Holy CRAP! 125V@102A into a cromotor, Video

[Alan B]

Cromotor Speed Estimation

The Cromotor motor is about double the power of a 9C.

You can do a quick calculation and based on 55 mph from 125V in 21.5" wheel like this:

your speed approximately = your voltage / 125 * your tire diameter / 21.5 * 55 mph

So an 18S Lipo and 17" moped rim comes out about 35 mph. Hills will be ignored.

[John in CR]

A 17" moped rim has a 17" rim, and the OD of the wheel will depend on the tire, but in all likelihood it will be greater than Zombies's. It's not like the retarded bike convention for tires.

[John in CR]

Zombiess, great reporting, but we need to know your weight for any kind of informed comparison.

[Alan B]

A 17" moped rim has a 17" rim, and the OD of the wheel will depend on the tire, but in all likelihood it will be greater than Zombies's. It's not like the retarded bike convention for tires.

Yes, of course you are correct. I used 23.5" for the tire diameter in my calculation above.

[Alan B]

Zombiess, great reporting, but we need to know your weight for any kind of informed comparison.

John what is magnet width and diameter of your dualspeed hub? How does that compare with Cromotor? (There is more to compare, but these are easy, the other items are not so easy).

[John in CR]

A 17" moped rim has a 17" rim, and the OD of the wheel will depend on the tire, but in all likelihood it will be greater than Zombies's. It's not like the retarded bike convention for tires.

Yes, of course you are correct. I used 23.5" for the tire diameter in my calculation above.

You caught me not paying attention to the voltage difference, though that's probably a bit big for a moped tire. My moto tires on a 17" are right at 23.5" and they're a lot higher profile than the moped tires I've seen. The huge difference in wind resistance will offset that in the other direction.

Also, once you get into those speeds tire size becomes pretty unreliable. eg My bike that Luke had up to 61mph when he was down pushing 120A battery side through the controller at 74V nominal (20s) had that 23.5" diameter wheel I mentioned above. My daily rider with the same motor is much lower and runs a 20" OD wheel, a moto 14" rim and tire, and it comes very close to the same top speed with the same voltage but at only 75-80A battery side. The moral of the story is that overcoming the wind is everything. If I tried that hubbie Luke used with the 17" rim on the bike I'm currently building, I have no doubt it would push through 70mph. Don't forget, I weigh 250lbs too, so weight has little to do with speed, except on hills, but it matters for acceleration.

[johnrobholmes]

... My wheels are being built as we speak by JRH = 17 inch moped rims, 12g spokes with 2.5 gazelle tires. ....

Ahh, so this is your wheelset I have been working on They are both loose laced and will be trued tomorrow.

[John in CR]

Zombiess, great reporting, but we need to know your weight for any kind of informed comparison.

John what is magnet width and diameter of your dualspeed hub? How does that compare with Cromotor? (There is more to compare, but these are easy, the other items are not so easy).

My high efficiency motor is a completely different animal, so I'll resist comparisons. The Cromotor is more like the motors I've used for 3 years, but with a 50mm stator instead of 40mm. Call the Cromotor a brute force beast that kicks the crap out of the old X5 (as long as you don't need to do pedal only) and be done with it. We should have had motors like this almost 3 years ago, but the factory I dealt with refused to believe that anyone would want this kind of power on a bicycle, so they didn't want to do a bike friendly axle and right side cover for me. Rephrase that, they refused to do it without a 1000 motor order. Of course I didn't know then how easily I could have ordered axle's and side covers only on the side, since this diameter motor has become a mainstay in China. Now ordering parts and pieces has become quite easy, and thankfully some Chinese guys are racing their stuff, so the guys with the parts available to them dirt cheap are figuring out how to stuff as much motor as will fit in 135mm width.

[zombiess]

I weigh 170lbs again I was up to 177lbs after vacation because I was eating good but now I'm suffering killer jet lag/sickness and am back down to 170lbs... grrr I'm 6'1. Call me 175lbs geared up to ride. I'm living on anti nausea medication right now, might have the flu or just really bad case of jet lag, I hate going West to East and I'm doing it again next week going to Europe for a week.

Found out something really interesting about the controllers I'm using and a problem I was having at low speed after doing the shunt mod. Turns out I was running 102A battery 80A phase. The EB3XX controllers are different. Prior to my shunt mod I was pulling -15ish amps on regen using setting 2, after the shunt mod dropped my shunt to 0.52x mOhm I'm still pulling -15ish amps on regen setting 2 instead of getting stronger as in previous models. Controller expects a 1.5mOhm shunt for software to be accurate so now I triple the battery current setting to figure out what I'm really pulling. Tested this tonight. 20A battery current = just over 60 amps.

Starting a new thread in the tech section about this http://endless-sphere.com/forums/viewtopic.php?f=2&t=35890, maybe others know this info but I didn't. Set phase battery amps to 60 (programmed it for 20A) and phase amps programmed to 100A and my low speed take off problem was gone and wheelie city was back. 1:5 ratio battery to phase current and this thing is an animal on just 60A battery 100A phase, a lot smoother too. I'll have to try upping the battery current to see how it effects things.

I was so busy testing setting troubleshooting this problem that I forgot my temp probe until I was done, but ran an grabbed it as soon as I realized the controller was warm so about 1 min between power off and temp readings.

FET Temp 48C
Ambient Internal temp 55C

FET temps were dropping faster than the ambient internal temp which was dropping much slower.
Hand on the cover motor temp check, slightly warm, even 10 mins after shutting it off

I tried different settings and was up to 102A battery current at one point again. Went back and edited my posts on phase amps.

Videos will be tomorrow or Saturday now that I figured out this last issue. Gotta get my rear brake installed tonight, I need it desperately.

[gensem]

LoL... that means your take off would be much faster and that also means your controller would probably smell bad with 100/240

[zombiess]

LoL... that means your take off would be much faster and that also means your controller would probably smell bad with 100/240

Take off... more like reverse catapult. At 100A phase and switch on the high setting I must be careful with the throttle from a stop.

Forgot to mention, top speed today was 56mph in the neighborhood. I wonder if this has the ability to put me in the 60mph club

[John in CR]

I weigh 170lbs again I was up to 177lbs after vacation because I was eating good but now I'm suffering killer jet lag/sickness and am back down to 170lbs... grrr I'm 6'1. Call me 175lbs geared up to ride. I'm living on anti nausea medication right now, might have the flu or just really bad case of jet lag, I hate going West to East and I'm doing it again next week going to Europe for a week.

Not jet lag, just a lack of good food. If you stayed with us for a few months, I'd put some meat on your bones with some good ole cajun cooking.

Load your bike down till it weighs 125lbs. Then put 90lbs in your backpack, since I ride around with at least an extra 10 on my back, and then we can compare performance for Alan B. Of course I'll just pull out my trump card with Hubmonster on my modded SuperV, which bows down to give hommage only to LFP's monster bike. That wouldn't be fair though since it's a bigger heavier motor that could never fit on a regular bicycle, which I'd consider insane anyway. You modded yours nicely, but with your light weight and high CG, you'll never be able to fully utilize the Cromotor. You might as well send it to someone who can give it a good workout, such as me.

If someone wants the most powerful hubmotor designed to fit regular bike dropouts, then I believe the Cromotor is it. Of course that's only until someone comes out with one made using a 40-50mm long stator with one of the larger diameter stators and rotors currently available.

[John in CR]

Zombiess,

WRT your current limit issues, doesn't your motor sound odd? Mine sound current starved below a 2.5:1 (phase/battery) current ratio. It's gotta be that your low weight isn't presenting much load for that big motor.

[zombiess]

Zombiess,

WRT your current limit issues, doesn't your motor sound odd? Mine sound current starved below a 2.5:1 (phase/battery) current ratio. It's gotta be that your low weight isn't presenting much load for that big motor.

Motor sounds good now at low rpm that phase amps are set at 100 and battery at 60A. Load caused an issue before I upped the phase amps and it would kinda cut out if I wasn't gentle at low RPM on both the 9C 2806 and the Hubzilla which led me to today's testing. I don't think the old battery current multiplied 2.5 times battery current holds true any more on these controllers but lets move this discussion to my new tech thread I created about this. Are you using an EB3xx controller? I suspect these are a slightly different animal than the EB8XX and EB2XX series (I own all 3 but have the most experience with EB3XX).

[hillzofvalp]

I want acceleration times.

[gensem]

Zombies... were is the video???? your late already!
btw get some timed runs from 0 to 50mph

[Enpro]

Zombies... were is the video???? your late already!
btw get some timed runs from 0 to 50mph

+1

[zombiess]

Video posted here
viewtopic.php?f=6&t=35925

[MadRhino]

Thanks for the vid, looks promising.

[Enpro]

60mph with a 20" wheel..
Very impressive indeed!