The Unofficial 'CroMotor' Owners Tech-Tips Thread

Hi all,

I just wanted to say thanks to all of you. I have recieved my Cromotor, and this is a great thread that has already answered a lot of my questions.
 
hillzofvalp said:
Emoto said:
My other problem is the groove machining should not pass the shoulder and therefore weakening the shaft
Click to expand...

I agree, but it still conflicts with the design constraint of getting the wires in line with the axle slot. Don't they do it this way on other brands, too?
Click to expand...
Not sure what you mean, can you elaborate, i think the main point being they went from 14mm to 16mm shaft and to machine it in this critical area back down to 12mm with a motor of this torque....... plus most people will custom mod the swing arm / droupouts.
 
Wiring Clearance

Think about where the dropouts are gripping the flats. If the wire exits on the flat side of the axle there is nowhere for it to go, as it runs right into the C washers and the dropout (or the disc brake adapter and/or disc). If it exits on the thread edge it can pass through the C washer and then the parallel dropout spacing behind the axle. There is not enough room to take this big wire bundle out without using the space between the dropouts, especially with the disc brake etc using most of the space between the motor and the dropouts.

A picture worth a few hundred words:

DSC_9244.JPG
 
Yeah, but they still take it too far. They mill past the shoulder (using centerline of tool as reference). Right? However, they. Coudve milled it with a smaller tool and taken more passes and 2x the time and nearly eliminated the overshoot. Last time i had motor apart, I noticed that the wiring harness could have a tighter fit I.e. they took off more than necessary everywhere. I'm guessing this slot was done manually..

Other topic: Has anyone calculated the saturation current of this motor? The 9C was like 75A.. I can't remember thecross sectional area. What is this? 100A?
 
There are alot of cromotor running already I dont think the stock axle is an issue.

Saturation should be around 20kw but I dont know the formula to calc it...
 
Saturation current would be specified in amp-turns. I'd have to review my notes but seems like it was about 480 amp-turns to the first knee of the 9C (from Justin's measurements documented here on ES), where it begins to saturate and the torque per amp drops. So with a 7 turn 9C it is about 70 amps, beyond which more and more power goes into heat. So you can exceed this and get more torque, but you will suffer much lower efficiency and heat gain.

What did we decide the Cromotor was, 4 turns? Now this is very rough, but if it has twice the iron due to doubling the width, then it might have a first knee around 950 amp-turns, and with 4 turns that knee might be 230 amps. This is very rough, don't take it as accurate.

Has anyone tested the Cromotor with 200 phase amps?
 
Alan B said:
Saturation current would be specified in amp-turns. I'd have to review my notes but seems like it was about 480 amp-turns to the first knee of the 9C (from Justin's measurements documented here on ES), where it begins to saturate and the torque per amp drops. So with a 7 turn 9C it is about 70 amps, beyond which more and more power goes into heat. So you can exceed this and get more torque, but you will suffer much lower efficiency and heat gain.

What did we decide the Cromotor was, 4 turns? Now this is very rough, but if it has twice the iron due to doubling the width, then it might have a first knee around 950 amp-turns, and with 4 turns that knee might be 230 amps. This is very rough, don't take it as accurate.

Has anyone tested the Cromotor with 200 phase amps?
Click to expand...

I do run it with 160a phase, and in a couple weeks i ll run it with 260a phase.
 
Alan B said:
Wiring Clearance

Think about where the dropouts are gripping the flats. If the wire exits on the flat side of the axle there is nowhere for it to go, as it runs right into the C washers and the dropout (or the disc brake adapter and/or disc). If it exits on the thread edge it can pass through the C washer and then the parallel dropout spacing behind the axle. There is not enough room to take this big wire bundle out without using the space between the dropouts, especially with the disc brake etc using most of the space between the motor and the dropouts.

Thanks for that alan my motor isnt in the frame atm, i know what you guys mean, thats why im looking at mounting the disc without the 8mm adapter [re drilling or modding the disc] giving enough room to redirect the wiring between frame and disc, if the normal disc pattern was used the adapter wouldnt be needed, reducing the shaft to 12mm in that critical section is a no no, i think hillzofvalp has a good point also
Click to expand...
 
The real question is how many amps can the stock 10ga phase harness take? I'm thinking of stepping it up to 180A from 145A as a cautious experiment. Putting this much torque through a 29" wheel is probably a very rigorous, if not, very stupid testing medium (I know.. I know.. Don't worry I'm switching it to a 20" wheel soon)
 
Alan B said:
Has anyone tested the Cromotor with 200 phase amps?
Click to expand...

I have with a 36 FET IRFB4115 controller. Settings were 100A battery 210A phase, 125V with it sagging to 119V (sag was lots of surface charge from being at 4.16 per cell, once it drops to 122V I only see about 3-4V of sag). It pulled really hard everywhere but above 50mph and topped out at 57mph. I have another 36 FET IRFB4115 (cut down board for custom enclosure) and a 24 FET IRFB4115 controller ready to go on my bike for testing. I want to see how far I can push the 24 FET version, I'm guessing it will safely do 120A battery 240A phase with 132V max. The 36 FET has buss bars but I did a stock setup on the 24 FET, both have matched banks of FETs to hopefully let me push them harder. I need to figure out how to install my really long swing arm next so I can really test out power in the 15-25kw range without worry so much about wheelies.
 
hillzofvalp said:
and? the motor lives?
Click to expand...
Of course it does. Ive also done 8 to 10kw into my 9c 2806 many times too and its OK. You just need to know when to stop. On my 9c that was about 8 to 10 mins of 50-55mph riding. Its runs a 20 inch tire too. When cold it could power wheelie at 20 MPH if I wasn't fully leaned over.

Its OK to do stupid stuff like this as long as you don't get stupid.
 
Alan B said:
I think a quick opening canopy for the GreyBorg would be great. But I don't think it is that easy.

Does the whole thing need to come off, or do you just need an access door?
Click to expand...

I like in a condo and ll probably have to take the batteries off to charge (24s A123) so i ll have to pretty much remove one side every single day.

Was thinking of something like this.... fairly big ball

http://uk.farnell.com/wixroyd/3230-w005/spring-plunger-smooth-5mm/dp/7068232
 
You probably meant "live in a condo". "condom" is something else altogether :)

To make the ball work you would have to restrain the cover with another metal tab so it could be pinched between the ball and the metal tab. Otherwise the cover is too flexible and will come off.

I wonder if some strong magnets would work. Epoxy them to the inside edge of the cover and let them stick to the steel frame tubes. That plus an insurance strap or two might do the trick.

You could do what Stevil does and just leave one side off. He straps the batteries in. It works well. This would certainly do for awhile until you came up with a solution for a removable cover.
 
3M came out with a new Velcro type fastener called Dual Lock. It comes in different strengths and, I think would work great for your covers. Awhile back I got a sample pack of their different types. The stuff has unbelievable sheer strength and can be mechanically attached (no need to rely on the glue).

Notice where you can request a free sample. They send a nice variety.

http://solutions.3m.com/wps/portal/3M/en_US/3M-Industrial/Adhesives/Promotions-New-Products/Reclosable-Fasteners/?WT.mc_id=www.3M.com/DualLock
 
Hi Ecologymagnet,
to buy this motor contact greyborg.com, or flip a PM to (user name) Accountant on here.
They are in Zagreb, Croatia.
 
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