Aussie EV Autocross Special

[galderdi]

Hi

I am an enthusiest in Australia. I have been competing in motorsport for about 10 years now in various vehicles including my 240z.
About 2 years ago I started getting serious with the idea of an electric autocross, motorkhana, khanacross special vehicle.
About 11 months ago I purchased an Advanced DC 9 inch brushed motor and started with that as my base.
I have designed and built the vehicle from the ground up.
Much of the running gear is from a Nissan Pulsar (small 4 cyl front wheel drive)









View attachment 1

 

[galderdi]

This past Sunday I entered the car in it's first event. It was a combined motorkhana/ Khanacross. The car showed potential. Overall I am quite pleased with the outcome. However my choice of batteries became the only real weakness. I am now considering a total upgrade of the batteries so I can harness the full potential.

There were a couple of other minor tweaks I have noted but they are minor improvements rather than wholsale changes.

Here are a couple of videos of its first ever competition:
[youtube]v_Up99z0VRU[/youtube]


[youtube]NjFtXrGrX28[/youtube]

 

[galderdi]

Can someone tell me what I am doing wrong with the Youtube posts?

 

[amberwolf]

Can someone tell me what I am doing wrong with the Youtube posts?

Just read the "tip" below the buttons when you hover over the YT one.

 

[Lurkin]

Damn Cool. Whereabouts are you in Aussie? Would possibly come to watch if there was a localish event. 8)

What are you using battery wise?

 

[galderdi]

North side of brisbane. We normally compete at Willowbank. But my most likely next event will be Gladstone/Rockhampton. I am currently running running full river hc14a batteries x 12.

But as I mentioned they are not working well for me and I will need to upgrade. I am considering some Tesla batteries.

 

[galderdi]

Can someone tell me what I am doing wrong with the Youtube posts?

Just read the "tip" below the buttons when you hover over the YT one.

Thanks, I didn't even know there was hover over there

 

[kiwiev]

https://endless-sphere.com/forums/viewtopic.php?f=7&t=69603

Sonic is above link

Welcome mate
Its EV sonic from diy electric thanks for coming over and sharing.

So you are running 144 volt?

The tesla packs are 56volt gives a hot charge with 2 packs at around 120volts but only good for 100 to 150 amp bursts

Will pm you
Cheers kiwi

 

[galderdi]

Some good news. I re-read the motor controller for the battmobile. It turns out the diagram was misleading. It showed an arrow pointing to a hex screw with the comment "clockwise for faster acceleration". So I made sure the hex screw was turned as far clockwise as posible. And yet I was getting major lag on Sunday. Tonight I read another portion of the manual. It turns out the hex screw is only a seal. It should be removed and then the adjustment is behind it......yay!!!!!! This should mean I can dial out most of the lag!!!!!!

thanks Kiwi,

yup 144v but I am thinking of using disassembled tesla cells not their packs.

 

[kiwiev]

[youtube]Hq-ZnOUKBLk [/youtube]

I think this is the right video but I was wanting to brake one down but at you can see you can't brake one down due to the coolind and heating construction.

Btw nice work on your chassis great work.

Cheers Kiwi

 

[Hillhater]

Several people are splitting down the Tesla pack 6S, 74P, 6kWhr modules.
Check the for sale adds,
Modules are being sold complete, custom packs, and even broken down as individual cells
https://endless-sphere.com/forums/viewtopic.php?f=9&t=67661

 

[oatnet]

Nice Job!

I am running the same 9" ADC FB1-4001a brushed motor on my street-legal dune buggy conversion, as well as on my VW bus conversion before that.

I'm using 42s of factory a123 modules that come in a 3p/60ah configuration capable of 1800a, and a 2000a Zilla controller. Overkill, a properly cooled FB1 will do 1000a for as much as 10 seconds continuous before melting down, 600-800a is probably a safer top end, which gives a powerful 220-260ft/lbs of torque IIRC. Unlike the Warp motors, our timing is fixed, making higher voltages a challenge. However, you can drill the case to advance the timing, and upgrade the brushes to Helwigs, to run higher volts. Did you break in the brushes on your motor?

I am all about lightweight builds these days, any idea what it weighs?
What controller are you using?

-JD

PS - the a123 modules in a 42s/3p configuration (60ah/153.3v off the charger) weigh 166lbs, about the same weight as your 14ah Pb pack. However their rating is to 100% DOD compared to the 50% DOD of lead so they deliver 9 times the ah, have a fraction of the voltage sag of Lead (and other low-C lithium cells rated to 80% DOD), and deliver 2,000 cycles.

 

[galderdi]

Thanks for the great information. No I haven't broken the brushes. I am running a Curtis 1231C controller. The car weighs about 1400 pounds in race trim. I will check out those battery options.

 

[galderdi]

Also I am now considering competing in the next event. Its a khanacross on feb 20 and I know my performance will be crap but it will give me another opertunity to refine all my settings.

 

[galderdi]

Nice Job!

I am running the same 9" ADC FB1-4001a brushed motor on my street-legal dune buggy conversion, as well as on my VW bus conversion before that.

I'm using 42s of factory a123 modules that come in a 3p/60ah configuration capable of 1800a, and a 2000a Zilla controller. Overkill, a properly cooled FB1 will do 1000a for as much as 10 seconds continuous before melting down, 600-800a is probably a safer top end, which gives a powerful 220-260ft/lbs of torque IIRC.

OK I am getting myself confused.
With your setup:
Which specific A123 are you using?
What is their individual AH rating?
How many is in a pack?
How many packs are you running?
How did you configure your connections within the packs?

For some reason my maths is failing me on this one. Your help will greatly appreciated.

 

[oatnet]

OK I am getting myself confused.
With your setup:
Which specific A123 are you using?
What is their individual AH rating?
How many is in a pack?
How many packs are you running?
How did you configure your connections within the packs?

For some reason my maths is failing me on this one. Your help will greatly appreciated.

Sure! The cells are a123's 20ah prisimatic LiFePO4 cells (diagram above), which are 3.65v off the charger instead of 4.2v-4.35v with LiCo variants like the tesla cells, which may be what is throwing off your maths.

This picture is an "exploded parts diagram" of my Dune Buggy's Pack. The a123 modules are the big beige/black rectangle in the forground, and the 2 smaller modules right in front of the silver battery box. They are connected by the 4/0 cables in the picture.

The modules are configured with (3) 20ah cells in parallel ("3p") for 60ah total. The big module has 28 cells in series ("28s") and weighs 106lbs, and the two smaller modules have 7 cells in series ("7s") and weigh 30lbs. Together, they make a 166lb 3p42s pack, which is 60ah/153.3v off the charger. This picture shows everything needed to mount the pack, 219lbs altogether, which is what helps keep my build around 1,000lbs.



Another thing that may be throwing off your maths is DOD. Lead Acid should only be discharged 45%-50% to get a good cycle life, so 7ah or less from your 14ah cells. Most lithium variants only yield 80% of rated capacity (80ah from a 100ah cell) when they drop to a cut-off voltage, but these a123 cells deliver very close to their rated 60ah capacity when discharged to a conservative 2.8v/cell.

Good thing about LiCo variants like the tesla cells are light weight and low volume. However, you need a lot of AH to be able to deliver high continuous amps. The a123 cells can do 30c, so you need a lot less AH to deliver the same amount of amps, so the pack can be smaller. Many EVs builders want a lot of AH for range, so the pack can deliver all the amps they need so the point is moot. However, my primary design criteria was to build as light as possible, so I needed the high C rating, I am not sure how important weight is to your build, but it is light. A123 also has a flatter discharge curve, so voltage does not drop off as quickly, and the low resistance means less sag under load to keep volts (and consequently KW) higher. And they have an inert cathode, and are good for 2,000+ cycles, compared to 300-500 from PB and many of the high-current LiCo Varients. Every cell out there is ideal for a different design criteria.


Here is a link to my build thread that has more detail, if you can tolerate the obnoxious number of pictures:
https://endless-sphere.com/forums/viewtopic.php?f=34&t=50717



And a youtube of a cruise in the dune buggy (wait past the spinning wheel in the beginning):
[youtube]46_EDW2tI98[/youtube]


-JD

 

[galderdi]

Perfect, now my maths is working. It sounds like one set of your 3 packs would be near perfect for my needs.

Thanks so much for the guidance. I will check back in with my progress.

 

[oatnet]

Okashira has the larger 28s modules here:

https://endless-sphere.com/forums/viewtopic.php?f=9&t=75710

I don't see much of the 7s3p modules anymore, but a Zilla 1K-HV controller could buck the voltage from a pair of 28s3p modules down to 150v/160v that the ADC could handle. 8) I'd break in the brushes to build up a patina on the commutator before blasting it with higher voltage and amps though - just spin the motor for a few days with a 12v battery, then blast out the carbon dust buildup with a vacuum or leafblower.

It looks like a lot of fun right now, great project, thanks for posting it!

-JD

 

[galderdi]

Thanks, I appreciate the interest and support. It is very satisfying when I look back and realise what I have done in 11 months. Also when I consider I have done it all myself with the exception of the motor/flywheel adaptor, flywheel modifications and the bends for the cage. Yes it is already great fun. No I just need to make it competitive. I don't think I've tapped the full potential of what I already have, let alone going even further with higher voltage. I don't know that I will need to do that, at least for the next season or so. Maybe once I have learned how to drive the thing I might start looking for more power. But right now I would settle for consistant performance out of the existing components.

I have a few brake, suspension and panel adjustments to make this weekend to be ready for the following weekend. That event is a khanacross, so it will be higher speed and I will remember my camera bracket for in car and GPS footage this time. But I only expect to be able to handle 6 runs at the most on my batteries and even then I wouldn't be surprised if half of them are impacted by sag half way round.

Aside from the battery power one of the changes with the most potential gain will be an adjustment of the Ackerman angle. On the higher speed corners I was finding the outer front wheel was really pushing/scrubing. I am fairly sure this is because I have shortened the wheelbase by about 8 inches without adjusting the ackerman angle to compensate. I have some ideas to achieve this but I doubt I will get anywhere near it this weekend.

 

[kiwiev]

So glad you came over here mate a much better forum IMHO

Pm me if you do look at A123 I would be interested too

Cheers Kiwi

 

[galderdi]

So glad you came over here mate a much better forum IMHO

Pm me if you do look at A123 I would be interested too

Cheers Kiwi

Yeah I am seriously considering that option but they seem to be really hard to get here. I am talking to a local ev parts supplier on Thursday about the options he can offer. I can't wait to have this all sorted. Meanwhile I need to dismantle the front end and make some adjustments this weekend.

 

[kiwiev]

So glad you came over here mate a much better forum IMHO

Pm me if you do look at A123 I would be interested too

Cheers Kiwi

Yeah I am seriously considering that option but they seem to be really hard to get here. I am talking to a local ev parts supplier on Thursday about the options he can offer. I can't wait to have this all sorted. Meanwhile I need to dismantle the front end and make some adjustments this weekend.

I believe that they are out of backdoor s in China someone please correct me if I am wrong. It would be good to have a Aussie supplier.

Cheers Kiwi

 

[Hillhater]

Yes , it is worth you time to do a forum search on those A123 pouch cells to get some background and understand the sourcing pitfalls.
They are excellent cells IF you can source genuine 1st quality product ( as sold by A123batteries.com). ...but there are some sources out there selling salvaged ( scrap ?) cells at attractive prices.
There are genuine resellers, but be sure to get good references !
There was a whole batch of these cells produced with a quality defect , that were officially scrapped by the manufacturer, but they keep turning up from apparent reliable sources.
There are various ways to help identify undesirable cells, but you should brief yourselves before embarking on any purchase....Unless you pay full price ($80/cell ?) from A123batteries.

 

[Dauntless]

I'd be interested in some clarity on your batteries. You're running 123's now but you're thinking of changing? An upgrade, or these are past their prime for competition? What's the setup you're really looking for?

 

[galderdi]

I'd be interested in some clarity on your batteries. You're running 123's now but you're thinking of changing? An upgrade, or these are past their prime for competition? What's the setup you're really looking for?

Not quite. I am currently running Full River high cranking AGM batteries (Hc14a). My theory was that they should give me enough current flow for short 40 second runs as per the video. All my testing seemed to indicate the theory was correct. But unfortunately pushing hard for more than about 20 seconds would exceed the battery capability and i'd be left with about 10% power.

For my next event I have no choice but to run the same setup as there is no time to resolve the issue. But I am targetting a better solution for the following event, 20 March.

The guy I am meeting on Thursday has a few traditional options, plus he imports second hand leaf batteries from wrecked cars. Most recently he has imported a batch of unpacked tesla cells. I have not committed to anything just yet. It will be a compromise between price and timeframes. The pouches doesn't look like it will be a viable option in the time I have.