DIY Electric Car Forums banner
141 - 160 of 368 Posts

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #144 ·
I made myself a - Corner weight device

It lifts the wheel using about a 10:1 lever and a fishing scale - up to 40Kg

Seems to work quite well

Now to using it
The Device is almost perfectly symmetrical right to left and nearly so from to back

But when I get in there is 100Kg very close to the RHS rear - this means that the RHS rear tire has more weight than the LHS
So that tire spins when I throttle -
I do have an LDS so the car still accelerates well

What I have done is to move the spring pan on the RHS front wheel so that that wheel drops lower

Now when the car is empty it sits RHS high - and when I sit in it it is almost level

The rear wheels with "me" in the car have almost exactly the same load
RHS is still about 15Kg heavy compared to the LHS

But now the front right is about 20Kg heavier than the LHS front

I will take it to the 1/8th mile drags like this - not sure about the Autocross

Comments?
 

Attachments

·
Registered
Joined
·
551 Posts
I made myself a - Corner weight device

It lifts the wheel using about a 10:1 lever and a fishing scale - up to 40Kg

Seems to work quite well

Now to using it
The Device is almost perfectly symmetrical right to left and nearly so from to back

But when I get in there is 100Kg very close to the RHS rear - this means that the RHS rear tire has more weight than the LHS
So that tire spins when I throttle -
I do have an LDS so the car still accelerates well

What I have done is to move the spring pan on the RHS front wheel so that that wheel drops lower

Now when the car is empty it sits RHS high - and when I sit in it it is almost level

The rear wheels with "me" in the car have almost exactly the same load
RHS is still about 15Kg heavy compared to the LHS

But now the front right is about 20Kg heavier than the LHS front

I will take it to the 1/8th mile drags like this - not sure about the Autocross

Comments?
Firstly congratulations on an excellent and simple solution to a common problem. The counter lever scales are brilliant. What are you charging for your IP?

I am not an expert in corner weights but what you have done certainly aligns with my understanding of the correct approach. I think you would be fine to run it like that at autocross.
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #147 ·
Hi Guys
We had our annual 1/8th mile Drags on Sunday
A lovely HOT day - maybe nearly 30C - we were sweltering

The Device was fine
First run the guy at the light tower joked about me needing to warm the tires NOT
Then I lit up both rear tires and nearly took the sensor out!
Gave me one hell of a fright! - and apparently surprised a lot of people

Don't know my time as Southern Dragways was having some difficulty with their kit

Second Run - took it a bit easier
Reaction - 0.935
60ft - 2.658
1/8th mile - 9.242 at 83 mph
Something happened just before the end of the run - something went "Click" and I suddenly had no power - I coasted to the end - turned around on momentum and lined up in the row to return
When I shut everything down and restarted - it all worked fine

Third run
I gave it a bit more welly - it snaked out of line - backed off then more welly and it snaked again
Reaction - 1.213
60ft - 2.755
1/8th mile - 9.646 at 85 mph
No mysterious shutdowns this time

85mph is about 4700rpm - oops - I had intended to keep it under 4500rpm

Owen was there with his pick-up so they put both of the electric cars together - we have similar power but I have just over half the weight
But it was fun seeing Owen go faster than some of the IC cars

Great fun day!

Wonder how many revs I can use before it blows up?

One comment was about the way I spun the tires
Normally the tires spin when you drop the clutch
I'm direct drive - when I booted it it would take off THEN spin the rear tires
Couple of people commented that it was "spooky"
 

·
Registered
Joined
·
157 Posts
I can think of 2 possible reasons it shut down.
1. Did you reprogram the controller awhile back with the bug fix? It had an issue where it could go over 100% duty, which resulted in the micro freezing up.
2. The PI loop might not be converging very well, so maybe it had a spurious current that tripped the hardware overcurrent. Right now I just have it permanently shut everything down if any of the 600amp IGBTs go over 600amp for > 3uS. I'm going to assemble one of the new boards, and will get the updated code working soon. work just keeps getting in the way. It's totally on my to-do list to get out of poverty, and stop working for the man. haha
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #149 · (Edited)
Hi Paul
Your controller is superb - oodles of power!

One of the marshals near the end of the track was very impressed by the sound the car made
He said it sounded like a supercharger
Don't know if he was hearing the sound from the controller or the sound of my 1500rpm forklift motor doing 4700rpm

Would the controller shutting down have made a distinct "click" noise?

I was blaming one of my contactors for the shutdown - but the controller makes a lot more sense

The next time I do some work on the controller I will make sure that I have the latest software

It was going scarily good at the end of the 1/8th - it was almost as if the acceleration was increasing in the last few seconds
 

·
Registered
Joined
·
157 Posts
Hmm, if there was an overcurrent trip, it wouldn't open the contactor or cause a click, so I'd cross that one off the list. That leaves > 100% duty for an instant, which could happen if you still had the old code on it, and you were going really fast AND really torquey (I hereby declare that a word haha). That is my current theory..
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #151 ·
Hi Paul
I'm using totally manual control of the contactors (switches) so the controller could not have switched one off
In fact I can't think of any reason why one would have switched! - I've been more worried about them welding shut

If I did exceed the 100% momentarily and the controller went from full power to OFF - would that make a noise?

When it happened I though I had blown the fuse -
I'm using the Chevy Volt fuse which is in the service disconnect - I decided that in the Volt it has to take 300 amps continuous and that therefore it would take 900 amps for a few seconds (probably)

I was surprised/amazed when everything started working again!

Next event is an Autocross with the longest straight only 100 meters - so I won't be able to get up to those sorts of speeds!

When I drive it on the road I have my 40% throttle switch - that's plenty fast enough!
 

·
Registered
Joined
·
157 Posts
Is your controller sounding like a white noise, like a hiss? Could it sound like a clicking noise if the hissing suddenly stopped? I'm grasping at straws right now. haha. I can't think of a reason the controller would make a clicking sound.
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #153 ·
Hi Paul
The instrument that detected the "click" was me while wearing a full face helmet and frightening myself
Not what I would call a totally reliable instrument!

The controller is quite noisy - in an electric car absolutely silent next to the dino burners - so when it stopped making a noise it could have been that I heard it as a click

I'm planning on leaving it alone and enjoying driving the car - I may do some investigation when winter comes
 

·
Registered
Joined
·
157 Posts
Wow!! that was so cool! Thank you for posting. What is the max motor amps set to?
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #156 ·
Hi Paul
I downloaded your software for 1200amps

no idea about actual currents -
I was too busy to look at my Cycle Analyst - and it seems to get all out of sorts when I use a lot of current and needs a couple of minutes to settle down and give sensible readings
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #157 ·
Autocross at Teretonga Park today

Did a dual drive with Willy Williamson
I must have done a crap job telling him how to work the video because the only ones we caught were the ones I set going - of Willy driving!

https://www.youtube.com/watch?v=1osxw8Tq-a8&feature=youtu.be

https://www.youtube.com/watch?v=gD6mII53taw&feature=youtu.be

https://www.youtube.com/watch?v=FznBsw1yQPA&feature=youtu.be

First run spin - controller shut down - they towed it back to the paddock - when I shutdown and re-started all OK

Lots of spins - with the LSD when you break traction both tires go and you go sideways!

My first run was 75.57 seconds
Willy - spun DNC
My second run I got brain fade and missed part of the course
Willy - 80.72 - big spin on final straight
My third run was 72.28
Willy - 73.35

I was 32nd overall (out of 42)

Great fun - enough power to spin off at any time - it was cold and overcast but dry
 

·
Registered
Joined
·
157 Posts
Avoiding the shutdown is an easy fix. Let me know if it becomes an extremely annoying issue.
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #159 ·
Last Grass Autocross of the season

https://www.youtube.com/watch?v=FXhA9gVPW94

I got the camera wrong (again) only one run filmed - I think I will move the camera so that I can see it from my seat

Great event!

I actually did quite well on the grass

130 seconds (spin) - video
117 seconds
111 seconds
106 seconds - that put me in-between the two Miatas that were running

I was running with all three power switches in the "low" mode - so 43% power -
On my final (fastest) run the "pedal hit the metal" for a couple of seconds on the fastest straight
(which is where I spun out on the first run)

Great fun!
 

·
Administrator
Joined
·
6,370 Posts
Discussion Starter · #160 ·
Hi Guys
I have been driving with the Volt battery for about 5 months - including some driving on the track
I don't have a BMS - but I do have a Batt Bridge - everything looks OK

So time for my manual battery check
I drove until I got the battery down to my minimum voltage -295v
Then started disassembling
( I have to take a few bits out of the way to get to all my cells)
Friday Voltage - 295v (measured by CA)
Saturday - voltage had gone up to 296.9v (measured by CA)

Voltmeter on both sides of pack - both 149.7v (added together 299.4v)

Using my Celllog 8M I checked all of the cells
max - 3.548v
min - 3.536v
range 12mv
Looking good!

So I charged it
341.6v on the CA
Voltmeter on both sides of pack - both 172.1v - 172.2v (added together 344.3v)

Using my Celllog 8M I checked all of the cells
max - 4.078v
min - 4.064v
range 14mv

So all looking good!
 
141 - 160 of 368 Posts
Top