Hello All! Also, new also sharing. electric go kart

[madstamm]

Hi to everyone...!

So here's my first post

We're a team of a few geers from switzerland. Started an after-work project half a year ago: a modified Kart Chassis (CRG Iris), with a three-phase motor and a few lead-acid batteries.
A 240 cell A123 pack is in development, in fact I charged the 1st cell today with the shiny new BMS PCB

- Some more detailed specifications
- Lots of Photos (check out "at josefs")
- First Burnouts 8)
- Our YouTube channel, which gets regular updates
- 1st version of the lead-acid charger.. 6 clamps under that heatsink .)

The goals are an e-kart that can take on and beat 100/125cc gas versions in driving dynamics, and run a race distance on one charge. Charge time should also be <30min.

I think we're about 70% sone construction... current status:
- Motor mount and belt-drive are finished
- Controller parameter tuning is about 90% done.. getting about 10kWs and 200Nm on the axle.
...expect about 30kW and 220Nm with the A123 pack
- Chassis-rework (centering the driving position and steering) is done
- Kart is very drivable on a flat surface (see Videos)
- ..but not yet race-ready, still too heavy, about 130kg without driver)
- Lead Charger electronics 90% done, Lithium version at about 70%...

Todos:
- Finish Lithium pack and charger
-> minus 35kg!!
-> plus 20-30hp
-> massiv regen possible
-> add 10min driving time (total ca 20m)
- optimizing the sensors
- all new paint/decals
- lower the seat
- driveability tuning
- etc etc...

Performance target:
sub 100kg w/o driver, fully tanked battery
over 30kW
over 220nm on the rear Axle
over 1kA Battery current ... hehehe, writing "kA" ist sooo cool
over 20min driving time at race speed
sub 30min charging time
very good driving dynamics/balance...

Current driving-impressions:
- acceleration is very nice .. Torque is massive and perfectly linear---
- sideways-dynamics are fun, but not fast ... too heavy, chassis flexing, etc etc

..ok, enough for now.
Any questions, shoot away.
madstamm at gmx dotnet

Greetz from the old country,

Mike + Velkart Team (Heinrich, Joseph, Peter, Rony und Beat)

A few pics for fun:

Josef, welding...

Peter, modern tuning

.. the "baby" tryout pack

Working on the rear Axle..

A fresh pulley .. compatible to the original sprocket

A brandnew clamp/u-voltage circuit.. led and optocoupler output

 

[def215]

the pictures that you posted up there just made me speechless. i am amazed by it. is it mounted on a shifter kart frame? keep up the great work. keep us updated also.

 

[dnmun]

and a '63 DS-19 in the shop too. gotta be strange. doc bass had a video of another electric go kart somewhere too.

 

[tostino]

Not trying to be negative, but it may work in your favor to raise the voltage, and keep the amps a little lower, and gear it down.

I can't imagine the heat you're going to waste running 1+kA.
What voltage were you planning on running?

And VERY nice kart by the way!!! completely impressed.

 

[madstamm]

Hi Guys,

Thanks for the comments

@dnmun:
The guy's garage is house to more than one DS

@tostino:
yeah, lots of amps. Lots of copper too though... should be 500W loss, peak, but that's at ~30kW, which we wont hit often.
Problem is that 84V is the limit of the controller (curtis 1238). And the controller is very nice indeed, very easy to use, interface to other stuff, and programmable.
And we wanted to go 3-phase.

If you know of a higher voltage, lighter, DC to 3-ph converter with a nice controller attached, let me know, much interested...

Mike

 

[Doctorbass]

Hello madstamm, Welcome to the E-S!

I think you will appreciate this forum more than you think!

You are at the right place! alot of passionated EV builder here!

Your project pics and video are very nice! great update and documentation.

I would agree on that about the lower Amp and higher volt... might be dangerous but your setup would loose weight and gain efficiency!.. after all.. 500W less in heat is 500W more in the motor!

I saw your A123 battery. and i wonder if you are configured only with 3P ??.. ( 16s 3P) for 1000A ??.. I guess not.. but that would mean you have 2 or 4 battery for having 16s 12P?

I guess you already know that the A123 are rated 70A continuous discharge and 10A charge (15 minutes charge) so for under 10sec burst and having an excellent thermal manqagement of the cell you could draw up to the famous 120A per cell but for 1kA you nees at least 8p.

I have a friend of mine, Robin Almasi from Montreal that rise thisone above to 100V ( 40S8P): http://www.evalbum.com/2718

this is some of his video:

[youtube]bERjkSTYOdU[/youtube]
[youtube]_sw9hN43YSo[/youtube]

12.32 at 97 mph o the 1/4 mile(400m) Drag lane
[youtube]3UOToi0fHNs[/youtube]

Doc

 

[madstamm]

Hi DB,

hehehe... of course we know DrB and the quebecois with the famous 70kW monster Zilla+A123+sturdy motor seems to be a very good recipe for speed! (crazy kart + killacycle)...

Thanks for the reply and looking at the pics!

The 3p pack is just a "baby" testpack... trying to get a feel for how the battery works, reacts to charging at different rates, etc...
Im just now soldering up the clamps, tuning them to 3.600±nothing clamping-volts.

Final pack will be 24s/10p, maybe one more s, or two more p. Will try to get a very modular pack, with some trick connecting features, etc. Hope the idea will work

Yes, high volts/low amps would be nice. However, we wanted a 3ph motor... like I said, hard to find anything other than the curtis controller. Maybe we have to have alook inside. I might be "tunable" No seriously, the 1238 is a *great* controller... maybe, just maybe, we can get the kart in good enough shape that curtis will do a custom unit for us

Regards,

Mike

 

[Doctorbass]

Hi DB,

hehehe... of course we know DrB and the quebecois with the famous 70kW monster Zilla+A123+sturdy motor seems to be a very good recipe for speed! (crazy kart + killacycle)...

Thanks for the reply and looking at the pics!

The 3p pack is just a "baby" testpack... trying to get a feel for how the battery works, reacts to charging at different rates, etc...
Im just now soldering up the clamps, tuning them to 3.600±nothing clamping-volts.

Final pack will be 24s/10p, maybe one more s, or two more p. Will try to get a very modular pack, with some trick connecting features, etc. Hope the idea will work

Yes, high volts/low amps would be nice. However, we wanted a 3ph motor... like I said, hard to find anything other than the curtis controller. Maybe we have to have alook inside. I might be "tunable" No seriously, the 1238 is a *great* controller... maybe, just maybe, we can get the kart in good enough shape that curtis will do a custom unit for us

Regards,

Mike

Have you calculated the power density vs total weight vs (voltage drop under load)?

I did that for my killabicycle drag ebike this summer.. I calculated the best number of P vs the added weight vs the best Vdrop to ensure that the additional power i get for every added P really worth it.

I'm, using a pack of 28s4p difided in 2x ( 14s4p) to be able to parallel charging at 51V using my Meanwell 1500W psu.( it draw 17A and 115V from the AC ! and give 1700W output continuous! ( it have a PFC integrated)

Here is what i calculated:

 

[madstamm]

Hi Dr.B,

We did the math as well... our main problem is getting enough energy onboard for 15-20min of racing. So far we're only estimating power consumption for this distance, and it will very with track-type, race length, temperature (time of year), etc etc.

So mainly, our battery needs to be modular. Have a nice idea to that end
The total weight of the vehicle is ~160kg, with driver, so ±2kg of batteries will not be a massive problem.

Again, the finished pack will be 20-26s, 8-12p, where the s will be modular, and the p fixed. Hence, deciding on "p" (8, 10, 12?) is most important.

Finished soldering the clamps/u-voltage-detection for the testpack yesterday, and mounted the 1st one this morning.

Regards,
Mike

All Sold(i)ered up:

LED *just* showing

The "babypack"

 

[madstamm]

A123 pack electronics are done!
3P, 16S, all clamped at 3.6V...

A short video, showing 16 sweet, glowing LEDs 8)
http://www.youtube.com/watch?v=5NBvPCRAVH8

Mike