Will a 250w Bafang front hub run ok on 48v?

[theRealFury]

Hey,

I currently have a 250w rated bafang front hub motor (http://www.szbaf.com/proshow.aspx?id=73) which is currently running on 36v. the suppied controller was really gutless putting out only 8 amps max and 5 amps constant at 36v. I recently upgraded to a keywin (e-crazyman) 25a brushless sensorless controller in an effort to get a bit more out of the motor. After the upgrade of the controller the motor has been given a new lease of life and now has much more get up and go and a little more top speed (from 14mp to 17mph) but it also seems that the battery pack i have (standard 36v 10ah supplied by alienbikes.com) is gutless as well. Peak amp draw according to my watts up meter is just over 18 amps and with that comes a 4-5v sag meaning most i can get out of the battery is around 700w burst on a fresh charge and after a while im pushing the 31.5v LVC.

what im wondering is, is it worth upgrading to 44v of lipo or a 48v battery with some bigger stones for this motor or am i asking for trouble even thinking of upping the voltage on it? also if upping the voltage is possible would it be likely to have much effect on speed?

thanks.

 

[johnrobholmes]

You can at least get more downhill speed, and maybe more flat speed if you aren't hitting the amp limits. Keep it under 18a and you should be fine at 48v.

 

[theRealFury]

You can at least get more downhill speed, and maybe more flat speed if you aren't hitting the amp limits. Keep it under 18a and you should be fine at 48v.

Thanks Rob, its speed on the flat im looking for as i know a small hub motor wont have much power up hills and down hill my bike quite easily goes 35+MPH so i end up riding the breaks down any decent hill anyway. Like most people that get into E-bikes, i went about it the wrong way.. i jumped in with an "entry level" kit before working out exactly what i wanted from it. Needless to say i wish i had done more research before buying my first kit.

now just a case of deciding on what bettery to upgrade to, i like everyhing about lipo apart from the whole LVC thing... if i go lipo i think ill end up getting a CA imported just for the programable LVC :?

 

[jbond]

Keep searching on here and you'll find people claiming that the small Bafangs can cope with 48v-20A. Your controller *should* be ok at 48v as well though you'll want to change the LVC.

What's not clear to me is how much battery you really need to support 20A. A Ping (or similar) 48v-10AHr should be ok, but running it at 2C may result in a shorter life and unacceptable voltage sag. If you go for something like 36v-15AHr you'll likely have the same problems you have now. Another alternative is Cellman's A123 based packs which should have less sag and cope with 20A better at some extra cost.

I'm afraid this game seems to be like many others. You have to actually own and use an electric bike before you can work out what you need. And there's an almost inevitable spiral as you think "it's great but I wish this bit was just a bit better".

I got a 2nd hand Ridgeback hybrid from N London last year and with a couple of upgrades, it runs really sweetly. Then last year I got an Alien Aurora. I find myself wishing I could have the lightness and sweet running of the hybrid with the power of the Aurora but that's probably not possible. I keep thinking that a Bafang SWX with a decent controller and a lightweight battery set on the Ridgeback might do it. But then I'd want more range and pretty soon I'd be into 6-7Kg of battery. And so it goes.

 

[FMB42]

What type of riding are you planning on doing with this setup?

Moderate to severe off road use is, imo, not recommended for these small geared hub units (at 36 or 48v) due to premature gear failure and over-heating problems. However, if you plan on using the bike for general pavement and/or light (smooth and relatively level) off road use then, 48v at 15-20 amps will probably be "OK" (you may want to purchase a spare set of replacement gears just in case). Just don't expect the gears to last if you plan on hitting on serious pot holes and/or doing any jumping and the like (on or off road).

 

[Rassy]

Fury, I purchased two front Bafangs and 48V controllers from JohnRobHolmes (See above post). Both of these motors were the "slow" wind made for 26" wheels, but I got one in a 20" wheel and the other in a 16" wheel to maximize hill climbing ability. I don't remember what the specs were for the controllers, but they both limit amps a little over 23A. At 48V I never had any problems with either. No heating issues, no gear stripping, etc. Of course, running in a smaller wheel is actually easier on the motor and controller.

Neither of these is being used right now, but it's not because anything is wrong with them, but rather I am just too happy with my through the gears trike set-up.

One reason I responded here is to mention torque arms. If you aren't already using torque arms it would probably be wise to add them before going up to 48V.

 

[jbond]

Moderate to severe off road use is, imo, not recommended for these small geared hub units (at 36 or 48v) due to premature gear failure and over-heating problems.

What is it about off road and geared hubs that leads to failure? Over-heating shouldn't be a problem if the controller settings are correct and conservative, even using full throttle at low speed. The axle is hollow but substantial so there shouldn't be any problems with axle bending. So we're left with torque reversals due to landing with power on. How easy or hard is it to strip the gears with this kind of abuse?

There are sources for steel gears for the Bafangs. Does that help off road use?

 

[theRealFury]

Thanks for all the replies people,

To answer a couple of questions.

What type of riding are you planning on doing with this setup?

Moderate to severe off road use is, imo, not recommended for these small geared hub units (at 36 or 48v) due to premature gear failure and over-heating problems. However, if you plan on using the bike for general pavement and/or light (smooth and relatively level) off road use then, 48v at 15-20 amps will probably be "OK" (you may want to purchase a spare set of replacement gears just in case). Just don't expect the gears to last if you plan on hitting on serious pot holes and/or doing any jumping and the like (on or off road).

90% of my riding is on roads and the other 10% is on cycle paths or countryside walking trails so i dont really do any jumping (apart from up or down the odd kerb and i never use the motor for this). I have no problem with the torque of the little motor so im not looking to stuff more amps through it, in fact if i could get it running on 48v and get a bit more top speed id happily limit amps to 10-15.

One reason I responded here is to mention torque arms. If you aren't already using torque arms it would probably be wise to add them before going up to 48V.

Thanks for the reply, im currently not using torque arms on the front wheel, im currently looking for some torque arms that will fit my fat oversized forks as they dont have any attaching holes on them so i would need a way of securing them to the fork as well. I make a point of not doing hard starts and rolling on the throttle steadily anyway as i know the internal gears are fragile and that hard starting is where the main damage is done. Once i find some suitable torque arms (i dont have the tools or knowledge required to make my own) i will get them installed for sure.

What is it about off road and geared hubs that leads to failure?

From what i have read it is the loading and unloading of the front wheel while the power is supplied that stresses the gears.

 

[FMB42]

What is it about off road and geared hubs that leads to failure? Over-heating shouldn't be a problem if the controller settings are correct and conservative, even using full throttle at low speed. The axle is hollow but substantial so there shouldn't be any problems with axle bending. So we're left with torque reversals due to landing with power on. How easy or hard is it to strip the gears with this kind of abuse?

There are sources for steel gears for the Bafangs. Does that help off road use?

Here's a link to the ES "Help finding a solution to Bafang gear stripping" thread.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=7031&p=105941&hilit=+knuckles+nylon+gears#p105941

I use my ebikekit "450"w rear geared hub motor for light duty off road use (level ground, no jumps, and little or no "ditches" or deep ruts). The dirt "tracks" I ride on are sort of like a "TT" circuit without the jumps. I have yet to have any gear problems with this unit. However, I do plan on purchasing upgraded (possibly metal) replacement gears (metal gears, while more durable, are said to be somewhat noisy under certain load conditions) . Note: the thread above seems to indicate that the gears may have been improved since the 2006 or 2007 production runs.


Excessive heat buildup in these small geared hub motors can be an issue due to their small mass and/or their internal design. Dogman, and many other more knowledgeable ES members, can probably explain this better than I can. Note: I don't run this motor in ambient temps that exceed 95 degrees F.

 

[jbond]

Here's a link to the ES "Help finding a solution to Bafang gear stripping" thread.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=7031&p=105941&hilit=+knuckles+nylon+gears#p105941

But see also this much more recent thread.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=20736&start=0&hilit=bafang

Several people reporting no gear problems with 48v-20A or even higher.

 

[FMB42]

But see also this much more recent thread.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=20736&start=0&hilit=bafang

Several people reporting no gear problems with 48v-20A or even higher.

Thanks, I saw that thread jbond.

I'm still waiting to see the customer feedback on these little geared hubs under moderate to heavy off road use. Until then, I'm going to limit mine to light duty OR use at 36v/20amps max.

The good news is that I'm now beginning to see these "Bafang" style/size geared motors marketed for both 36 and 48v.

It does indeed look like these motors are beginning to overcome their reputation of "stripped" gears.

 

[docnjoj]

I ran mine for over a year @54 volts with no problems but on the street. My trike weigs 80 lbs and I am 220. I finally got a 9C since the gear whine was noticible and we ride in a fairly quiet area. They are not extremely noisy but the DD motors are much quieter. Cellman says his geared ones are quiet but I have never tried those brands like Ananda.
otherDoc

 

[theRealFury]

I ran mine for over a year @54 volts with no problems but on the street. My trike weigs 80 lbs and I am 220. I finally got a 9C since the gear whine was noticible and we ride in a fairly quiet area. They are not extremely noisy but the DD motors are much quieter. Cellman says his geared ones are quiet but I have never tried those brands like Ananda.
otherDoc

Thanks for the reply docnjoj,

what kind of amps were you running at 54v? i do agree that the gear whine is noticable especially when going up an incline or at low RPM but i dont mind it personally. Im hoping to upgrade to a DD hub next year but for now im just going to get used to this mini hub while i save some $$ for lots of Lipo or a large Ping.

 

[docnjoj]

Well the controller is an old Infineon with its shunt soldered a bit so I occasionally could hit 30 amps on hills. Usually I run at about 10-15 amps and even less on some level roads as I always pedal. I averages about 15wh/mile with the old Bafang and about the same with the 9C. I rarely if ever run over 20 mph and mostly at 10-15 mph, sometime less. I always pedal.
otherDoc

 

[chroot]

I have a question, I have a bafang rear geared hub motor 250w and will it work with my Lyen controller -LiPo (84v) if I set my CA adjust ampere limit 14-15A at 84v? Since I killed my 9C motor 5k watts blew hall sensor. I need use ebike for commuter for temporary.

Let me know asap, thanks

 

[spinningmagnets]

There have been several issues when trying to see how far a particular motor can be pushed into its safety margin before difficulties occur. I would recommend installing an inexpensive temp probe as a first step ($15-$20). Even if you still encounter failure ay some point, the temperature the failure occurred at is vital informantion to share. Her's some options:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=22187&p=368641#p368641

 

[outside]

Hello everyone, I'm new in this forum,
I used it, both a 36V to 48V. Of course it is better to 48V
with Bafang SWXK 220W 36V run on 48V , I made these two reports:
http://www.bellitaliainbici.it/brunate_bisbino.htm
http://www.bellitaliainbici.it/val_imagna.htm

 

[theRealFury]

There have been several issues when trying to see how far a particular motor can be pushed into its safety margin before difficulties occur. I would recommend installing an inexpensive temp probe as a first step ($15-$20). Even if you still encounter failure ay some point, the temperature the failure occurred at is vital informantion to share. Her's some options:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=22187&p=368641#p368641

Well i have decided to leave the little bafang on 36v li-ion and over the coming months im going to be piecing together a 2nd ebike based around a 9c 2806 motor and 44.4v of lipo. I will then be giving the bafang to the missus and dragging her out on some summer rides with me .