Overkilling the Go-Kart Again (67.2v Chevy Volt battery -> 87.6v Headway 38120HP)

[Functional Artist]

I spent some time and reassembled the packs and got them on the kart with the active balancer. There is still a bit to do to clean up the wiring (ran out of loom) and I am switching to an isolated 12v system for my lights and other accessories (parts on the way). I took a little video of the kart here:

Why active balancing?
...is it needed, for that pack?
...please elaborate

Field weakening?
...you have mentioned this before
...but, please elaborate (in more detail)

* Um...also, I' don't have a "problem"
...it's a "gift"

 

[EpsilonZero]

Why active balancing?
...is it needed, for that pack?
...please elaborate

I wanted the active balancer because the pack has used cells in it and it quickly gets them within 0.005v when I top balance. A regular balancer would work too, albeit slower.

Field weakening?
...you have mentioned this before
...but, please elaborate (in more detail)

Basically the controller expends some additional current at higher RPM to counteract the back-EMF where the motor otherwise would not be able to spin any faster (voltage limited). The motor then acts as if it had weaker magnets at high RPM, so it can continue to generate power to higher RPMs without any increase in voltage. I had it turned on when I hit 65 when I first tried out the new battery pack.

I ran across an interesting side-by-side someone did on a motorcycle with an ME1304...

 

[EpsilonZero]

I got the isolated 12v system done and made some time for making a night video. I tested with field weakening on this time, but it isn't necessary to get more speed since I have enough voltage. Here are a couple of clips.

 

[EpsilonZero]

Here's a new video of the kart from my drone. The wheels have been swapped out for Hoosier racing slicks. The fronts are pretty soft, so I rapidly pickied up a lot of rocks from the old pavement.

 

[Functional Artist]

Very Kool!
...but, them people should MOVE them cars off of your go kart test track

 

[Bmr4Karts]

What wheels and tires are those on the drift and the non-drift setups?

 

[EpsilonZero]

The "driftier" tires are 6ply Toros. The others are Hoosier R80s.

 

[Bmr4Karts]

The "driftier" tires are 6ply Toros. The others are Hoosier R80s.

Where did you get the wheels for the R80s and what size are they?

 

[EpsilonZero]

Comet Kart Sales.

Wheels are 5"x5" and 7 1/2"x5"
Tires are R80s 10x4.50-5 and 11x6.00-5

I had R55s on the front to try to reduce plowing, but they were too soft and picked up a lot of rocks. I switched to front R80s when I modified my front spindles for Ackermann and the turning is fantastic now. Sticky tires are not needed.

 

[EpsilonZero]

The new ME1904 is here... the overkill continues.

 

[Functional Artist]

Um...specs?

We want specs!
We want specs!
(I could probably just look it up)

We want specs!
We want specs!

 

[EpsilonZero]

Um...specs?

We want specs!
We want specs!
(I could probably just look it up)

We want specs!
We want specs!

The ME1904 (ME1114) supposedly has a 67.8Nm Stall (up from the ME1719's 39Nm), but I have seen a dyno of an ME1304 (liquid cooled version) running with only 500A with a 78Nm max torque. I have a KLS72701-8080NPS that can output 700A and am expecting to almost double my max acceleration. The voltage constant seems to be similar to the ME1719 so I shouldn't lose much maximum RPM while I can dump a lot more amperage into the motor.

The "old" controller and motor are off. I started revising my wiring for the upgrade and just need to come to a final decision on mounting the main contactor, the 1000A shunt, and the frame I welded up for the controller. I would like to get everything together next weekend.

 

[EpsilonZero]

Well, it works...

 

[madprofessor]

Is that some kind of hard-as-plastic slicks on that thing? Video looks like the road must be iced over. Wonder what would happen if you could get some traction. Wheelies should be in your future.

 

[EpsilonZero]

Is that some kind of hard-as-plastic slicks on that thing? Video looks like the road must be iced over. Wonder what would happen if you could get some traction. Wheelies should be in your future.

No ice. I just spun a couple times on the way out and tested the brakes which locked the rear wheels immediately. I have some settings to adjust...

I am using Hoosier R80s, which are the hardest compound they have. I spun them a bit more in the garage and had to sweep out the tire dust. I guess I basically fine grit sanded them to get them looking like that.

 

[Functional Artist]

Nice work
...but Holy Sh!t

...can you pack much more on that kart?


How about a "walk around" video showing & explaining about the components
...& then, a "proper" test ride, demonstration video.

You've put alot of work (& thought) into your kart
...so, show it off

We need more than a15 sec video, from 1/4 mile away.

 

[EpsilonZero]

Nice work
...but Holy Sh!t

...can you pack much more on that kart?


How about a "walk around" video showing & explaining about the components
...& then, a "proper" test ride, demonstration video.

You've put alot of work (& thought) into your kart
...so, show it off

We need more than a15 sec video, from 1/4 mile away.

I think I am done packing stuff on the kart. I will make a video after I get the settings dialed in. It has been drizzling on and off, so I haven't been able to do much except make a mess in the street in front of my house today while testing.

 

[madprofessor]

It has been drizzling on and off,

I hadn't ever considered that possibility. If all of that amperage potential got caught in a sudden thundershower that soaks everything and the driver too, is there any guarantee that the whole kart wouldn't become an afro-making machine?

 

[EpsilonZero]

I hadn't ever considered that possibility. If all of that amperage potential got caught in a sudden thundershower that soaks everything and the driver too, is there any guarantee that the whole kart wouldn't become an afro-making machine?

Nothing would happen with the major components. I'd be more worried about potential corrosion with the switches on the dash.

 

[EpsilonZero]

We need more than a15 sec video, from 1/4 mile away.

How about a 14 second video from a first person view?