Controller advice please for Bafang 36V 250W

Samd

Samd

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Jun 28, 2011
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Ballarat, AU
Hi Guys,
I just bought a cheap Bafang rear wheel unit on ebay. Not laced in and no cassette, but will learn that later...

I have successfully rebuilt a brushed Aprilia Enjoy with a brushed controller YiYun LBD14 for thirty bucks delivered) in the last few months. I'm handy with a wattmeter, LiPos and a soldering iron.

But this new bike will be a runaround for my wife's pushbike. ****I haven't dealt with brushless yet.***

I need some quick and dirty advice on a cheap controller please. I'm in Australia. Happy to import. Would be nice to get higher wattage, but not so important. I'd like to start with plug and play.

Hoping it will be as cheap as the tnc scooters.

Hoping someone can quickly guide me. I will do a lot of reading tonight but am sure someone has been down this path already.
 
I have a 36v 350w "Bafang" style motor that runs well with an Infineon 20amp controller. Your motor should run well with any number of low to mid cost controllers.

However, the real question here would be what battery type/capacity are you running (i.e. lead acid, LifePo4, Lipo, etc, .)? This, of course, can be very important when it comes to LVC and/or current limit settings and/or programming capabilities (I'm guessing that you'll want something in the range of 15-20 amps for that motor).

You'll also probably want to select a controller manufacturer that offers an installation and/or wiring diagram (and, if possible, a fair degree of customer support).

Ebike.ca, Lyen, Cell-man, and Ebikekit all offer decent controllers at reasonable prices (with Cell-man and Lyen probably being the lowest cost of the 4). You can also go the "Ebay" route (which I'm not big on) as a means of further reducing the cost (again, just make sure that you select a retailer that offers a wiring diagram at the very least).
 
I found ordering direct from china to be the cheapest route by a large margin. Just bought my second 72V 1500W 40A controller off aliexpress for US$33 shipped. #OT100. Search for brushless controller.
 
E crazyman used to the be the guy, for straight from china controllers at good prices. Don't know if he's still there on ebay.

Generally 36v 15 amp is the standard for those types of motors, or less. 10 amps if the battery is really weak.
 
Awesome advice - awesome people.

Probably two Turnigy 8s 5.8Ah like my Aprilia Enjoy. I don;t know which bafang model yet - it was only 68 bucks so I took a gamble. Just as for my brushed motor - I am assuming you can 'overvolt' these ok and let the current limiter on the controller limit the total power well beyond the rated 250W?

Not sure if the unit is geared. We live in a flat location. I read up about the plastic gears wearing out under heavy load. Happy to replace the unit down the track - 68 bucks!
 
i have a bafang 250.... run it with an infineon 36vm25 amp c ontroller...ping 36v,12amp battery...no probs.. approc 1800 miles...did change on gear to steel :mrgreen:
 
Anyone hooked up a wattmeter and measured what power a 250 watt rated motor can consume?
 
That depends largely on the controller.
 
Do the math, volts x amps = watts. So say you run a 36v battery that is actually about 40v. 250 divided by 40 is a puny 6.25 amps. These motors are often run at 36v with 20 amp controllers, so 800 watts is not so unusual.

The thing to consider though, is the lower wattage controllers allow smaller and cheaper batteries to be used. So you may want to look at stuff that only reaches about 400w, such as a 10-12 amp controller. That way you can get a 10 ah cheapie lifepo4 battery and not murder the battery with too much current going out.
 
The math doesn't worry me dogman, I have am a mech\elec eng. I should have asked the question better. How much power should a bafang typically handle for flat town runs before I have to make new gears on a laser?

I want to run an 8s battery setup like I do in my aprilia enjoy. I might be better buying a 24v 20a controller so I don't get premature low voltage cutout with a 36v controller? I would be feeding it 33 volts 20amps then.
 
Samd said:
The math doesn't worry me dogman, I have am a mech\elec eng. I should have asked the question better. How much power should a bafang typically handle for flat town runs before I have to make new gears on a laser?

I want to run an 8s battery setup like I do in my aprilia enjoy. I might be better buying a 24v 20a controller so I don't get premature low voltage cutout with a 36v controller?
Click to expand...


I ran my Bafang 250w motor for 6 months on this controller at 36v and did somewhere in the region of about 1600miles. Never had a problem on the flats, it was only once i got into offroad riding with some steep climbing that i started to crunch the gears, thats the reason i got rid of it in the end.

This controller peaks at about 750w so gives a fair bit of power to that little bafang, i certainly wouldnt recomment running the motor an any controller much more powerfull than this.
 
Thanks Fury - top advice.

Somethign else has been gnawing at me. Brushless controllers seem to have a different key switch config. With a brushed key switch, there's usually two wires. No rocket science there - connect a switch and you are away.

If I read the brushless controller diagrams right (most seem the same as the link you sent Fury), there seems to be a third wire on the main battery connection (pos/neg/key). I assume I have to feed the thin 'key' wire a positive voltage about the same as the controller rated voltage or no magic will flow out of the unit?

I plan to run the 24v controller at 8s - which is closer to 30V.

Sorry for the questions gents....
 
No problems on the questions, thats what we are here for :)

the 3rd wire refered to as the 'Key' wire is basically an on off wire for the controller, either just bundle it with the main power wire and connect it together with that to your battery voltage, or you can put an on/off switch on it and ground it to your battery so that you have an extra layer of protection before you can twist the throttle and the motor run.

Just a note, the standard controller i linked you to im my earlier post has an LVC set at 31V for a 36v battery. If you are going to buy this controller and run 8S you will need to speak to the seller of that controller before purchasing (ebay name is e-crazyman. He is a nice guy but not english so his english isnt the best) as he can reconfigure the LVC to a safe voltage for your 8S (probably arround 27v to 28v depending on how conservative you want to be if you ask me). Another option would be to run the controller on 10S which would be a little faster.
 
Samd, most 24V brushless controllers will happily run 8s lipo.
If you are worried then just ask the seller to confirm before buying or open it to check the component voltage ratings when you get it.
 
Thanks guys.

Makes good sense. I currently run a 8s and 24v brushed controller on my Aprilia Enjoy and let the current limiter control power.

So I took the gamble last night and ordered a 24v 350W rated brushless controller from ebay for 33 bucks and will see how I go with 8s supplying it. Should get about 500 watts if it works.

Thanks for the keyswitch advice too - makes sense.
 
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