Emmo Knight (Grom clone) salvage

[pwd]

Continuing work getting the motor to fit well. In addition to getting the axle shoulders spaced correctly, I also had to make sure the brake plate was going to line up. I used 3 large washers with an ID of about 20mm for the axle. The trick is to then put a bolt and another washer between the inner toque plate and the brake plate for a tight fit.

Test fit:


Having inner toque plates made mounting the wheel a bit of a challenge, since the toque and brake plate has to line up with a knob on the inside of the chain stay. I couldn't just slide the motor on, it had to go in on an angle so I could fit the brake plate slot through the frame "knob".

Example with the old motor:


Mounting the tire and valve stem was a job on its own but it worked out well. I had to go with a 90 degree valve stem so it would clear the motor casing. Went with a Kenda K413 130/70-12 because it was less expensive and looked like a decent tire.

This morning I had my first test ride with the new setup. The 3 speed switch was nice for getting used to the bike. I have a bit of regen working on the controller and will turn it up once I'm more conformable on the bit and am sure the axle isn't going to wiggle loose.

I know the 3 speeds are unique to my bike's programming but here were my impressions:
Speed 1 - Ok - pretty much like it felt in stock form with a limited speed: good for a legal mode
Speed 2 - more acceleration (just enough to match average green light take off) and can cruise along with city traffic nicely (probably up to 65 km/h)
Speed 3 - uncorked: rocket like acceleration with no speed limit - I also think that field weakening is kicking in. Max battery current set to 150A and max phase set to 530A.

battery pack was low and only stated off with 3.6V/cell and ended at about 3.45V/cell - I probably should have charged it more before riding but I couldn't resist.

The bike is very much in an unfinished state with no fairings, lights, horn 12V, ignition switch or any sort of display. I also need to tune the controller some more and get more comfortable with the Fardriver Android app.

Here it is charging before it's next ride...

 

[pwd]

This bike is so much fun, quite comfortable and stable. I was out for 3 one hour rides one day. I'm getting "the wave" a lot when passing by oncoming motorcyclists; which is pretty funny.

I've fitted the headlamp, although a bit hastily. It isn't very bright which may be the Aliexpress LED I bought but I will have to test further.

The Fardriver controller has plenty of settings to play with. I changed the throttle to sport instead of line which has made it a bit more snappy. The ramp is quite nice and easy to control. I may go for less ramp for a bit more aggressive takeoffs. I've also turned up the max battery current to 235A and phase current should be hitting the 530A max of the controller now... I will have to test.

 

[skeetab5780]

nicely done! Top speed?

 

[pwd]

Not sure on top speed exactly but I would estimate around 100km/h / 60 mph - I'm currently trying to figure out how to get the original speedometer working with the Fardriver controller.

 

[fechter]

I hope your torque arms are made from really strong material. That's a lot of phase amps. Keep those axle nuts really tight.

Looks great so far.

 

[pwd]

Thanks fetcher and skeetab.

I've been riding this bike as much as possible since my last post. I've dialed in the Fardriver controller so the acceleration is more aggressive. I wasn't hitting my peak battery current settings but I am now. Fardriver parameters that I changed:

Ratios In Speed:
Set all to 100% up until my max motor RPM - now it's pulling hard. IE: 125RPM :100%, 250RPM:100% 1500RPM: 100%, 1625RPM 45%
note that my rated motor RPM has been set to 1525RPM - any percentages after that RPM control flux weakening percentage

Throttle Response:
3 - Sport

Throttle Acc Step: 224 (this is the max value)

I'm now seeing the controller pull the programmed 235A from the battery pack. That is the max I want, otherwise the voltage sag would be too much when nearing ~3.6V per cell resting; trying to keep the cells over 3.2V under load. I'm drawing about 20kw from the batter pack: this thing takes off like a rocket - although I'm only seeing a max of 400 ish phase amps. I'll have to do some more monitoring. I've chatted with a young motorcyclist and he was blown away at the speed of this thing.. "dude, what is going on with that bike!".

I've also got all the plastics back on. Luckily this bike came with some extra parts. The front forks were leaking fluid so I swapped in the other forks it came with...hopefully those don't leak. The front fender was also pretty cracked up so I also swapped out that for an extra front fender it came with.

I've ordered a new display to show pack voltage and *hopefully* speed.

One picture for now... I keep forgetting to take one while outside.

 

[MorbidlyObeseKoala]

Awesome result in like 6 weeks. Jealous of everyone's motivation and productivity. Mine is real low with a toddler running around.

Have you reached a top speed?

 

[speedy1984]

Hi,so did you feel any difference when changing the ratio in speed settings?Is the field weakening kicking in earlier now?

 

[pwd]

Awesome result in like 6 weeks. Jealous of everyone's motivation and productivity. Mine is real low with a toddler running around.

Have you reached a top speed?

Thanks; I have put quite a few hours (and money) into this build up to this point. If I had a toddler... I'm not sure how I would get anything done. As much as I like to spend an hour or so being able to wrench on it; sometimes things turn out better when I chip away at it instead of rushing.

No top speed determined yet but I'm estimating around 100km/h

Hi,so did you feel any difference when changing the ratio in speed settings?Is the field weakening kicking in earlier now?

Yes, I did feel a significant difference. Field weakening should be kicking in at the same point as before though (If I understand correctly, field weakening doesn't kick in until the motor reached the rated motor rpm parameter value). What did change was the phase and line current peaks. Before I wasn't hitting max battery current for more than 1 second because most of the RPMs "ratios" under the rated motor rpm parameter were under 100%. It was:
125 RPM: 100%
250 RPM: 90%
375 RPM: 80%

etc...

now it looks like:

125 RPM: 100%
250 RPM: 100%
375 RPM: 100%

 

[speedy1984]

Right ok,so say my rated rpm was 5000 but my 138v3 motor revs out till 7500 do i 100% all settings untill 5000 or to 7500 for max current fella?

Cheers

 

[pwd]

Right ok,so say my rated rpm was 5000 but my 138v3 motor revs out till 7500 do i 100% all settings until 5000 or to 7500 for max current fella?

Cheers

I can't say for sure but in that case if your Fardriver has motor rated rpm set to 5000; set all the settings to 100% up to and including the 5000RPM increments for the strongest current levels. Anything set for rpms over 5000 will be flux weakening current percentage.

I also read that for flux weakening; you should avoid setting it too high and the percentage should be programmed to taper off as you approach your max desired rpm. Example with your 5000 rpm setting:
5000 RPM 100% -< Regular phase and battery current limit
5500 RPM 50% -< Flux weakening current percentage since you are now over the 5000 rpm "rated" parameter value
6000 RPM 45%
6500 RPM 35%
7000 RPM 5%
7500 RPM 1%
8000 RPM 1%
... etc

Here is a discussion on it that may explain it better (if you can sign in To Facebook):
https://www.facebook.com/groups/electricmotorcyclebuilds/permalink/2461235124013844/


Here is the important bits from that Facebook post:
Rotational ratio of a said percentage to phase/battery amps .% after your rated motor rpm speed will define the percentage of available field weakening . Hope this helps

Soo 100% until you reach rated speed and after that ramp down to 50% using 50% of your rated rotational speed . 2000 rpm rated = 2000 rpm 100% and 3000 rpm MAX 50% to prevent a runaway

 

[speedy1984]

Thats brill info fella thank you :thumb:

 

[pwd]

Photo from tonight's ride. Had to go off the pavement for a bit for a pit stop

 

[pwd]

The bike was out of commission for nearly 2 weeks since the FarDriver controller failed (I'm still not sure why). The new controller (same model) has arrived. I had ordered a heatsink to add to the controller since my old one was just a flat aluminum plate. Interestingly enough; the new controller now has a heatsink built onto that aluminum plate. Kind of a bonus but makes me think that perhaps that previous controller design had overheating issues?

OLD:
View attachment 1

NEW:


I have shipped my old controller back to SiaEcoSys at my expense ($136 CAD) to have them repair it. Interested to see if I get a new one or they fix the old one.

 

[fechter]

What was the bike doing when it failed?

 

[pwd]

It was a hot humid day and I had just turned the controller ignition on to move it from the shop to outside. A few seconds after I twisted the throttle and the bike lurched forward a bit; the controller started beeping and gave me the "mosfet high side" error.

 

[fechter]

OK, sounds like you weren't abusing it at the time and it wasn't overheated. Guess those things can happen.

 

[pwd]

I finally got my new speedometer working with the Fardriver. Details on Fardriver settings here: https://endless-sphere.com/forums/viewtopic.php?f=30&p=1732398#p1732398

It's not much different than the original speedometer except that it shows battery voltage.


Link to display on Aliexpress:
https://www.aliexpress.com/item/1005002330675536.html

Did a test ride this morning after calibrating the speedometer and it seems decent. If I had to nitpick I'd say the speedometer response is a bit slow, but that is probably the case with most of the cheap boards. I was able to replace the original speedometer board with the new one; it was a drop in replacement! (quite rare on my builds). The trip meter (resets when powered off) is useful. I had to bike up to 106 km/h; just to answer the most common question. It might have a bit more speed in it; especially if I increased flux weakening a tad but it's more than what I need.

 

[amberwolf]

I've fitted the headlamp, although a bit hastily. It isn't very bright which may be the Aliexpress LED I bought but I will have to test further.

I've tried a few different LED headlamps supposedly designed to replace incandescent / halogen bulbs, and none of them were even slightly adequate in brightness (nothing even resembling the claims for them) or in directional beam shape, used in a housing designed for the incandescent. So I'm still using a Sylvania halogen (this is in an ex-KIA headlight unit on the front of the SB Cruiser cargo trike). I was going to link to the posts with pics comparing them, but the posts themselves seem to have gone missing from the trike thread; searches on any term that might possibly have been used in them can't find them.


I also have the same front bezel/headlight assembly you have there (along with a bunch of similar ex-grom-clone parts), that will be used on Cloudwalker cargo bike, but I haven't tested it with LED vs incandescent yet.

 

[pwd]

I've tried a few different LED headlamps supposedly designed to replace incandescent / halogen bulbs, and none of them were even slightly adequate in brightness (nothing even resembling the claims for them) ...

I've tried to aim my headlight a bit better for a more accurate test and tried it out when it was dark out and have encountered the same issue. Even on "high" beam; the light wasn't really cutting the mustard; especially for speeds over 50km/h. I also had a look at the BMS and I wasn't even drawing 0.1A from my 86V pack with the high beam on; that also includes the current for the DC to 12VDC converter and idle power of the controller. It was supposed to be "40W" light: https://www.aliexpress.com/item/4000512745606.html?spm=a2g0o.order_list.0.0.21ef1802po8LHo but is likely less than 8W.

I may try out a different LED bulb in the future

 

[amberwolf]

If you find a useful LED replacement headlamp that actually works like an incandescent does, as far as brightness and beam pattern out of it in a headlight fixture made for the standard incandescents, let me know, as I'd love to find something that doesn't waste as much power as heat as the Silvania halogen I'm still using.

 

[MorbidlyObeseKoala]

If you have specific requests and don't mind tweaking something to fit your needs (this thread seems to suggest you have that ability), the nerds on Reddit at /r/flashlight can be of assistance to find an led solution for you.

Calling them "nerds" might seem harsh on a forum for extremely technical discussion of electronic propulsion, but just wait until you explore that topic a bit. They are an encyclopedia of knowledge and have very specific tastes for beam pattern, light color, throw distance, power consumption, flashlight build quality, etc. The list goes on.

Definitely a helpful bunch if you state some criteria upfront.

 

[pwd]

Thanks for the info, I may dive into that in the future.

 

[Spamh8r]

Great build- I'm looking at those same batteries. Pity you couldn't use the BMS leads. Anyone have a clue what the connector type is called? It looks similar to a JST connector.

edit to add: Mind if I ask what you're using to charge it?

 

[pwd]

edit to add: Mind if I ask what you're using to charge it?

I'm using one of these:
https://www.aliexpress.com/item/1005004231492849.html

It's nothing special but does the job. The same units can be found on Aliexpress etc.. under many different brands. I just adjusted the output voltage via one of the trim potentiometer inside.