# extreme buget performance build



## Kreb (Apr 30, 2008)

I have something of a fabrication background, and have built kit cars before. I've been planning a unique build using components from a Miata with a space-frame chasis for a lightweight package - or as light as one can get using lead-acid that is. Anyway, a thought occured to me today that it'd be neat to try to put a car together for the Grassroots Motorsports 2009 challenge. 

http://grassrootsmotorsports.com/events/2009-challenge/

The trick is getting together the electric components for $1,000 to $1,500. In a perfect world, I'd like a 144 volt system. I've been browsing here and reading Bob Brant's book, and I know that there's no way in hell that I'll put together a first-rate package for that kind of money, but I wonder if something could be cobbled together from leftovers and rejects? There are those publications that talk about making a rudementary system for something like $400, but I'd like a 0-60 in something less than thirty seconds

Any thoughts? A fool's errand?


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## jb_elec (Sep 9, 2008)

Given that alot of times your cometition is going to be a V8 swapped miata or v8 swapped rx-7, it'll be really tough to make that happen. Probably not impossible though. You can get a descent motor and descent controller for < $2009 but getting a motor, controller and batteries for < $2009 may be difficult. I suppose though if you go to extrmemes and build your own motor and controller from scratch you may be able to get there.


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## Kreb (Apr 30, 2008)

I have no illusions of winning. With an EV's torque characteristics and low CG, I can see one doing fairly well on the autocross course however. The idea is the fun of responding to a challenge, doing something new, and opening some eyes.


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## TheSGC (Nov 15, 2007)

I would say your best bet would be forklift salvage yards for the motor (get a beast like a 11-13 inch series wound), a GE EV-1 84+ volt forklift controller with bypass contactors and then find a battery recycle center and get cores that load test ok and try charging them.


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## Kreb (Apr 30, 2008)

Thanks for the feedback. I'm in the San Francisco Bay Area. Can anyone recommend forklift and battery salvage operations that are friendly to scroungers?

Oh yes,the event will be the San Diego edition which will use a 1/8 mile sprint rather than a 1/4 mile - this will favor an EV as well.


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## judebert (Apr 16, 2008)

I was looking at the rules, which say that the regular class must be "Production-based" cars. Does this mean you'll have to run in the Special class? Even if you used a commercially produced chassis instead of a custom-built one?

I can imagine stuffing some homemade EV components in an old Honda Civic hatchback and taking a prize home if they let you run with the other regular cars.


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## Kreb (Apr 30, 2008)

> I can imagine stuffing some homemade EV components in an old Honda Civic hatchback and taking a prize home if they let you run with the other regular cars.


 That would be admissable. Folks are runing things like Motorcycle engines and any number of engine swap variations, so electric would be fine. Now bear in mind that judging encompases autocross, drags and concours, so if you make a fast rat, your score will suffer on the concours. 

Now my idea would be to enter the Locost class, which is more freeform. You can strip the car to it's basics - I'm thinking 500 to 600 pounds for the non-electrical components. That would allow a bunch of old-school lead-acid and still come out under 2000 lbs.


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## TX_Dj (Jul 25, 2008)

Ok, so now you're talking about autocross and drags. That's kinda like "range under hard driving" and "Max acceleration and top speed"... You'll need a lot of runtime to do the autocross, and you'll need a lot of amps to do the drags.

Your batteries now have to have enough Watt-hours to make it thru the autocross, and enough amp delivery to make it thru the drags.

For the record, 144v even with an AGM like a Yellowtop will still come out 500-800 lbs, with a cost of $3000 for the batteries alone.


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## Kreb (Apr 30, 2008)

The batteries are the bugaboo. I have very little enthusiasm for hunting down tired batteries and trying to breath life into them. I think that this idea is going into the "nice, but......." category. Oh well. Unless someone has an inspiration they can pass on.


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## judebert (Apr 16, 2008)

Autocross times generally come in less than two minutes. Anything longer is either a really slow car or a really long course. Of course, you're either accelerating or braking through most of it, so you use a lot of energy, but it should still be useful even with a small AH pack. 

While you'd like the high amp output of an AGM or gel pack, you don't really care about killing off the batteries, so you could go with a flooded pack. In that case, you'd want high voltage, but you could take lower current. 

As others have said, the batteries are the bugaboo. I'm imagining stripping an old 2-door car to the bone, filling it with tiny junkyard lead-acid batteries (maybe motorcycle batteries) and running a homemade controller that expects *really* high voltage, but never asks much for current.


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## Wiredsim (Jul 4, 2008)

See if you can find a battery recycler.. Often times batteries are swapped out in industrial UPS packs that can still be used for an application like this.


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## john818 (Aug 1, 2008)

Good luck, Kreb! Building an electric Locost that cheaply is going to be tough. I see that you can recoup some expenses by selling donor parts. That'll help a little.

I'd bet your weight goal is easily achievable, though. ICE Locosts seem to end up around 1400 lbs. for the 4-cylinder cars. 2000 lbs with 144V of batts should be easy. Finding space for the batts and keeping the car balanced might be tough. If the rules don't require a passenger seat, maybe you can put some in its place, and balance the driver's weight. Your passengers wouldn't mind sitting on a battery box instead of a seat, would they?

If you don't mind my brainstorming, maybe you could go with a mid-engine configuration, or even rear-engine since the motor is so light compared to an ICE. There are people who have done or are working on middy Locosts. The more compact drivetrain might leave more room for batteries.

If you do this, keep us posted!


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## NZero (Jan 30, 2010)

what about doing away with a controller and using some relays with control for 0 1/3 2/3 and 3/3 throttle? just a thought, the drag is only going to be a dead short anyway lol


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## piotrsko (Dec 9, 2007)

I'm hearing of batteries (?) out of wrecked prius's going for a couple of hundred a set. Haven't seen any here in Reno but there be more of them your way.


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## kerrymann (Feb 17, 2011)

I had jokingly thought about doing this for lemons since the "fuel tank" is considered saftey equipment and not part of the cost cap. I think the batteries could be passed off as the "fuel tank". 

If not used aircraft batteries would be your best bet since you need peak amps, not a lot of ah. I got my 29lb, 24V, 880amp batts for cheap because aircraft are much more stringent when it comes to replacement. If you play your cards right you could get them for free. And they actually have great peak power/weight ratio.

I would do the forklift route would definitly be the way to go as you could actually make money and get a good motor, wiring, etc. As far as a controller I think realistically you would be cost limited for anything performance. My only thought was a 2 speed throttle by doing parallel series switching with maybe a LARGE resistor to keep the power under control during the autocross coming out of the corners (with a LOT of feathering of the throttle!


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