Kepler Friction drive comes of age.

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
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Kepler
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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 12, 2017 3:00 am

Had my first Vesc failure today. Dont know what caused it. I was just doing bench testing at the time. It would program fine but refused to spin the motor. Did a fault scan on it and it came up with the dreaded DRV8302 fault code. Probably the most common fault that occurs with Vescs and not an easy fix. It means the DVR8302 chip needs to be replaced which requires serious SMD assembly skills to do.

I am tossing up if I buy the tools to able to replace the chip and Youtube the how too or I just pay someone to do it. I am thinking the latter. There is a guy in Canada that replaces the chip for $30 plus postage so I will shoot him an email i think.

I have a spare VescX so I am still mobile. I am also waiting on delivery on a Maytech Vesc from Ebay. They have sold hundreds and at $100 USD with free postage, probably the best deal around at the moment.
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Re: Kepler Friction drive comes of age.

Post by Samson » Aug 12, 2017 4:07 pm

I tried a VESC from MayTech on a Turnigy SK3-6354-260 motor at 24VDC with your friction drive. The VESC ran the motor fine with no load for over a half hour or so while testing with the wheel in the air. I set it up with a 10 Amp current limit. I only got about 2 Km on the road before it quit. I engaged it when I got to a short hill pedaling at 10-15 KmHr and it immediately faulted and would not resume. I have not had time to troubleshoot it yet. Very disappointing. :x

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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 14, 2017 6:10 am

That's annoying. Sorry to hear that. My Vesc had been prefect up to now. Ironically I am sending mine off to Canada for repairs. $30 USD plus postage so not too much pain.

Email for repairs is: johnnyrepairservices@gmail.com

I have never used him before but seems reputable. Not much too loose if it doesn't work out. I will let you know how it all goes.
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Re: Kepler Friction drive comes of age.

Post by Slowrider » Aug 14, 2017 9:56 am

Kepler wrote:Had my first Vesc failure today. Dont know what caused it. I was just doing bench testing at the time. It would program fine but refused to spin the motor. Did a fault scan on it and it came up with the dreaded DRV8302 fault code. Probably the most common fault that occurs with Vescs and not an easy fix. It means the DVR8302 chip needs to be replaced which requires serious SMD assembly skills to do.

I am tossing up if I buy the tools to able to replace the chip and Youtube the how too or I just pay someone to do it. I am thinking the latter. There is a guy in Canada that replaces the chip for $30 plus postage so I will shoot him an email i think.

I have a spare VescX so I am still mobile. I am also waiting on delivery on a Maytech Vesc from Ebay. They have sold hundreds and at $100 USD with free postage, probably the best deal around at the moment.
Hi, did you set the max Erpm limit to max 60,000 in the BLDC software ?
I use a Vesc on my Esk8 and before we startet to limit this setting it was a common fault to fry the DRV if you did not set this limit.

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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 14, 2017 4:14 pm

No I didn't. It has always been set at the default setting of 100000. I have only just started testing this higher kv motor so perhaps the higher eRPM produced by this motor caused the failure. Hopefully that was the cause as I hate having failures and not having any idea why it happened.

Thanks for the heads up Slowrider.
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Re: Kepler Friction drive comes of age.

Post by Maxid » Aug 23, 2017 5:20 am

Kepler wrote:DRV8302 fault code
Did you use a 4.12 VESC oder a VESCX? FOC?
FOC is known to cause DRV errors on 4.12 hardware - the only way to circumvent this is to either go VESCX or the new (way more expensive) VESC6.

At 7S your 330kv motor also caused 7*4.2*7*330=67914 ERPM which is more than what the VESC is capable of.
The VESC6 is supposed to do 150000 no problems but its a serious investment.

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Re: Kepler Friction drive comes of age.

Post by artteth » Aug 23, 2017 3:48 pm

Maxid wrote:
Kepler wrote:DRV8302 fault code
Did you use a 4.12 VESC oder a VESCX? FOC?
FOC is known to cause DRV errors on 4.12 hardware - the only way to circumvent this is to either go VESCX or the new (way more expensive) VESC6.

At 7S your 330kv motor also caused 7*4.2*7*330=67914 ERPM which is more than what the VESC is capable of.
The VESC6 is supposed to do 150000 no problems but its a serious investment.
150000 erpm in foc mode?

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Re: Kepler Friction drive comes of age.

Post by Ecyclist » Aug 24, 2017 6:42 pm

artteth wrote:
Maxid wrote:
Kepler wrote:DRV8302 fault code
Did you use a 4.12 VESC oder a VESCX? FOC?
FOC is known to cause DRV errors on 4.12 hardware - the only way to circumvent this is to either go VESCX or the new (way more expensive) VESC6.

At 7S your 330kv motor also caused 7*4.2*7*330=67914 ERPM which is more than what the VESC is capable of.
The VESC6 is supposed to do 150000 no problems but its a serious investment.
150000 erpm in foc mode?
VESC 4.12 and VESC-X (aka FOC-BOX) have the same drv problems. They are not recommended to run over 60000 erpm.
FOC-BOX because of better layout and aluminum case (better passive cooling) can handle more amps.
VESC-6 can handle 150000 erpm or more and more amps but it costs 3x more and it is still in development stage. Unfortunately VESC-6 is not good for more than 12s packs. OK for e-sk8s but low for e-bikes IMHO.
For my next build I'm using VESC 4.12 with aluminum case. I purchased the case from a dude in Lithuania.
https://endless-sphere.com/forums/viewt ... 31&t=85528
It is mid power (2000-2500 watts) FS mountain bike.

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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 24, 2017 8:06 pm

I have now set 60,000 erpm as suggested and still using FOC. I am running the 320 kv motor on 7S 18650 with FocBox. Have done a couple of hours of operation so far and all is good. I did around 4,000 km on my original Vesc FOC mode without a problem however this was always on lower kV motors that would be under 60,000 erpm.

On another note, I opened up my FocBox to add some longer power cables but noticed a burnt component on the PCB. The unit surprisingly still works fine but I am not sure what the long term effect this component failure would be having on the unit.

Anyone got any idea what the blown SMT capacitor does?
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Re: Kepler Friction drive comes of age.

Post by amberwolf » Aug 24, 2017 10:33 pm

Being "open source", I expected to easily be able to locate schematics/etc for it, but all I can find with google for this one is a bunch of marketing and advertising, and responses to same (most of them asking when theirs would be shipped and stuff like that).

So I can only offer a guess, that it's probably a noise filter cap for the shunt signal.

Best guess on how it got damaged was a power wire touching it's end (during factory testing?); it vaporized at least most of the cap's solder-cap, plus damaged the trace (separating it from the PCB surface under the copper, at the least) from it all the way to the vias on the shunt's end.

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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 24, 2017 11:14 pm

Thanks for that. I was thinking it was a filter Cap also. Considering the trace is so badly damaged, I don't think i will worry about replacing the Cap at this stage.
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Couple of questions...

Post by dbIsMe » Sep 12, 2017 3:27 am

Been testing the drive on my bike and having a lot of fun and I love its simplicity. I guess I am kind of taking it a little outside its intended use, but hey, that's how we have fun, right?

I have a couple of things hoping people might be able to give me some tips on.

1. Vesc Amps setting. I don't quite get the relationship between the Motor Amps, Battery amps and Absolute Max on the Motor Config page of BLDC tool. Lets say I have a motor capable of 80A, a battery 100A, and the vesc itself can do 50A - all sustained Amps. What would be the best setting if I actually want to do 25A x XX Volts. Should I put motor to 25A, battery 100A? Motor to 80A and battery to 25A? Both to 25A? Something else? And what about the Absolute max? What would be the best to keep the Vesc as cool as possible?

2. Drive with low tyre pressures. I'm testing on a hardtail mountain bike. Ignore the off road and tyre tread issues for the moment. For my testing I'm just running around on flat ground cement with basically a slick tyre. But for offroad purposes its a 29x2.2 @ 23psi tubeless slick tyre. I'm trying to set up the drive so that the engagement is in a "line from pivot point on the swing arm, through the centre of your motor, and through your wheel hub". But it seems that for me to get grip and not slip at lower pressures, I need to push the motor further into the tyre. This is not a problem in itself, except, that the drive won't disengage from the tyre once the throttle is released. It's like it becomes 'trapped' because of the deformation of the tyre. I'm not sure if there are any ideas on this? Do I need to try to 'slacken off' the drive engagement angle so the motor engages lower on the tyre than the optimum above?

TIA
db

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Re: Couple of questions...

Post by artteth » Sep 12, 2017 5:30 am

dbIsMe wrote:Been testing the drive on my bike and having a lot of fun and I love its simplicity. I guess I am kind of taking it a little outside its intended use, but hey, that's how we have fun, right?

I have a couple of things hoping people might be able to give me some tips on.

1. Vesc Amps setting. I don't quite get the relationship between the Motor Amps, Battery amps and Absolute Max on the Motor Config page of BLDC tool. Lets say I have a motor capable of 80A, a battery 100A, and the vesc itself can do 50A - all sustained Amps. What would be the best setting if I actually want to do 25A x XX Volts. Should I put motor to 25A, battery 100A? Motor to 80A and battery to 25A? Both to 25A? Something else? And what about the Absolute max? What would be the best to keep the Vesc as cool as possible?

2. Drive with low tyre pressures. I'm testing on a hardtail mountain bike. Ignore the off road and tyre tread issues for the moment. For my testing I'm just running around on flat ground cement with basically a slick tyre. But for offroad purposes its a 29x2.2 @ 23psi tubeless slick tyre. I'm trying to set up the drive so that the engagement is in a "line from pivot point on the swing arm, through the centre of your motor, and through your wheel hub". But it seems that for me to get grip and not slip at lower pressures, I need to push the motor further into the tyre. This is not a problem in itself, except, that the drive won't disengage from the tyre once the throttle is released. It's like it becomes 'trapped' because of the deformation of the tyre. I'm not sure if there are any ideas on this? Do I need to try to 'slacken off' the drive engagement angle so the motor engages lower on the tyre than the optimum above?

TIA
db
motor amps=motor torque
you can set motor amps as high as you want (limiting factors-overheat vesc/motor and slipping of the motor)
battery amps= max speed = max watts (watt= amps multiply volts)

make video how you set up motor and how hard motor engaged in tyre

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Re: Couple of questions...

Post by dbIsMe » Sep 12, 2017 6:20 am

snip snip re vesc amps settings...

artteth wrote:
dbIsMe wrote: 1. Vesc Amps setting. I don't quite get the relationship between the Motor Amps, Battery amps and Absolute Max on the Motor Config page of BLDC tool. Lets say I have a motor capable of 80A, a battery 100A, and the vesc itself can do 50A - all sustained Amps. What would be the best setting if I actually want to do 25A x XX Volts. Should I put motor to 25A, battery 100A? Motor to 80A and battery to 25A? Both to 25A? Something else? And what about the Absolute max? What would be the best to keep the Vesc as cool as possible?

TIA
db
motor amps=motor torque
you can set motor amps as high as you want (limiting factors-overheat vesc/motor and slipping of the motor)
battery amps= max speed = max watts (watt= amps multiply volts)
But motor, battery and absolute max amps are all different, so which one is the limit ? If I set motor to say 80A, then battery to 100A, and absolute to 130A, does vesc just ask for the minimum of these settings? And what is the effect on heat etc.

Maybe I should put it another way. eg, let's say I want limit to 500W, and my battery is 20V. Motor is capable of 80A, battery 100A, and the vesc itself can do 50A - all continuous Amps. So 500W/20V = 25A. What values for each of the amps settings are best to put in to keep the vesc operating best and coolest? How is it best to limit the Amps to meet a certain power level? By motor amps, battery amps or absolute amps? And if the vesc is only capable of 50A continuous, wouldn't putting anything above 50A potentially be trouble?

Cheers

PS: I guess I'm kind of assuming that vesc is the 'weaker link' as the motor and battery are rated higher for continuous current draw.

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Re: Couple of questions...

Post by artteth » Sep 12, 2017 5:57 pm

dbIsMe wrote:snip snip re vesc amps settings...

artteth wrote:
dbIsMe wrote: 1. Vesc Amps setting. I don't quite get the relationship between the Motor Amps, Battery amps and Absolute Max on the Motor Config page of BLDC tool. Lets say I have a motor capable of 80A, a battery 100A, and the vesc itself can do 50A - all sustained Amps. What would be the best setting if I actually want to do 25A x XX Volts. Should I put motor to 25A, battery 100A? Motor to 80A and battery to 25A? Both to 25A? Something else? And what about the Absolute max? What would be the best to keep the Vesc as cool as possible?

TIA
db
motor amps=motor torque
you can set motor amps as high as you want (limiting factors-overheat vesc/motor and slipping of the motor)
battery amps= max speed = max watts (watt= amps multiply volts)
But motor, battery and absolute max amps are all different, so which one is the limit ? If I set motor to say 80A, then battery to 100A, and absolute to 130A, does vesc just ask for the minimum of these settings? And what is the effect on heat etc.

Maybe I should put it another way. eg, let's say I want limit to 500W, and my battery is 20V. Motor is capable of 80A, battery 100A, and the vesc itself can do 50A - all continuous Amps. So 500W/20V = 25A. What values for each of the amps settings are best to put in to keep the vesc operating best and coolest? How is it best to limit the Amps to meet a certain power level? By motor amps, battery amps or absolute amps? And if the vesc is only capable of 50A continuous, wouldn't putting anything above 50A potentially be trouble?

Cheers

PS: I guess I'm kind of assuming that vesc is the 'weaker link' as the motor and battery are rated higher for continuous current draw.
vesc fets 300a rated (too weak for you?)
if you want 500w so set 25a battery
motor amps you can set as high as you can (slipping and overheating are limiting you (too many amps and it will slip) (to many amps and it can overheat (touch motor stator with your finger))
amps making heat
phase amps making heat ( i can set 150phase amps and use only 5battery amps)
absolute is limit when phase will became more than absolute vesc shut down(vesc trying to use only set phase amps but they can jump too fast )
and you say Motor is capable of 80A and how you know this? how you calculate this?(http://www.zelenavozila.com/cromotor in the text the write (Continuous power handling: 5000W (please read the following note about wattage ratings), if you stall the motor at zero RPM and put 4000W into it of course you will melt it, even 1000W could would damage it) so 10kilos 6000w motor can be killed with only 1000w and you say your small motor can handle 80amps(on 20v is 1600w) and it all because 1000w=1v and 1000amps(amps=heat) and 1000w=1000v and 1amp)
you need to learn how brushless motor controller works
set your motor in clamp
set 50battery 80 phase 150 abs and bloc mode
then run from pc and set 1500erpm (right tab rpm)
then try to stop motor with your hand and look at the currents (phase and battery)
then set 5000
then try 20000(careful)
then try set 3-5amps current and motor will spin to it max rpms and will be horribly but try to stop it with your hand and it will stop super easy )
experiment and learn how it works (with vesc its super easy(other way you need to fry electronics on 1000+dollars and study tech school))

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Re: Kepler Friction drive comes of age.

Post by Kepler » Sep 12, 2017 10:29 pm

Perhaps just to simplify the explanation a little:

Leave absolute amps at the default of 130A. It will act as a safety under extreme conditions.

Set battery amps with the following considerations:

1> The safe continuous amps your battery can supply.
2> The maximum power you want to run your drive at.
----Choose which ever one is the lowest as your set point.

For example:
3P7S pack with 10A continuous 18650 cells. This means the pack is capable of 30A continuous.
Target max power selected is 500W / 7S nominal voltage (25.2V) = 19.8A

In this case you would then set your Battery amps to 20A.

If the cells were rated at 5A, then we would have 15A continuous. Cell rating would be the lowest of the two and as such we would set our battery amps to 15A

The motor amp setting is a little harder to explain so the following is an abstract way of visualizing the effect ( This is not actual motor control theory).

Equal battery and motor amps (Say 20A) will have the following effect:
100% throttle 100% or duty cycle and 100% motor RPM will basically feed 20A to the motor however, if we start going up a hill and our RPM reduces due to the load, the available amps will drop off proportionately to the motor RPM (more or less).

So at 100% throttle 100% or duty cycle and 50% motor RPM, the motor will now be fed around 10A.

If we now set the Battery amps to 20A and the motor amps to 40A we will see following effect:
100% throttle 100% or duty cycle and 100% motor RPM will still feed a maximum 20A to the motor.
However, we now have a 2:1 motor amp to battery amp ratio which means at 50% motor RPM we would be feeding the motor with (20A x 50%)x2 = 20A and hence the motor will pull harder under load.

So a higher motor amps to battery amps ratio will give you an increase in low down grunt which will also have the effect of putting more load on your speed controller and motor under these conditions.

I think it is best to set motor amps as a ratio to your battery amps. A ratio of 1.5 is what I typically use as this gives me a gentle assist at low speed and greater assist at high speeds which to me is perfect. However, if you are looking for more hill climbing assist, a ratio between 2 and 2.5 might suit you better.
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Re: Kepler Friction drive comes of age.

Post by dbIsMe » Sep 13, 2017 2:16 am

Thanks for the replies.

a) Does it make any difference to the amps settings for motor/battery if I'm using a throttle set to current mode vs duty cycle in the ADC app config?

b) Also should the rated max amps of the VESC itself fit into this? Eg, if the VESC is only rated at 25A continuous, then I assume battery volts shouldn't go above that? Motor volts would be OK to go above it?

Thx again
db

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Re: Kepler Friction drive comes of age.

Post by ScooterMan101 » Sep 13, 2017 10:02 am

Kepler,

Are there any video's on how to set up a VESC and RC motor ? ( Whole video from getting out of the package to end , not just FOC mode )

Do you have to be on the internet to program a VESC ?
or
can it just be used off line to program it ?
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Re: Kepler Friction drive comes of age.

Post by dbIsMe » Sep 14, 2017 5:21 am

Something has been bugging me for a while, and I just wanted to mention it. I think we should keep in mind that Kepler is providing the drive bracket and it's really our decision on the infinite battery, motor & esc combinations. Kepler has gone above and beyond the call of duty in sharing his experience with motors, controllers etc. I guess I can't help asking questions here as a lot of the searching I've done has results that are more specific to skateboards or RC, and so I feel pretty guilty about digging down into VESC settings and values here as it should probably be on a VESC forum somewhere.


Anyways, to your question Scooters, firstly you don't need to be online to program the vesc. You just download the BLDC tool, connect via USB and then away you go.

I don't think there is a complete end to end video on VESC setup. But, I found Kepler's PDF manual he provides with the drive bracket is good at showing what is required. I used that and a couple of youtube videos (not just Kepler's) to become comfortable with what I needed to change. I also used the eBike throttle setup from his youtube channel as well. I've found using the VESC software etc itself pretty easy. The VESC screens look confusing and have a million values, but there are many tabs you don't need to use and most(?) fields you are not entering data yourself. It's not idiot proof, but well, if I can do it.... :lol:

db

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Re: Kepler Friction drive comes of age.

Post by Kepler » Sep 14, 2017 7:23 pm

dbIsMe wrote:Thanks for the replies.

a) Does it make any difference to the amps settings for motor/battery if I'm using a throttle set to current mode vs duty cycle in the ADC app config?

b) Also should the rated max amps of the VESC itself fit into this? Eg, if the VESC is only rated at 25A continuous, then I assume battery volts shouldn't go above that? Motor volts would be OK to go above it?

Thx again
db
The relationship between battery amps to motor amps ratio has the same effect whether it is current mode or duty cycle.

With regards to the Vesc max rating, yes this should be taken into account. you can add this as a third parameter when setting the battery amps. Setting should be the lowest number of all 3 parameters.
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Re: Kepler Friction drive comes of age.

Post by Kepler » Oct 01, 2017 9:48 pm

Put together a quick walk around of the the drive on my daily commuter. I average around 100km a week on this bike and look forward to every ride.

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Re: Kepler Friction drive comes of age.

Post by Jestronix » Oct 12, 2017 4:20 am

What a great setup. 500w on a road bike would be perfect for commuting. I love the stealth look. I just started using a BBSHD for commuting, it's great I can keep up with the fast moving road bikes and get to work without too much of a sweat. However I like the look of the Kepler more , only other Kepler riders would know, or those with a keen eye.

I'm really keen to know what other controllers can be used, like a 6fet sinewave controller, certainly not as stealth but much cheaper.

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Re: Kepler Friction drive comes of age.

Post by LockH » Oct 12, 2017 12:12 pm

Hehe... One used Kepler friction drive posted as For Sale on September 13... and as SOLD on October 12.
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Watts called "good resale value". :lol: 8) :wink:
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(Current ride? High speed lawn chair.)
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Phoenix Ebike Promotions conversion kit (work in progress. More drink holders, etc etc)
https://endless-sphere.com/forums/viewt ... 15&t=60564

Buk___
10 kW
10 kW
Posts: 714
Joined: Jul 28, 2017 5:59 pm

Re: Kepler Friction drive comes of age.

Post by Buk___ » Oct 21, 2017 1:49 am

[quote="Kepler"] The drive doesn't work in wet weather unless you add grip tape to the can because the metal surface of the drive will slip on the tire. My rational is just dont use it in the rain. /quote]

Two thoughts crossed my mind when reading that which may or may not be of interest.

1) Could you stretch a piece of old inner tube over the width of the can so that you have rubber on rubber which ought to both give better grip and reduce the chance of excessive tyre wear. A cheap and easily replaceable sacrificial component.

2) Attach a piece of 3D printed plastic or carved rubber shaped something like the wooden bobbin in this picImage so that the v-shaped shoulders press onto the sides/shoulders of the tyre, so that the v-shape acts in a similar manner to a v-belt pulley wheel.

(Trying to think how you'd source a suitable block of rubber the only thought that came to mind was the rubber suspension cones from Austin Mini hydraulastic suspension.Image which are easy to source in the uk; though turning it might be an interesting challenge :))

dbIsMe
10 mW
10 mW
Posts: 22
Joined: Jul 24, 2014 2:25 am

Battery options...

Post by dbIsMe » Jan 18, 2018 4:53 am

Hey there. Thought I would toss this in for other's consideration

I had been inspired by some of the earlier builds that used standard Li-Ion power tool batteries, especially mhaskell's powered by 18650s.

Over the hobby batteries, I liked the:

*Can take the knocks - made for heavy duty tradesman
*Battery protection
*Chargers with protection etc
*Some can cater for high power draw

There's now several tool batteries made based on the 20700 as used in the Tesla. This has higher continuous power and/or longer run time. Bosch (powercore) makes some, as does Metabo (lihd) and probably others.

Now, I'm scared of batteries. But this guy isn't. And he has continuous runs at some currents I would never even think of, eg 100A. :twisted:

It opened up new options for me for my relatively short journeys; 1 battery pack and a 20V motor. Smaller. Lighter. :D

The other thing that I became more familiar with is the 3D printing for battery mounts for these power tools. There are several around that can be readily modified to add bolt holes for bike bottle mounts.

Cheers

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