Banding together for the E-bike cause.........

[recumpence]

Hey Guys,

John Rob Holmes and I were talking on the phone at length today about the E-bike market and products that are available for RC conversions. We discussed starting a thread about HV110-EV controller and throttles. So, I am starting that thread here, but with some added info;

Most guys on this forum are pretty knowledgeable and can setup throttles, controllers, batteries, etc. But, many people who read these forums, but do not post, cannot. We have each had numerous people request custom setups such as ESC programming and capacitance increase, as well as throttles setup to use, chargers, batteries, etc. John and I are doing our best to work together and not step on each other's toes. Here are a few things we have come up with;

#1 We will both be setting up HV110-EV controllers. These are controllers with doubled capacitance and preprogrammed for EV use (proper LV cutoff, proper motor start characteristics, proper PWM, etc). I have already sold many HV110s setup this way for my own customers. John will be doing the same thing.

#2 I am making ready to go twist grip throttles for sale. These are basically Magura throttles with servo PWM output and BEC power built in. Astro Flight is working on producing these for us. But, for now, I will be building them at my shop. These do not have current limiting. They are just a PWM output throttle with BEC power output for those who are unfamiliar with doing this themselves.

#3 I will be providing him with drives as he needs them. We are also working together on ideas for items that will aid in the use of my drives (sprocket adaptors, mount parts, etc).

We have discussed other items as well, but these are the main things I wanted to tell you guys about.

Lastly, I want you to know VRDublove and I are working together on trike drives. We are both retailers for KMX and are setting up karts to sell. I am doing what I can to work out mounting details and provide him with drives while I build my own trikes here. Also, Gary Goodrum and I have been going back and forth about RC conversions. He and Methods are working on the sensored Astro motors and controllers. I will be providing him with drive units, assuming the sensored setups work out.

I will be stocking Astro motors in silver and black, double shaft and single shaft. I will be stocking ESCs, throttles, freewheels, chargers, and a few battery packs. I also stock KMX Karts new in the box. I will eventually be stocking a couple EV-KMX karts in various guises as time allows to build them.

So, those of us who are on the front edge of this, are doing our best to stay off each other's toes and help each other out. If we band together to a degree, we can accomplish more that each person trying to be a one-man-band.

Anyway, that is what's happening here. I am sure John will chime in shortly.

Matt

 

[johnrobholmes]

I couldn't agree more. This really is an emerging technology development and the more at the table the merrier.


Within the next year I will be releasing an Ebike specific controller that is made in the USA. It will have extra I/O ports and be built with hall sensor, temp sensor, and a few other inputs ready to go. Right now I have two RC controllers tying up my cash, but as soon as it is freed I will start developing the new controller.

 

[John in CR]

Matt and John,

I haven't been following many of the threads. Are we to the stage now with proven motors and controllers to have the kind of reliability required for a commuter bike? I really want to try one of the lightweight RC based rigs, but I'm hesitant to let go of the absolute reliability I have going with my 30lb hub wheels.

Are there any discussions of this "banding together" to produce one of the 2 speed trannies that Miles has come up with? That would seem useful for every non-hub motor rig.

Lastly, how are those White Industries freewheels holding up under high power use? Has anyone had a failure yet?

John

 

[johnrobholmes]

I have at least 1000 miles on my HV110. Besides the random blown cap it has been running strong and never even gotten hot.


Motors are the easy part IMO. Get them efficient, or get them big enough to bleed off the heat.

 

[mclovin]

Within the next year I will be releasing an Ebike specific controller that is made in the USA. It will have extra I/O ports and be built with hall sensor, temp sensor, and a few other inputs ready to go. Right now I have two RC controllers tying up my cash, but as soon as it is freed I will start developing the new controller.

Yeah!!!!!!

Any possibility you will have motor reversal as part of your controller?

 

[mclovin]

Motors are the easy part IMO. Get them efficient, or get them big enough to bleed off the heat.

It seems that you and Matt prefer the Astro Flight inrunners - correct me if I'm wrong. Have you considered using a heat sink (i.e.fins) around the body of the stator? Do you think it's needed?

 

[MitchJi]

Hi,

Motors are the easy part IMO. Get them efficient, or get them big enough to bleed off the heat.

It seems that you and Matt prefer the Astro Flight inrunners - correct me if I'm wrong. Have you considered using a heat sink (i.e.fins) around the body of the stator? Do you think it's needed?

With the AstroFlight you are going with efficient.

 

[johnrobholmes]

If you want to get more power out of a motor, yes you can heat sink it. The cost addition would be pretty high for the astro motor, unless an extrusion was used for making the outer can.

I have never used an astro motor on an ebike before, but I own quite a few astro motors otherwise. The quality is top knotch, and the price is also great for the size and power. I am purchasing a 3210 and 3220 astro for testing purposes.

Reversing could be done fairly easily. Probably a push button setup, either momentary or latching switch.

 

[Miles]

The cost addition would be pretty high for the astro motor, unless an extrusion was used for making the outer can.

For us, it would probably be better to have the fins running circumferentially. Shouldn't be too difficult to fab. Pure Aluminium would be best, though... Maybe just press the rings on individually?

 

[mclovin]

Hmm. I wonder. I hope I'm not too far off topic.......

Just thinking out loud here: I would think that the greatest need for cooling would be during low RPM (high current) operation ergo low air flow moving over the motor. I wonder if the fins were mounted axially oriented and a fan affixed to the end of the shaft and basically turn it into a TEFC (totally enclosed fan cooled) motor may be better for low speed operation. That may result in more balanced cooling as well. I don't know really. Just thinking.

 

[Miles]

Yes, but a fan would draw power, at all times. This is mostly about efficiency gains, right? The Astro 3210 has Samarium Cobalt magnets, so running it hot is not so much of a problem for the motor. I guess we need to do some calculations....

Anyone here set up to do CFD? It would be interesting to model both implementations and see how they compare.

 

[recumpence]

I am stocking Astro motors (both 3210 and 3220) in black. Just the black color will help dissipate heat a little bit. Also, many of my motors will be double shaft, for a variety of reasons. For ,one thing, that will make it easy to install a fan. Yes, the fan will reduce efficiency. But, for super high power, efficiency is not a big deal.

The PK Ripper 3210s at full throttle (50mph) get pretty hot. About 170F. But, they still run fine. That is doing full throttle blasts pulling a 195 pound rider sitting straight up into the wind. I believe we will be mounting a fan soon to help a bit.

One thing to remember about the Astro; As an inrunner, the windings are right on the inside surface of the can. That makes the can feel hotter than an outrunner because you are getting relatively direct heat from the windings, not passive heat through air to the rotating can like an outrunner. So, an outrunner can may feel cooler, but the windings are hot, while the Astro may actually be running with cooler windings.

Don't get me wrong, I LOVE my Plettenberg. But, the Astro is 90% as good, at 40% the price.

Matt

 

[liveforphysics]

Just the black color will help dissipate heat a little bit.
Matt

For surfaces with equal heat conduction, yes, a flat black body will more effectively radiate IR.

However, AlO3 is the ceramic chemical coating which is anodization.

25-30 W/m•°K

For aluminum, you are looking at

250 W/m•°K

It's the thermal equal of putting a thin thermal blanket over an aluminum part.


Best Wishes,
-Luke

 

[Miles]

This is what I suggested using to D. : http://www.birchwoodcasey.com/sport/blueing_index.asp?categoryID=1&subcat=5&prodcat=79 You'd need to prepare the surface well, though....

 

[liveforphysics]

Agreed Miles.

Blueing or dipping in draino, and then boiling in a penatrative black dye would both be much better options than the little ceramic thermal blanket you put on a part when you anodize.

 

[Miles]

So, although anodising increases emissivity, a much greater proportion of heat is dissipated by conduction/convection when there is a significant airflow. So, the gains from increased emissivity are more than cancelled out by reduced conduction through the surface to the air. Is that a fair summary?

 

[liveforphysics]

That's a very fair summary Miles.

It's also very easy to calculate. Lets do a best possible case scenario example for a 3210. Give it the black surface the best possible emissivity value of 1, and lets give the raw aluminum a complete absence of emissivity value, 0.
Say a 70degF day outside, and the surface of the astro is at 250F.

The surface area of the 3210 is 0.0249m^2

The maximum possible heat the motor can radiate is 1.48w at 250deg F, and this is assuming it's a true perfect black body.

1.48w maximum possible advantage vs a theoretical surface which radiates no energy at all.

Best Wishes,
-Luke

 

[John in CR]

But the real limitation is the surface area and conduction+convection to the outside air, which is going to far slower than the conduction through this extremely thin thermal blanket.

As a real world example, one of my controllers seem too visible to me as a silver color mounted under the motor cycle seat on my bike. I painted it black, making it virtually invisible, and the paint obviously has a far lower coefficient of thermal conductivity than the aluminum I painted over. Nothing else changed, airflow, etc., and the controller seems to run cooler with the paint...definitely not hotter. I attributed the cooler feel to greater emissivity of the black over the somewhat shiny aluminum.

John

 

[recumpence]

Or maybe the pain is insulating well enough that you do not feel the heat?

Matt

 

[northernmike]

Perhaps I'm out of line here, but...

I can't help but wonder:

Why concentrate so much on cooling? Why not instead design systems that don't generate that much heat in the first place?

Does it mean a triple-motor drive for something like the PK?

Does it mean more FETs?

Seems to me if heat is the enemy, why not choose not to create it rather than have to deal with getting rid of it?

In all the residential distribution work I'm doing (33 story condo under construction) we de-rate and de-rate and de-rate until things meet code. The main feed to the upper floors is roughly 400ft of 1000MCM - 5,200lbs of aluminum. This to handle 1200A at 600V. Will it ever get even warm? I doubt it.

Conductors aren't supposed to get hot, are they?

Is there that much of a weight penalty to engineer heat loss out of the equation?

 

[gogo]

Bottom line is that you will have X amount of heat for X amount of power. Your choice is in where that heat is and how you will dissipate it.

 

[mclovin]

Seems to me if heat is the enemy, why not choose not to create it rather than have to deal with getting rid of it?

That's a good question.

I don't know that we have a choice really - to generate heat that is. The wires in the motor are wrapped over themselves and around/through the steel laminations effectively creating a block of metal that gets hot. As long as current flows through the windings there will be heat generated. If the motor could be streched out very long and thin with a tremendous surface area then getting hot would probably disappear as an issue. But it would still generate heat it just wouldn't get hot. I think the choice is how to deal with the issue. Or wheteher or not to be concerned in the first place.

Personally I'm looking to maximize performance for the fewest dollars spent. So, If I can squeak out a few more watts and extend my range a few more miles it may be worth it to add some cooling stuff to my system. I don't want to buy more batteries and use a bigger (more expensive) motor as a work around.

Cheers.

 

[Miles]

For any motor you choose, the lower the armature temperature is kept, the less the resistance and therefore the greater the efficiency (assuming that less/no energy is spent doing the cooling, of course).

 

[mud2005]

I like the sound of that magura twist throttle, sounds like it will allow me to eliminate the BEC and servo tester I have wired to my HV110
If that is the case, put me down for 1 ASAP. how are you handling orders? how much will it cost?

 

[recumpence]

As for the heat issue;

My bikes are overpowered. That being the case, heat is generated, but rarely sustained because the huge wattage they produce is delivered in very short bursts. My KMX trike, for example, will be running twin 3220s. I highly doubt heat will be an issue at all. Heck, it will be tough to make the motors warm on that thing unless I am doing hard stop and go runs.

Mud,

Yes, the throttle assembly will totally eliminate the need for the servo tester and BEC. The throttle will take your 36 or 48 volts in and put out the 5 volt supply and the PWM the ESC requires all in one assembly.

As for cost, it looks like $140. That is because Astro Flight has not put them into production yet. So, I will begin building them myself. I have to buy components and mod them for use, then assemble the whole thing. Hopefully Astro will be able to get them to us cheaper ($100 would be nice). But, again, for now, I will be making them myself. My throttles are on their way to me right now, I have servo tester boards here for the PWM signal, and I am ordering the power supplies for the BEC part of the system Monday.

Matt