# Rippy kart



## Karter2 (Nov 17, 2011)

Do you have somewhere in mind to run when its built?
Most local tracks wont let anything unusual on the track since public libility was enforced on them.
But if you have a private road or old airstrip ..neat !
Also brakes dont get much of a workout on regular karts/tracks so i wouldnt hope to get much back from regen.


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## RIPPERTON (Jan 26, 2010)

Karter2 said:


> Do you have somewhere in mind to run when its built?
> Most local tracks wont let anything unusual on the track since public libility was enforced on them.
> But if you have a private road or old airstrip ..neat !
> Also brakes dont get much of a workout on regular karts/tracks so i wouldnt hope to get much back from regen.


We have an EV festival here once a year where odd things get demo'd on a kart track.
I could get inventive finding other places to drive it.
Dont get much regen on a race track I know but its the same as with the race bike ie you dont have the weight of the disc and caliper. Id rather have front brakes as they are always on the ground.


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## RIPPERTON (Jan 26, 2010)

Front disc brakes go on. Started with extra large hubs and shortened them a bit to put the inner bearing under the disc. Welded a flange on for the disc.
The caliper mount brackets have been laser cut from 4mm mild steel.


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## RIPPERTON (Jan 26, 2010)

E Stop and throttle go in.
This is the same Ford Falcon throttle pot I used for the regen on the race bike back in 2011.
Il have to change the master cylinder so I have a banjo bolt at the start of the system and a built in micro switch to activate the regen.


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## blondebikes (Dec 26, 2017)

is there a particular reason why your using the regen circuit only on the brakes? and not a mico switch pot box on the accelerator?


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## RIPPERTON (Jan 26, 2010)

Are you talking about throttle off regen ? Kelly doesnt need a micro switch for that, I can config it in so I have X amount of regen at zero throttle, engine brake so to speak.
But to answer your question, I like to coast on throttle off.


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## blondebikes (Dec 26, 2017)

Yeah, that does answer. It never come into my planning while building the kart.

I'm almost all on or all off and hard on the brakes. Haven't found a track where coasting is used.


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## kennybobby (Aug 10, 2012)

We have an electric raceway over here called Veloce that runs 48V italian karts where laptime is the deciding factor to win. We have had some special events where it was wheel-to-wheel racing, but that ended up like bumper cars at the carneval.

i started off using the full on or full off/brakes-on technique, but soon found my laptimes were not up with the top racers, so i changed to using no-brakes. The karts just don't have enough torque to accelerate and make up speed after a braking or regen move.

They are a blast to race but it is surprising how beat up you feel after 10 laps wide-open in a kart with no suspension.


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## blondebikes (Dec 26, 2017)

Yeah it definitely takes it out of you.
I'll get this new kart of mine running and wire up both for comparrasons.
See if I like the coast function.


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## RIPPERTON (Jan 26, 2010)

Slowly moving forward, I took a few weeks to figure the exact structure of the battery trays. Using 30x3 equal angle I simply branched out from the side of the chassis without any real triangulation other than the web of the angle.
The end pieces are tangent to the top of the frame tube and the central pieces are out from the center of the tube.


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## RIPPERTON (Jan 26, 2010)

https://www.youtube.com/watch?v=q4GWUNPu1VI
Got the first pack in and took it for a hoon around the block.
Quite impressive on 85v and a 200A Kelly ctlr.
Straight away faster than a rental kart but with one 17kg pack on the left side of it, the steering is scary. It rails right handers nicely but pushes straight ahead in left handers. Once I get the other pack into it the steering will work properly again but with twice the power (175v 200A 28kW)it will have other kinds of steering problems.
The hybrid disc-regen brakes are phenomenal, like hitting brick wall.
You can hear the pads grinding away at the discs and the motor is moaning under regen.


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## blondebikes (Dec 26, 2017)

Done well.
What speed do you think your getting up to? 70-80klm/h?

Enough torque to break traction?


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## Karter2 (Nov 17, 2011)

The way kart handling works by " weight jacking" to lift the inside rear wheel in corners, you may have to stiffen the chassis to compensate for the extra weight out on those panniers.
But there should be adjusters for king pin inclination , that will also help.


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## blondebikes (Dec 26, 2017)

Mine will be a little different with the intrepid chassis. I've put my D&D over axle. And batteries where the 2stroke would be. With only 9kg of battery key weight will be to have enough torque to break traction.


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## RIPPERTON (Jan 26, 2010)

Karter2 said:


> The way kart handling works by " weight jacking" to lift the inside rear wheel in corners, you may have to stiffen the chassis to compensate for the extra weight out on those panniers.
> But there should be adjusters for king pin inclination , that will also help.


Jacking is necessary only because of the single piece axle and single motor.
With electric drives we can easily go to twin motors and split the axle then remove the rearward tilt of the steering axis leaving only the inward tilt for self centering effect.
Then we have a 4 wheeled kart ie one that has its inside rear wheel firmly on the ground delivering traction like its supposed to.
Would not want to stiffen the chassis as a bendy chassis is the only thing a kart has for suspension. The ability for the chassis to twist keeps all 4 wheels on the undulation ground.
Im currently devising a way to right the steering C brackets so they are perfectly upright. Theres a lot of cutting and welding going on down here.


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## Karter2 (Nov 17, 2011)

Sure, if you planning on splitting the axle and running 2 motors ?
If not, you will experience some impressive understeer.
It wont matter if you are not worried about ultimate performance, but i can assure you it will handle poorly.


> ...... but with one 17kg pack on the left side of it, the steering is scary. It rails right handers nicely but pushes straight ahead in left handers. I


....that alone should give you a heads up as to what to expect.
The reason it pushes (understeers) in left handers, is because it cannot "jack" the weight off the left rear due to the extra pack weight out on that side pannier. 
Vice versa on the RH corners where the pack weight is increasing the jacking effect.
Running both packs will improve the LH corners somewhat, but it will not be a balanced handling set up.
Ideally, any exta weight should be centrally located to minimise its effect on handling.
Remember , chassis flex depends largely on the all up weight it is carrying.
I was simply suggesting you may have to stiffen the chassis to compensate for the extra weight those batteries out on the panniers.
There are many kart classes that run twin motors, high power motors (100+ hp), and they all manage quite successfully with a solid axle and "weight jacking" to compensate, and chassis set up to suit the weight and power.
The "art" in kart set up is a fine balance between chassis stiffness (adjustable) , king pin inclination,(adjustable), front and rear track width adjustments ( adjustable) etc etc
Even seat position and location points are changed to suit track conditions.
OR.... Maybe this would be simpler.... http://www.peerlessgear.com/node5380.aspx?nid=300843
.


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## Functional Artist (Aug 8, 2016)

RIPPERTON said:


> https://www.youtube.com/watch?v=q4GWUNPu1VI
> Got the first pack in and took it for a hoon around the block.
> Quite impressive on 85v and a 200A Kelly ctlr.
> Straight away faster than a rental kart but with one 17kg pack on the left side of it, the steering is scary. It rails right handers nicely but pushes straight ahead in left handers. Once I get the other pack into it the steering will work properly again but with twice the power (175v 200A 28kW)it will have other kinds of steering problems.
> ...


 
Hello Ripperton,

Nice kart & EV-mods

Could you share your motor & controller wiring diagram?

Specifically, on this set up, are you using 
...a standard contactor, a reversing contactor or just the E-stop switch?


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## RIPPERTON (Jan 26, 2010)

Functional Artist said:


> Hello Ripperton,
> Nice kart & EV-mods
> Could you share your motor & controller wiring diagram?
> Specifically, on this set up, are you using
> ...a standard contactor, a reversing contactor or just the E-stop switch?


Its as simple as I can make it. Theres just one manual E Stop button for the main battery cables.
Theres a 12v battery under the steering wheel which will later be replaced with a DCDC once the battery pack goes to 175v.
Theres an on/off switch and reverse button on the sides of the dash.
Would like to add a volt meter so I have a vague idea of when the battery is flat.


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## Functional Artist (Aug 8, 2016)

RIPPERTON said:


> Its as simple as I can make it. Theres just one manual E Stop button for the main battery cables.
> Theres a 12v battery under the steering wheel which will later be replaced with a DCDC once the battery pack goes to 175v.
> Theres an on/off switch and reverse button on the sides of the dash.
> Would like to add a volt meter so I have a vague idea of when the battery is flat.


 
OK, so the 12V battery powers the controller (switched by the on/off switch)
How does the reverse button operate? (do you use reverse much?)

Are you running IIRR 85V thru just the E-Stop button?

I have used a small Amp/Volt meter, usually to monitor the amp draw when testing different motors
...or like this "Turbo" overvolting test

https://www.youtube.com/watch?v=H-704ZyJkaU

...it seems to give decent voltage readings too


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## RIPPERTON (Jan 26, 2010)

Got my second battery almost finished. This will straight away double the power of the kart going from 85v to 170v but will add 20kg.
Later I will split the Motenergy 0913 into 2 separate motors each having its own rear wheel to drive independently as the rear axle will also be split in 2. With a second 200A Kelly added, this will double the power again.
Could end up with 50kW

Had some new steering yokes laser cut and bent. I will cut the tabs off the original yokes leaving just the backing plate to weld the new yokes to in an upright position. No More Jacking !
Good to see you also doing a Kart Travis.


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## frodus (Apr 12, 2008)

Can't wait to get mine going! Ordered batteries today (Not lipo, but decent bats for now). I've been reading through some of your builds.... it's been a while since I've put something together. It's exciting.

Need some more videos on YT of this thing.


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## RIPPERTON (Jan 26, 2010)

Awesome got my Kart thread back !
so Ive split my axle in 2 and put a double centre bearing on a new cross member.


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## RIPPERTON (Jan 26, 2010)

Ive also split the old 0913 in 2 and started mounting it on the left side of the kart.


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## RIPPERTON (Jan 26, 2010)

Got my first motor together and it works properly even with the hall sensor facing the main magnets directly but theres a different problem.
The magnets are induction heating the rear motor frame.
From dead cold, if I put my hand around the rear bearing I can feel the tristar shaped motor frame heat up to about 60C in 40 seconds of about 2000 rpm.
The area where the red line is getting hot.


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## major (Apr 4, 2008)

Hi RIP,

You need a steel backing plate on rotor magnet assembly. Will likely increase torque also.

Regards,

major


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## RIPPERTON (Jan 26, 2010)

major said:


> Hi RIP,
> You need a steel backing plate on rotor magnet assembly. Will likely increase torque also.
> major


I wonder how that would effect the hall sensors ability to read the magnet polarity as the steel plate would loop the fields.
Fiorenza (Motenergy) said the field shape and strength changes with load and that would freak the hall sensor out.
Will keep trying though.


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## RIPPERTON (Jan 26, 2010)

Rapid Prototyping eh.
8.7mm thick acetal tristar goes on but now just the hall sensor screws are heating up.
I think I should give up electric motors and go into induction water heaters.


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## RIPPERTON (Jan 26, 2010)

major said:


> Hi RIP,
> You need a steel backing plate on rotor magnet assembly. Will likely increase torque also.
> Regards,
> major


Yep but should I make a laminated one or just one piece.
It just going to be mild steel so I could make 5x 0.5mm.
Fiorenza said I made an eddy current brake so I basically had an inbuilt dyno tester.


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## major (Apr 4, 2008)

RIPPERTON said:


> Yep but should I make a laminated one or just one piece.
> It just going to be mild steel so I could make 5x 0.5mm.
> ...


Hi Rip,

You understand that I'm talking about a steel plate on the back of the magnets which will rotate along with the magnets, right? I'd like to see what the rotor looks like. Know the flux spec for the magnet? Or the grade and size? Will help determine size of steel back plate. No need to laminate.

Regards,

major


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## RIPPERTON (Jan 26, 2010)

major said:


> Hi Rip,
> You understand that I'm talking about a steel plate on the back of the magnets which will rotate along with the magnets, right? I'd like to see what the rotor looks like. Know the flux spec for the magnet? Or the grade and size? Will help determine size of steel back plate. No need to laminate.
> Regards,
> major


Yeah we are replacing the 2mm thick cover plate with the oval holes in it.
We could go 3mm thick steel.
The magnets are 16mm thick


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## RIPPERTON (Jan 26, 2010)

This is the coil side.


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## RIPPERTON (Jan 26, 2010)

Laser cut 3mm mild steel backing plate ($40) but still exhibits induction heating of the hall sensor screws.
The hall sensor still works facing the main rotor magnets without windows in the backing plate.


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## piotrsko (Dec 9, 2007)

So how about brass mounting screws? Anything non magnetic. Not like they are a high stress fastener.


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## kennybobby (Aug 10, 2012)

Induction occurs in any conductive metal, so brass would heat up also.

It's not clear if your steel shield is actually touching the magnets, and it would be preferred if not a stainless steel, but rather some sort of magnetic iron sheet metal. There are certain iron alloys that are made to enhance magnetic conduction, but those wouldn't be necessary if it was just plain iron and not stainless (some stainless is non-magnetic).

[edit] removed sketch since it was made on the front winding surface, not the back.


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## RIPPERTON (Jan 26, 2010)

The backing plate is 3mm mild steel and its touching the magnets.
It would have to be screwed onto the rotor alloy because it stops the magnets being pushed out by the coil.
Im going to try the Hall sensor screws in 316 Stainless Steel.

So I replaced the standard steering yokes with new ones welded in an upright position. Gave it some toe in and went for a drive. Awesome !!! The new steering is super light but a bit twitchy. Could gear the linkage down a bit more.
The new single motor has more power that the old double and now Im going to make another single motor for the other side  

Heres the new no jacking rear end while turning lock to lock.
https://www.youtube.com/watch?v=cn3GIj3aQ0I


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## RIPPERTON (Jan 26, 2010)

Almost finished mounting the second motor.


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## RIPPERTON (Jan 26, 2010)

https://www.youtube.com/watch?v=U88eN0xY7Js


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## MattsAwesomeStuff (Aug 10, 2017)

90 horsepower on a glorified magic carpet. Love it.


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## brian_ (Feb 7, 2017)

RIPPERTON said:


> Heres the new no jacking rear end while turning lock to lock.
> https://www.youtube.com/watch?v=cn3GIj3aQ0I


It appears that you are assuming that all of the diagonal jacking is due to the steering geometry. I think you'll find that the reaction to cornering force - the way it twists in response to the force toward the centre of the turn to push the driver around the corner - tends to jack the chassis as well. The structure is relatively soft in longitudinal torsion forward of where the seat attaches, so most of the lateral load transfer required due to the driver's mass is done by the rear axle; there is nothing accidental in kart design, and this is desired with a rear drive axle having no differential. You won't want so much of this with your two-motor system's differential action.

Someone with lots of kart experience and/or an analytical interest in karting dynamics might be able to support or correct this.


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## RIPPERTON (Jan 26, 2010)

MattsAwesomeStuff said:


> 90 horsepower on a glorified magic carpet. Love it.


Maybe 72 hp.
The maths says
170v x 400A = 69kW x 80% = 54kW
Im feeling every bit of that 54kW let me tell you.
Ive had to turn the regen down from 100% to 65% as I just did a 360
braking into a turn.
Engine brake was also turned down from 20% (max) to 5%
It weighs 102kg at the moment.
Im going to have to add water cooling for the motor frames as the magnets are not the most efficient shape and probly generating heat.
The motors are very noisy especially on regen but not a growl more a singing whine.
The steering is perfect. With the jacking geometry removed the wheel is light and very little angle is needed. The whole chassis feels right going through a turn and theres nothing stupid happening back there.
The throttle does nothing to detract from the way it tracks around a turn.
Doesnt understeer or oversteer.
I can roll on hard like Im going for a slide and it just hooks up a launches.


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## kennybobby (Aug 10, 2012)

Do you think the motor frame is heating up due to induction from the magnets or from heat in the windings?

Thanks for sharing the video-- that's another awesome machine you have created and built.


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## RIPPERTON (Jan 26, 2010)

kennybobby said:


> Do you think the motor frame is heating up due to induction from the magnets or from heat in the windings?
> Thanks for sharing the video-- that's another awesome machine you have created and built.


Oh, I wasnt very clear about the frames heating up.
The magnets are good now and the induction heating on that side of the motor has been reduced to a minimum. The 316 Stainless Steel Hall sensor screws remain cool even after a thrashing.
This time its the the other side of the motor. Theres the normal heating of the coil windings and that goes straight into the main aluminium motor frame with the cooling labyrinth. Im associating this heat with the increased noise coming from the motor. I noticed with a standard Motenergy rotor, the 0913 makes very little noise and those magnets have a very particular design but my 16mm magnets have a very simple design just designed for brut strength.


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## RIPPERTON (Jan 26, 2010)

Found an RC track about 20ks from my place which is free to use.
Extremely tight but unfortunately quite dirty. Invisible to the eye but lots of sand and dirt which could have been the reason the front was pushing on corner entry. (understeer).
Theres lots of reasons why a kart understeers so I will have to test it at other tracks to see if the problem repeats.
Was able to give full throttle on the back straight and full brakes too. Brake switch is hanging on and cutting the throttle.
https://www.youtube.com/watch?v=70NHStu8whc


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## bigmotherwhale (Apr 15, 2011)

Sweet kart! are you running two controllers into two motors? if you want to increase cornering on tight circuits you could try an active diff, i would try by putting two finger throttles for left and right on the steering wheel to see how it behaves.


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## kennybobby (Aug 10, 2012)

It looks like heat in the tires and the motor windings, how did you solve the issue with the frame heating up?


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## RIPPERTON (Jan 26, 2010)

bigmotherwhale said:


> Sweet kart! are you running two controllers into two motors? if you want to increase cornering on tight circuits you could try an active diff, i would try by putting two finger throttles for left and right on the steering wheel to see how it behaves.


Yup 2 ctlrs and 2 motors.
It was understeering going into turns off throttle but it was most likely the dirty track causing that. On the way home in the van I went to scratch the back of my neck and felt a layer of dirt on my skin kicked up by the rear wheels.
I need to get onto a clean track before I start fixing things that arnt broke.


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## RIPPERTON (Jan 26, 2010)

kennybobby said:


> It looks like heat in the tires and the motor windings, how did you solve the issue with the frame heating up?


Havnt solved the heating. Its going to need water cooling. I might try a self pumping system with a small radiator behind the ctlrs.


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## RIPPERTON (Jan 26, 2010)

Its water cooled !
Self pumping didnt work so fitted the usual 12v coffee machine pumps that I use on all my vehicles. 3l per minute, simple.
Now I will be able to get some real range figures without risking any dark matter.
Got some new 8/12 silicone tube from Perth overnight !. Across Australia overnight ! Ordered 10am Wednesday, received 2pm Thursday.
Gecko Optical.


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## RIPPERTON (Jan 26, 2010)

Moving the battery packs forward may not have an adverse effect on the steering but will allow me to move the controllers out to the side of the kart which will keep the kart better planted during corners. They are about 3 kilo each. Heres a photoshopped image


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## RIPPERTON (Jan 26, 2010)

Just came back from a test trip at Cameron Park Kart track in Newcastle.
Clocked a 1:05.681. Not bad for its first time on a proper track.
http://www.nkrc.com.au/wp-content/uploads/2014/09/NKRC-Lap-Records-updated-Nov-2015.pdf
Heres the lap record sheet. I compared my self to senior national heavy (fat old bastards) at 56 seconds clock wise.
The chassis felt good and got it to go around turns fairly well.
I had to get on the throttle gradually coming out of turns especially when I was still pointed at the grass.
Too much throttle and it would go straight ahead.
When I was pointed down the straight I could floor it and it was quick. Nothing broke overheated or fell off. Awesome
https://www.youtube.com/watch?v=U88eN0xY7Js


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## RIPPERTON (Jan 26, 2010)

The fact I am understeering or pushing under throttle coming out of turns proves my theory of splitting the axle and removing the jacking geometry increases traction in the rear end. During the turn exit, both rear wheels are gripping to the point of causing the understeer.
Now all I have to do is fix the understeer. I thought the controllers would comply to the differentiation in the rear wheels.
Time to move the battery boxes forward.


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## brian_ (Feb 7, 2017)

RIPPERTON said:


> The fact I am understeering or pushing under throttle coming out of turns proves my theory of splitting the axle and removing the jacking geometry increases traction in the rear end.


Proof or not, this does seem like good evidence that the rear has better traction than the front.



RIPPERTON said:


> During the turn exit, both rear wheels are gripping to the point of causing the understeer.
> Now all I have to do is fix the understeer. I thought the controllers would comply to the differentiation in the rear wheels.
> Time to move the battery boxes forward.


Understeer simply means that the front tire slip angle is greater than the rear tire slip angle... not that anyone is going to measure slip angles in this situation. While rear tires tied together without a differential and not breaking traction will cause understeer, that doesn't mean that there's any problem with the differential action that you're getting just because you're understeering.

Shifting weight forward will give more tire load for more traction at the front, but you'll also need more traction there because the mass is further forward. If there isn't enough front tire, this might not help. Very front-heavy vehicles routinely understeer badly.

I assume that you're feeding the same accelerator signal to both controllers, so they produce equal torque. You could build a sophisticated dynamic control system, but it would probably work well enough to just offset the controller inputs - outside of the turn higher than inside, in proportion to lateral acceleration. An acceleration sensor is easy now (every smartphone has one), but you can also use speed and steering angle. The outside tire has more traction so it can handle more torque, and the difference will rotate the kart into the turn.


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## RIPPERTON (Jan 26, 2010)

As it turns out, the front tire pressure was a bit high which could easily cause understeer.
So I made some 35 tooth sprockets which should bring top speed up to about 120kmh. The 90kmh sprockets were 47t.
Had to also make some new clamp type sprocket carriers as the previous grub screw ones wernt really up to it.
Copied off the original ones except I swapped the sprocket and sprocket flange around so I could get the sprocket close to the motor frame.
Im baffled that the motors still do 6200 rpm at 170v after all the surgery they have had.
Up to Brisbane for the AEVA AGM this weekend. Collecting my race bike from the Museum on the way up and taking the kart too.


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## RIPPERTON (Jan 26, 2010)

The new 120kmh sprockets are on and the kart still has that same launch power but its at a slightly higher speed.
I thought the taller gearing would kill the corner exit speed.
The new sprocket hubs took ages to make but the are great and will also make some new 90kmh sprockets to fit them just in case.


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## RIPPERTON (Jan 26, 2010)

After 6 years and 4600km of racing and practice in the race bike, some of the YGS LiPo cells are starting to go low voltage, ie they wont charge above 3.8v.
This started to happen to the previous Enerland cells after 2 years, (2011-2012).
So the kart pack is showing some cell blocks with persistent low voltage.
When I try to balance a bad block up to 4.2v, the bad cell produces heat and
conducts the heat to every other cell in the block through the bus bar. This heat is also conducting into the 2 neighbouring cell blocks through the bus bars, (red arrows).
For this reason, the bad cell probably wont go thermal because its being cooled by 17 other good cells around it
As I dont have any spare cells at all, best solution is to leave this whole block out and replace it with a bus bar, then use the 5 good cells to replace other bad cells else where in the packs.
Its the most practical repair as it only lowers the battery voltage by 4.2v and is the minimum reduction in capacity...assuming I can fix every other bad cell with the 5 good cells.


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## RIPPERTON (Jan 26, 2010)

Heres the Z shaped busbar in place. Bending the 4mm alloy plate 90 degrees causes cracks so had to weld it back up. Preheating the bend zone helps a lot.
Pic showing LiPo cell swelling. This cell was low voltage. Not sure what causes the swelling.


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## RIPPERTON (Jan 26, 2010)

Heres the new battery pack layout.
Moved them forward a bit for more weight on the front wheels.
Positioned them parallel to the kart and upright to broaden the weight and
also provide a big hole to stand in while getting in and out the kart.
Allows the ctlrs to be mounted further out and forward leaving more room
for radiators behind the seat.


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## Emyr (Oct 27, 2016)

RIPPERTON said:


> Not sure what causes the swelling.


Swelling is a result of electrolyte decomposition generating oxygen, hence the flames typical of unattended swelling. Decomposition can be caused by undervolting and/or heat.

There's no way to restore the electrolyte, so that cell's dead.


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## RIPPERTON (Jan 26, 2010)

Hi Emyr
the swelling Im talking about is a solid mass not gasses.
Now circled in red. its a hard thickening.
Ive seen cells like this actually still perform ok.


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## RIPPERTON (Jan 26, 2010)

Latest top down shot of new layout. The new battery mounts come from further back outside the frames twist zone.
Seems to steer better but needs to have the rear wheels moved further out as its picking the inside one up mid corner.
Still more work to do with seat backrest support and larger radiator both mounted off the old ctlr mounting brackets.


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## RIPPERTON (Jan 26, 2010)

Got the back rest support and larger radiator and brackets in but then I go for a test drive and the left ctlr blows a few banks of Mosfets.
Have some 300A units to put in but the are 2kg heavier each for extra power I dont need.


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## boekel (Nov 10, 2010)

RIPPERTON said:


> Got the back rest support and larger radiator and brackets in but then I go for a test drive and the left ctlr blows a few banks of Mosfets.
> Have some 300A units to put in but the are 2kg heavier each for extra power I dont need.


Or maybe you do need the extra power to not break them


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## kennybobby (Aug 10, 2012)

*Molten Metal*

Can you post the part number of those FETs attached to the Positive Rail? 

They look tiny for 50A devices if 4 were in parallel for each phase, and they weren't sharing very well--like that first device was trying to carry all the current.

And the copper trace doesn't appear sufficient for that current level, or some sort of overcurrent event on that phase blew the traces and FETs.


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## RIPPERTON (Jan 26, 2010)

boekel said:


> Or maybe you do need the extra power to not break them


Hi Boekel.
These 200A ctlrs were largely underworked, I could rarely use full throttle for fear of breaking a chain due to the considerable traction of tires running at 1bar. And at 70 odd hp you quickly run out of track meaning you cant accelerate for very long even at 3/4 throttle before you need to get off the amps and brake for a turn. After a good run, the ctlrs were just warm.
This blown ctlr is virtually impossible to fix. The extra 4kg of the 300A ctlrs is going to take a lot away from the karts cornering dynamic.
The only thing I noticed as I was rolling the kart backward down the driveway to go for a test drive was the left motor was cogging as though 2 phase cables were bridged (shorted) and not letting current flow (generated by the movement of the magnets). I booted the ctlrs and as soon as I tried to apply throttle I heard a small pop.


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## RIPPERTON (Jan 26, 2010)

*Re: Molten Metal*



kennybobby said:


> Can you post the part number of those FETs attached to the Positive Rail?
> 
> They look tiny for 50A devices if 4 were in parallel for each phase, and they weren't sharing very well--like that first device was trying to carry all the current.
> 
> And the copper trace doesn't appear sufficient for that current level, or some sort of overcurrent event on that phase blew the traces and FETs.


Cant see any number on the Fets or rail. There are 14 Fets per phase.
The Fets popped at about 2% throttle.
Ive had similar failure because of bad insulation between Fets and heatsink.
I just took all the heatsinks off and the rubber insulation strips all looked good.
Dont know what cause the fail so I dont want to try to rebuild it fearing it will pop again straight away


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## kennybobby (Aug 10, 2012)

RIPPERTON said:


> ...The only thing I noticed as I was rolling the kart backward down the driveway to go for a test drive was the left motor was cogging as though 2 phase cables were bridged (shorted) and not letting current flow (generated by the movement of the magnets). I booted the ctlrs and as soon as I tried to apply throttle I heard a small pop.


That's a good clue, i was wondering if a shorted winding could be the cause of the FETs failure. Might need to inspect that motor carefully before blowing the 300A ctlr.


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## RIPPERTON (Jan 26, 2010)

After much grumbling and mumbling about lost cornering speed due to 4 extra kilos of ctlr, I finally fitted the 300A Kellys after rugedizing the caps with Selleys Kwik Grip. Its running again now with config set at 80% power which might be 80kW.


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## RIPPERTON (Jan 26, 2010)

Latest track test at the local RC car track.
Some kids video'ed me from the trackside.
https://www.youtube.com/watch?v=AZdPenlk5qg


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## boekel (Nov 10, 2010)

Looks like fun!

But I think you missed a part of the track


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## RIPPERTON (Jan 26, 2010)

Went out to Eastern Creek Kart track to see if I could get some practice laps in but it was a race day so I went dumpster diving for used tires.
Found some almost fresh Bridgestone rears the right size that turned out to have 18mm wider contact patch than the ancient Dunlops that were on there.
AAAAAnd guess what ...... it goes round corners now.... like a particle in a Hadron Colider.


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## RIPPERTON (Jan 26, 2010)

Also welded some pedal extenders on for my Sasquatch legs and reduced the mechanical advantage of the brake pedal over the Master cylinder as there was a bit of front disc locking going on.


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## RIPPERTON (Jan 26, 2010)

https://www.youtube.com/watch?v=pZujdFY21gA
Spent a whole day at Marulan Driver Training Center and the new used tires only stepped out once. Should have got the fronts as well but will splurge on a full set of new tires.
The recent mods made big improvements especially for the brakes, they are much less dangerous but still need a bit less mechanical advantage in the linkage. This will reduce reaction time, harden the pedal and shorten the pedal stroke.
The top speed is still lacking, it seems that the new lower gearing didnt make any difference but the Marulan track has a much bigger main straight that the Cameron Park kart track.
My best lap was 1m2s, same as the brown MX5 at the end of the video. The Kart record for the is track is 54 seconds and with a 60kg driver, some new tires and taller top speed I think I can beat that.


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## galderdi (Nov 17, 2015)

nice work as always mate. Shame it isn't eligible as a motorkhana car or it would be game on!!


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## RIPPERTON (Jan 26, 2010)

galderdi said:


> nice work as always mate. Shame it isn't eligible as a motorkhana car or it would be game on!!


Its still is game on Galderdi, just bring your weapon down to Marulan.

After 6 laps (9.6km) Ive charged for 2 hours and 20 minutes with a 500W charger, thats 1.15kWh or 120Wh/km.
http://www.batterysupports.com/72v-...n-lipo-battery-charger-20s-20x-36v-p-445.html
Just bought 4 of these for $560AUD which makes for 3.3kW of charging grunt should have the packs recharged in 20 minutes.
Also ordered a set of MG red (medium hard) tires for $260.
Did the rpm check and the wheels are spinning at 120kmh at 6200 motor rpm.
Could go to a 17t motor sprocket for 160kmh.
Will have to add a battery pack cooling fan.


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## galderdi (Nov 17, 2015)

Never say never. Keep us informed of your upcoming activities and I'll keep it in mind


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## RIPPERTON (Jan 26, 2010)

Whinging all this time about understeering being caused by weight bias or steering geometry was probably the simplest thing all along. Tires are old and shagged. Can relax though, got the new MG reds to go on for the next track day.
One observation I have made about standard "kart engineering" (sic) is the fact that the brake pedal and master cylinder are on opposite sides of a major flex zone in the chassis. So you are supposed to think that the force input to the MC is smooth and linear when you are lolloping into a turn and the chassis is tweaking around underneath you.... lol
Towards the end of the track day I noticed my battery boxes were getting warm so I settled on a ram air cooling system.
The bakalite busbar frames are grooved where they face the busbars to allow air to flow along them.
So here are some ram air ducts in 2mm alloy and atrocious welding


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## RIPPERTON (Jan 26, 2010)

Heres the 3.3kW charger for the kart. Cost $558 AUD for 4x 84v 10A units.
The kart is the same voltage as the R1 but Im charging each pack separatly as its easier to find 84v chargers than 174v ones.
Have removed the 8kWh pack out of the R1 and cannabalised some cells out of it to fill that space in the kart pack that has the busbar in it.
I can make some more kart packs in aluminium for the R1.


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## RIPPERTON (Jan 26, 2010)

Improving driver comfort, Ive grafted on a shoulder restraint in 4mm alloy and more atrocious welding. Wont have to use the steering wheel to stop myself from being flung out in fast turns. Now should be ready for the New MG tires and some real grip.
Got some stick on flyscreen repair to go over the air scoops but when I took it out of the packet found that it was fake fly screen like a big sticker and doesnt let air flow through....


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## RIPPERTON (Jan 26, 2010)

Rebuilt both battery packs with fan forced air cooling design.
At the last trip down to Marulan the packs got hot with repetitive sessions.
Sections of the Bakalite insulator were removed to allow air to flow over the bus bars. Overlay fan panels welded on to form a shallow cavity and exhaust holes on the opposite side. 
Massive volt meter going into dash panel.


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## RIPPERTON (Jan 26, 2010)

Sold the chargers cause they were 4 volts too low plus anywhere you plugged them in they would blow a breaker somewhere and yould get in an argument.
Had some custom ones made to 88v but they are only 13A each.
The Rippy Kart is now for sale $8k.


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## MattsAwesomeStuff (Aug 10, 2017)

RIPPERTON said:


> The Rippy Kart is now for sale $8k.


Wait what?

You just finished it.

Was that the plan all along, or, what's up? Current situation type of woes?


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## RIPPERTON (Jan 26, 2010)

MattsAwesomeStuff said:


> Wait what?
> 
> You just finished it.
> 
> Was that the plan all along, or, what's up? Current situation type of woes?


Would put it down to too many toys. Just realised Enduro riding is my favourite sport so an electric one of those would keep me happy for ever.
The kart really is too fast for me, I would crash it sooner or later and get real messed up. Its highly strung but very exciting to drive.


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## blondebikes (Dec 26, 2017)

Mmmmm can not recommend rocky mountain altitude powerplay enough!!!!
Would love your kart. I'm still halfway through mine.


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## MattsAwesomeStuff (Aug 10, 2017)

RIPPERTON said:


> Its highly strung but very exciting to drive.


Seeing how hard it is for people to sell finished DIY EVs, (i.e. I can't remember the last time I saw it, everyone just parts them out), at the very least take it to a track for a day and get some 1st and 3rd person footage.

I hope you can recover some of your cost for it, but, looks like almost everyone ends up having to sell for basically scrap. :/


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## blondebikes (Dec 26, 2017)

I think alot is to do with cost of batteries here in aus. Super expensive to arrange new units. So buying a complete kit and using all the good bits is cost effective. It's why we buy wrecked tesla isn't it?

I did the same theory for mtb my whole life. Buy a complete mass produced bike giant, specalized etc bike for the kit. To put all the kit onto a more boutique frame I liked.


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