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Need new motors? Grind a gearbox? Adding teeth to a pinion?
#147262
So, unfortunately one of my famed Nichibo 775-9009f motors failed. I was lucky enough to get two for free from Taiwan as a "sample". Needless to say I can't find them anywhere really. I've found it a couple times from overseas sites requiring a minimum orders quantity of hundreds or thousands.

Anyway, I've pretty much given up on coming across those again. Here's the motor specs and I was using them with 21T pinions in 7R gearboxes @ 24 volts with an ESC.

Nichibo 775-9009F
Input Voltage: 12V DC
No Load Speed: 20,500RPM
No Load Current: 4.8A
Stall Torque: 806.37 mN-M
Stall Current: 143.70
Maximum Output Power: 504 W
Max efficiency: (75.5%) 17,668RPM , 27 amps, 102.55 mN-m

Since I can't find another 775 motor that's this fast (I'm paying attention to Input voltage and no load speed)---I'm trying to find a suitable replacement and pinion gear that will be equal or better speed without any less torque than I had.

I think the closest motor I could find is a Johnson HC785LP. It seems close enough in RPM but with more torque that I might be able to run it with 22T pinions and get the same speed (or better??) any thoughts or can anyone confirm if my comparison is on track with what I'm trying to do. Should I expect less, equal or better top end by switching to this Johnson with 22T pinions?

Johnson HC785LP (775 motor)

Input voltage: 18V DC
No load Speed: 20,950 RPM
No load Current: 2.90A
Stall Torque: 1175.03 Mn-m
Stall Current 138.64
Maximum Output Power: 644.74W
Max efficiency: (78%) 18,310RPM, 19.9 amps, 148.10mN-m
#147265
I'm a bit intrigued about the longevity of a motor rated for 20k RPM at 12V running at 24V. Did you really run it at that voltage (40k RPM)? What is the current limit on your ESC? That is likely your critical torque limiter.

Regardless, the Johnson isn't very similar -- it's the same RPM but at 18V, not 12V. You'll only run ~28k RPM at 24V.

You may look at Vex Robotic's775PRO (19k RPM @ 12V, 134A / 710mN-M stall). Vex 775PRO motor

Ebay has several listings for Machibo 9511 motors, which would also be somewhat close -- likely 16-17k RPM @ 12V (there is no posted spec so I'm interpolating from the 8016/8514/9013 specs). They larger wiring than the Nichibo but more of it (11 turns), so the stall current is probably about the same and it will put out more torque. The specs for the Mabuchi 9013 motor show ~8.3mN*m/A and 21kRPM @ 18V (14k @ 12V). For torque, I'd guess the 9011 would be 7mN*m/A, vs. 5.7mN*m/A for the Nichibo motor per your specs.

http://www.ebay.com/itm/MABUCHI-RS-775WC-775-9511-Electric-Drill-Saw-High-Speed-Motor-DC12V-18V-19000RPM-/262414819022?hash=item3d19245ece:g:tfQAAOSwJAtZO3Y9

Lastly, if you really want that much speed you may be better off with a 1st-gear-less gearbox, but I don't know what you are putting it in. You can see my mod in the "Quad Damage" thread. I use two 775 motors per gearbox, driving 2nd gear directly. This should be able to drive more power and torque for the same speed, with less heat per motor, but it's definitely a bigger hack.
#147267
Well I've got a lot to respond to, so I'll start at the top :) As for the longevity, I've had these motors in for almost exactly a year now. My daughter is the speed demon and drives her jeep in the grass in our backyard with the occasional dirt patch. The great thing about these Nichibo 9009F's is that their operating range is from 12-24v so they're made for this kind of stuff. Although you're right, I didn't realize it at first but my ESC was my current limiting factor. I initially did the "Eastcoast power up" ESC conversion from Wesley which was a Yiyun YK31C 24V 500W unit. After about 3-4 months of driving the jeep the controller melted the solder off a rectifier diode on the board and the main (battery) power connector melted as well. All my connections were soldered...so I'm not sure why the connector melted. At that time I was running 19T boxes, and one of the first gears was trashed too. When the controller was working I think I clocked her around 10-11mph in very short grass.

fast forward a bit... I was on a mission to modify the Yiyun YK31C controller...I wanted more current out of it but I really didn't want to bother with re-wiring the whole jeep with a different controller when I already spent a bunch of time neatly wiring this one. So, I starting googling... I noticed one way to get more current out of these ESCs is to add solder to the current limiting shunt. You effectively lower the resistance of the shunt by doing this, which allows more current for the same voltage rating. I chose not to do this because you can't really calculate the change you're making--there's no fine tuning. It's like hammering a finish nail with a sledge hammer. However, I did something similar. I chose to do a current reference bypass on the circuit, so I can modify the reference point directly with a 1k trimmer. I can fine tune from 0W to Max. The concern here is that I can overdrive the components by turning the trimmer up too high. So, to make sure I couldn't to that--I spent a good amount (a lot..) of time researching the Yiyun circuit diagram and it's components. I replaced various MOSFETs with much higher current rated versions along with a couple other components. According to the components I changed, this should now be a 1000W 24V ESC. I also added a 12V PC fan to cool the circuit as some piece of mind insurance to protect my work. ;p. I also replaced the battery & motor wires on the board with 8ga wire. Thinking back I probably should have just used 10ga...it would have been a lot easier.

so, I got the Frankenstein ESC running with the Nichibo motors and decided to throw in 21T gearboxes and spent the $$ for some metal 1st gears. I clocked my daughter at 16mph (gps speedometer) and mom came running out with helmets... I'm sad to see these Nichibo motors go :( my goal was to reach close to 20mph on pavement. The other night we noticed one wheel wasn't turning, when I took it apart I discovered that the shaft of the motor was wobbling. the motor would still spin but the output shaft had worn a new groove...wallowing out it's original hole moving the pinion away from 1st gear.

As for the comparison, I did notice the 18V rating on the Johnson but I failed to follow through working out the math. (ultimately 28k rpm vs 40k rpm). The Johnson "seemed" similar enough that I could make up the difference it was lacking in rpm with a higher count pinion. buuut, now that you point it out its quite a difference.

The Vex motor sounds like the closest out of anything but I'm worried about it having less torque than my Nichibos. I'll definitely check out your quad damage thread to see what you did there.
#147268
Nice -- that's some impressive speed, and it sounds like the mods to the scooter controller paid off. I'm still surprised the motor lasted that long at those speeds. The current 9009F spec on Nichibo's website shows 21k RPM @ 12V and a 12-14V range. Most of the larger brushed motors seem to have manufacturer's specs that top out at ~25k RPM, max, so you were definitely running it hard.

You wouldn't lose much torque with the VEX motor -- it's only about 5% lower per amp, and you will be current-limited (the 9009F has a higher stall rating, but you can't make use of that).

Assuming your controller's limit is now ~100A (so 50A per motor), I mocked up a few scenarios in my spreadsheet:

Image

(for reference, I estimate the stock setup, with wiring and switch losses, etc., is 28-32 N*m with a 19T gearbox)

You would lose a bit with the Vex all the way around, although overall it's a more efficient (power-in vs. power-out) motor, that only affects battery life and motor life (a little). You could use the Mabuch 9511 with a 23T gear but it would be slower. I'd guess that setup would have a bit more torque than your current one, but as I said there are no official specs -- I assumed 7mNm/A vs. 8.3mNm/A for the 9013 which has specs.

If you got adventurous and decided on a dual-motor setup, you could really push it -- at least to the limits of the 2nd (still plastic) gear. Note that at 24V you'd barely be pushing the motors as each one is only running at 12V, and to really take advantage of it you'd want 36V -- that's still just 18V per motor (23k RPM each) .

I'm currently running this in an F-150 with the cheapest 775 motors I can find and tiny 11T gears. I ran it for awhile without a controller (eg. just stock wiring) at 24V -- without soft start it was a bit of a head-jerker. I've run it for a few hours with the speed controller at 36V including in packed and loose dirt with traction aids and it moves along just fine. (~12.5mph on 13.5" tires). To get the speed you're looking for at just 24V, you'd need a 19 or 21T gear. 36V with a 17T gear would get you well past the 20mph goal with 35% more torque than you have now, if nothing else in the gearbox gives (the 2nd gear is spinning 5x stock speed at that point).

My wife nixed further 36V running on pavement in our cul-de-sac. I'm going to build a similar setup with 14T gears for the newly-acquired Mustang, which should be a bit less likely to tip than the F150. I'm still only targeting 15mph @ 36V though -- 20mph would really be something :shock:.
#147292
Awesome. Thanks for the chart, that's helpful. Yes, I'm surprised my Nichibos lasted that long too. I first found the 9009F on the "Motor Database Sticky" thread @ viewtopic.php?f=9&t=7832
Rinowish is the one that said the 9009F is rated 12-24V...that's where I got that from.

I'm currently digging around for all my motor choices and i've found a couple with the specs I'm looking for but most of the difficulty comes down to actually finding a supplier for these motors. The VEX motor you mentioned is a good option. I'd really like a Johnson HC785LP-025. It's input voltage is 14.4VDC, no load speed of 21,363rpm, stall torque 1134.68nNm (150.36mNm @ max efficiency) & max output power of 634.85 W. no load current is 4.06 amps and 26.56 amps @ max efficiency. I've got the datasheet for the motor but unfortunately they don't list the voltage operating range. I'd bet it's at least a few volts higher than my 9009F--but of course I'd try it at 24V anyway:) However, I can't find this motor anywhere specifically. Johnson makes several variants of the HC785LP. The numbers after "LP" denote the variant.


Nichibo makes two other 775's that are interesting but I can't seem to find a supplier for either :(

Nichibo 775BE-9509F 12v @ 22,000RPM, 913mN-m stall torque (151.86mN-m @ max eff) but it's operating range says 6-12v
so I'd probably be pushing these even harder @ 24v than my 9009Fs...

Nichibo 775-8513SF 18v @ 21,000rpm, 1095mN-m stall torque (131mN-m @ max eff) operating range 6-20V
I like this one even though it's 18v (and not 12v) @ 21,000rpm , the fact that its operating range is higher @ 20v and increased torque made me think it would last longer @ 24v and i might be able to acquire the same speed with a 23T pinion. In actuality though, I bet this would end up being the same as putting in a Mabuchi 9511 with a 23T (still slower overall).

Nichibo also has an intriguing 755 series motor (same diameter as 775 but shorter in length) that seems like it might be just as speed capable as my 9009F's but with a higher operating voltage of 9.6-20v and a little more torque, surprisingly. It's listed as:
Nichibo 755-8016SF: 18v 23,000rpm op. range 9.6-20v 811mN-m stall torque (131.96mN-m @ max eff)

So, unless someone can find a Nichibo supplier for any of these motors I think we're down to two motor choices. The Vex motor the mentioned and this Johnson I found on Ebay. BTW--any idea what the operating voltage range is for the VEX?
Here's the one I found on Ebay:

http://www.ebay.com/itm/JOHNSON-RS-775- ... SwaIRZsQh0

In general, I like what I see but I'm a little confused by it...because I can't find a 775 model on Johnsons website that matches these specs & there's no torque #'s on the Ebay listing. operating range is 10.8 - 16.8V
Their test data shows:
10.8V speed 16,650rpm
14.4V speed 22,200rpm
16.8v speed 25,900rpm
So my questions are... is this thing real? What Johnson model # is it? What are the torque #'s? Assuming this thing is 'real' and the torque #'s aren't horrendous--I'd think this would be the one to go for. ...now--what to do with the 4mm output shaft diameter? :/
#147302
I found a Johnson catalog here:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiD9f_-x7XWAhUni1QKHWtDBtEQFggoMAA&url=http%3A%2F%2Fwww.ermec.com%2Fjohnsonelectric%2Fcatalogo%2F2007%2FJE_Motor.pdf&usg=AFQjCNG6BYfp0uWdldykUXE_z8UhnpKQjQ

This lists a "HC785P-001" that matches the specs you listed:
12V nominal
No load = 21000 RPM, 4.3A
Stall = 127A, 623mNm
Max Efficiency = 64% (really low)

Two things:
(A) This is a 60mm length motor (755-size can). This means a 10-15% less mass and cooling area.
(B) The torque constant is quite a bit lower (4.9mNm/A) than any of the other motors, including the 9009F; you'll be down >15% torque vs. your previous setup.


Given how hard you want to push these, I'd probably avoid a 755 motor. The Nichibo 755-8016SF would match up pretty well vs. the Mabuchi 9511 -- but I'd give the edge to the Mabuchi for longevity as it has a longer case/internals and lower winding resistance (= less heat production for the same current). And it may be easier to find given the # of them on ebay (buy a spare?).

Vex doesn't list a recommended upper range on the 775pro motor, but I'd guess they'd be reluctant to endorse running it over 25k RPM, as would likely any of these manufacturers. However, it has ball bearings front and rear (unlike at least the Mabuchi 8514 motors and the lesser 775s I've gotten). Did the 9009F have ball bearings?
#147308
Wow, that's odd. I wouldn't have guessed from the "785" designation that it could actually be a 755 motor can size. What's odd though is that you can't find the one you did from Johnsons website. if you go here and click on the platform drop-down of "35-54" I don't see it in there...but obviously from your link it exists.
http://www.johnsonelectric.com/en/produ ... -dc-motors

However, according to the information I was given by the ebay seller--the motor length is 65.5mm and a no load current of 2.76A. Which doesn't match the 755 johnson you found. ...weird.

I am not certain if my 9009F had ball bearings to be honest but I'm pretty certain it does.
Also, the people @ VEX responded to my question about Max operating voltage on the 775Pro. He said: "The nominal voltage for the 775pro is 12V; however, you should be able to push it to 15V if needed"

I heard 24V... :)
#147310
LOL :).

One thing about the Vex motor that is interesting is that the no-load current draw is extremely low. 0.7A @ 12V is just 8W, and it's running 18700 RPM. Likely due to the ball bearings but I'm not sure. It certainly helps on efficiency though, and should reduce the overall stress in the motor vs. the 9009F which the spec suggest used over 45W to do the same thing -- all of it going into heat.

You had also said that the 9009F "wore a new groove"-- which sounds more like a oil-impregnated bronze bearing setup.

If you get the 775pro, please post your impressions. I've been looking at it for awhile but have too many other modification projects already in flight.
#147315
I bet you're right about the 9009F having a oil impregnated bushing type setup. It's not listed in the specs whether it's a bearing or not and I haven't taken the motor apart yet. Can't tell with the pinion still being attached at the moment. safe to assume if it were ball bearing they'd be advertising it.

Good point about the Vex motor...sounds much more efficient and reliable than my 9009F's...but if mine held up as long as they did it sounds like the Vex's will hang in there even longer. If I get the Vex 775Pro I'll definitely post my results.

Here's a video of our "Bad Company" Jeep. This was a couple days before the motor failure. We drove it over to my neighbors house and I had him clock it driving on concrete with his radar gun (he's a cop). She was doing 13mph--and that was 5 minutes before the motor problem showed up. so obviously the new groove as already well worn when we clocked it. 13mph with a tired old worn out motor...not too shabby. also explains why i wasn't seeing the 16mph that I once did.

excuse the kid crying noises in the background ;p
#147332
Nice! That thing is flying pretty well :lol: . I'm still waiting for the kids to get in a "real" accident -- they're forced to wear their helmets whenever driving but that's pretty limited protection. That concern is mostly why all 3 of our vehicles have a top speed of 8mph +/- 1 .
#147345
Thanks. Yea I hear ya, our kids wear helmets too but this was right before mom ran outside with them. Lol. I forgot to grab it since it was supposed to be a quick "test run".
#147393
*Update*

I was able to get Nichibo to make some more sample motors for me (at a cost). These are custom though. I got them to make a dual ball bearing version of the 775-9009F which they call the 775B"-9009F. I'm waiting on the final performance sheet because they still need to make the motors so they can test them. However, I was told the dual ball bearing upgrade "wouldn't do much for efficiency" but would of course reduce vibration, current draw and I won't have to worry about an inside sleeve bearing wearing out (which is what mine did).

I wanted 4 of these motors but unfortunately shipping cost is too much. The motors only cost me $10/ea but the shipping is $61 for a box that weighs 1kg or less. 3-4 motors would have costed me another $61. :(

I'll post the performance data when I have it.
#147394
Ok, now that's seriously awesome. :D

However, I don't really want 775 motors. I want some of the (even larger) 997 series one -- another 50-70% larger, still running 18-24k RPM, 1000-1200W peak output per motor -- what could go wrong? :lol: . Who did you contact?

The 997s are really only going to be useful with an all-metal gearbox, but that's on my want-to-build list as well (2-stage, 42-49x reduction). I may be better off just going the scooter motor route (sealed, higher mass)...
#147395
Yea, I thought about that a few days ago..trying to fit a 997 series motor but i originally thought it might not be worth the effort to try to adapt it to the stock motor location. That was until I saw your 1st gear delete mod. wouldn't be that bad doing it that way. Have you narrowed down a good high rpm 997 series motor?

An all metal gearbox? that would be great! But how the hell do you intend to do that? lol--all metal gears too?

I'll PM you with who I contacted.

I wish I hand a DC brushed motor "design tool" that could let me input different values and options for certain size motors and see what's actually physically attainable. If I had that, I'd know what I could feasibly ask for in a custom motor build. :roll:

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