to a nearby laser cutting services and got the parts cut in 5 mm Mild steel

it took hardly ten mins for the cut . 5 mm was the max thickness their machine could cut




 
since i dont have a welding machine i went to my local guy to help me weld it . attached a small clamp on the rear plate which can be removed for motor removal



 
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