9c kit and uphills

alexscard

10 W
Joined
Aug 7, 2021
Messages
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Hi, i'm probably going to buy a 7x9 nine continent kit, and power it with a 72v battery and a commander around 30A of continuos discharge. Anyone that have experience with this kit can tell me his opinion about if i risk to melt down the motor when i will use it on strong uphills like 15% or 20% of slope? (I want to power it with such an high voltage so to have a good max speed)
 
will take about 8 minutes up a long hill full throttle to fry that motor, but if you are smart about it the setup can last for years
 
obviously, how many A are you using, what kind of 9C is, and what % of hill are very important variables for ipotize how long the motor can work before frying. Did you consider them in saying "8 minutes"?
I mean, a 6x10 at 20A is very different from, say a 8x8 at 40A
 
You didn't mention whether you will be pedaling or not, and how long the climbs are. I pedal with a similar setup and terrain, with statorade to help with cooling. I will usually pull over after a mile or so of sustained climbing to check how hot my motor is. With the right controller, and temperature probe to monitor the motor, you could have the controller keep the motor from melting down automatically (roll back power when temps are too high).
 
well usually i just have to run across a 300m uphill with maximum about 15% of slope, but sometimes during the summer i use the bike to go in the mountains that means around 1100mt(0.68miles) of height in 25km(15miles) of road.
About help the motor with my legs, considering that is a fast motor, i don't think my legs can help much.
(i'm 75kilos)
 
alexscard said:
well usually i just have to run across a 300m uphill with maximum about 15% of slope, but sometimes during the summer i use the bike to go in the mountains that means around 1100mt(0.68miles) of height in 25km(15miles) of road.
About help the motor with my legs, considering that is a fast motor, i don't think my legs can help much.
(i'm 75kilos)

You will need to pedal. With a fast motor with only 30 amps, you won't be zooming up a 15% grade without pedaling:
https://ebikes.ca/tools/simulator.html?motor=9C212_6T_SA&batt=cust_72_0.05_24&cont=cust_30_90_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=15

9.7 minutes to meltdown @ 17mph, even with statorade.
 
I get about 10 minutes of Wide Open Throttle (35A) on a 12-18% steady climb before the 14 AH battery begins to droop enough I'll back off.

Phaserunner-MAC 10T on a trike, total weight with me is 260 lbs. I pedal at about 100 watts and average speed in the a 15-17 MPH range.

Phaserunner heat sink never rises beyond ambient by 20° F. MAC internal reads about 190° F, external about 15° over ambient.

Climbing is always the struggle. The 9C loves to spin but it takes quite a bit of grunt to make that happen up steep ascents for any hub motor.
 
intersting that simulator, i didn't know it. but i have to understand all it shows now :mrgreen: for example, what's the line where there is written 17.8mph?
other thing, i see there are various 9c to choose from, but the code/name that uses for the various 9c are unknown to me, i have always used the 6x10 7x9 8x8 9x7 ecc

p.s. what's a statorade?(i'm not eng. mothertongue)
 
i'm playing with the simulator, and even on plain, if with that motor i go at 10km/h(6.21mph) after just 2.7 minutes it says that i would overheat. is this anyhow close to real? seems very strange to me. i already had fast hub motors, and they work with no problem going slowy for many miles
 
Don't draw any conclusions until you read and understand all the information regarding the simulator. For fast wind motors, you may observe that backing down the throttle may increase the time before meltdown, since WOT may dump more energy into heat when the motor isn't running in an efficient range.
 
But.. 7*9 shouldnt be considered fast wind, isnt It?
I'm wondering, if someone wants a motor that has an High Speed(lets Say from 40mph on) but that can also make uphill without overheating, what motor should buy?
 
Most want to go fast with to little then kill the battery and overheat the motor and controller.

You need to figure out what you need. and start from there. Speed is like cars how much can you afford. 40 mph is not bike speed. Most kits will do 30 but not to long. Its the wind your pushing, the faster you go the more you push. This cost money.

The higher speed motors people put smaller wheels, lower voltage or get more turns of copper in the motor to slow it down.

The simulator is a tool, worth learning. Statorade is a fluid used in motors to help move the heat to the outer part of the motor to help cool it. Let's you run more amps without cooking the motor.

by alexscard » Sep 22 2021 1:51pm

But.. 7*9 shouldnt be considered fast wind, isnt It?
I'm wondering, if someone wants a motor that has an High Speed(lets Say from 40mph on) but that can also make uphill without overheating, what motor should buy?
Top
 
It all depends.
What do you already have?

If starting from scratch then you figure out the terrain you will be riding, how steep the hills are, how fast you want to go.

You could buy a 2T or 3T motor
- Have the hub motor laced into a 18" or 20" bmx bicycle rim to get extra torque out of it due to the gearing (diameter of wheel, smaller = more torque less speed, larger = more speed less torque easier to overheat.)
- Then you figure out the battery and controller.

You could go 96V, you could go 78V, 60V, 52V, 48V, 36V
Then you need to figure out what battery you want, buy from a known reputable entity, throw the dice on some back alley mystery gamble (ebay/amazon/alibaba/aliexpress), or build it yourself.

What amp discharge you want for the batteries BMS

Then you match the battery to the controller, do you want programmable controller, do you want Bluetooth, do you want Sinewave, FOC, Field Weakening or any other specific controller feature or do you want to cheap out and buy a generic trapezoidal controller with little features.

Of course you can select your route and do a trip sim
https://ebikes.ca/tools/trip-simulator.html
or motor sim
https://ebikes.ca/tools/simulator.html

To really dial in your numbers.


alexscard said:
But.. 7*9 shouldnt be considered fast wind, isnt It?
I'm wondering, if someone wants a motor that has an High Speed(lets Say from 40mph on) but that can also make uphill without overheating, what motor should buy?
 
Hi, i'm probably going to buy a 7x9 nine continent kit, and power it with a 72v battery and a commander around 30A of continuos discharge. Anyone that have experience with this kit can tell me his opinion about if i risk to melt down the motor when i will use it on strong uphills like 15% or 20% of slope? (I want to power it with such an high voltage so to have a good max speed)

Here is a 9c RH212 with 'standard' winding:

https://ebikes.ca/tools/simulator.html?motor=M2707_SA&batt=B7223_AC&cont=cust_30_70_0.03_V&grade=15&hp=150

That is 30 amp controller, 72v battery, 150 watts of pedaling (which is a fairly high workout), and 15 degree slope, and statorade cooling.

From a cold start you have about 14 minutes of climbing before you overheat. That's a 7 km climb, which is a pretty impressive hill.

Here is the same setup with a 20 inch wheel:
https://ebikes.ca/tools/simulator.html?motor=9C212_7.5T_SA&batt=B7223_AC&cont=cust_30_70_0.03_V&grade=15&hp=150&cont_b=cust_30_70_0.03_V&motor_b=9C212_7.5T_SA&batt_b=B7223_AC&hp_b=150&grade_b=15&wheel=20i

No problem.


You can also go dual motors and that will solve the problem pretty well.
 
(i have a mtb with 27.5" wheels)

Btw, In order to have less overheating problems, for what i know a slower motor should be an option. So i thought to buy a 6x10 instead that a 7x9, and tried to simulate the thing; surprise, according to the simulator, they both overheat at the same way:
https://ebikes.ca/tools/simulator.html?motor=9C212_7.5T&batt=B7223_AC&cont=cust_30_70_0.03_V&grade=15&hp=0
https://ebikes.ca/tools/simulator.html?motor=9C212_6T&batt=B7223_AC&cont=cust_30_70_0.03_V&grade=15&hp=0&wheel=27.5i&throt=100
why is that? anyone has an explanation? (i hope selected the right motors, i took the only 9c with higher torque and slower speed than the 7x9)


About the statorade..i will buy the kit in a shop in europe, and i see no statorade option, is there a way to add it on my own ?
 
your wheel is too big and the motor is too small

6x10 is 60
9x7 is 63

so there is technically more copper wire inside the 9x7 motor which makes it better IMO
 
You can buy statorade from Amazon or Grin. 5ml per motor. Need to recheck after a time, my time is due its been 3yrs.
You can drill a filler hole or open up the motor. Read up before drilling the hole don't want to get shavings from the drilling in the motor.
As far as your motor, Just get a leafmotor if you want a 7sp or a QS 3000w if you can live with a single speed. Both can have custom turn counts to get top speed. Top speed 20-25mph plus hill climbing or 40mph and small hills.

Statorade
by alexscard » Sep 23 2021 3:53am

(i have a mtb with 27.5" wheels)

Btw, In order to have less overheating problems, for what i know a slower motor should be an option. So i thought to buy a 6x10 instead that a 7x9, and tried to simulate the thing; surprise, according to the simulator, they both overheat at the same way:
https://ebikes.ca/tools/simulator.html? ... de=15&hp=0
https://ebikes.ca/tools/simulator.html? ... &throt=100
why is that? anyone has an explanation? (i hope selected the right motors, i took the only 9c with higher torque and slower speed than the 7x9)


About the statorade..i will buy the kit in a shop in europe, and i see no statorade option, is there a way to add it on my own ?
 
ZeroEm said:
As far as your motor, Just get a leafmotor if you want a 7sp or a QS 3000w if you can live with a single speed. Both can have custom turn counts to get top speed. Top speed 20-25mph plus hill climbing or 40mph and small hills.

excuse me but i don't get what you mean with "custom turn counts", in what these motors differ from a 9c?

p.s. my bike has disk brakes, how could i adapte a 9c kit with that?..
 
by alexscard » Sep 23 2021 9:08am

ZeroEm wrote: ↑Sep 23 2021 8:13am

As far as your motor, Just get a leafmotor if you want a 7sp or a QS 3000w if you can live with a single speed. Both can have custom turn counts to get top speed. Top speed 20-25mph plus hill climbing or 40mph and small hills.
excuse me but i don't get what you mean with "custom turn counts", in what these motors differ from a 9c?

p.s. my bike has disk brakes, how could i adapte a 9c kit with that?..

They are wider with more iron to handle more heat.

All of them work with disc brakes. Not sure about the 9c. Custom turn counts, when you order you can tell them what speed you want and they will custom configure the motor.
 
maybe there's something i don't get with the simulator, or maybe i've been taught wrong. The point is, between the 7x9 and the one slower but with more torque, the difference in efficiency at the various speed on the simulator is very low.
They told me that the max. efficiency of an electric motor is at about 80% of its max "speed". And that a 6x10 should go way better on uphills than a 7x9 with a non negligible less risk of overheating. i don't see this in the simulator. Anyone have hints about this?
 
alexscard said:
maybe there's something i don't get with the simulator, or maybe i've
They told me that ...
Who is "They"?

If you want better guidance, then you may want to provide all of your desired specs at once (in one post)
https://endless-sphere.com/forums/viewtopic.php?f=3&t=66302
 
ok i make a recap;
I came from a bbs02, burned in uphill after 2 years of use, at 48V.
I have to change motor, and in a forum about ebike of my country, in order to have more speed but also good performance in climbing, they told me that an option is to buy the highest torque 9c(6x10) and power it at 72V. This user that i trust because i've known for a long time and for sure know more than me about ebikes, told me also that if i buy a 7x9 i could overheat it if used for climbing. Of course he's not god and he can be wrong, but i'd like not to melt an other motor.
I don't know a lots of kits, only bafang and 9c and cristalyte to be honest, and i was planning to pass to a 9c 'cause i found it in a shop at a good price(280€ all the kit)(i'm inside ue).
i have a mtb 27.5".
 
Go with the Leaf 35H 1500W if you can afford it, or the mxus/qs 3kw but the Leaf will do you just fine.
Add Statorade, get a good battery and a good charger.
Play around with the Trip Sim and Motor Sim, Leaf 35H 5T is on the motor list.


Same motors, different winding count have the exact same torque. You just change things around a bit to achieve it. Again, play around with the simulators, the Leaf 5T is on there, the 9C are on there, the MXUS 3kw are on there, pedal power, wheel diameter, volts, amps, blah blah blah blah
is to buy the highest torque 9c(6x10) and power it at 72V.
 
alexscard said:
ok i make a recap;
I came from a bbs02, burned in uphill after 2 years of use, at 48V.
I have to change motor, and in a forum about ebike of my country, in order to have more speed but also good performance in climbing, they told me that an option is to buy the highest torque 9c(6x10) and power it at 72V. This user that i trust because i've known for a long time and for sure know more than me about ebikes, told me also that if i buy a 7x9 i could overheat it if used for climbing. Of course he's not god and he can be wrong, but i'd like not to melt an other motor.
I don't know a lots of kits, only bafang and 9c and cristalyte to be honest, and i was planning to pass to a 9c 'cause i found it in a shop at a good price(280€ all the kit)(i'm inside ue).
i have a mtb 27.5".
You have information about your brakes, details about your terrain (% grades), your weight, speed, etc. scattered throughout the thread. You didn't really clarify if you'll pedal, just saying that with the fast wind, you wouldn't be able to. Anyway, that's why stickies exist, so that you provide enough information for the best chances of getting help. Not everyone will have the patience to go through all of the posts to get the tidbits of information they need to help you. But there are some folks that have that patience, and are willing to*go through the the Q and A process to extract that info.
 
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