Search found 253 matches

by hias9
Dec 20 2020 8:34pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

Can you please show me the link where the weaker magnet motor is more efficient? If you assume the motors have the same Kv (stronger magnet motor rewinded) did you lower resistance and inductivity by 10-20% for the faster winding? Let‘s please compare at the same voltage. The idea is only upgrading ...
by hias9
Dec 20 2020 7:59pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

Just set Kv 10% lower and increase hysteresis losses by 16.5% and Eddy losses by 21%. Here is an example comparing at same speed: https://ebikes.ca/tools/simulator.html?motor=cust_10_0.12_0.2_23_1_0.02_0&batt=cust_85_0.03_16&cont=cust_459_459_0.02_A&frame=mtn_tuck&hp=0&mass=120&a...
by hias9
Dec 20 2020 6:30pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

If I compare the stock motor with the motor with stronger magnets (without rewinding, so different Kv) at the same speed (using throttle on higher Kv motor), the motor with stronger magnets has higher efficiency. The PWM losses of the controller are probably not considered in the simulator, but they...
by hias9
Dec 20 2020 11:36am
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

If you increase just the magnetic losses, but don't lower Kv this makes no sense at all. What exactly are you trying to simulate that way? 10% stronger magnets without rewinding could be simulated by: Decrease Kv by 10%, Increase Eddy Losses by 21%, increase hysteresis losses by 16.5%. Only increasi...
by hias9
Dec 20 2020 9:47am
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

It's the other way round. Eddy losses increase proportional with B^2 and hysteresis losses with B^(1.6). Also you did not lower Kv. Without lowering Kv the results make no sense. If you leave the Kv (so you assume rewinding the motor also) you need to adjust resistance and inductivity. If you just i...
by hias9
Dec 20 2020 6:30am
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

I found on the internet a common value to calculate hystheresis losses is that they are proportional to B ^(1.6). Changing from N38H magnets to N48SH magnets would increase magnetic flux by about 10%. For only simulating stronger magnets (Kv / 10%, Eddy losses * 21%, Hystheresis losses * 16.5%) effi...
by hias9
Dec 19 2020 10:17pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

Custom Motor. I think 10% stronger magnets (10% more flux) would lower Kv by 10%, but increase Eddy losses by (10%^2 = 21%).
I am not sure by how much it would increase hysteresis losses.
by hias9
Dec 19 2020 6:51pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

I tried on the motor simulator a few months ago and according to the motor simulator, stronger magnets would result in higher efficiency also at higher rpms.
If the magnets are 10% stronger, I think Kv would be 10% lower and eddy losses 21% (1.1^2) higher, but still this results in higher efficiency.
by hias9
Dec 19 2020 6:42pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Re: Stronger Motor Magnets

N45SH magnets would have a temperature limit of 150 degrees celcius (SH=super hot), N45UH would have a limit of 180 degrees Celsius (UH=ultra hot), so that would not be the problem. Obviously Kv would be lower and drag would increase, but that's okay. I am trying to increase efficiency while the mot...
by hias9
Dec 19 2020 5:25pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 30
Views: 816

Stronger Motor Magnets

On the usual larger Chinese hub motors, mostly magnet grades N35(S)H or N38(S)H are used. As far as I know stronger magnets increase efficiency, but Eddy losses would also increase. Would stronger magnets only be more efficient on lower rpms or also on higher rpms? Is there a technical reason why th...
by hias9
Dec 13 2020 12:35pm
Forum: EBike Technical
Topic: Sabvoton 72xxx 21S regen
Replies: 14
Views: 703

Re: Sabvoton 72xxx 21S regen

84V should be about 80% for a 21S pack. But my Sabvoton measured 2-2.5V more voltage than real which makes the regen issue worse. I used the Sabvoton for over a year at 22S and had no problems besides the regen issue. Regen on lower speeds is quite weak with the Sabvoton by the way. But of course it...
by hias9
Dec 13 2020 11:16am
Forum: EBike Technical
Topic: Sabvoton 72xxx 21S regen
Replies: 14
Views: 703

Re: Sabvoton 72xxx 21S regen

No problem. Unfortunately there is no real solution to this unless you can somehow convince MQCON to make a modified firmware which is very unlikely. If you want to use a 21S battery, just live with the fact that you will not have regen for the first part of your ride or go for a different controlle...
by hias9
Dec 13 2020 5:00am
Forum: EBike Technical
Topic: Sabvoton 72xxx 21S regen
Replies: 14
Views: 703

Re: Sabvoton 72xxx 21S regen

I can only speak for the Sabvoton I had.
It was an unlocked 72150 without the display. At the same time there were 72150 with displays available which are locked to 150A/350A and have a different firmware. I don't know if these units also have this 84V or 85V regen limitation.
by hias9
Dec 12 2020 4:38am
Forum: EBike Technical
Topic: Sabvoton 72xxx 21S regen
Replies: 14
Views: 703

Re: Sabvoton 72xxx 21S regen

I have used an unlocked Sabvoton 72150 a few years ago with a 22S battery. It worked fine, but there was one problem: Regen was not possible before battery voltage was down to somewhere around 84V. I did not find a solution, this is probably a firmware limitation. So with 21S you would not have rege...
by hias9
Dec 10 2020 11:48am
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

I did not expect that setting fw current to 25% would already make the motor spin that fast. After I took a look on my mobile and saw the rpms in the app I did not increase throttle further and stopped immediately. However I felt confident going up to 2100rpm no load after that :D
by hias9
Dec 10 2020 8:59am
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

It probably allows even more than 200% rpm boost, but I am not going to try it with rim, tire and tube installed. I am also a bit worried about the spokes because they are only 13/14ga butted spokes. Yes, that is what I run the motor top speed on the flat. BEMF is only slightly above mosfet limit wh...
by hias9
Dec 10 2020 12:55am
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

BAC4000.

But as I mentioned, these rpms are of course without load. While riding I don’t reach half of that value.
And if you want to run it deep inside field weakening area for a long time, I don’t think that would be very efficient.
by hias9
Dec 09 2020 10:45pm
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

No, still wye not delta. It's just the fw that causes these no load rpms. Without fw Kv is about 11.7
by hias9
Dec 09 2020 9:36pm
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

I am using torque control, not speed control. If I twist the throttle by 20% it results in 2500rpm. I guess no load speed at the max field weakening current it is set to (87.5amps) would be somewhere around 3000rpm at full throttle, but I don't want to try it. No load rpm without field weakening are...
by hias9
Dec 09 2020 8:47pm
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Re: Maximum centrifugal load for hub motor wheel

The problem when I set max field weakening current lower is that there is significantly less power available in the field weakening area and top speed would also decrease significantly. Yes, no load wheel speed at 20% throttle was a bit above 2500rpm which is 300kph or 186mph. I did not want to go f...
by hias9
Dec 09 2020 7:15pm
Forum: EBike Technical
Topic: Maximum centrifugal load for hub motor wheel
Replies: 13
Views: 416

Maximum centrifugal load for hub motor wheel

I have a 45mm magnet height hub motor with Hubsinks inside a 24'' DH rim with DH tires and DH tube, so significant weight on the outside and spokes are only 13/14ga butted. When using torque mode on the ASI controller with 25% field weakening current, no load speed is very high. I stopped at about 2...
by hias9
Dec 08 2020 8:28am
Forum: Items for Sale - New
Topic: Compact Field Oriented Controller, ASI + Grin, limited run
Replies: 1272
Views: 285008

Re: Compact Field Oriented Controller, ASI + Grin, limited run

The jerking I only have when running the motor no load. It's happening at higher rpms than I reach while riding. But even with current regulator bandwidth set to 0, while riding near top speed deep in field weakening area, I have about 15% less power and motor current at 100% throttle than have at 5...
by hias9
Dec 07 2020 12:59pm
Forum: Items for Sale - New
Topic: Compact Field Oriented Controller, ASI + Grin, limited run
Replies: 1272
Views: 285008

Re: Compact Field Oriented Controller, ASI + Grin, limited run

With my ASI controller the motor is jerking at some point in field weakening area. The problem I have is that with no load and some field weakening, only for the first 10-15% of throttle setpoint, more throttle results in more motor current and higher rpm. Around 15% the motor is jerking. And for 20...
by hias9
Dec 05 2020 11:35am
Forum: Battery Technology
Topic: Waste Heat Calculation Help
Replies: 8
Views: 412

Re: Waste Heat Calculation Help

Just R * I^2, so at 10A 0.8W for copper or 3.2W for nickel.
by hias9
Dec 05 2020 6:14am
Forum: Battery Technology
Topic: Waste Heat Calculation Help
Replies: 8
Views: 412

Re: Waste Heat Calculation Help

The amount of heating power (in Watts) is R * I^2 (Resistance * Current^2). The resistance of the wire (in Ohm) is c * (length in meters) / (area in mm^2) Use c=0,0171 for copper and c=0,0693 for nickel. So 12.6cm of 0.27mm2 wire would have a resistance of 8mOhm in copper and 32mOhm in nickel. To ca...