Search found 222 matches

by hias9
Feb 21 2021 8:52pm
Forum: Items for Sale - New
Topic: Compact Field Oriented Controller, ASI + Grin, limited run
Replies: 1271
Views: 273896

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

Do you mean throttle gain (Volt/Volt) ?
by hias9
Jan 31 2021 6:26pm
Forum: Vendor Relations Corner
Topic: Accelerated Systems ASI BAC 4000 & BAC 8000 FOC BT Controllers
Replies: 152
Views: 42009

Re: Accelerated Systems ASI BAC 4000 & BAC 8000 FOC BT Controllers

Anybody knows how to disassemble a BAC4000? The controller I need to repair was the only one not bought from ASI, but from this scammer here who opened this thread. So I need to repair it myself. Never received a reply from him after it stopped working over a year ago.
by hias9
Jan 29 2021 11:00pm
Forum: Motor Technology
Topic: Some Motors Incompatible with Statorade / Ferrofluid cooling?
Replies: 36
Views: 1991

Re: Some Motors Incompatible with Statorade / Ferrofluid cooling?

I think the first theory is the most realistic one. On the second picture you can also see little points of rust on the aluminium cover plate. Probably some of the iron-based particles of the ferrofluid got there. The bearings (both the original Chinese ones and the ones I use) are sealed on both si...
by hias9
Jan 29 2021 1:49pm
Forum: Motor Technology
Topic: Some Motors Incompatible with Statorade / Ferrofluid cooling?
Replies: 36
Views: 1991

Re: Some Motors Incompatible with Statorade / Ferrofluid cooling?

So maybe the problem was caused by sealing the cover plates which I did when I added the Statorade.
I might need to drill a vent hole which would be opened after riding to let any moisture escape.
by hias9
Jan 29 2021 3:01am
Forum: Motor Technology
Topic: Some Motors Incompatible with Statorade / Ferrofluid cooling?
Replies: 36
Views: 1991

Re: Some Motors Incompatible with Statorade / Ferrofluid cooling?

Does not really look like water entrance in my case. Never noticed any moisture when I opened it and never had this rust from the inside on the bearings before using Statorade. Anybody using Statorade having the same issue?
by hias9
Jan 29 2021 2:19am
Forum: Motor Technology
Topic: Some Motors Incompatible with Statorade / Ferrofluid cooling?
Replies: 36
Views: 1991

Re: Some Motors Incompatible with Statorade / Ferrofluid cooling?

What you see on the pictures are the interior sides of the bearings. On the exterior sides there was only very little rust even after 1.5 years of use. My side covers are sealed so the only way for moisture to get inside the motor would be via the cable. However so far I never noticed any moisture w...
by hias9
Jan 28 2021 10:06pm
Forum: Motor Technology
Topic: Some Motors Incompatible with Statorade / Ferrofluid cooling?
Replies: 36
Views: 1991

Re: Some Motors Incompatible with Statorade / Ferrofluid cooling?

Do you guys also have rust at the bearings when using Statorade? This is the Chinese bearing (left side) after a bit over a year with Statorade. Technically it was still ok. https://i.ibb.co/9Z0FhDw/DSC-3298.jpg The bearing (right side) in the background is a FAG bearing after less than 2 months wit...
by hias9
Jan 27 2021 3:59pm
Forum: EBike Technical
Topic: Thermal Epoxy to glue Magnets
Replies: 0
Views: 158

Thermal Epoxy to glue Magnets

I am using Statorade + Hubsinks on a 23 pole pair motor with flat (non-curved) magnets. Has anybody experience with thermal epoxies which are okay up to 150 degrees Celsius? I am not sure by how much it would improve overall heat transfer from stator to shell. Does anybody have values (in W/mK) for ...
by hias9
Jan 09 2021 7:21am
Forum: EBike Technical
Topic: XT 90 antispark
Replies: 10
Views: 648

Re: XT 90 antispark

When I was using XT90S antispark connectors with a 22S lipo battery, the connector usually started to spark after about 10 or 20 connections. Maybe always plugging it in only half and wait for a second before plugging it in completely helps, but I did not try that. On my 14S battery the XT90S still ...
by hias9
Jan 07 2021 1:16am
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 29
Views: 630

Re: Stronger Motor Magnets

Is there a way to calculate the optimal point of the hysteresis curve if you know the amount of back iron (it‘s about 7-8mm thick for these motors) ? If I would replace the magnets with ones that are 10% stronger, but Kv would only decrease by 5%, that would probably mean that the back iron is satur...
by hias9
Dec 27 2020 7:25pm
Forum: EBike Technical
Topic: Maximizing Copper Fill
Replies: 7
Views: 298

Maximizing Copper Fill

Hub motor stators usually have a piece of wood and paper on top of each stator slot.
Is this additional insulation or too keep the copper windings where there are?

Would it be a good idea to remove these pieces and add maybe 1-2 strands of winding wire to increase copper fill?
by hias9
Dec 26 2020 4:51pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 29
Views: 630

Re: Stronger Motor Magnets

Yes, the Chinese motor manufacturers would only do it if ordering a high quantity.
by hias9
Dec 25 2020 9:22pm
Forum: EBike Technical
Topic: Rotor Material
Replies: 9
Views: 169

Re: Rotor Material

They are already made of cast aluminium so there is not that much room for weight reducing. I also thought about cooling fins on the sideplates, but machining them will not be cheap I think.
by hias9
Dec 25 2020 8:48pm
Forum: EBike Technical
Topic: Rotor Material
Replies: 9
Views: 169

Re: Rotor Material

I came across a study and one result was that torque was halved by removing the back iron completely. I agree, reducing back iron is most likely a bad idea.
Looks like there is only a bit of weight reducing potential on the cover plates.
by hias9
Dec 25 2020 8:23pm
Forum: EBike Technical
Topic: Rotor Material
Replies: 9
Views: 169

Re: Rotor Material

I am not sure by how much the back iron actually decreases Kv and if the amount of back iron can be reduced without a significant increase in Kv.
But I am also not optimistic that reducing back iron is actually a good idea.
by hias9
Dec 25 2020 5:38pm
Forum: EBike Technical
Topic: Rotor Material
Replies: 9
Views: 169

Re: Rotor Material

Yes it is back iron. Are there ways to calculate the effect on the motor Kv?
Because machining a rotor made of copper or aluminium just to test it would not be cheap.
by hias9
Dec 25 2020 4:09pm
Forum: EBike Technical
Topic: Rotor Material
Replies: 9
Views: 169

Rotor Material

The 3kw 45mm magnet height motors I use (similar to mxus 3k) have a rotor made of about 8mm thick steel which is almost 6lbs without the 46 magnets and cover plates. On the outside of the ring I use aluminum Hubsinks.
How would a rotor made of aluminium or copper affect the motor properties?
by hias9
Dec 20 2020 10:01pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 29
Views: 630

Re: Stronger Motor Magnets

The copper losses in this case did not decrease because there was a change to the windings. They decreased because with the stronger magnets you need less amps for the same torque, and copper losses are proportional to I^2. So it’s probably not just 1-2%. I am just wondering why they only use N35(S)...
by hias9
Dec 20 2020 9:18pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 29
Views: 630

Re: Stronger Motor Magnets

But you need 10% less motor current for the same torque (before considering losses) so less copper losses and this probably outperforms the increased magnetic losses.
This diagram is just about cogging losses which will definitely increase.
by hias9
Dec 20 2020 8:34pm
Forum: EBike Technical
Topic: Stronger Motor Magnets
Replies: 29
Views: 630

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: 29
Views: 630

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: 29
Views: 630

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: 29
Views: 630

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: 29
Views: 630

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: 29
Views: 630

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...