Lemons launches EV class - and $50k prize for overall race win in an EV!

I would imagine you would need the batteries to be protected from the driver if they were in the passenger compartment.  They would have to be positively secured, with no possibility of injury to the driver (including leaking battery acid).  That could add complexity to a fast exchange of power.

Also, I think Lemons has a mandatory five minute minimum pit time for “fuel” stops.  As far as the timing loop goes, almost every single track has a timing loop in pit lane as well, so you don’t lose a lap.

Doesn’t quick charging the batteries in 5 minutes make them get hot? I don’t know squat about this, just wondering. 

sergio said:

Doesn’t quick charging the batteries in 5 minutes make them get hot? I don’t know squat about this, just wondering. 

Considering that the amount of power required to do that would be roughly the same as steel processing plants use to melt steel, yes, it would.

In reply to tikibug :

I've never seen the bible belt in such a positive light.

No minimum pit stop time in Lemons.  Champ, AER, and Lucky Dog all have minimums. 

Meeting the rules, this is beginning to look like an April Fools prank.

I don’t mean to insult you guys who are obviously much smarter than I but this doesn’t sound like something to be done on a Lemons budget.

I think the $50,000 in nickels is safe for a few years

sergio said:

I think the $50,000 in nickels is safe for a few years

The 1MM nickels for the first autonomous vehicle win is still up for grabs from 2012.  So probably.

But, imagine if you could do both in the same race!

Would be hilarious to see someone take stripped hearse and use coffins filled with batteries that slide and connect. I’d imagine that you could change them out in less than a minute.  Getting vehicle weight down would be an issue. A Volvo wagon with a hearse style cargo bay? 

codrus said:

Teslas get about a lap and a half around Laguna Seca before the the batteries hit the max temperature and you lose most of the power to prevent them from overheating.

I don't doubt it. The only battery I know of that has active water cooling for operation is the Volt.

alfadriver said:

In reply to volvoclearinghouse :

So a Tesla 85kwhr battery weighs 1200lb, if the interwebs are right.  

There's basically two ways to approach this:

a) super light chassis, meeting minimum wheelbase requirements (82" for LeMons) and crash structure requirements, a quick change battery of about 1 hour on-track capacity (~60kWhr or so), figure out a way to do a 1-1/2 minute battery swap, and hope for Karma.

b) pile on a pair of Tesla packs, ~170kWhr, into a stout chassis (I'm thinking full size truck/van chassis, they can be made to handle) and shoot for range, also figuring the larger capacity pack might not heat up as much.  And hope for Karma.

In reply to volvoclearinghouse :

The 60kWh Tesla is still at least 850lb.  So the shape would have to be really good to do a big block + trans swap in 1:30.

(From what I can see on the interwebs, there's an 85 kWhr and an 60kWhr battery for the S. And I would suspect they would be the best start for a complete battery pack that would have a good capacity in a small car.)

If you could break the batteries down to maybe 2 or 3 that can be distributed through the car....

GIRTHQUAKE said:

codrus said:

Teslas get about a lap and a half around Laguna Seca before the the batteries hit the max temperature and you lose most of the power to prevent them from overheating.

I don't doubt it. The only battery I know of that has active water cooling for operation is the Volt.

Actually the Tesla battery is water-cooled (or at least liquid cooled, IIRC it uses a silicone-based coolant similar to computer coolant), the problem is that the motor overheats. Check this out:

https://www.quora.com/How-does-the-cooling-system-in-electric-motor-work-on-Tesla

alfadriver said:

sergio said:

Doesn’t quick charging the batteries in 5 minutes make them get hot? I don’t know squat about this, just wondering. 

Considering that the amount of power required to do that would be roughly the same as steel processing plants use to melt steel, yes, it would.

Yep the battery cooling system would be working hard during such a fast charge for sure.

In reply to alfadriver :

I would suspect it would be faster to change, extending your analogy, 1 big block + trans than 2 or 3 Honda engines + trans.  The main thing is just dealing with the mass of the pack.  

But weight brings all sorts of other challenges, not to mention cost.  Perhaps like a Spitfire chassis (83" WB) and a 60kWhr pack?  If nothing else that would be fun as hell to drive.  

The whole "rest of your car has to be 500 bucks" thing sort of makes it very hard? Or is the "500" dollar thing not really enforced?

What about going for efficiency instead? I wonder if you could drive 7/10ths and basically use no brake pad - ie 100% of braking is regen. Find a track with a low average speed and lots of turns so that you can minimize wind resistance and long sections of acceleration/braking. 

Take a car with a good cd already, and chop 10 inches out of the middle so the whole thing is skinnier (and you loose like 4 sqft of frontal area). Tape up all the seams, etc. 

Our range assumptions so far all treat the electricity like gas, in that once it is burned to go forward it never comes back. But that isn't quite the case with electrons.

It'll take a smaller motor and battery pack than previously discussed. 

In a 150 kW (200 hp) CRX powertrain duty cycle on a tight track is about 50%, and about 15% of the energy put in can be recaptured on deceleration  (1g decel at 80-100 MPH takes a lot more than 200 hp!)

For 1-hour stints with the track under caution 20% of the time my slide rule says 50-60 kWh. That's about a 700# battery replacing a 70# fuel tank, but we are removing a 300# engine and gearbox and replacing it with a 100# motor/reduction, so net weight gain is 430#.

The hard part will be EVERYTHING. There is no easy part to this car.  Part 1 is a raceworthy RWD conversion on a CRX because the weight distribution will soon approach a 911's. Part 2 is building battery packs in the passenger seat and in the hatch area including enclosures that are simultaneously safe and temporary. Part 3 is developing a way to haul two 350# battery packs out of the car at the same time in seconds. Part 4 is convincing your motor and controller that they are still in the donor vehicle enough to be able to run, and then tuning them so that it doesn't panic in its new lighter home. Part 5 is cooling an EV powertrain well enough that it's able to regen rather than dumping heat into the brakes. Part 6 is getting enough downforce and tires under the car without a big drag penalty so that it's clearly the fastest car on track and can make up for hourly swap stops...

Maybe, just maybe, a factory Porsche effort with most of a Taycan under an old Boxster could get it done. This is not a prize I expect to be collected within 3 years.

There is a way this prize could be collected tomorrow.  It would be a major logistical challenge, but here goes:

You somehow get 70 or 80 teams to all build EVs, and all apply for one specific race.  And you simultaneously somehow organize it so NO other types of cars apply to enter.   

An EV is guaranteed to win, no matter how E36 M3ty it is.  

In reply to chaparral :

do you wanna be on my team? 

volvoclearinghouse said:

There is a way this prize could be collected tomorrow.  It would be a major logistical challenge, but here goes:

You somehow get 70 or 80 teams to all build EVs, and all apply for one specific race.  And you simultaneously somehow organize it so NO other types of cars enter.   

An EV is guaranteed to win, no matter how E36 M3ty it is.  

I think the organizers would sniff this out. but if we had a mole...

chaparral said:

It'll take a smaller motor and battery pack than previously discussed. 

In a 150 kW (200 hp) CRX powertrain duty cycle on a tight track is about 50%, and about 15% of the energy put in can be recaptured on deceleration  (1g decel at 80-100 MPH takes a lot more than 200 hp!)

For 1-hour stints with the track under caution 20% of the time my slide rule says 50-60 kWh. That's about a 700# battery replacing a 70# fuel

Interestingly, we came up with almost the exact same kWhr number for an hour of track time, using two different approaches.  

Robbie said:

volvoclearinghouse said:

There is a way this prize could be collected tomorrow.  It would be a major logistical challenge, but here goes:

You somehow get 70 or 80 teams to all build EVs, and all apply for one specific race.  And you simultaneously somehow organize it so NO other types of cars enter.   

An EV is guaranteed to win, no matter how E36 M3ty it is.  

I think the organizers would sniff this out. but if we had a mole...

They might.  But hey also might look at it as a helluva publicity stunt, and not care.  LeMons doesn't get *rich* running these races, but they make enough that the $50k payout isn't going to hurt too much.  

In reply to volvoclearinghouse :

Totally agree. So can we up the ante and get 70-80 teams of autonomous electric cars? The real lemons racing of the future?

In reply to Robbie :

Yes, as long as we can build a DeltaWing. That'll cut us down to 25kWh of batteries. Just have to figure out how to get one through the ruleset.