The E-cumbent - A project by Matt Shumaker

[recumpence]

Glad to know it will work with my E-Logger. Another $150 goodie I already own that I can make use of. Actually, that one item will give me more information than any other single gadget.

So, I just came in from a full throttle (never let off) 6.5 mile ride at 38mph (hit 40 on a couple occasions). The roads were hilly and I got hard on the throttle the 4 times I had to stop (intersections). So, this is an absolute worse case scinerio. My power consumption was 26 WH per mile on that ride.

So, with this motor, I am at 16 WH per mile at 20mph if I nurse it and 26 WH per mile at 38mph if I am hard on it.

Seems like a pretty good overall efficiency for each. It could be improved on of course. My next task on this bike is a secondary drive consisting of a Plettengberg 10-18 on 24 volts (already have the motor, cells, and ESC for it). That would be good for 400 watts continuous. It should be good for gnetle cruising 16 to 18 mph with the powerhouse motor for high speed, high power running. That seondary drive will be ints own completely separate drive system mounted just forward of the rear wheel under the dropouts.

Matt

 

[johnrobholmes]

Awesome project. I come from an RC background as well so I am very familiar with the components. My first build uses a 4035 outrunner and 6s ESC. Hauls me around just fine, although a bit anemic for my pleasures.

 

[recumpence]

You should start a thread on it. There is growing interest in RC motors for e-bikes on this forum.

Welcome by the way. :wink:

Matt

 

[recumpence]

First major technical issue today.

My ESC blew. I think it was going bad for a while. The other day it would not arm. It had become sensitive to the EMF put off by the motor when it would chirp on arming. Then today I noticed the motor chirp was considerably quieter and higher pitch than it usually is. "Hmm, I wonder what that could be?" Then I plugged it in and as soon as I began rotating the throttle, I heard a slight pop followed by a tiny burned odor. Toast. So, I will send it in for repair.

I have another one due to in any day now. I will check on that spare ESC to see when it is due to arrive. If I have to, I have another one in an RC car I could remove. But, I would rather wait.

This ESC is one of two I recieved from Castle Creations free as a sponsorship deal a year ago. I have a feeling they were returned defective and repaired or something. The Castle ESCs I have purchased have never failed.

Anyway, it is obviously a bummer.

Matt

 

[dirty_d]

i think i might know why, its rated for 110A continuous right? but you said the max current is 150A, im guessing there is some sort of current limit at 150A. the motor will pretty much always be hitting the 150A limit during acceleration and only drop down very close to no-load speed, so it might have just overheated from being run at 150A too long. these things are made for planes right, the propeller accelerates to full speed very quickly right, so the current will pretty much always be at or below 110A unless the prop is too big for the motor. im going to start working on a sensorless bldc controller that will have an adjustable current limit, no idea when ill get done though, i still need a brushless motor to test with.

 

[recumpence]

That may be the case.

I am looking into the Kontronic Power Jazz ESC next. It is rated at 120 amps continuous 200 amps for 15 seconds. It will also run up to 63 volts and is waterproof.

Matt

 

[Miles]

Yes, I was looking at that, too

http://www.kontronik.com/Powerjazz2006e.htm

 

[recumpence]

This can get expensive, I must say. But, I figure it is a research project on how much performance can be obtained in a very light weight package.

I found one supplier who sells that ESC for $384.

Matt

 

[dirty_d]

recumpence, but your motor WILL try draw over 200A except near no load speed, what you need is a controller that has a current limit for the continuous current, not the peak rated short term current.

 

[recumpence]

The PowerJazz will take 120 amps continuous (of course, so will an HV110). My slipper clutch will not allow more amperage draw that I allow anyway. But, admittedly, I have been running it tighter and tighter for better accelleration. So, either I overamped my ESC by running my clutch too tight, or it was a bad ESC to begin with.

I really wish my data logger would arrive. That way I could set my slipper to slip at 100 amps.

Matt

 

[johnrobholmes]

If you have been using a normal watt meter, you will be surprised at how many spikes it lets slip through undetected. The faster sample rate really shows you how hard the motor works on acceleration. Even little tiny outrunners will burst 100 amps.

 

[recumpence]

Agreed. I totally understand that.

This is a work in process. It will get sorted out.

Again, this my indeed be a bad ESC to being with. It has, after all, given me 200+ miles so far. I think the Terminator is just too much motor (as I am asking alot from it).

Matt

 

[johnrobholmes]

I just need to figure out why my outrunner isn't giving the performance that it should. I have a feeling it is the ESC at fault, as it doesn't want to keep synch under variable load.

 

[eP]

Agreed. I totally understand that.

This is a work in process. It will get sorted out.

Again, this my indeed be a bad ESC to being with. It has, after all, given me 200+ miles so far. I think the Terminator is just too much motor (as I am asking alot from it).

Matt

If you need 100+ A currents, so start to make thicker all your current wires. Add big caps 1000u/63V just before ESC and measure what is the voltage drop at your battery pack under 100 A load.
Maybe you need next one battery pack (if the drop is too deep ).

 

[johnrobholmes]

My original problem was voltage drop under load. Without the eagle tree logger I would have never known either.

Cant wait to see some data collection from you.

 

[recumpence]

Before my logger took a dump, I was able to get good data. The voltage doesn't sag hardly at all. I see maybe 2 volt drop under load. My cells are very much up to the task.

I asked Castle Creations about caps. They said it would (or could) confuse the ESC. I was told the caps the ESC has are enough.

Anyway, I will get it sorted out. :wink:

Matt

 

[eP]

Before my logger took a dump, I was able to get good data. The voltage doesn't sag hardly at all. I see maybe 2 volt drop under load. My cells are very much up to the task.

2 volt under what load ? 100+ Amps ?

I asked Castle Creations about caps. They said it would (or could) confuse the ESC. I was told the caps the ESC has are enough.

That is very strange ! In which way bigger caps could confuse ESC ?
Caps just acting like very efficient (low drop) battery pack - so ultra low Rs pack could confuse ESC too ? I'm confused.
It's hard to belive (for me) very small caps are enough for 100+ Amps loads.

 

[recumpence]

Before my logger took a dump, I was able to get good data. The voltage doesn't sag hardly at all. I see maybe 2 volt drop under load. My cells are very much up to the task.

2 volt under what load ? 100+ Amps ?

That was when I was running the AXI. It pulled far less wattage than my Plettenberg.

Bear in mind, typical e-bike cells cannot handle big wattage. These cells are rated at 100 amps continuous 150 amps for 30 seconds.

I asked Castle Creations about caps. They said it would (or could) confuse the ESC. I was told the caps the ESC has are enough.

That is very strange ! In which way bigger caps could confuse ESC ?
Caps just acting like very efficient (low drop) battery pack - so ultra low Rs pack could confuse ESC too ? I'm confused.
It's hard to belive (for me) very small caps are enough for 100+ Amps loads.

I am not an engineer. I just know what I was told. This was part of a conversation I had with them regarding ultra capacitors. I was told the ESCs are designed for input from a battery pack, not large capacitors, so not to mess with that.

Just repeating what I was told. I am not an engineer. So, I have to build it and test it before I know something for sure.

I am merely trying to make my bike the best it can be. I have already far exceeded my expectations. Now I am just trying to get every last ounce of performance out of it in its current mechanical configuration.

My bike is more complicated than a bike needs to be. It is also expensive. But, the performance is good enough that I want to push it as far as I can.

Matt

 

[eP]

2 volt under what load ? 100+ Amps ?

That was when I was running the AXI. It pulled far less wattage than my Plettenberg.

I was afraid there was that case. So i ask again what is the voltage drop under 50A load ?
You can double it for 100 A load.
It could be much more than 2V drop i'm afraid.

Bear in mind, typical e-bike cells cannot handle big wattage. These cells are rated at 100 amps continuous 150 amps for 30 seconds.

Yes, i know.
But still voltage drop is able to limit your max speed i'm afraid.
So this is the reason why you should do tests (voltage drop measures).
Pack's interconnections are very impotant too for the same reason.

If you lower your voltage drop under extremal load, so you could lower your gear again ( for Plettenberg, i'm assume you have taller gear now ) to reach the same max speed at the same or lower load.

I am not an engineer. I just know what I was told. This was part of a conversation I had with them regarding ultra capacitors. I was told the ESCs are designed for input from a battery pack, not large capacitors, so not to mess with that.

It is a bit of misunderstanding.
I didn't say about ultra caps. Ultra caps are quite different animals.
I'm talking about quite normal electrolitic caps used for lowering voltage drop across wires between your battery pack and ESC.
The longer wires - the higher additional voltage drop under heavy load.
Such capacitors have 1000uF = 1 mF (mili Farad ) = 0.001 F capacitance for example.
Ultra caps are 100 to 3 000 000 times larger ( capacitance of course) than that. (0.1F to 3000F)

I'm trying to help you reach a little better performace under extremly heavy load.

Best regards

 

[recumpence]

Yes, you are correct about the connector drop. One thing I plan on doing is eliminating the bullet connectors between the ESC and motor as well as minimizing wire length. I also plan on shortening the battery leads. I do not see any cell heat, but I do get wire heat. Under heavy load the wires run about 20 degrees above ambient temperature. I know there is a loss there.

This thing is very quick, I must say. I am not too worried about perfection. However, eliminating any losses is very important.

I am open to any changes/additions to help my setup run to its peak.

Matt

 

[eP]

Tell us Matt what are your gear stages ratios now ?
We need to know what is your motor rpm at 38mph (26 inch wheel 500 rpm). Then we will know what is the back EMF voltage at that speed.
I'm afraid that voltage is still low and your throttle is 100% wide open.

 

[johnrobholmes]

How long are the battery wires to the ESC solder points?

 

[recumpence]

I have changed the ratios (primary, secondary, and final) so many times in the last couple weeks that I do not remember. :wink:

I know it is roughly 16 to 1. But, I will have to check that for you.

There is 16 inches of wire between the cells and the solder points on the ESC.

I appreciate the willignness of you guys to analyze this for me. I am a great fabricator and mechanical problem solver. But, I am not an engineer.

Matt

 

[johnrobholmes]

You need to half your battery wires. 8 inches should really be the max, any more and you will blow fets. Elongate the motor wires if needbe, they can be 1000 feet long with only resistive losses.

 

[recumpence]

Really. Wow, thanks!

I will mount the ESC closer to the pack.

Man, great info. I appreciate that. :wink:

Matt