Advise on cheap ebay controller for 72v qs205

Can anyone with hands on experience advise on a cheap ebay controller for my qs205 running on a 72v system? I cannot afford anything nice, I dont care what waveform it runs, I dont need regen breaking, Im just wondering if youve had good luck with any of the <$50 controllers out there?

EVFitting store which is Greentime on Aliexpress/Alibaba. Has SENSORED and UNSENSORED controllers.

HKSunwin on ebay might have some cheap SENSORED controllers.

Wait a minute, WHICH 205? If your motor draws too hard on the controller it'll turn ugly real quick.

People used to like Greentime, recently some have said they went downhill. I'd like something close to 200amps sensorless for some 18 of those melons I've got laying around, but are they up to it anymore?

https://www.ebay.com/itm/GREENTIME-15-Mosfet-48-84V-1500W-45Amax-Dual-Mode-Sensor-Sensorless-Brushless/362842210917

https://www.ebay.com/itm/48-72V-1500W-Electric-E-bike-Scooter-Brushless-DC-Motor-Speed-Controller/352985062668

After wearing out a few real nice Lyens controllers, I economized and started using cheap ebay scooter controllers on my vintage 5304 motor. They don't last forever, but typically you get a year of high use riding out of one. Or not, when one died immediately I got it replaced by the vendor.

With the bargain stuff, just look for one with lots of length, so 18 cheap ass fets in it, vs just 12.

I like to look for self learning, which is becoming standard more and more.

The QS205 V3 does not run with just any ebike controller. It is supposed to be run with a sine wave, and is known to fry most older infineon based (and clones) square wave controllers. I have fried 3 myself before finding one that does the job, and still running.

So ideally you choose one sine wave, for any sine wave controller will run the QS205.
If you want to run a cheap square wave controller, it is a gamble unless you can find the exact version of the board, that is usually not spec by sellers.

MadRhino said:

The QS205 V3 does not run with just any ebike controller. It is supposed to be run with a sine wave, and is known to fry most older infineon based (and clones) square wave controllers. I have fried 3 myself before finding one that does the job, and still running.

So ideally you choose one sine wave, for any sine wave controller will run the QS205.
If you want to run a cheap square wave controller, it is a gamble unless you can find the exact version of the board, that is usually not spec by sellers.

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I have searched for concrete evidence of this, found none but your experiences Rhino. No doubt your experience is yours... but.. I want to know why..... If you could link I would appreciate. I run my motor ( even though not a v3)(same 36 mag config/pole) with a trap controller no prob...

but....
what about the square waves? For sure gona damage? You said one DID work for you... so what is it? That makes them blow? Doesnt QS sell a square wave? I thought the YKK they sold was square... and we all know MikeinPhilli loves those for his QS builds ( fellow ebikerbuilder with some experience with these hubs... here in Philla) ... I have seen many bikes built with them in this combo.

I want to know, I am about to hook one up.

Thank you guys for the input, thats rad. Ill pull trigger on something today, I just cant afford to be frying $300-$500 controllers like i did my last one. One year out of a sub $100 is totally worth it.

DogDipstick said:

...
what about the square waves?

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The one that I run has infineon eeb-3 board. It was by luck, after frying 3 of those that I had here on the shelves. I am not an expert in electronics. A friend did check them all and said that, those that I had fried were eeb-1 and eeb-2. He did build later with the same QS205H50v3 and found the same board as mine to run it first try. Then he had found the eeb-6 is also running it fine. The newer infineon is a sine wave in a different casing.

QS motor are selling many square wave controllers, but they spec this motor to be run with sine wave only. Maybe none of the square wave controllers that they have can run it.

Trying this cheaper one out first:

https://www.ebay.com/itm/48-72V-1500W-Electric-E-bike-Scooter-Brushless-DC-Motor-Speed-Controller/352985062668