which controller parts to change for higher voltage & amps

[daveyjones97]

having decided im too poor to buy a proper ebike setup for now i want to find a controller to run a 2000w universal motor i found on ebay for $16.
im thinking a basic pwm controller (anyone reccomend one?) and replace/add more fets and main capacitor. would i need to replace any other parts to run a controller at double its rated voltage and current, im guessing i would.
the wish list is pwm 0-100% 72v and 35a continuous. i dont want regen or any other flash functions, amp and voltage limits would be nice. regular ebikes are 3 phase or gutless so im not hopefull about a proper ebike controller on the cheap.
if theres a good simple schematic id have a go at making one.
opinions and reccomendations please guys

 

[migueralliart]

having decided im too poor to buy a proper ebike setup for now i want to find a controller to run a 2000w universal motor i found on ebay for $16.
im thinking a basic pwm controller (anyone reccomend one?) and replace/add more fets and main capacitor. would i need to replace any other parts to run a controller at double its rated voltage and current, im guessing i would.
the wish list is pwm 0-100% 72v and 35a continuous. i dont want regen or any other flash functions, amp and voltage limits would be nice. regular ebikes are 3 phase or gutless so im not hopefull about a proper ebike controller on the cheap.
if theres a good simple schematic id have a go at making one.
opinions and reccomendations please guys

If you got it at that price I am guessing it is a brushed motor, if that's the case I have no ideas.

If it is a BRUSHLESS motor then 72V the hua tong controller is the best bang for your buck....

 

[daveyjones97]

yes its a brushed universal motor so i only need 1 phase pwm to run it. Im aware of the drawbacks of brushes but id like to think i could build a cheap ebike this way to have fun with until i save up for a proper setup.

 

[amberwolf]

having decided im too poor to buy a proper ebike setup for now i want to find a controller to run a 2000w universal motor i found on ebay for $16.

2KW at what voltage? Being a universal type, my guess is that'd be at 115VAC, or something like 130-150VDC, because that is what many universal types are designed for.

If so, it's going to run a lot slower and produce less power at a lower voltage. Might still be able to do the job you want, but you will have to test that. The treadmill motor (PMDC) that I used on CrazyBike2's first attempt at a drivetrain was made for 100VDC+, and I was going to run it at 24V or 36V, geared appropriately to drive my bike's regular pedal drivetrain at pedal input speeds. Seemed like it might work ok, but I never did road test it, as I got powerchair motors with gearboxs attached that made everything a lot easier.


Definitely need more info about that motor before being able to help a lot with how you can use it.


The nice thing about brushed is you can use just a switch to control it, although it will wear the switch pretty quickly if it wasn't made specifically for the purpose. :lol:

You *can* build your own controller for brushed stuff, but sometimes when going for higher power the layout and such becomes a lot more important than you'd think, and you may blow up a lot of parts in the development process (I did, and eventually gave up and used a modified/repaired ScootNGo controller, then a 2QD from http://4QD.co.uk, and later a Curtis golf cart controller). It's fairly straightforward in design and construction, but you'll only find out by testing the thing whether it will hold up to the use you have for it. None of mine did, except the modifications to the ScootNGo controller. Others have had better luck, like Numberonebikeslover (Naeem) here on ES.


To run the typical controller at double it's ratings, you may end up doing so much work to it that it'd be cheaper to just buy one with those ratings (especially after you blow it up a few times figuring out all of what needs to be upgraded :lol: ).

Brushed motor systems on ebikes aren't all gutless; just some of the more popular pre-built ones can be, as they have tiny batteries that can't supply much power (or not and still give decent life), so they limit the controllers from being able to drive the battery hard. (resulting in the mtoor not having a lot fo punch). The brushed system on CrazyBike2 was powerful enough to repeatedly destroy chainrings and pull chains apart, bend axles, destroy rims, etc.

Brushed mtoros are also typically less efficient than brushless, resulting in hotter motors for the same work performed. This sin't always the case, but often enough to make the generalization.


I'd like to see what you come up with, though, as I always like seeing people's completely-DIY setups.

 

[daveyjones97]

thanks, its from a karcher pressure washer and has 230/50hz printed on it. I was wondering about simple voltage doubling circuit but i dont know anything about how inefficient they are or how to integrate them with the controller. I have read the 4qd and 4qdtec sites but he doesnt seem to do 1 offs and as you stated if im going to end up wrecking and replacing a controller id sooner do it to a cheap one.
As a wise man once said; happiness is when ability exceeds ambition.

 

[whatever]

you can buy high power brushed controllers very cheaply,
they are used on three wheel trikes in china, you can get 60v no probs, but I"ve used them and the fets were rated for much higher voltage,
I ran without mod on 100v. Price in china is about $20usd, via aliexpress maybe a bit more.
very reliable, they make quite a bit of noise though, a squeel under load or at start up. They tend to be not too high amp ( 20 or so amps) but i'm sure you could up the amps easily with a shunt resistance mod, if you cant find I'll find some on the net

 

[amberwolf]

thanks, its from a karcher pressure washer and has 230/50hz printed on it. I was wondering about simple voltage doubling circuit but i dont know anything about how inefficient they are or how to integrate them with the controller. I

Check with Solcar here on this forum; he's designed a controller that might do what you want.

 

[daveyjones97]

thanks guys, il start looking into it. also going to look up the effect of voltage on universal motors. i think if the load stays constant the speed is affected the same as a regular motor, please correct me if im wrong. the problem i have is guessing the speed it will run at as that varies with load, high load lower speed, low load more speed all for a fixed current and voltage. for gearing im planning on using bicycle primary to gas kart secondary chain and sprockets to give 25:1 reduction overall. im betting on the motor running approx 5000rpm.

 

[amberwolf]

I don't recommend working out any gearing until you know what RPM the motor has at the nominal voltage you want to use.

Set up a tachometer (optical is safest; magnet for a hall type might fly off unless you band it on), then hook it up to a battery, and see what RPM you get. At a guess you'll get between 50% and 70% of that speed when loaded, depending on the load and gearing and voltage. The closer you are to it's rated voltage, the better off you'll be, power-wise, and the closer the ratio will be.


Most of those universal motors spin WAY faster than you'd expect, especially if they're small for the power output, requiring quite the geardown to use on a bike.

 

[daveyjones97]

oh dear this is gonna sound dumb; whats an optical sensor? i know about strobe lights for car ignition timing and magnetic, hall sensors but not too sure exactly what you mean. i dont have any scientific background or trade so i do have gaps in my tech knowledge but you're right i do need to nail down an expected rpm to volts.
oh, and while im saying dumb things, what about adapting a cordless drill esc. i have absolutely no idea how feasable that might be, but while elsewhere i had it pointed out to me how cheap cordless drills are, you get batteries, charger, esc, a motor that could be used for something else, whats not to like?

 

[amberwolf]

oh dear this is gonna sound dumb; whats an optical sensor? i know about strobe lights for car ignition timing and magnetic, hall sensors but not too sure exactly what you mean.

Optical is essentially the same as the car strobe in principle. I've borrowed an optical tachometer from a friend to test out some motors when I first started on my CrazyBike2 project; it was quite helpful. He's going to eventually bring it over again to help with my latest powerchair motor project testing, once we both have time at the same time.

oh, and while im saying dumb things, what about adapting a cordless drill esc. i have absolutely no idea how feasable that might be, but while elsewhere i had it pointed out to me how cheap cordless drills are, you get batteries, charger, esc, a motor that could be used for something else, whats not to like?

It's even possible to use the entire drill as the drive for the bike...but it won't handle the continuous power to drive it by itself; it would just be an assist to your pedalling. I considered something like that in my early motorization days, but had no cordless drill to do it. I don't think the ESC in the drill will handle the power, even on a different motor--at least not constantly. I dunno if they have protection in there to shut it down if it can't.

I did test out some possible drive ideas on the bench using a regular 115VAC powered drill, running on 36V SLA, and it wasn't enough to get usable power out of, becuase I didn't have enough speed to then use a reduction to get torque out of to drive a bike wheel with a load on it at any useful speed. I then tried using permanent magnets instead of the field coils and it worked even less well becuase I think the airgap was wrong (too big, probably); I dont' really know.

I suspect that in order to get useful power from yours, a motor that was designed to run at 230VAC, you'll need something close to or beyond that in DC from your battery to get it to spin at a useful rate that still lets you get useful torque from it.

That's the problem I also had with things like vacuum motors...I have a few rated 2hp+, but that's at like 10kRPM on 115VAC. They'll run on the lower voltage DC at a still-impressive speed...but need quite the reduction to get them down to useful speeds on the bike, while still being able to provide any torque...and then they get quite hot when put under loads, becuase they were meant to be constantly air-cooled as you used the vacuum. I'd wind up having to keep a fair bit of the ducting around the motor off the vacuum body, as well as the vacuum fans on there, or have the motor burn up pretty quickly under the loads I wanted it to take.

 

[daveyjones97]

thanks, am i right in thinking i could put also put the motors spindle in my pillar drill, set to a known rpm, and put 7.2 or 12v across the field coils and measure the amps & volts out? I havent got access to any sort of strobe right now. Im going to research controllers and mods to them, no one seems keen on very high voltage controllers for the beginner....

 

[DATABASE00]

not sure on my thinking but Im trying to build an ebike with a 2.25 H.P. 10 Amps , 90 Volts. CW Rotation . 4700 RPM motor from a treadmill
tring to run it off a 60 volt controller so it wont be crazy fast as far as rpm but I have not hooked it up yet to determin torque or if it has enough power yet. But when I plug motor into 12volt batterry it turns pretty good.