Re: Only 1 electric car in Lemons?

Wonder if you can run plain generators. like Honda, Yamaha, Onan.
how would you wire the kill switch system?
Always wondered if relays are allowed. So when main kill switch is flipped to off, it powers down all other gizmos.

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27 (edited by Klayfish 2016-01-14 06:35 AM)

Re: Only 1 electric car in Lemons?

Yeah Phil, I agree the EV Spark will likely be worthless when they come off lease soon.  But for a here and now I'd bet if you can find a Copart sourced Mitsu i-Miev, you could get it stupid cheap right now.  Hell, you can find a low mileage 2012 or 2013 for under $7k on Autotrader all day long.  I've seen them as low as $5500.  And that's the asking price.  I doubt they fly off the lot, you could probably bargain like mad.  I'd imagine a wrecked one is near worthless.

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28 (edited by chaase 2016-01-14 06:50 AM)

Re: Only 1 electric car in Lemons?

Judge Phil wrote:

An electric Lemons car isn't going to be on the track very much compared to a gas car, but it will be more fabulous.

/agree

If you don't have the regenerative braking system and all of the other stuff, the batteries will drain pretty quickly.  If you can maintain those systems, it will help a bit. The other option would be to drive at regular road speeds and try to stay out as long as possible. What fun is that though?

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Re: Only 1 electric car in Lemons?

And now there have been two. Come on slackers, we need someone else in Class E to race against.

Everybody grab your brooms, it's shenanigans!

30 (edited by OnkelUdo 2016-09-19 05:44 PM)

Re: Only 1 electric car in Lemons?

rmcdaniels wrote:

And now there have been two. Come on slackers, we need someone else in Class E to race against.

So how many golf cart batteries do you think the dustbuster could safely fit...after the almost 900# engine and tranny are removed.

Re: Only 1 electric car in Lemons?

So many ideas!

I have all the spinny/ inverter bits from one of these mated to a rwd  transmission

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Re: Only 1 electric car in Lemons?

Congrats on progress so far!

What are the future plans to get to Jay acceptable speed and longer stint length? How long did battery swaps take? Pictures too please of the drivetrain.

25X Loser - Delinquent Racing - '86 Rust-Tite Merkur - 9 years (when do I get to stop?).

Re: Only 1 electric car in Lemons?

How about 3 or four identical electric cars, drive into the pit, plug in, hop into a freshly charged one, head back out, DOMINATE!

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Re: Only 1 electric car in Lemons?

We'll need a better motor and controller. While this thing drives around town just fine, seeing normal acceleration and speeds; on a race track it quickly overheated the motor and started killing batteries. We had to be extremely careful when driving it to keep it running.

EV motors and controllers are not really made for long-term continuous acceleration. They can handle hundreds, or even thousands of amps for short durations, but their continuous use rate is relatively low. We are researching other motors and controllers now.

We'll also need better battery technology. Lead-acid is the best for price/KWH, but it is extremely heavy, bulky, and slow to recharge. We'll need lithium-ion to make this work. We're looking at salvage yards now for wrecked donor cars. Chevy Volts seem to be good candidates; there are a decent amount of smashed-up ones and the prices are relatively low. I'm targeting $100-$150/KWH as an energy storage cost that will let us move forward, and I think that's doable.

Our goals for this race were to double the previous EV distance record and to never be towed off. We accomplished that, barely. Our goals for the next race are to double the current record (55 laps on a 2.3-mile track), not be towed off, and to pass another running car on track. The first two are definitely doable, but the third will require a relatively slow and poorly driven race car to be out there with us, so that one's probably also pretty doable.

Everybody grab your brooms, it's shenanigans!

Re: Only 1 electric car in Lemons?

billybobster wrote:

Congrats on progress so far!

What are the future plans to get to Jay acceptable speed and longer stint length? How long did battery swaps take? Pictures too please of the drivetrain.

I'll make a story post with pictures in the next day or two over in the crappy race section.

Everybody grab your brooms, it's shenanigans!

Re: Only 1 electric car in Lemons?

swindrum wrote:

How about 3 or four identical electric cars, drive into the pit, plug in, hop into a freshly charged one, head back out, DOMINATE!

This is what they do in Formula E


mcdaniels wrote:

We'll also need better battery technology. Lead-acid is the best for price/KWH, but it is extremely heavy, bulky, and slow to recharge. We'll need lithium-ion to make this work. We're looking at salvage yards now for wrecked donor cars. Chevy Volts seem to be good candidates; there are a decent amount of smashed-up ones and the prices are relatively low. I'm targeting $100-$150/KWH as an energy storage cost that will let us move forward, and I think that's doable.

I was actually thinking about building an electric Lemons car.  (It was a that would be cool type project)  What I was thinking for battery changes is you build a rack of lead acid or whatever cheep battery you could find.  You then build 5 or so of those racks (Recharge time/drain time = # of racks) and hot swap them in and out of the car.

I was thinking like 10 lead acid batteries in a steel frame.  They would all be linked together with on connector of the pack.  You could add as many packs as needed. 


My other thought for the car platform was to get a crashed Tesla.  They probably could be had cheep if you sold the battery pack, and you would have AWD so you could DOMINAT.

Moot Point Racing - 1991 Volvo 240 - #496

Re: Only 1 electric car in Lemons?

kakarot1232001 wrote:

Wonder if you can run plain generators. like Honda, Yamaha, Onan.
how would you wire the kill switch system?
Always wondered if relays are allowed. So when main kill switch is flipped to off, it powers down all other gizmos.

I did the math on this the other day and its just not super feasible.  Let say you have a target of 100hp

100[hp] = ~75[kW]
Motor efficiency ~ 85%
75[kW]/0.85 = ~88[kW] into the motor

This mean you would need a 9 of the 10,000[W] Honda generators to run at full throttle all the time.

Lets assume a best case scenario where there is an average full throttle use of 50%.

88[kW] * 120[s](avg lap time) * 50% = 5280000 [Joules] ~= 1 BigMac Meal per lap
5280000[J]/120[s] = 44[kW] of continuous generation

The lap time drops out so it doesn't really matter, although for a larger track you would spend a larger percentage of time on the gas. This is because you accelerate at a much slower rate then you brake.


To run off batteries you need the following

To run for ~30min at 100hp and 50% average load you need

88kW*(30[min]*60[s/min])*50% = 79200000[J] = 22[kWh]

From Optima's website it looks like their batteries have about 50[Ah] on average so

12[V]*50[Ah] = 600[Wh] = 2160000[J]

22[kWh]/ 600[Wh] ~= 37 batteries*$225 = $8325/pack

Moot Point Racing - 1991 Volvo 240 - #496

Re: Only 1 electric car in Lemons?

Lead acid has some other limitations around continuous discharge. You end up with a battery that's only 30% discharged, but won't provide any current until you let it sit for a while. That's partially alleviated by using twice as many 6v batteries, but then you run in to other logistic issues.

Also the weight is dangerous. The batteries weigh 85 pounds each. A steel frame to hold ten of them could weigh 900 pounds or more. We didn't want to be slinging those around.

Teslas are expensive and complicated. They also don't use the best battery technology. Every other manufacturer is using the LG batteries. I think that Tesla overcame engineering challenges by throwing money at them, while other manufacturers were more practical.

We're looking at something more like a Leaf powertrain, as it is simple, light, and cheap. There are some Smart EV motors out there for dirt cheap as well.

Everybody grab your brooms, it's shenanigans!

Re: Only 1 electric car in Lemons?

rmcdaniels wrote:

Teslas are expensive and complicated. They also don't use the best battery technology. Every other manufacturer is using the LG batteries. I think that Tesla overcame engineering challenges by throwing money at them, while other manufacturers were more practical.

We're looking at something more like a Leaf powertrain, as it is simple, light, and cheap. There are some Smart EV motors out there for dirt cheap as well.

I agree with you on Tesla's.  It was just a thought that I had(mostly because I saw a Tesla on Co-Part and was like I wonder if you could run that), I never even looked into other EV manufacturers.

Lead acid has some other limitations around continuous discharge. You end up with a battery that's only 30% discharged, but won't provide any current until you let it sit for a while. That's partially alleviated by using twice as many 6v batteries, but then you run in to other logistic issues.

Also the weight is dangerous. The batteries weigh 85 pounds each. A steel frame to hold ten of them could weigh 900 pounds or more. We didn't want to be slinging those around.

There will be limitations to whatever battery type you run.   I think it is all about weighing the options,  price vs weight vs capacity vs availability vs safety.   You could make it with all Lithium Ion's but you would spend a fortune and be at risk of catching on fire and exploding all the time.

Its an ambitious project no doubt

Moot Point Racing - 1991 Volvo 240 - #496

Re: Only 1 electric car in Lemons?

Electric cars don't typically need as much HP, unless they want a high top speed. We'll be happy with 70 MPH. Electric cars have an enormous amount of torque though, and it is available anywhere in their RPM range, so they come off of a corner fast and get to their top speed fast. We're targeting a peak HP of 50.

The rest of the math is mostly correct. Our Sam's Club deep cycle batteries had 96AH at 12v and we could get about a half hour out of ten of them without discharging them very deeply.

Like about everything else, the big challenge is going to be thermal management. I've been digging through technical specs on batteries, controllers, and motors, and none of them are really suitable for endurance racing, which is hours of always being at full throttle or full brake. That's why when you take a Tesla to the track, you get about 4 laps out of it before it gets too hot and you have to stop flogging it.

What we found with our car is that you have to drive it like an extreme hyper-miler in racing conditions. Luckily one of our drivers has a hybrid as a DD and is in to hyper-miling, so he figured it out quickly. We developed four rules that allowed us to keep it out there:

Never drop below 30 MPH
Never exceed 40 MPH
Never exceed 100A current draw
Never use the brakes

Now we just need to upgrade the 35 year old powertrain so it can handle roughly double the current number with occasional 400A bursts, and lighten it while upgrading the suspension and steering so we can carry more speed in the corners. Having to stay full track right because we are so slow also hurt our momentum; if we could take a decent racing line then we could also be faster and more efficient.

Everybody grab your brooms, it's shenanigans!

41 (edited by mully006 2016-09-20 07:49 AM)

Re: Only 1 electric car in Lemons?

rmcdaniels wrote:

Electric cars don't typically need as much HP, unless they want a high top speed. We'll be happy with 70 MPH. Electric cars have an enormous amount of torque though, and it is available anywhere in their RPM range, so they come off of a corner fast and get to their top speed fast. We're targeting a peak HP of 50.

Ya I was just making up a number. 

Like about everything else, the big challenge is going to be thermal management. I've been digging through technical specs on batteries, controllers, and motors, and none of them are really suitable for endurance racing, which is hours of always being at full throttle or full brake. That's why when you take a Tesla to the track, you get about 4 laps out of it before it gets too hot and you have to stop flogging it.

I would look into this site.  http://www.robotmarketplace.com/product … _main.html

They sell components for Battle Bots.  All the stuff is pretty robust and an output a lot of power.  This for example can handle 150A continuous with surges up to 300A < 1s.  You could also look into making your own speed controllers, it probably would be cheaper and you could add liquid cooling to keep the temperature down.  I think you are right that it will be very hard to find an off the shelf controller that can handle the power under endurance racing conditions.

Moot Point Racing - 1991 Volvo 240 - #496

Re: Only 1 electric car in Lemons?

mully006 wrote:

I would look into this site.  http://www.robotmarketplace.com/product … _main.html

They sell components for Battle Bots.  All the stuff is pretty robust and an output a lot of power.  This for example can handle 150A continuous with surges up to 300A < 1s.  You could also look into making your own speed controllers, it probably would be cheaper and you could add liquid cooling to keep the temperature down.  I think you are right that it will be very hard to find an off the shelf controller that can handle the power under endurance racing conditions.

This is the conclusion I came to.  Build your own.

Couple of months now I've been toying with an EV conversions for Lemons.  Looked at the numbers hard enough that it might actually work.  Lithium-Ion is the battery of choice.  Self made motor controllers with liquid cooling integrated is a must.  Being able to liquid cool the motor and the battery packs would be a huge plus as well.
Only thing slowing me down is the cost.  I've got reasonable solutions for the significant problems, but damn if it isn't expensive to pull it all together.

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