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

[EpsilonZero]

Well, I decided I was leaving some rpm and torque unused with the ME1719 even with flux weakening, so I ordered some headway batteries in what are apparently transformer modules. I shucked them in various degrees and checked the fit to confirm I didn't screw up and they all fit as I'd hoped without even having to completely disassemble them. So, I am able to reuse the copper bus bars and such. A bonus is there is more leg room in front now. The weight difference is about +3 pounds compared to the RELiON and Volt batteries I took off.

I need to go pick up some more metal stock so I can put together a more compact casing to connect the modules to my existing battery platform that I made for the Chevy Volt module. I'll probably even cut it down a bit since the footprint is a bit improved. I have an active balancer on the way that I will use to at least top balance and monitor these used batteries so I can see how the cell groups behave in real time. A new buck converter rated for the higher voltage is also on the way to run the lights and other accessories.

I didn't have a whole lot of time to mess with these yet, but I will get working on it this coming week. Afterwards, I might even weld an extension on the back of the Razor and throw the RELiON on along with a new motor, controller, etc.

 

[EpsilonZero]

I made some progress...

In order to tie the rear two modules together and keep out debris on the motor side, I cut a mild steel sheet to size and drilled a grid of holes to match the bolt holes between the two modules.



...after bending the sheet to cover the top of the modules (hammer and bench vise not shown here) and a quick trip to my specialized paint shop...



...the new part is ready for install...



I also made a second zinc-plated sheet to add some rigidity on the other side, but didn't do as good a job cutting it with my antique snips. I have a couple small sheets of plexiglass to make windows over the visible headway cells next. The whole thing is currently clamped between angle iron and held down by 3/8" threaded rod with a flat cross bar. One more bolt from the bottom module is through the front angle iron preventing movement as well. I haven't decided if I want to cut down the platform or not since this install isn't as wide as the Chevy Volt module. I will probably save that until after some testing.



Here's one of the modules prior to disassembly, for anyone interested:

 

[EpsilonZero]

This afternoon, I finished up a few things and got the kart running along with the new buck converter for accessories. The active balancer is still on the way, so I individually charged each module to 28v (below max) to get them acceptably top balanced for now.

I took it out for a test ride and forgot I had the motor limit set to 6500 and field weakening still on and got to see how fast the kart can get to over 65mph before I realized it. The motor is designed for 60-72v and torque doesn't start to drop off until about 4800rpm at 72v, with each 12v buying about 800 more rpm. So, pretty much full torque is available to the 5500rpm rating of the motor.

The controller makes a high pitched warble now on regen braking (it is rated for pack voltage of 90v), but everything seems fine and the full acceleration to top speed is awesome. The extra leg room is pretty nice, too. I'll do some more pictures and a performance video later.

 

[journeyman846]

Any updates on this? I'm about to start a similar build and wondering how yours turned out.

 

[EpsilonZero]

I got everything hooked up and did a couple of test rides before disassembly to check the cells. One module had an unusual drop in voltage. I ended up finding three dead cells in a parallel bank and some mildly weak parallel banks. I probably blew that bank myself being lazy with checking balancing. Oops.

So, I ordered 12 new cells from Battery Hookup, but they sent two used cells in the first shipment... so they sent out two more... which were also used cells, so they sent out two more... which got misdirected and took a few extra days to get here. In the meantime, my active balancer suddenly stopped reading two channels and I ordered a new one while hashing it out with the original company I purchased from. I just need to plug the new one in and test it. The final two cells arrived yesterday and I precharged them for installation, so I finally have all the parts. I am going to replace the remaining cells and loc-tite the last 128 bolts before reassembly. I might get it back together this next week or so when I get some time. This ended up taking so long (mostly from delays) that my wife even complained that I haven't been able to give the kids go-kart rides.

 

[journeyman846]

That's disappointing to hear. I have used them twice for my last two projects and had a really good experience, minus it taking a little while to ship.

 

[madprofessor]

Over 65mph and you're not done adding to it yet? You have a pair that clank.

 

[EpsilonZero]

Over 65mph and you're not done adding to it yet? You have a pair that clank.

A lot of this hobby's allure for me is the repeated challenge of coming up with ideas and making them work. That's why I didn't do something like buy a NineBot GoKart and call it a day. I think Functional Artist has the same problem in a way.

This configuration can run the motor at high enough rpm and with enough power that I am confident I could simply swap for my 14t motor sprocket and run over 75, but I think I am probably done pushing for more raw speed after this. Then again, CarsandCameras took this frame to 74mph (albeit slowly with a 9000rpm Predator) and it might be fun to beat that...

 

[madprofessor]

I hope you took a considered look at Ike just before that speed run. Full leathers, kneepads, gloves, full-face helmet, no face-shield but at least there's wraparound safety glasses, decent shoes.
The faster the dash, the deeper the rash.

 

[EpsilonZero]

I hope you took a considered look at Ike just before that speed run. Full leathers, kneepads, gloves, full-face helmet, no face-shield but at least there's wraparound safety glasses, decent shoes.
The faster the dash, the deeper the rash.

Yeah... I wouldn't look to CarsandCameras as paragons of safety and I know they wouldn't claim it. An open face helmet and shorts are pretty much their standard safety equipment. I think the precautions he took were only because of how scary the steering is on that frame at speed when you don't have experience with it. He didn't bother with his 65mph lawnmower flip. Anyway, I have full armor including a full face helmet and even armored boots.

 

[Bansil]

Lol...no need to bash. I like them because they are....almost human neighbor kids we had as friends.
Problems arise when stuff like , leave road in 70 nova,327,4speed...we beat the other car BUT...we took out 210 ft of "stuff" light pole, cable box, telephone box....barrel rolled 4 times....

My question is this....is it safe to go get an ice-cream or cold beverage ....depends.

 

[madprofessor]

Tame. Try leaving the road in a '73 Barracuda, 318ci, automatic, at 112mph when the right front tire explodes.
Note: Could have been worse, that sweetheart would do 135mph all night long.

 

[Bansil]

Lol...buddy just bought it and right front spindle locked up..you could put your pinky finger in the roof crease made by guide wire on pole..
I got pictures somewhere....

Funny thing is we left the 69 firebird sitting in my parents yard....thank GOD we only killed a Nova

 

[EpsilonZero]

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:

 

[Functional Artist]

Nice ride
Almost 60 MPH on a bike path

Kool display
...could ya tell us, about it?
...what's it tellin' ya?
...come on "spill the tea"

 

[EpsilonZero]

The display is a Galaxy S10+ with DigiHud for my speedometer and the ENJPower app to monitor the battery cells (Bluetooth) along with GPS Logger in a pop-up to log GPS data. The phone is hooked to a Quad Lock weatherproof charging head that I swivel up with a motorcycle mount. It also has a rare 3.5mm jack that I hook to my helmet for audio when desired.

 

[madprofessor]

Way fancier than anything I've got or even know how to use, Epsilon, but thanks for pointing out a simple idea to me.

hook to my helmet for audio

My Campark 4K camera has a jack for an external mic w/foam wind silencer it came with, only about 4' long wire but that's fine. As long as the camera's clipped to the kart in the open frame setup and not in the waterproof case, the mic jack is accessible. I'll clip the mic to my helmet's chin strap and be able to do commentary for later research after test runs. Stuff like rpm as it changes, the GPS speed, how the steering feels in different stages, etc.

 

[EpsilonZero]

I'll clip the mic to my helmet's chin strap and be able to do commentary for later research after test runs. Stuff like rpm as it changes, the GPS speed, how the steering feels in different stages, etc.

I've noticed some Youtube channels using the commentary style even when talking about something else while riding (e.g., FortNine). It seems to work out pretty well.

 

[journeyman846]

Man that thing flies! That first turn was a bit sketchy lol, thought you were for sure going to go in to the forest. And yes, FortNine is the best, watched his videos before buying my first bike.

 

[EpsilonZero]

Man that thing flies! That first turn was a bit sketchy lol, thought you were for sure going to go in to the forest. And yes, FortNine is the best, watched his videos before buying my first bike.

The sketchyness along with an accompanying thumbnail made it my most quickly watched video that basically nobody watches. Sort of a 65mph lawnmower flip approach, except I am not willing to flip nor would the frame do it without actually hitting something going sideways. I'll turn up my RPM limit and tinker with field weakening again next.