Rated power ?

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Cees   10 mW

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Rated power ?

Post by Cees » May 10 2019 11:42am

What is the nominal power of this Bafang motor and the max rpm ? What will be the expected max speed with 20 inch tires on a flat road ?
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E-HP   100 kW

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Re: Rated power ?

Post by E-HP » May 10 2019 2:31pm

Cees wrote:
May 10 2019 11:42am
What is the nominal power of this Bafang motor and the max rpm ? What will be the expected max speed with 20 inch tires on a flat road ?
May be similar to these:
https://www.aliexpress.com/item/BAFANG- ... tm3w7F&s=p
https://www.amazon.com/Conversion-Wheel ... B07H4MX5J7
https://www.ebay.com/itm/EU-STOCK-36-48 ... 2292763820

500 watts, 325 rpm; maybe 19-20 mph with a 20" wheel as a guess.

Cees   10 mW

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Re: Rated power ?

Post by Cees » May 11 2019 4:55am

Today my maiden trip on my fat tire bike, yes indeed 20 inch wheel diameter.
The dealer promised me 33 kmh (which is 20 mph) but I only get 28 - 29 kmh (17,5 mph) and this is on a flat road with tire pressure of 1,5 bar (to reduce drag as much as possible). The battery is 48 V (don't want to switch to a 52 V accu yet). What can I do to get to the 20 mph ???? Maybe they fitted the wrong controler ?????

If I look at internet at a Bafang 500W 48 V motor (like your third picture) they are much bigger in size (mainly in the width (about twice) and not in the diameter).

Edit : controller see picture.
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Re: Rated power ?

Post by Cees » May 11 2019 4:58pm

Is there an expert on this forum who can help me please ?

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wturber   10 MW

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Re: Rated power ?

Post by wturber » May 12 2019 12:52am

Cees wrote:
May 11 2019 4:58pm
Is there an expert on this forum who can help me please ?
I'm no expert, but I'm pretty sure you have three options.

1) Larger wheel.
2) Higher voltage
3) Different motor

Given the amp output of your controller, it is unlikely that power from the controller is the problem unless you happen to have a fairly weak battery that is sagging under load. One way to confirm this would be to elevate the bike so that the motor driven wheel is off the ground and see how fast the tire will go with no load. This assumes that you have a display that connects to the controller/motor that gives you speed in mph.

Oh - one other thing to do is to verify that whatever you are using for a speedometer is giving the correct speed. Maybe you are actually going 20 mph?

You can use a cell phone GPS based speedometer for that. Be aware that most of those GPS based speedometers tend to have a delayed response. So make sure you are holding the speed for about 15 seconds or more.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Chalo   100 GW

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Re: Rated power ?

Post by Chalo » May 12 2019 1:09am

Cees wrote:
May 10 2019 11:42am
What is the nominal power of this Bafang motor and the max rpm ? What will be the expected max speed with 20 inch tires on a flat road ?
Check out this power and speed calculator:
http://kreuzotter.de/english/espeed.htm

And check out this motor simulator:
https://www.ebikes.ca/tools/simulator.html

Assume that your fat tires have 4x the rolling resistance of normal tires with the same tread pattern. Assume that you have 500W of motor power to use. If the calculator result doesn't match your real world result, it's probably because the speed that your motor runs doesn't match the speed you want to go.

If you learn to interpret motor power and torque charts that the motor manufacturer publishes, you can make better predictions about the performance you can expect.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Rated power ?

Post by Cees » May 12 2019 3:17am

Thanks wturber,

Unload (so the rear wheel is from the floor) the C965 diplay (Tucano branded but it probably a Dillinger made LCD) gives a speed of 35.4 kmh (= 22.1 mph). Does this mean like you suggested that my battery pack is not ok if I only get a speed of 17.5 mph loaded (i am not really heavy 80 kg, flat road and the tire are at 22 psi which is really high for fat tires). I assume that if a bike supplier advertises with a speed of 20 mph it is loaded since it makes no sense to give a speed unloaded.

Yes I will try to use a gps app to determine the speed, good idea :-)

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Re: Rated power ?

Post by Cees » May 12 2019 3:33am

@ chalo

In both simulators I get more than 25 mph (that is even 40 kmh) !!!

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Re: Rated power ?

Post by Cees » May 12 2019 4:46am

I just used a GPS speedometer app on my mobile and it gives exact the same value of the max speed of 28 - 29 kmh (17.8 mph).
Last edited by Cees on May 12 2019 6:04am, edited 1 time in total.

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Re: Rated power ?

Post by Cees » May 12 2019 4:52am

What about these (behind the password) display settings. What do they do ?????
It is a C965 display (Tucano branded but probably it is a Dillinger manufactured display).


CUL 15 (ranging from 10 - 30)
HAL 1 (ranging from 1 - 15)
AS5 12 (ranging from 0 - 12)
Hd6 0 (ranging from 0 or 1)
HdP 0 (ranging from 0 or 1)

Does anyone know what they are for ??????
Can they influence the top speed because they are not at the right value ????


Edit ok I found it already :

CUL 15 (ranging from 10 - 30) : MAX Current Limit set
HAL 1 (ranging from 1 - 15) : Magnetic Pole numbers of speed sensor
AS5 12 (ranging from 0 - 12) : # of Cadence magnets
Hd6 0 (ranging from 0 or 1) : sets the throttle to 6km/h; 1=ON, 0=OFF (default 0)
HdP 0 (ranging from 0 or 1) : toggles the throttle power/current level to match the PAS level. 1=ON; 0=OFF (default 0, full power
independent of PAS level)


So what will happen if I increase the CUL from 15 to 18 (controller has max of 20 A) ??
Does it help to increase the top speed ?
Will it overheat my motor (or even the wires to the motor get burned ? ) ????

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Re: Rated power ?

Post by wturber » May 12 2019 11:38am

Cees wrote:
May 12 2019 3:17am
Thanks wturber,

Unload (so the rear wheel is from the floor) the C965 diplay (Tucano branded but it probably a Dillinger made LCD) gives a speed of 35.4 kmh (= 22.1 mph). Does this mean like you suggested that my battery pack is not ok if I only get a speed of 17.5 mph loaded (i am not really heavy 80 kg, flat road and the tire are at 22 psi which is really high for fat tires). I assume that if a bike supplier advertises with a speed of 20 mph it is loaded since it makes no sense to give a speed unloaded.
It tells us that you have a slow wind motor if its unloaded speed is 22.1 mph. The battery might not be up to snuff, but frankly, I just don't know and don't have enough experience with slow wind motors. The only way to know for sure would be to measure the volts or amps drawn while riding top speed. But if you tell us more about your battery, someone here might be able to make an educated guess.

I'm getting about 22.5 mph on the slower Bafang motors on the simulator - for instance the Bafang G60 500W. But these motors may not be exactly the same as yours. In fact, they are almost surely not since their unloaded speeds are a bit faster at 24mph and a bit more. But what the simulator does tell us is that 500 watts should get you to 22.5 mph or so. You only need about 400 watts to get to 20 mph and about 300 watts to get to 18 mph - which is about what you are getting.

So right now my best guesses are that a setting on your controller is limiting the power to the motor, that the battery has a problem, or that the controller setting are somehow not correct for the motor. But if you bought it from a dealer and the dealer said 20 mph, then why not have him tell you why it isn't doing that?
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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wturber   10 MW

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Re: Rated power ?

Post by wturber » May 12 2019 11:51am

Cees wrote:
May 12 2019 4:52am



Edit ok I found it already :

CUL 15 (ranging from 10 - 30) : MAX Current Limit set
HAL 1 (ranging from 1 - 15) : Magnetic Pole numbers of speed sensor
AS5 12 (ranging from 0 - 12) : # of Cadence magnets
Hd6 0 (ranging from 0 or 1) : sets the throttle to 6km/h; 1=ON, 0=OFF (default 0)
HdP 0 (ranging from 0 or 1) : toggles the throttle power/current level to match the PAS level. 1=ON; 0=OFF (default 0, full power
independent of PAS level)


So what will happen if I increase the CUL from 15 to 18 (controller has max of 20 A) ??
Does it help to increase the top speed ?
Will it overheat my motor (or even the wires to the motor get burned ? ) ????
15 amps at 48v is 720 watts. You only need 500 watts to get to 22 mph. So that's probably not it. Try it anyway if you like. Just don't stay at that power for very long. But I'd probably bring it back to my dealer before I'd start fiddling with this setting.

I think HAL and AS5 should only affect your speedometer reading. But those reading are correct, so I wouldn't fiddle with them.
Hd6 and HDP seem to be set in a way that shouldn't limit top speed.

I found this manual. You may want to check other settings. Specifically whether there is any speed limit set. Kinda obvious and I'd guess you've checked that. But just in case.

https://www.brightonebikes.co.uk/upload ... l_2017.pdf

Also, if you are using PAS levels, make sure you have that at "3", "5", or "9" whichever is the maximum for your configuration
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

Cees   10 mW

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Re: Rated power ?

Post by Cees » May 13 2019 12:59am

Hi all,

I am.living in The Netherlands and bought the bike via internet in Spain so a trip to the dealer which has an actual shop in Barcelona is not easy.

When i ride the bike and look at the surrounding traffic i get the feeling the bike goes faster than the 17.5 mph the displays shows. So which wheel diameter you put in the display settings ???? I have a 20 inch wheel diameter fat tire bike BUT if i measure the actual diameter it is even at least 23 inch. So what do you put in the display ? the actual diameter or the theoretical diameter the bike is rated at. Or is the setting in the display the rim diameter (thus 20 inch) and not the wheel diameter ??????? I am confused now 🤔🤔🤔 If i make the calculation (23/20)* 17.5 = 20 mph and it fullfills the spec. Several speedometer apps on my phone gave 17 - 18 mph but maybe the apps are not accurate enough ????????? By the way the torq of the engine feels strong and if I make a sharp turn at low speed be sure the PAS is at 3 (my bike has 9 levels) since the motor controller is more like an off and fully on switch.

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Re: Rated power ?

Post by Cees » May 13 2019 1:07am

@wturber


If i look at the power reading at full throttle during acceleration the displsy shows 960 W so i guess the motor power is not limited.

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Re: Rated power ?

Post by Chalo » May 13 2019 3:56am

Cees wrote:
May 13 2019 1:07am
@wturber


If i look at the power reading at full throttle during acceleration the displsy shows 960 W so i guess the motor power is not limited.
What's the reading at full speed?
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Rated power ?

Post by Cees » May 13 2019 4:30am

@ chalo

Reading at full speed is 17.5 mph

What about my question about the wheel diameter setting ?

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Re: Rated power ?

Post by Cees » May 13 2019 5:35am

I increased the current limit from 15 to 18 A in the display (the current max of the controller is 20 A). I do not experience any change in top speed on a flat road nor torque uphill.

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Re: Rated power ?

Post by dogman dan » May 13 2019 7:35am

To get your 20, you do need 52v. Sorry if reality sucks.

Do confirm your speed read out is accurate, like ride with a car going exactly 20 mph, or check your distance read out with a very accurately measured km or mile.


You might be on the correct wheel setting, but have a tire that makes that inaccurate, unless your display allows setting it to the mm. Fat tire would be too big for a stock 20" or 26" setting to be accurate. It would roll farther per revolution, because the tire is taller than normal.


Bet you are closer to 20 mph than you think.. But even if you are, that full speed you got promised only lasts a block, then you slow down as your battery drains.

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Re: Rated power ?

Post by Cees » May 13 2019 7:58am

Thanks Dogman. Yes you are probably rihgt and i need 52 V. I will try if the bike dealer wants to exchance my 48V battery for a 52 V battery.

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Re: Rated power ?

Post by Aeron » May 13 2019 8:42am

Cees wrote:
May 13 2019 12:59am
So which wheel diameter you put in the display settings ???? I have a 20 inch wheel diameter fat tire bike BUT if i measure the actual diameter it is even at least 23 inch. So what do you put in the display ? the actual diameter or the theoretical diameter the bike is rated at.
I don't know the hardware you have, but the proper answer should be "none of that": a decent bike computer / speedometer should require the wheel perimeter, i.e. the distance the bike moves forward when the wheel makes one turn. For a given rim diameter, different tires will yield very varying perimeters, hence incorrect speed reading with the same settings (a 26"x1.5" tire has a very different outer diameter and perimeter than a 26"x2.5", but both are the "same" 26", but not really the same 26").

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Chalo   100 GW

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Re: Rated power ?

Post by Chalo » May 13 2019 11:58am

Cees wrote:
May 13 2019 4:30am
@ chalo

Reading at full speed is 17.5 mph
I mean what is the power reading at full speed? If it's less than half of the 960W you get on acceleration, then you've simply moved into the upper end of the motor's RPM range, and every little bit of extra speed will diminish motor power more.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Rated power ?

Post by Chalo » May 13 2019 12:02pm

Aeron wrote:
May 13 2019 8:42am
I don't know the hardware you have, but the proper answer should be "none of that": a decent bike computer / speedometer should require the wheel perimeter, i.e. the distance the bike moves forward when the wheel makes one turn.
For an e-bike controller console, it's more typical to choose between a few preset diameter values.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Rated power ?

Post by E-HP » May 13 2019 7:48pm

Cees wrote:@ chalo

In both simulators I get more than 25 mph (that is even 40 kmh) !!!
Did the simulators include an adjustment for the additional rolling resistance of the fat tires?

Going from a road tire to a 1.75" off road tire loses 1.5 mph per the first simulator, so probably more with a fat tire. Maybe try maxing the tire pressure on your fat tires and see if it affects top speed.

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Re: Rated power ?

Post by Cees » May 14 2019 12:21am

@ E-HP. The tire pressure is already at max. Which is printed on the tire that is 1.5 BAR rear and front which is very high for a fat tire which are normaly around 0.5 Bar.
Last edited by Cees on May 14 2019 12:33am, edited 1 time in total.

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Re: Rated power ?

Post by Cees » May 14 2019 12:24am

@ Chalo. At steady full speed the power is about 350 W during acceleration the power is at 960 W.

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