Light dirt bike, QS 120 70h motor, custom steel frame

Do it! I've been running 66a @ 24s for awhile now. Previously 16 and 18s, ~100a and ~80a respectively. I try to always gear for around 35mph max speed (and am happiest with 24s -charges quick @ 14a.)

Just cracked my bht open today and looks similar. Needed sprocket change which is welded, so upon cutting welds I gave throttle while holding sprocket.
Bad idea- no smoke but just grunts now and don't spin.

Just came on here to see what's up with bht's lately and maybe troubleshoot windings- glad yours is holding up bro. Post a link if you decide to refresh either bearing? I'll be doing the front except might just swap to spare.
 
IMG_20191021_113127 (Medium).jpg

IMG_20191021_095044.jpg

so here's my smaller 11t. basically i bored a hole through a standard motorcycle #420 sprocket then welded a shaft through it. keyway cut w/ a hacksaw :lol: will ride it later, expecting a bit more thrust w/ less top speed

yeah that front bearing is rusty and getting a bit rough so i replaced it. easy to find, not an exotic size. i also changed out the stock grease from the bearing w/ a quality EP grease. the back bearing is fine so i didn't replace

PS hope you get your BHT working again. have you tried running it in sensorless mode? just to make sure it's not a hall issue...
 
Well done with keeping the bolt and key/keyway. I hadn't had any issue with the quick-lazy of welding it, till I also tried quick-lazy with removing it lol.
Turns out my bht is just fine, But will have to see about fixing or another >84v >18fet controller

Will you upload a vid of yours in action when you turn it up? They are such a fun setup with some juice and proper gearing imo!
 
nutnspecial said:
Well done with keeping the bolt and key/keyway. I hadn't had any issue with the quick-lazy of welding it, till I also tried quick-lazy with removing it lol.
Turns out my bht is just fine, But will have to see about fixing or another >84v >18fet controller

Will you upload a vid of yours in action when you turn it up? They are such a fun setup with some juice and proper gearing imo!


will do! when it stops raining :lol:

the yuyangking YKZ7280 is here. wasn't expecting it to be this huge. the KLS7230 is already a chunky controller the YKZ manages to make it look tiny :lol: but all that size for just 80A max, the kelly is 120A max

IMG_20191028_134900 (Medium).jpg
(L to R: kt 6fet, YKZ7280, kelly KLS7230, cheapo 18fet)
 
Just cut the same Kelly shell to bits to give my vesc a heatsink deffo the same one the holes on top were offset the same till I cut it, I had it given to me blown up so it's had some use at least.
https://endless-sphere.com/forums/viewtopic.php?f=35&t=97557&start=50

That controller is huge shouldn't be any issues getting airflow over that, best of luck hope it goes well.
 
IMG_20191101_173656 (Medium).jpg

yyk overdrive.jpg

so there it is ziptied to the bottom of the saddle. the "overspeed" mode gave me back all the lost speed when i moved to 11t motor sprocket (from 13t). so i got a very nice increase in thrust due to the gearing change, further boosted by the increase in controller amps (from 55a to 80a). bike feels a lot more lively now.
 
IMG_20191102_111009 (Medium).jpg

jszh vs ga vs 26f.png

the higher amp controller needs better cells. i'm taking a gamble w/ these cheap (PHP95 or USD1.86 per piece, landed) chinese cells made by JSZH (jiangsu zhihang new energy). i've cycled a cell and got 97.8% after 152 cycles :shock: that's pretty good cycle life!

here's the raw data from the cycle test. in retrospect i set the LVC too low at 2.5V :lol: if you look at the discharge curve it begins to fall off the cliff at around 3.2v. but this didn't seem to hurt the cell at all :lol:


Code:
JSZH 18650 2600mah TEST!
charging time: 2:06 == 126 mins
rest: 0:05
discharging time: 0:54
rest: 0:05
TOTAL: 190 mins == 3.16~hrs per cycle

1.5a charge, 3.0a discharge, 2.5v cutoff

1 cycle: 2711mah
10: 2704
14: 2681
18: 2726
22: 2710
27: 2690
33: 2685
36: 2690
39: 2688
42: 2702
45: 2696
48: 2701
51: 2693
54: 2678
57: 2665
60: 2700
63: 2666
66: 2677        
69: 2690
72: 26xx
75: 2659
78: 2661
81: 2658
84: 2644
87: 2671
90: 2666
93: 2665
96: 2655
99: 2668
100: 2665
101: 2663
104: 2660
107: 2661
110: 2656
113: 2651
116: 2660
119: 2657
122: 2649
125: 2619
128: 2636
131: 2609
134: 2643
137: 2650
140: 2645
143: 2646
146: 2643
149: 2646
152: 2651
 
That should be well worth your time. What controller do you pair it with?
 
macribs said:
That should be well worth your time. What controller do you pair it with?


QS is bundling it w/ the votol EM100. this motor is an IPM internal permanent magnet motor so to be safe i ordered the controller as well. the votol as an option to use SPM or IPM

vtipm.jpg
 
Ok, not familiar with that votol controller. If QS pair'd the motor with that controller I am sure it will work well.
If not, you can always look at the controllers from vasiliSk, the nucular controllers. I've heard those work very well with that motor. In fact I think the nucular inventor actually got that qs motor in his test bench....
 
IMG_20200415_170041.jpg

IMG_20200415_205547.jpg

[youtube]eS4FApp2IDc[/youtube]


they're here finally! 1st test went well w/ a square wave controller. will test the votol tomorrow

RPM per volt is 38 (without timing advance, flux weakening). almost the same as the BHT. won't have to change my gearing which is why i picked this motor in the first place...
 
IMG_20190115_192321823.jpg

Don't mean to bomb your thread with pics but just want to say your on the right path with geometry and layout, the pic above is to show how not to do it even though the ride is not to bad a position for a short arse or kid the hardware layout is terrible

The weight is centred but high inbetween legs with my added high weight the suspension works overtime to stop a rocking horse type ride over bumps and then the battery tips back with a wheelie making it easy to flip if you try so being a lowish powered bike no big deal but if the power level was pushed on the design it would be a widow maker long before something well thought out would become out of its depth.

The battery is in the wrong position to get it low in the frame and the controller couldn't be any further away from the motor unless they placed it on the fork leg the cabling is needlessly to long over a metre from top of battery to controller and then same for the motor phases when careful planning would have got these down to 15cm or around 7 times shorter if the bike was 72v maybe if cut kuberg some slack but they choose a 48v system pushing 12kw so the wires have to cope with 200amp + burst phases are 6 awg and the battery 4awg, I'm knocking the bike but to be honest it's the best ride I've had im just being picky with it the front forks themselfs are amazing and the motor is naughty aswell with the battery and controller both keeping it well fed really I love it and blast it about quite often but if I was to rebuild a frame then I could love it more I know that much.

For me a simple design with clever packaging wins the day everytime it's the success of the original mini and many things alike, I like the design thought and process coming forward so far keep it up.
 
sqbatt.jpg

thanks but tbh i did make a lot of compromises for the sake of simplicity e.g. my 17s6p rectangular battery is arranged 17x6 which puts the weight high and forward (this can be felt while riding). a squarer pack would fix this relatively minor issue at the expense of a lot less elegant strip layout

glad you posted the kuberg! i'll be copying some parts of the swingarm :lol:

IMG_20161005_151836[1] (923)-1335x1335.jpg
 
Sub'd again these new QS motors are looking pretty hefty, curious how it does on this bike since mine weighs similar
 
skeetab5780 said:
Sub'd again these new QS motors are looking pretty hefty, curious how it does on this bike since mine weighs similar


got high hopes for this motor. it'll probably be the "final" motor for this frame :lol:

just got the frame extended at the bottom. needed butt welds (which i'm not a fan of) on both this flat part and the round tube. all parts beveled for penetration. to prevent blow through there's an aluminum backing plate for the flat pieces. for the round tube inserted smaller round piece inside


IMG_20200428_150800.jpg


IMG_20200428_180204.jpg
 
I've always had to use a washer on my swing arm to stop binding
 
trazor said:
Great progress! I'm curious about which method you use to bend tubes.
And the tube notching is perfect how you did it?



IMG_20200502_124210.jpg


IMG_20200502_124149.jpg


thanks to the lockdown the shop that does my bending is closed. so here's another covid mini project. extremely simple bender. just a stack of plates. i even cheated a bit and used acrylic for the inner layers. the pipe isn't pressing against the plastic so no issues there. in the middle are some aluminum shims to tweak the stack height
 
Looking good,

Can I ask why you are not running the motor concentric to the pivot anymore? Was there an issue with it or something else?

Thanks
 
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