Project #3. Two motors, Three wheels, Six grand!

[recumpence]

Actually, Ackerman is achieved easily with only one tie rod. The steering spindles need to have their arms angled inward to achieve Ackerman.

The reason many trikes have two tie rods is because they use indirect steering (handlebars that pivot under the seat). With direct steering like the KMX and Catrikes use (along with others), you have tillers directly mounted to the steering kingpins. This is a bit more positive steering. However, again, to achieve Ackerman, angled spindle arms are required.

Also, suspension trikes normally use two ties rods to eliminate bump-steer and to mantain proper toe-in through out the suspension travel.

The KMX (in fact, every trike that I am aware of) has proper Ackerman.

Matt

 

[recumpence]

Progress is being made.

I did all motor wiring (lots of 10ga wire), all battery wiring, throttle wiring and installation, and controllers are installed in the console.

All that is left to do is solder the motor wires to the controllers, and solder the main connectors to the battery pack and controllers and it is done! I am dying to ride it. But, I refuse to rish this project. I am actually going out of town untill Sunday. So, it won't be running for a few more days.

It is geared for about 35mph as it sits with 12,500 watts available. It may, indeed, smoke the rear tire.

Anyway, the center console is a nice added touch, that is also functional as it holds a water bottle. I will be mounting a cycle computer and a voltage display on the top of the throttle box below the knob. That small knob, by the way, is a throttle end point adjustment. It is not a current limiter. It is a throttle (top speed) limiter. That way I can let people ride it while it is set for something less than full throttle depending on the person riding it.

I have a second trike I am building too. That trike uses one 3210. It will be running a few days after this trike. Also, there are two other KMX trikes being built by other forum members right now. So, expect the board to be innundated with trikes soon.

Enjoy!

Matt

 

[grwsaltspring]

Hey Matt;

Great to see the progress, I was wondering how it was going. Your build has definitely gotten my curiosity up about an E-trike!

Cheers Greg

 

[recumpence]

Getting a trike to truely handle well is a difficult thing. I spent alot of time pedal testing this thing as it sits to get the handling sorted out. It turns out a huge amount of weight needs to be over the front wheels to get decent cornering. With me on it, the trike has 205 pounds on the front wheels and 65 pounds over the rear wheel (102 pounds per front wheel and 65 at the rear). That may sound horribly out of whack, but it corners awesome this way! Also, I have the seat layed super far back. So, though the CG is far forward, it is also very low. That makes for decent braking without too much endo tendency. I may have to move the seat back a couple inches to adjust it a tad, but it would not be much.

At this point, I am concerned about wheelspin. I may have to go to a wider rear tire with low pressure to get the traction I need.

We will see soon enough.

Matt

 

[boostjuice]

Hey Matt, Looks fantastic!
There is only one thing that worries me.... Isn't 10AWG wire a little wimpy for the sort of current you will be pulling? I mean if your HV-140's are pulling 140Amps each through 50Amp rated wire wont the voltage drop cause some significant wire heating, wasting both battery power and possibly limiting the max current your motors can consume?
I realise that ESC's and Lipo packs usually have only ~10AWG wire stubs for connection, but that is probably ok for the very short wire runs like you get inside model aircraft.
The wire runs on your bike are much longer. Sorry to be a stickler...I'd just hate to see such a beast not performing to its maximum potential.

 

[CNCAddict]

The windings inside the motor are much longer and much smaller gauge. 10ga. is more than large enough.

 

[grwsaltspring]

Hi again Matt;

I for one appreciate your willingness to share your experience with your builds. So thanks for the info re: bike handling.

I'll be interested to see how this build stacks up against the next one.

I live in a rural area and the roads are pretty bumpy. I'm curious as to how you like the trike at speed without suspension.

Cheers Greg

 

[recumpence]

The ESC supply wire from the pack are 4 runs of 10 gauge for positive and 4 runs for negative. The motors each have 3 runs (6 wires total for the two motors) of 10 guage wire from controllers to the motors. It should be fine. We shall see soon!

Matt

 

[Storm]

So smooooth and clean at the back, spagetti at the front, argh?? The console looks great but do you need to mount the controllers there? You've probably got some crazy way of packaging that I cant see atm.

 

[liveforphysics]

The windings inside the motor are much longer and much smaller gauge. 10ga. is more than large enough.

Inside the motor, the job of the windings is to allow the magnetic field to build in exchange for the voltage applied across the windings, and to have 100% of the applied voltage to drop over the length of wire.

Voltage that drops before the motor doesn't do anything but waste energy and hurt performance.

My setup with 8awg was dropping over 1.5v under load over the length of the wires at 250amps, that's 375w of power being wasted in warming wire. Swapped it out for double runs of 4awg, and now I get about 0.2v of drop, or 50w of power being wasted in warming wire. As the end user, I can't feel differences of only 325w of power, but it's nice to know it's getting used, and it could amount to an extra mile of range from the pack.

 

[CNCAddict]

The windings inside the motor are much longer and much smaller gauge. 10ga. is more than large enough.

Inside the motor, the job of the windings is to allow the magnetic field ........ at 250amps, that's 375w of power .....

Oh dear. I do believe it's time for me to change my user name to "xeramotors". Is that even possible? Also, if Matt is pulling 250A for any lengthy period of time he's going to have have more problems than just voltage drop in the wiring. I just get a bit "irked" when I see one of the "doers" getting critiqued. Nothing more.

 

[Miles]

Oh dear. I do believe it's time for me to change my user name to "xeramotors". Is that even possible?

Hi David,

It definitely is possible. It's beyond my power, though....

 

[Miles]

Do you want me to ask for this change?

 

[recumpence]

I agree I need thicker wire to reduce losses. However, weight is an issue as is room to run the wire. Besides, I will only be pulling huge wattage for very short bursts (maybe 4 seconds at a time while I accellerate). I am open to changing wire, though. I am a car audio guy at heart and do not mind running lots of wire.

The wiring up front will be cleaned up and I am making covers for everything. The controllers are only there for airflow, and to be able to reach my main disconnect. No other reason. They may go on top of my pack later on. But, I do not want a flamout screwing up my pack (if that occurs).

Thanks for the compliments. I hope it runs well.

Matt

 

[deecanio]

Hi Matt,

i just had a catch up with the build, simply amazing quality (what else?)
can't wait to see this thing run, should be an astounding piece of kit, have you quit your day job yet? :lol:

D

 

[recumpence]

D,

Nope, still workin.

Storm,

Thanks for the critique. I have an idea on how to remount my controllers. That will really clean up the front of the trike and eliminate more than half my motor wire length!

I would not even have thought of it if you hadn't mentioned the wiring.

Matt

 

[liveforphysics]

The windings inside the motor are much longer and much smaller gauge. 10ga. is more than large enough.

Inside the motor, the job of the windings is to allow the magnetic field ........ at 250amps, that's 375w of power .....

Oh dear. I do believe it's time for me to change my user name to "xeramotors". Is that even possible? Also, if Matt is pulling 250A for any lengthy period of time he's going to have have more problems than just voltage drop in the wiring. I just get a bit "irked" when I see one of the "doers" getting critiqued. Nothing more.

Dave, I know you build awesome motors, and I have lots of respect for you and your work.
I absolutely agree that Matt's wires are perfectly able to avoid failure. I also think his builds are fantastic! However, if you are looking to optimize performance, and I think that is the whole nature of a build like this, then I can't see why you would object to minimizing around a volt of drop in the supply to the ESC's. It seems like a very cheap and easy 2-3% power boost. As far as pulling 250A goes, do you not think he will put a 125A load per motor through a pair of HV140 ecs? I regularly draw 250-300amps between the pair of infinion controllers feeding the RC motors I modded with hall sensors, and the motors stay in a reasonable temperature range for the relatively short time intervals of hard acceleration.

3ft of 10awg for +and - leads with 250amps across it will drop ~1.52v

3ft of 4awg for + and - leads with 250amps across it will drop ~0.375v

3ft of 4wg double runs for + and - leads with 250amps across it will drop. ~0.1875v (this is what I switched to using for my bike).

Certianly not NEEDED, but if you are looking for making the most of your available battery power for hard acceleration, it will improve performance. In my world of tuning ICE engines, getting a 2-3% gain in acceleration for the cost of a wire would be a the greatest thing since sliced bread when often it takes hundreds of dollars in parts and tuning to find another 2-3% in performance engines that are all ready well developed.

Best Wishes,
-Luke

 

[recumpence]

I will be running about 16 inches of wire between the motors and ESCs with my remount of the ESCs.

I expect 300 amp pulls for short bursts with this setup. That is only a few seconds at a time, though. Actually, it is only geared for 35mph at this point. The accelleration should be mind-bending.

I am open to big wire if it is not too long (too heavy). I have a roll of fine strand 4 guage here from my car audio days. 8)

I am going out of town. I will be back Sunday working on the beast.

Matt

 

[liveforphysics]

That is awesome Matt. Getting the wires to 16" runs will make even 10awg not be much of a performance difference, and running 4awg for 16" will be about as good as anything could get for E-bike wiring.

I hope you and Dave didn't take offense to the voltage drop stuff. You guys do much nicer work than the caveman looking parts I build, and nothing at all was wrong with your original wiring layout, which would have looked and performed great.

I hope you have an excellent vacation, and we are all excited to see more progress on your build when you come back.

-Luke

 

[recumpence]

I am back.

Luke, I appreciate the kind words. I feel like a total retard when it comes to electronics, though. That is why you get PMs from me from time to time. :wink: I have a huge amount of respect for guys like you and Miles and Methods. My skill is in mehcanical design and vision. I can think up and make happen most anything mechanical (within reason). But, I am very behind the curve in other areas.

I am very thankful that we are all willing to work together on these projects, between Fechter with his board, Methods working on controllers, Gary's BMS, and Miles with the all around knowledge and willingness to help us out.

This is a great place to hang out.

Sniff, sniff, where did I put those tissues?

MAtt

 

[recumpence]

IT LIVES!!!!

OK, I got all wiring done and gave it a bit of a charge. But, I could not wait and had to take it out for a ride.

A few impressions;

#1 Absolutely STUPID power! The trike smokes (does not just spin, it SMOKES) the tire on accelleration! It is freakin CRAZY to ride! I was smelling tire rubber the whole ride.

#2 It handles fantastic! Also, as the rear tire heats up, it begins hooking really well and corners awesome at that point. Once the tire is hot, it does not want to slide around corners. I have to throttle it hard to break the tire loose to make it slide around the corners.

I do have one problem, though. This may be related to my pack being relatively low on power. But, I am having problems with one mtoro occasionally not wanting to start up in sync with the other motor. So, one motor runs significantly hotter than the other because one is occasionally not starting up properly. I am getting a single flash error on one ESC telling me that ESC is seeing a "Jammed" motor or that the motor is not starting up properly.

My guess on this is one of two possible things;

#1 The controllers may not be programmed exactly the same.
#2 The battery may be a bit low (it is low) and that may be making the one motor not want to start properly. I am guessing that because it was far worse after I put a mile or two on it and my little bit of charge lowered a tad.

Anyway, I need to double check my ESC settings to make sure they are all identical one to another. My PK ran fine. So, I am guessing this will be OK.

Anyway, this rear tire will NOT last long. This thing is a tire smoking monster! It accellerates like a Vette!

Now, I just need to fix the startup issue.

Matt

 

[TPA]

Please allow me to be the first to request video!

 

[recumpence]

OK, motor problem solved. There was one motor bullet connector that was disconnected and shorting.

Holy freaking COW!!!! This thing is a top-fueler! It is actually hard to ride. That is untill the rear tire heats up. Then it is a wicked BEAST! They do not make smileys big enough!

To give you an idea how much power this thing has, the pack is low, and it still spins the tire on only ONE motor! With both motors, the tire SMOKES! I did a donut in the street and after one good donut, the tire got hot, hooked and the trike tipped a bit.

I think I will go to a wider rim, wider tire (same tire as the rear used on my PK) and run lower pressure in the tire for more hook. But, then again, I like the "Mechanical fuse" affect of tire spinning. Besides, it still accellerates so hard I felt like I was getting pulled off the rear of the seat because it is so layed back.

It goes 5mph (rolling start) to 35mph in about 50 to 60 feet. It is hard to tell because I am trying to figure out just when the tire stops spinning.

Totally freakin WICKED!!!

I am psyched!

Matt

 

[Grinhill]

(someone had to do it!)

 

[VRdublove]

That's awesome Matt!! I knew you'd love it, mine is just silly with a single 3220, I can't imagine TWO! How's the motor heat after some spirited riding? I'd like to get a small muffin fan on mine, I'm sure it'd make a world of a difference.

Charge it up and enjoy it!