Electric KOH and Desert Builds - Technical Discussion

[Wicked Al]

This thread is to discuss electric builds and anything technical related to electric racing. It is not for political discussion about energy policy or other personal opinions about going electric. This isn't even about green, it's about taking advantage of the pros of going electric and addressing the cons of going electric.

I am starting a build for racing KOH so this is my primary topic. I expect to do desert racing and WORCS with it too at some point, but for right now, primary concern is KOH. I am not one of the teams gifted with a drivetrain, this will be of my own design for both the drivetrain and chassis. There are advantages going electric provides that ICE can not. The EV packages given out I would consider Gen 1 technology, I am developing Gen 2 technology.

Gen 1: Swaps an ICE drivetrain for an electric drivetrain
Gen 2: Other things which I am not going to talk about now, but as I get IP secured I will.

Here is the basic structure of the vehicle:
UTV class. RS1 style single seater. 72" wide, 90" wheelbase, 4 motor, 4WD, 200hp (250 or 300hp option if testing determines it's needed), 23" min front wheel travel, 25" minimum rear wheel travel, 35" tires, 95mph top speed, 1888ftlbs torque, 40kWh hot swappable batteries. It will have my Cross Link suspension, anti feedback steering and .... other stuff.

No CVT's will be hurt in this build, unsprung mass will be acceptable, scrub radius, KPI, caster, camber, bump steer, track width delta will all be controlled and, if you look at it long enough, will be downright beautiful.


It has already been named, we call it, Rock-E.

I am not an EV drivetrain expert. Inverters, vehicle control units, battery management systems, Can Bus are all mental pits for me. I understand the basics, but details, no. Experts will be needed, fortunately I know a few.

The chassis will be relatively easy to design and build, though I will most likely sub out the final product after I get the geometry where it needs to be. I can make steel stick together, but many can do it so much better than I can.
The motor gear reduction units will be fully custom. The steering will be highly modified. If I stay with 64" width I can use standard suspension arms, if I go 72" (which is the plan), all of those will be fully custom. The Cross Link shocks will be heavily modified.
I will be soliciting sponsorships for it. This is a technology development platform, not only as the initial build, but ongoing development over the next several years. As sponsors come on board, I will post up. If you are interested in sponsoring electric vehicles in general, post up! I am sure there are a lot of teams who can use some help with both $, expertise and product.

Racing is not the path of least resistance. (oooooh)
We do it 'til it Hertz! (Booooo!)
If you see a Sine, Wave, or follow the arrow, your choice. (Staaahhhop!)
Please keep questions Current. (Sob...stop...)
Thank you, I'll be here all week.

Who is building electric and what are your challenges?

 

[jon coleman]

are you doing the 4 wheel motor deal like lordstown?, this is cool, pictures, paaaaleeez

 

[Wicked Al]

Nope. The motors will be chassis mounted.

I'm finishing up getting my Cross Link Rzr back to stock to sell and get out of the shop. Parts are coming in for the new build, as soon as I get the space set up, I'll post some pics.

 

[Klaus]

Batteries.

Are you using LFP chemistry?
What cells?

Are you building your own with small modules or use a turnkey type solution?

Where do you source them? ... and how is that going?

 

[Wicked Al]

Batteries.

Are you using LFP chemistry?
What cells?

Are you building your own with small modules or use a turnkey type solution?

Where do you source them? ... and how is that going?

LFP. Cells haven't been chosen yet.

I have enough room to play with existing modules but may go custom when I start critically analyzing the power needs and space for it. I have a friend who builds packs, very energy dense and robust with integrated BMS, but about $700/kWh. He'll build them any way I need them. I also know a company that is bringing in their own battery production line, if their format fits...which I think it will, I may go with those. Much less expensive but it may sacrifice other attributes such as energy density/volume or weight density/kWh. Choices. Not sure how fast this line will come up to production, we'll see. As a development platform, I expect over time we will swap in different systems to continue to strive for improved energy density and fast swap capability while keeping an eye on safety and cost.

 

[FourLow]

Oooooh, I'm in for this one. Stoked to see the progress.

 

[Wicked Al]

Here's a sketch...still playing with ideas and still not settled on final configuration. The tubing in the lower back passenger compartment is the shock mount if I go with double a-arms in the back rather than trailing arm. Obviously the trailing arm shock mount would be considerably forward...right behind the driver seat. The reason I put this option in there is it makes it more favorable as a possible candidate for moving the design to commercial production. I wouldn't use a second seat for racing so access isn't important, but I'd really like this to be a plausible retail option...I may want too many things . The bottom rails between the front and rear section has an arch to provide an additional 4" of clearance for clearing boulders.

Another idea I haven't settled on is if it should truly be a single seater (all about performance) or if I should configure it as a wider vehicle capable of two seats sxs, again, as a viable commercial option.

Option:
1. Single seater, trailing arm, 72" wide, all about racing and product R&D.
2. SxS seating, capable of a second row of seats, 64" wide is a more popular commercial size, still 90" wheelbase, double a-arm rear suspension. All about a possible retail vehicle.

Sub option, 64 or 72" width?

Keep in mind, I can get 20+inches of wheel travel out of a double a-arm set up. 20" travel for 64" wide or about 24" for 72" wide.

My thought process is to mock the vehicle up using these parts. I can cut and hack and even make steel stick together (but it won't look nice) so I can essentially dry fit and test a configuration. Depending on what attributes I want to end up with, and after the appropriate testing to ensure clearances and usability, I will then have the whole shebang redone with appropriate sized tubing, structure and parts custom made (such as extending arms, axles etc) to end up with a primo race quality vehicle.

The final parts just came in for me to get my old Turbo S finished and sold, then the build starts on this one. Frame came in (Turbo S 2 seat as a base, will get chopped) along with hubs, calipers, bearing carrier and knuckles. Front brakes from a 4 seater.

I made good use of Facebook marketplace ads, Craigslist and Google. Not easy finding some of these parts. I also found a set of shocks to use for mock up, but they are not the Turbo S Velocity shocks, different sizes. I thought the overall length and stroke were the same for all Turbo XP RZR's...not.

Before I start chopping, I need to settle on a configuration, what do you think?

Alex

 

[johndjmix]

What about the battery swaps? How do you plan to set this up?

--John

 

[Wicked Al]

What about the battery swaps? How do you plan to set this up?

--John

Hot swap modules. I plan on having enough battery for either a 50 minute race or 50 miles. My assumption is 40kWh will do this. After testing, I'll adjust accordingly. I'd like to do a WORCS race without worrying about batteries. Anything longer will require a swap.