Lark Streamliner EV motorcycle Project

**larkmachineco** · 4 Weeks Ago

test fit 1.jpg
Battery.jpg
overview.JPG
Hello,
I am new to the forum and it was suggested that I post on this forum to share my project with the EV motorcycle community.
I would love to hear from you guys about your thoughts and ideas!

I am building an EV Morotocycle streamliner to try to break the SCTA and FIM EV motorcycle record (hopefully above 250mph)

Some basic specs:
22kWh battery LifePO4 32650 Cells (salvaged from a dyno traction battery)
200kW motor and inverter combo (can't say what brand)
Custom chassis
DJ safety Parachete and Fire suppression system
Custom fabricated front end and R6 rear swing arm
Custom VCU (ardiuno based)
R6 cooling system and custom reservoir

Undetermined:
Tires
Wheels
Bearings

Other fun engineering systems:
Body fiberglass
Retractable stabilizers
Automatic parachute release on tip over
System operating code
Battery disconnect unit

I've been trying to film some build videos for youtube.
Check them out over at my channel
https://www.youtube.com/channel/UCYy...ZF6cWWAiTYRHXg

**Spoonman** · 4 Weeks Ago

Looks like a super interesting project dude and I really hope it comes off for you - but a sustained 10C from LiFe?.. can they do that?!?
..They're a bulky chemistry too.

They'll likely be fine for development but I expect you'll have to switch to a smaller capacity battery with much higher discharge for the event itself - assuming a runtime of 5mins or less you could get a sustained 200kW output from titanate packs very easily and a 12kWhr total should suffice and the pack would be significantly smaller and lighter.

**larkmachineco** · 3 Weeks Ago

Originally Posted by Spoonman

Looks like a super interesting project dude and I really hope it comes off for you - but a sustained 10C from LiFe?.. can they do that?!?
..They're a bulky chemistry too.

They'll likely be fine for development but I expect you'll have to switch to a smaller capacity battery with much higher discharge for the event itself - assuming a runtime of 5mins or less you could get a sustained 200kW output from titanate packs very easily and a 12kWhr total should suffice and the pack would be significantly smaller and lighter.

When I first got the batteries, I did not know what they were. They were free and that was the main selling point.
I capacity tested them and the built a discharge rig to test the voltage drop and temperature rise for various discharge rates. They had no problem doing 10C for 4 minutes. very small rise in temp. I got them to do almost 20C for more than 10 sec.

LifePO4 will be ok without a BMS too, should make the vehicle very simple

The two main reasons for the larger capacity are 1. my charge rate capabilities (generator and charger combo) are limited. If I want to run a couple of times a day, I will need to put in more than 10kWh for the longer tracks. a little bit of extra juice can help me shake down the bike without fast charging 2. I need to keep the voltage drop at max load to a minimum.

Most of the run the bike will be wanting to burn out so I figure it will only be at max power at the end of the run. and, more weight = more traction (my limitation for acceleration)

I got all the cells to fit (video coming soon).

I would love to use something better, but I think LifePO4 is the best fit for this application. (cost effective, simple, and powerful)

**frodus** · 3 Weeks Ago

Sweet project. Do you know what brand cells they are?

I know the Saft cells I have are rated for like 300A or so for 30s, and they're 40Ah cells, so like 7-8C without any issues. They're lifepo4 (they call them superphosphate) as well.

I'd still do a BMS especially when you're pulling that much power, If you have a cell group go too low, you should at least have a warning light of some sort. It's easy protection and won't add a ton of cost. I've been using the Zeva BMS and it's a nice cost effective design.

How many Amps and Volts is the inverter?

**larkmachineco** · 2 Weeks Ago

I will have individual cell monitors, but I will not have any balancing, or charge control.
https://www.amazon.com/PACK-Battery-...+voltage&psc=1

I think the brand is Optimum. I have batch test them to confirm they will function well.
The System in 115s25p. 415V and 600A. Cells are 3.2V and 4Ah
Any bms with 115s is not going to be affordable unfortunately.

I was trying to use a Master/slave system made by LT, but it turned out to be pretty expensive

**frodus** · 2 Weeks Ago

As long as you can hear those. I wouln't ever leave the vehicle unattended during charging.

I'd suggest monitoring with something that has an output that can be used to drive a relay to shut things down. All of the battery fires I've heard of are because of overcharging a cell group. Without a means to disconnect the charger if a cell group goes over, there's no safety mechanism and it could be dangerous. As long as you're 100% sure you will be the "means of disconnect" of the charger, that's fine.

Side note: I'm an Sr. EE, and I've worked for Manzanita Micro, Synkromotive and Elithion on BMS systems and done support for them. I've also worked with Orion and built my own BMS. I don't care about balancing (I assume you're going to do that yourself), but monitoring is of utmost importance.

Just be super careful.

**Ted Dillard** · 2 Weeks Ago

Originally Posted by frodus

Side note: I'm an Sr. EE, and I've worked for Manzanita Micro, Synkromotive and Elithion on BMS systems and done support for them. I've also worked with Orion and built my own BMS.

^ he always waltzes that out. mister SENIOR EE. well LAH DEE frikkin DAH

I KEEED. I KEEED.

**frodus** · 2 Weeks Ago

Originally Posted by Ted Dillard

^ he always waltzes that out. mister SENIOR EE. well LAH DEE frikkin DAH

I KEEED. I KEEED.

Go back to work Ted

**tomdb** · 2 Weeks Ago

I will second having a BMS that monitors, nothing is more dangerous than a cell going overvoltage or inverse voltage.

Plus who wants to sit waiting around for a pack to charge, and looking at an 'commercial' BMS system I would say +/- 1000$ will get you something you can trust. Not RC grade mass made toys.

Luckily iron phosphate is forgiving yet then again you want the pack in optimal condition before a run.

Please reconsider what you find expensive

one fire will ruin everything.

Example of an available option ( I have used it myself):
120 Cell $1,345
https://www.orionbms.com/products/orion-bms-standard

My side note: reverse engineered plenty OEM bms systems, plus had a go at designing my own cell monitoring slaves and now designed my own bms master.

Any details on the drivetrain or chargers would be appreciated.

**Ted Dillard** · 2 Weeks Ago

I'm gonna play devil's advocate here for a minute. My experience with Formula Ford builds (Skip Barber had his shop in the next town over and a friend worked there) is that the cars were built to last one race, and basically one race only. Tearing the car down and rebuilding it for the next race is what kept my friend in a job. If the man's on a budget, and is careful, I don't see it being impossible to get the most out of the pack without a BMS, with the assumption that between races he's going to have to do a lot of TLC.

I think we tend to think about builds here like we're all building daily commuters, or something that has to behave like an appliance. Race bikes, especially LSR bikes, are a completely different animal.