Hub Motor Upgrade 500W to 750W

[amberwolf]

I cant do Ferrofluid as those fixes dont seem to be legit and look hackerd to me. someone needs to develop a hub motor with forced air cooling or something with a vent and a screen or filter or something.. I know it wouldnt be water proof but id choose the cooling over water proofing....just make sure its a good screen or filter to keep dust debry from getting in the fans.

Sounds like you have some hours and days of searching and reading to do. (there is a LOT of material to go thru).

There are a number of threads that discuss the merits of various cooling methods, including at least one by Justin_LE specifically for testing methods of heating and cooling of hubmotors, with actual test data.

There is also the http://ebikes.ca/simulator, which for motors that have thermal test data, will *show* you what happens under whatever conditions you setup in the simulator.

I'd also recommend reading the "motor power ratings" page on ebikes.ca, as it will help explain some of what others have been trying to point out on here.


Learning what's already been done, and then seeing how it works in the simulator, may save you some time and money in reproducing all of this on your own.



FWIW, if you're really a perfectionist, I would recommend listening to what people have been telling you here, as you may be able to make a "perfect" system for your needs and usage scenario by doing that. But by resisting concepts discussed here, you may not be able to make something that will really do what you want to do, without overstressing the parts you use and shortening their lifespan, at best. (and at worst, not do what you want at all).

Unfortunatley most of the "perfectionists" I've met (including the one I see in the mirror) are not really perfectionists...they're just stubborn.

 

[amberwolf]

FWIW, a lawyer can't change reality, either. Even if you can get one to accept your case, this stuff is made the way it is, and it's going to continue to be made like that whether we like it or not, because it works for most people, and it's cheap to do this way. Even if you won a case against a company for providing a solution that didnt' do what you wanted it to, or wasn't alterable to do what you wanted (highly unlikely), it wont' solve your problem.

The solution to your problems is to get the stuff that does exactly what you want now, and perhaps leaves you upgrade paths in the future. The way to do that is to either learn everything there is to learn about all this stuff, so you can find all the things you need on your own, or design and build your own stuff that does exactly what you want (some people *have* done this), or provide us with a complete and detailed list of exactly what you need the system to do, and all of the exact conditions it must be able to do those things under, and a budget (if any) you must stay within.

Then we would be able to help you find a solution (or set of them) that will meet your needs.


A good start would be to specify what you've got for a bike, preferably with pics attached to your post so we can see waht you have to work with mechanically to know what might fit.

Then specify your weight along with the bike's, and anything else you need to carry while riding.

The terrain you need to ride on, hills, road slopes, riding style (do you gun the throttle or feather it, do you like to pedal and how much/hard, etc), is riding done in traffic or on open roads, the road conditions, environment (winds, temperature ranges, rain, etc).

The speeds you need to go, and how far at what speed.

Any preferences you have for types of components, or specific features you require the system to have (does it need to be programmable? Do you need a display? What exactly does the display have to be able to show you? What features do you need programmability or adjustability for?

Etc.

The more information and details you provide, and the more clearly you post them (meaning, paragraphs, sentences, etc, not just a wall of text that is very difficult to read and parse), the more likely it is that someone will be able to help you find the right solution.

 

[devlin016]

okay so no one laugh but maybe i dont understand where to measure some things go right over my head please bare with me... But i measured it with a tape measure and I got 3 inches which is 76.2mm is that possible it doesnt sound right. im attaching a picture of what i measured. if it is right id say its 75mm. is there anymore measurements i need to take like my controller box??? and my terrain type is pretty much everything this thing needs to be all purpose and i need to not worry about loosing power if im going up a road or something..20mph + would be nice anything slower feels to slow. Id like to just upgrade my existing bike instead of scraping everything... scraping everything would mean buying that bike was a failure and I just cant have that yet.

 

[amberwolf]

Can't see the pic, but are you measuring the dropouts, or the spoke flanges?

Becauase about 3" sounds about right for a fatbike motor's spoke flanges.

If you really want the perfect measurement the easy way, you need to take the wheel out.

Otherwise try maanebedotten's method, but like his extra suggestion, I'd use an L-square or T-square to make it a little more accurate or at least easier to line up with the dropouts.

If you don't want to do any of those, I recommend using google to find other sites that suggest various methods of determining dropout width, or axle shoulder-to-shoulder distance, or hub OLD (overlocknut dimension).

You may wish to start reading up on Sheldon Brown's bicycle info and maintenance site; its' full of very useful information you are going to need at some point, if not already.

 

[devlin016]

im not sure why you cant see the picture are you running a adblock or something similar I couldnt use the forums built in attachments as the picture was bigger than 1.5MB but I do think its 75mm after search for other hubs of that size.

 

[devlin016]

im measuring the gap between the the spokes across the hub motor...so like the edges of the motor across each other.

 

[amberwolf]

Well, my question is, why are you measuring the spoke flanges, when you said you wanted to measure the dropouts?

 

[devlin016]

im attaching a compressed picture i guess i should of done that from the start sorry.

 

[devlin016]

cause im ignorant man but im trying... just a few gaps of knowledge im missing.

 

[devlin016]

"Just put a ruler between the spokes on top of the motor and eyeball it." i guess i understood that wrong

 

[devlin016]

okay after i googled measure bike dropouts i got the understanding the measurement is between the 2 spots the rear wheel bolts to the frame. that measurement looks about 8 inch but its harder to tell.... what could that be because 8 inch is 203.2mm so maybe the dropouts are 195mm?? doesnt that sound right??? isnt 195mm a standard pretty much for fat tire hubs?

 

[devlin016]

how do you guys know the rpms of my current motor? I cant find any info on it

 

[Dauntless]

how do you guys know the rpms of my current motor? I cant find any info on it

I didn't look too hard but I didn't find anyone mentioning that, so I can't comment on what might have been said.

If you were just asking how to find the rpm:

My working number for a 26" wheel to go 1 mile is 780 revolutions. If the bike is going 30mph that's half a mile a minute and 390rpm. If you were going 15mph and 195rpm, I might guess that at best for 500w, one would think your 36v motor had a KV of 5.5. This means one volt would give you 5.5rpm, so the 36v gives the 195rpm and then 48v gives 260rpm. Generally not so perfectly linear, but it works for your reference.

Your paperwork specs might give you a number that says KV. If so I would guess it will be around 5, but perhaps it might shock me. But these bikes are usually lacking info people on ES want because most people never work on their bike.

 

[2old]

You got the "width" determination correct, the distance from the inside of the dropouts (the two "cutouts" that secure the wheel). Since the tires are four inches wide, this measurement (and using your numbers) suggest 190 mm (about seven and one - half inches.
However, you should measure this as carefully as possible because the frame is probably aluminum and you don't want to "spread" it much if the new wheel is wider. If it's slightly narrower, you can space it out. You made a good choice for your initial purchase, but don't fall too much in love with the bike since for that price, the bike components can't be too high end.

 

[maanebedotten]

how do you guys know the rpms of my current motor? I cant find any info on it

Doing math hurts my head so I just use the motor calculator-tool-thingy at ebikes.ca for stuff like that. It is the most awesome tool for ebike tinkerers, you can use it for so many things. Your wheel diameter is probably somewhere between 28"-29", so just plug that into the calculator to see your wheel rpms at different speeds. If you also set the battery to 36v, motor type to Bafang BPM and controller to 20a the performance curves should match your bike pretty well.

I have to admit I cracked up a bit when I realized you had no idea what dropouts are, but all that really matters is that you figured it out and got a ballpark measure. I dont think the fatbike manufacturers have ever settled on a standard, I think I have seen anything between 150-200mm on different models. That is one of the reasons I dont like fatbikes. I want to be able to move stuff between different bikes so that whenever I upgrade something I can let the takeoffs trickle down through my bikes and essentially upgrade several of my bikes with only 1 purchase.

I have no idea what motors are available for your dropout width. As long as the axle is long enough you can always use spacers on a narrower model, but if your frame is aluminium you can only stretch it out 5mm or so before things get sketchy.

 

[devlin016]

about seven and one - half inches is what it exactly looked like I havnt read a tape measure or a ruler since grade school lol... but its safe to say its either 190mm or 195mm... im kinda leaning towards 190mm now because if thats what about seven and one - half inches is.

 

[2old]

Now you know what to look for. The MAC, a geared motor which could have been a consideration (although their best supplier, em3ev, doesn't represent them anymore), is 170 mm, so not a candidate IMO because, while you could space the axle out, the brakes and cassette would need to be spaced too. Also, as previously mentioned, a separate front hub system night be a good consideration that you could use sporadically as needed, and would serve as a back up; if one system failed, the other would get you home. Again, you'll need to measure dropout width which probably is 135 mm (about five and one-half inches).

 

[devlin016]

I wouldnt want 2 hubs running off 1 controller.. as no hub has identical windings they will start to fight each other at higher rpms. not to mention the requirements on the controller. but what if there was like a toggle switch that made it front wheel or rear wheel drive.... now thats an interesting idea.

 

[amberwolf]

You can't run two brushless motors off one controller, without them being identical and physically locked together, anyway (not possible with independent hubmotor wheels). There's a number of threads about this.

There are also a LOT of threads about 2WD, AWD, etc, with many ways of doing it.

But in any case, you need a separate controller for each motor. You can use one throttle to control both, or separate ones, etc. Depends on your preferences. I've done both; presently the trike has one throttle for both rear wheels, and the PAS also controls both.

 

[devlin016]

well i think thats a no go for me then.. i dont want to bulk my bike up with equipment I cant use 2 controllers..my bike wont be ugly alot of ebikes are just plain ugly... unless maybe the front wheel hub was like 250w and the controller was super small and i could fit all controllers in one controller box and the box didnt get too hott blah blah blah im aware of all that stuff. i was just thinking maybe 1 controller could switch between the front and rear hub. i cant think of a immediate reason why thats not possible but im also not as knowledgeable with this stuff as I am with other things.

 

[amberwolf]

As I noted, you would want to read up on 2WD, along with many other things you dismiss out of hand, as you are still making unwarranted assumptions. It takes time to learn about this stuff, but it is worth doing, if you really are a perfectionist (and not just stubborn) and want a perfect bike that does everything you want it to.

If you want to switch between two hubs, eitehr you'd need to plug and unplug the wires directly, or you need a switch that can handle the phase voltage and phase current that these would see. The voltages aren't quite as big a deal as long as you always power off before switching, but the current on some systems can be hundreds of amps very short peak (it is much higher than battery current), and at least dozens of amps continous. This makes for a pretty large switch, and you need three of them.

If you use sensorless motors, that's all you need is three high current switches. But if you have sensored motor / controller, you need another three (or four) low current low voltage switches to swap the hall sensor wires over too.

Each switch must have one pole and two throws, or a 1P2T, also called SPDT. You can get ganged versions, but costs go up sometimes dramatically the more poles you put in one switch, especially for high current versions.

By the time you enclose and wire them up, a second controller will be smaller than the switchbox.

 

[devlin016]

shit man why cant i just have my perfect world....

 

[2old]

BTW, I meant two distinct systems something I, and many others have accomplished easily. Doesn't have to be "ugly"; you just need to be creative. However, it's clear you're here to argue, so I'll sound off.

 

[devlin016]

im not even sure what im arguing im just absorbing and asking.

 

[devlin016]

so does anyone think this motor would work good as a replacement and i replace the controller later on.

https://www.aliexpress.com/item/4000922209481.html