80v AWD Performance Build

[Mr.Mediocre]

Hey everyone,
It took me almost a year to get everything put into place to get this build going but it is finally here and I wanted to share my progress.

Backstory:
I work for a company that makes battery powered stuff and so naturally as a car guy would, when I started I thought… “How do I make something really cool that I can ride using some of our discarded products?” I started setting stuff aside and each time I kept taking the idea bigger or better or should I say bigger and faster.

It later came to me that I should do something performance based since we don’t make those things, and being in the marketing department I thought that’s a fun story to tell. Here are all these pieces I pulled and this is what I made, this is how they work in this performance application and here’s how they work for normal stuff…

So, I ran into one of our service guys that works on a ton of this stuff and saw his mix of parts he used to make something. I told him that I wanted to put a ridiculously fast motor onto a racing kart chassis. (I know it’s been done but the work would be minimum.) He told me there are always spares lying around and next time I saw him he’d get me something good. Well that wasn’t a lie, he got me the biggest motor we use. And I know size doesn’t alway matter but I also know that in this case, it might.

But wait there’s more, It wasn’t just the motor; it was the rear differential, axles, disc brakes, front axle… basically I got the whole drivetrain in pieces. I had to jump into a dumpster and cut the front and rear off the chassis to get it all but I was way too happy to do so.

Once I realized that I had so much a an almost complete vehicle I found it hard not want to use a much of it as possible. So I scrapped the racing kart idea and decided to use what I had to build something closer to a cross kart. It was tempting to build an off-road version since I had adjustable coil overs all, but I really wanted to embrace the low to the ground kart feel and be able to rip through corners. (Hopefully) I am however keeping it so a simple tire swap and pool over swap will give me the off-road ride if I want it in the future.

So that bring me to the build.

Two of my many concepts.

 

[Mr.Mediocre]

The components:

Front & Rear chassis with suspension:
Let me tell you, these are no joke. If it wasn’t for my lack of funds I would have stripped this completely and started a full tube chassis build to trim weight and have a cleaner look because these things were stupid heavy.


The Motor:
Diameter - 7” , Length - 13” , Weight - ~85 lbs.
I’m not sure I believe all the specs on the motor itself because to me it doesn’t sound crazy. But I know the original unit can be tuned to get up to 40-50mph which is more then fine for me, I’ll have more fun with all the torque anyways.



The Controller: Curtis 1234se
I just realized I haven’t taken a picture of the controller yet but I should handle whatever I need.

 

[Mr.Mediocre]

The initial Mock-up:

Here are a few of my original mock ups once I got the components home.



I cut the shock towers off because I was still aiming for a kart with that lower center of gravity. You’ll see in later photos that I have since welded them back on. Although I shortened the front towers.



Test fitting a tire that I really wish would have fit. Nothing this small will clear the brake rotors so I’m forced to use a wheel more than twice this size.

 

[Functional Artist]

Kool project!
...but, prebuilt complete units? (that's cheating)

I'd have to design & fabricate the whole thing(s) myself
...each & every piece (one at a time)

JK work with, what ya got to work with

Um...an 85lb. motor? (that's a lot on a kart)
...& what size/kind of battery pack are you gonna power it with?

 

[Mr.Mediocre]

@Functional Artist yeah I agree, I’d much rather build out the whole thing but for now I’ll take and Frankenstein the prebuilt stuff together. I’d like to tell myself that this is the proof-of-concept and then once I get this working I’ll go back and rebuild a custom frame… but you know how that goes.
Once I opted in to use the driveline I knew the original idea would be out so weight is less of an concern right now. I weighed the chassis as it sits with the middle section welded in and I’m at about 375lbs before battery and motor. All in I’m hoping to stay under 650lbs.
For now I will be testing it with six 80V 4ah packs in parallel. I’ll have a low, medium, high performance mode and at the peak it may give me 10 minutes of thrashing around. But the battery is something I’m still playing with since I can get my hands on a few other options.
My original plan was to stay with this six port battery box so I could run lighter and just swap battery packs out instead of the weight of a bigger pack and the wait of it charging. See what I did there?

 

[Mr.Mediocre]

Here is some updated photos of my progress.

I connected the front and rear suspension members together. It had been a little over a decade since I had last welded so I’m not too mad at my welds here.



Because the way the rear and front lines up I needed to go on the inside of the front tubing. So I cut and hammered that in for a cleaner look. I’ll weld that up later.

 

[Bmr4Karts]

You are going to need a huge amount of battery power to move all of that kart.

Those 4ah packs likely top out at 25-30 amps max before the BMS protects the cells (if there is a BMS) so 180 amps max, less continuous. I know you said it’s a test setup but the weight of your vehicle ready to run is going to be very amp heavy at 50 mph.

 

[Mr.Mediocre]

@Bmr4Karts Yeah I know that will be my biggest challenge for power for sure. That and the craving for longer runtimes.

These packs do have built in BMS and are rated at 40 amps continuous I believe, so that should give me 240 amps to work with. If it wants more then that I have access to 8ah packs that can handle 65 amps continuous.

Even with that, I'll have to consider the controller is 2 min RMS rating of 350 amps and 60 min RMS of 150 amps.

 

[Functional Artist]

Um...a 650lb. kart? (I'll say it again, "that's a lot")

I don't think my ElMoto is much over 500lbs.
...& it is a full-size motorcycle with a 8kW motor& 48V 50AH pack (~48 MPH top speed & ~20-mile range)

Kool batteries & box
...but, they are designed, for use with, the size of motors used in like handheld power tools? (drills & trimmers & such)
&
Aren't they kinda expensive? (6-80V batteries plus the box)
...for only ~10 min run time?

Yup, IMO your gonna want/need a lot more power (sooner than later)

Maybe like, OEM Lithium battery modules, harvested from electric cars

For example, I've been working with the 48V 50AH modules, out of Chevy Volt electric cars
...& (2) of them "in series" would create a ~90V 50AH battery pack
...easily capable of 200A
...dimensions are ~10" x ~10" X ~20"
...would weigh ~100lbs.
...& (retail) cost ~$1,000.00

Just some "food for thought"

 

[Mr.Mediocre]

So I realized it has been some time since I posted an update. With everyone one in our house getting sick on rotation and work being super busy I didn’t have much time to work on the kart. But I have made some progress and was able to get my hands on some more components so now I can start mocking up a bit more.

So, I cut the front shock mount shorter so I could see over it since my seat will be so low. I took the 5-6” that I cut off and re-welded it to add an extension that will give me a spot to mount the dash and steering column.

I bought a used seat from a local spot that sells used stock car parts. I spent way too long trying different layouts for the seat and where the battery and controller would be located but landed on this. Pushing the seat back further and mounting the controller just behind it. Putting the battery up front will help with the weight balance and also keep it lower to the ground.


This was a bracket that I cut off the front end early on and set aside. I was able to re-use it by cutting the ends off welding it in as a cross-brace and then using the ends as a seat mount. Next on my list is to cut and notch those and weld the bracket back, then making the bottom bracket.

Here is a mock up of the wheels I found for it. I wanted 12” wheels but they wouldn’t clear the brake calipers so I had to stay with 14” wheels. I do plan to put lower profile tires on this as well.



Once I lock in the seat, the next steps will be to extend the nose and front end. I mocked up the front end with cardboard and some wood. This will be where I house the battery too.


After landing on some of the final positions for things I through a bunch of the components onto the kart and weighed both the front and rear end, as well as weighed the kart from the middle.

The test results:
Rear Weight - 330 lbs.
Front Weight - 200 lbs.
Total Weight - 530 lbs.

I even sat in the seat to see how it balanced out pretty well. At that point it was close to 52% to 48% rear to front balance respectively.

Next Up:
- Finish rear seat bracket
- Start bottom seat bracket
- Extend frontend & mock up battery mount
- Weld in steering rack mount and footwell
- Mock up brake & accelerator pedals

Hopefully the next update isn’t as far apart as this last one!

 

[redflash]

incredibly cool, but don't you miss the smell of gas in the garage ?

Da Redflash

 

[Mr.Mediocre]

incredibly cool, but don't you miss the smell of gas in the garage ?

Da Redflash

haha that’s why I have this as my daily driver, so I can show up smelling like exhaust and gas everywhere I go!

 

[redflash]

aahaa, next prokect.....350/ 350 into the german car ! I put a 350 combo into an xj6 jaguar.......my wife hated it !

Da redflash

 

[Mr.Mediocre]

aahaa, next prokect.....350/ 350 into the german car ! I put a 350 combo into an xj6 jaguar.......my wife hated it !

Da redflash

Haha everyone has suggested an LS swap but if the motor goes I’d probably find a V8 Mercedes engine to put into it!

 

[MTScott]

Cool project, keep it going.

The controller really dictates everything as I understand it. The one you specified is rated at 36-48V, 450amps. I assume it will regulate the 80v down for you? If so, the 240A draw capability of the pack will go up. i.e. if drawing at 40V, the amperage capability at the end of the line effectively doubles. 200A at the motor at 40V, is only 100A at the battery pack at 80V (in a perfect world with 100% efficiency). This will of course change as the voltage in the packs drop, but you see what I mean. I think you could count on always have at least 300A on tap. 450 might be a stretch all the time, but you are close. I think it will be rare that you're asking a full 450A, except at WOT, full load, low RPM. The controller can ask for (48V*450A) 21,600W, the fully charged battery pack can provide (80V*240A) 19,200W. So a very hard pull could trip the BMS. It might also be that the motor won't accept this much, but we'll find out. The motor most likely will take everything the controller sends it until it burns up.

Also.... what will it take to get you to pull more stuff out of the dumpster and mail it to me in UPS compliant boxes

 

[Mr.Mediocre]

Cool project, keep it going.

The controller really dictates everything as I understand it. The one you specified is rated at 36-48V, 450amps. I assume it will regulate the 80v down for you? If so, the 240A draw capability of the pack will go up. i.e. if drawing at 40V, the amperage capability at the end of the line effectively doubles. 200A at the motor at 40V, is only 100A at the battery pack at 80V (in a perfect world with 100% efficiency). This will of course change as the voltage in the packs drop, but you see what I mean. I think you could count on always have at least 300A on tap. 450 might be a stretch all the time, but you are close. I think it will be rare that you're asking a full 450A, except at WOT, full load, low RPM. The controller can ask for (48V*450A) 21,600W, the fully charged battery pack can provide (80V*240A) 19,200W. So a very hard pull could trip the BMS. It might also be that the motor won't accept this much, but we'll find out. The motor most likely will take everything the controller sends it until it burns up.

Also.... what will it take to get you to pull more stuff out of the dumpster and mail it to me in UPS compliant boxes

Thank you, I appreciate it! I am super excited to get it running.

So I actually have the 1234SE-63 which is 48v-80v. I found these specs in the manual.


Weirdly though, the service manual from the UTV it came out of has this listed in it.


I keep trying to calculate the performance I could get. If the controller says a max of 350A and I am running a nominal voltage of 76v then that means I could theoretically push 26Kw to the controller right? The weird thing is the motor specs. In the image above you can see motor specs and those actually match the motor I have. That’s what confuses me, it says it’s rated to 48V and to overvolt it by 1.5 times seems like a lot to me.

Also @MTScott I definitely run into random stuff so if you are looking for anything specific I can keep an eye out!

 

[Mr.Mediocre]

I got the rear seat bracket welded in and was able to get the bottom seat supports in as well.

I started to mock up the pedal assembly but ran into fitment issues so put pause on that to try and work on the foot support.


I also got my wheel adapters in so I can test out my ride height. I was able to get some of the materials for the nose mock-up. I was also given another battery option. 82V battery 40ah with built-in BMS. Using this battery exclusively would mean I have to add the charging port and needed a charger for it too. I still may set it up to where I can switch between this battery and the other battery box with the removable batteries.
@Functional Artist haha I’m sure this battery isn’t much better than my most recent ones I had but I‘m glad I have some options now. Once I get this all settled in and setup I’ll have to see if some of my extra battery resources can help some others out here.

 

[Mr.Mediocre]

that thing is going to be ridiculous!!! nice job!

Thanks, that’s exactly what I’m aiming for!

 

[MTScott]

I keep trying to calculate the performance I could get. If the controller says a max of 350A and I am running a nominal voltage of 76v then that means I could theoretically push 26Kw to the controller right? The weird thing is the motor specs. In the image above you can see motor specs and those actually match the motor I have. That’s what confuses me, it says it’s rated to 48V and to overvolt it by 1.5 times seems like a lot to me.

Also @MTScott I definitely run into random stuff so if you are looking for anything specific I can keep an eye out!

So, everything in those pictures looks like awesome stuff to me . It would be fun to get my hands on one of those motors, and any of the suspension parts.

I'm not an EV expert, but I do have some electronics knowledge and did research building a homemade EV for commuting. It didn't pan out dollar wise (a ****box gas commuter is still cheaper to operate than buying batteries), so I didn't build it.

So... take information from me as if I'm an amateur (I am) hashing it out with you .

I think you'll get plenty of performance.... you just want to make sure you don't burn anything up. This seems like stout stuff for what you're building. I'm guessing it'll rip.

Is that controller what comes on these UTV things you're getting parts from? Is it the same motor from the same UTV? It seems like a very nice sophisticated controller...

I think the batteries are sized fine for the controller, voltage wise that is what it wants. The 350A rating I see elsewhere for that controller is peak <2 minutes that it can deliver to the motor. This doesn't necessarily mean it'll ask 350 from the batteries, i.e. if the controller is pushing 350A at 40V this is only creating a draw of 175A on an 80V battery pack after it is all regulated out. The controller "wants" to run at 150A or less continuously, and those packs will deliver that in a set of 6 parallel quite easily, for how long.... eh, we'll see .

I don't think the 82V battery will gain you much... The controller will regulate the input voltage as it'll accept a wide range, and then deliver what the motor needs and your foot is asking for. If you were jumping from 48V packs to 80V it would be significant, but this isn't worth it.

The 82V rating must be due to different batter chemistry? Is one style lithium ion, and the other lithium phosphate? It would make sense to me that the 80V packs are lithium phosphate, as the math works out that they have 25 cells rated at the nominal 3.2V per cell. 82V could mean it is lithium ion (but the math doesn't work out clean for nominal 3.6V cells). It could also mean that marketing got involved, and 82V sounds more better. In fact, the "82V" rating could be very misleading, as 82/4.1 = 20 cells of li-ion at peak recommended charge voltage, nominal voltage of such a battery is 72V, but again, if marketing gets involved, they might tell you that the nominal voltage of the pack is 74V using 3.7V per cell. Anyway, I'd look closely at this and read the fine print on the batt specs. The 80V packs may indeed actually be a higher voltage pack that the 82V stamped batteries.

DC is a lot simpler (for me) to think about. This is all AC stuff though, it appears. An AC controller has to do it different via digital Frequency variation and/or PWM, and I'm not sure how that pans out voltage/amperage wise at the motor. What is clear as that while your batteries are at 80V, they can deliver (80*40*6) 19,200W (less as the actual voltage drops). I don't think that motor will want 350A, even though the controller can deliver it. I think you have plenty of controller, and likely, the battery pack is fine. If it isn't, you can just figure out how to add 2 more packs. You will need at least 6 at a time though, me-thinks.

/brain dump off

Looking forward to your progress.

 

[MTScott]

Okay so I can't help myself. I found specs on both of the greenworks 80v and 82v batteries. They are both nominally 72V packs, indicating they are 20cell packs, that will really both likely peak at 82V (if the charger will take them there). I'm guessing the 80 vs 82V rating is to make it clear which pack is for the commercial product line, and which is for common grade products. So, the only thing I'd base my choices on is Ah rating, both of which have varying options. Now that I've looked at their stuff deeper, it seems like you're using a 6 bay receptacle device that might come on one of their lawn mowers to create the "pack" on the cart.