Lithium battery options for electric racers/dragsters

C

CroDriver

100 W
Joined
Jun 11, 2009
Messages
167
Location
Croatia
Let's say we're only limited by weight. I'll take 400kg (880lbs) as a acceptable weight.

A123:

a123-cell.jpg


50 parallel X 112 series = 5600 cells = 392 kg (860 lbs)

280 pack voltage @ 2,5 cell voltage

370 pack voltage @ 3,3 cell voltage

403 pack voltage @ 3,6 cell voltage

115Ah/42,5 kWh stored energy

30C continuous - 30 X 115 = 3450 A

50C 10 sec - 50 X 115 = 5750 A

If we look at the discharge graph:

A123dischargegraph.jpg


...we can see that the voltage drops to 2,7V @ 17C, so I assume it drops below 2,5V @ 30C.

So the pack voltage at 30C would be somewhere around 280V.

280V X 3450A = 966 kW / 1300 hp continuous!!

If the cells are purchased directly from A123 as developer kits one cell would cost 18,3$.

18,3$ X 5600 = 102.666 $

The Chinese ebay cells are around 7$

7$ X 5600 = 39.200 $

Yes, it is damn expensive but they are the best, by far...

Headaway

instock1.jpg


I have purchased a couple of them, they look pretty nice. It's way easier to build a pack out of those than of the A123 cells. Headaway cells have screw terminals

100_0487copy.jpg


13 cells in parallel X 104 series = 1820 cells = 405 kg (890 lbs)


260 pack voltage @ 2,5 cell voltage

333 pack voltage @ 3,2 cell voltage

374 pack voltage @ 3,6 cell voltage

130Ah/43,2 kWh stored energy

10C continuous - 10 X 130 = 1300 A

15C peak - 15 X 130 = 1950 A

20C pulse - 20 X 130 = 2600A

Discharge graphs:

5C

5C.jpg


10C

10C.jpg


15C

15C.jpg


If I had the cells, I wouldn't push them beyond 10 C because they sag to 2,5V.

What would happen at 20C?!


The pack voltage would drop to 260V at 10C

260V X 1300 A = 338kW / 473 hp continuous

The cell voltage drops to 2,1-2,4V @ 15C so the pack voltage would be ~ 240V

240V X 1950A = 468 kW / 627 hp

EVcomponents sells one cell for 17$.

1820 X 17$ = 30.940 $

ThunderSky

DSC04011.jpg


Yeah, yeah.. They are pretty lame but just to compare them...

72 X LFP160 Ah = 403 kg (888 lbs)


180 pack voltage @ 2,5 cell voltage

230 pack voltage @ 3,2 cell voltage

259 pack voltage @ 3,6 cell voltage


160Ah/36,8 kWh stored energy

3C continuous - 3 X 160 = 480 A

5C - 5 X 160 = 800 A

10 pulse - 10 X 160 = 1600 A (4 sec)

Luckily I saved the old specs sheet, the new one doesn't have this discharge graph

TSdischarge.jpg


Hmmm, it's not helping much with 1C discharge

OK, let's say TS drops to 2,3 @ 10C, to 2,5 @ 5C and to 2,8 @ 3C (wild guess, I have no idea)

201V X 480A = 96,5kW / 129 hp continuous

180V X 800A = 144kW / 193 hp (peak?)

165V X 1600A = 264kW / 354 hp (pulse?)

The cell voltage drops to 2,1-2,4V @ 15C so the pack voltage would be ~ 240V

240V X 1950A = 468 kW / 627 hp

12.672$ @ 1,1$/Ah

Looks like Headaway is quite a good alternative

Any other ideas?

CroDriver :)
 
Try with 35C LiPoly. They will have the biggest amount of stored energy. I recomend to use only 350kg of battery and rest 50kg put into carbon wall between driver and battery pack.
 
HAL9000v2.0 said:
Try with 35C LiPoly. They will have the biggest amount of stored energy. I recomend to use only 350kg of battery and rest 50kg put into carbon wall between driver and battery pack.
Click to expand...

Hello my friend :)

You know my plans for the future so I can't risk playing around with explosive LiPo cells... I need something I can build over and over again. Something reliable and safe.
 
There is LiPo that will do 50c continous, or 90c for bursts of 10seconds. At 50c it drops to 3.55v, at 90c it holds 2.9v.

For a drag application, any other battery would be a fools choice.
 
liveforphysics said:
There is LiPo that will do 50c continous, or 90c for bursts of 10seconds. At 50c it drops to 3.55v, at 90c it holds 2.9v.

For a drag application, any other battery would be a fools choice.
Click to expand...

Never heard of any LiPo that can be used in EVs other than Kokam

Could you give me some link or name so I can google it?
 
809grams per 6s 4.4Ah pack.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10090&Product_Name=Polyquest_XF_4400mAh_6S_45C_-_90C_Lipoly_


For your 400kg of battery, you would get 494packs, at 50c (3.55v from Ir drop), you can do 4.686kw per pack continuous, or 2,314Kw (3,103HP) continuous discharge.

For a drag application, I would definitely be using the safe burst discharge rating on them of 90C. This would give you 2.9v*6cells*4.4Ah*90C*494packs, which would give you, 3403kw (4,563HP).
 
lol, you could match A123's performance with just 114kg of packs, and save yourself 286kg (629lbs).

That would be like saving yourself the entire weight of a giant Big Block Chevy drag racing V8 and TH400 tranny. lol
 
liveforphysics said:
809grams per 6s 4.4Ah pack.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10090&Product_Name=Polyquest_XF_4400mAh_6S_45C_-_90C_Lipoly_


For your 400kg of battery, you would get 494packs, at 50c (3.55v from Ir drop), you can do 4.686kw per pack continuous, or 2,314Kw (3,103HP) continuous discharge.

For a drag application, I would definitely be using the safe burst discharge rating on them of 90C. This would give you 2.9v*6cells*4.4Ah*90C*494packs, which would give you, 3403kw (4,563HP).
Click to expand...

The figures sound great but 494 packs would cost 160.000 $. That's out of the budget for this project

Do they sell the cells they're using separate? Maybe they're cheaper

liveforphysics said:
lol, you could match A123's performance with just 114kg of packs, and save yourself 286kg (629lbs).

That would be like saving yourself the entire weight of a giant Big Block Chevy drag racing V8 and TH400 tranny. lol
Click to expand...


Yap, that would be a hell of a dragster...
 
Or, if you're on a tight budget, and you just want to match A123's output, go with something like this:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10096&Product_Name=Turnigy_5000mAh_4S_35C_Lipo_Pack

$70 bucks a pack, you get 10seconds of 45C discharge, or continuous 35C discharge.

5Ah*4cells*45C*3.2v (estimated V-drop from Ri) 2.88Kw per pack. So, 335 packs to match A123's performance. These packs are 554gr each, so 185Kg to match A123's 400Kg battery performance.

335 packs @$70 each $23,450
 
I get special prices at that company, and those weren't even my special rates (forgot to log-in). The above pack can be had for under $20,000 if I just logged in and bought it, but from experience, I know if I were to dicker with them a bit, on a quanity this large, I'm pretty confident I could get the pack under $15,000. They love to dicker.
 
liveforphysics said:
I get special prices at that company, and those weren't even my special rates (forgot to log-in). The above pack can be had for under $20,000 if I just logged in and bought it, but from experience, I know if I were to dicker with them a bit, on a quanity this large, I'm pretty confident I could get the pack under $15,000. They love to dicker.
Click to expand...

This would be OK for me...

I planed to make that order by the end of this year or in the first weeks of the next year. I will research a little what other options I have by then
 
Just so we have all the details to best evaluate battery choices, this is to be a drag car for taking the electric drag racing 1/4mile world record I assume? It's not a street and strip type of build, but rather just a dedicated dragster right?
 
Hal9000 - Hobby city goes nuts and gets super pissed and will even cancel accounts if you post private prices in forums. They freaking hate that. I would send quantity price info via PM only.
 
liveforphysics said:
Just so we have all the details to best evaluate battery choices, this is to be a drag car for taking the electric drag racing 1/4mile world record I assume? It's not a street and strip type of build, but rather just a dedicated dragster right?
Click to expand...

Basically yes, but there's no reason why it couldn't be used fore some other things or even to go to the shopping mall :mrgreen:

Let's prove that electric racers are better than gas dragsters in all fields :)

HAL9000v2.0 said:
That is the pack I suggested before. I will find the price list and will send it to you.
Click to expand...

Hvala prijatelju :)
 
As a guy who drag races, sponsors two cars, and builds racecars and racecar engines, I've put a lot of thought into the same goal you're trying to reach. Electric's could beat gasoline drag cars if done right. They could perhaps run similar to methanol drag cars (5seconds).

I worked out the right way to reach this goal a year ago or so. There is only 1 path that makes sense.

#1. You know you've got no top-end. Just accept that, and it's OK, because the first half of the track is where 90% of the impact on your time comes from anyways. This does change the ideal chassis choice. If you want to run 6's, you need to buy a chassis setup for 5.5's, because you're going to need to have the short-track of a 5.5sec car to make a 6 second pass. If you go with a 6second chassis, you're going to be lucky to make 7s, because it's not setup for the 60' you're gonna hit it with.

#2. Get a 2-3 year old retired pro chassis that ran consistently. Don't even look at what the MPH was, and the ET will hardly matter either. Get a chassis with the lowest consistent 60ft time you can find. These chassis have 50 years of fine tuning and professional R&D into them to arrive at the place they are now. Trying to convert a chassis designed for another purpose, or trying to build your own would easily reach $100,000 in R&D, and only leave you with a disappointed flop. Getting a car to 60ft is a dark art refined by wizards over hundreds of millions of dollars poured into the design. Even just 1 degree of different placement on a linkage arm in the rear suspension can be the difference between a total failure of a drag car, and a winning setup. Trying to find that on your own is just a foolish waste of time and resources.

#3. There are no weight limits for electric drag yet. Exploit this fully! No reason the final car should be over 1,000lbs with you in it. If it is, you're just wasting your time and money. A heavier car needs more power, and it stresses all the drivetrain parts harder, and it's gonna be breaking and unreliable.


A year ago, I looked up the costs of available used chassis, battery cost, custom motor cost, and throwing in a 30% random unexpected crap budget, I estimated I could do what you are trying to accomplish for under $60,000 total investment.
 
How would these chassis go with the differing weight placement of the electric setups Luke? Or would it
be possible you think to setup the electric dragster to distribute weight in areas similar to the ICE dragsters setup
so as not to require too much additional chassis tuning? Be hella lot cheaper to get an electric dragster down the quarter mile
than a top fuel dragster thats for sure LoL

KiM
 
Put two killacycle drivetrains on a drag car chassis.. like he says, be easy to keep under 1500 pounds so it should be pretty quick. Add some fancy traction electronics so each pair of motors knows what the other is doing, should be good to go.
 
Oh wow guys, thanks a lot for the support!

liveforphysics said:
As a guy who drag races, sponsors two cars, and builds racecars and racecar engines, I've put a lot of thought into the same goal you're trying to reach. Electric's could beat gasoline drag cars if done right. They could perhaps run similar to methanol drag cars (5seconds).

I worked out the right way to reach this goal a year ago or so. There is only 1 path that makes sense.

#1. You know you've got no top-end. Just accept that, and it's OK, because the first half of the track is where 90% of the impact on your time comes from anyways. This does change the ideal chassis choice. If you want to run 6's, you need to buy a chassis setup for 5.5's, because you're going to need to have the short-track of a 5.5sec car to make a 6 second pass. If you go with a 6second chassis, you're going to be lucky to make 7s, because it's not setup for the 60' you're gonna hit it with.

#2. Get a 2-3 year old retired pro chassis that ran consistently. Don't even look at what the MPH was, and the ET will hardly matter either. Get a chassis with the lowest consistent 60ft time you can find. These chassis have 50 years of fine tuning and professional R&D into them to arrive at the place they are now. Trying to convert a chassis designed for another purpose, or trying to build your own would easily reach $100,000 in R&D, and only leave you with a disappointed flop. Getting a car to 60ft is a dark art refined by wizards over hundreds of millions of dollars poured into the design. Even just 1 degree of different placement on a linkage arm in the rear suspension can be the difference between a total failure of a drag car, and a winning setup. Trying to find that on your own is just a foolish waste of time and resources.

#3. There are no weight limits for electric drag yet. Exploit this fully! No reason the final car should be over 1,000lbs with you in it. If it is, you're just wasting your time and money. A heavier car needs more power, and it stresses all the drivetrain parts harder, and it's gonna be breaking and unreliable.


A year ago, I looked up the costs of available used chassis, battery cost, custom motor cost, and throwing in a 30% random unexpected crap budget, I estimated I could do what you are trying to accomplish for under $60,000 total investment.
Click to expand...

Huston, we have a problem... :)

I'm from Croatia. Here in Europe we have a lot 1/4 mile races but no dragsters. We are modifying regular cars up to 1000-2000 hp, the most cars are around 500hp. 10 sec is a damn quick run here. I don't know if we have any professional drag racers in Europe in general, but I'm sure for this part (south east) of Europe. Maybe UK or Germany have some dragsters...

I ordered a GTM and payed the deposit a few weeks ago

IMG_2966b.jpg


I wanted to build the components in this car. 2X dual Kostov 11" and two (or even four) Zilla 2K EHV could take a lot of power. Two differentials and AWD would bring the power to the road.

I already have the first and only dual Kostov 11" which was custom built for my BMW project that's almost finished. I'm very very satisfied how things are going with this project so I'm quite confident with the next one

I have a great team. I'm sure we can do this.

What do you think is a realistic time with that kind of setup?

But again, I would rather use LiFePO4 batteries because I would like to produce kits. A kit can't be built with LiPos, I would be responsible if someone blows his neighborhood away. :mrgreen:

Ypedal said:
this would be one hell of a project... how many motors/controllers would this take ! lol... ( can't imagine pushing that much power thru one motor, or a controller in existance big enough to push it )
Click to expand...

3-4 motors would defiantly be enough
 
My daily driver grocery getter 1992 Honda Civic can run 10s.

I was thinking you were looking for something to break records, like trying for 6second passes.

If you want a drag chassis, get a "national dragster" magizine, and browse the classified section in the back. You can find a retired sucessful drag chassis and body for $10-15,000, complete with all the safety gear you need and an FIA certified roll cage that cost $5,000 to build alone.

They are always available, always cheap, and it would work soooooo much better than any other car chassis. You can even understand how much of an advantage it would be to start from one of these chassis. Your kit chassis there will never go under 1.5second 60ft times, it wouldn't matter how much power you have. Its never going to break any records, and its never going to show gas burners what electric can do. You put the drivetrain that would make that car go 10s into a drag chassis, and its gona run 8s, and feel no stress and no wheelspin or traction concerns.

You can hit these chassis with a house, and they just leap forward with no complaints. Its just increadible how well they work. Damn easy to set them up, just make an adapter to the rearend that comes with the chassis, and hit it with everything your electrons can muster. Place the battery to equal the weight bias and COG that the original car had, and its gona break world records.
 
liveforphysics said:
My daily driver grocery getter 1992 Honda Civic can run 10s.

I was thinking you were looking for something to break records, like trying for 6second passes.

If you want a drag chassis, get a "national dragster" magizine, and browse the classified section in the back. You can find a retired sucessful drag chassis and body for $10-15,000, complete with all the safety gear you need and an FIA certified roll cage that cost $5,000 to build alone.

They are always available, always cheap, and it would work soooooo much better than any other car chassis. You can even understand how much of an advantage it would be to start from one of these chassis. Your kit chassis there will never go under 1.5second 60ft times, it wouldn't matter how much power you have. Its never going to break any records, and its never going to show gas burners what electric can do. You put the drivetrain that would make that car go 10s into a drag chassis, and its gona run 8s, and feel no stress and no wheelspin or traction concerns.

You can hit these chassis with a house, and they just leap forward with no complaints. Its just increadible how well they work. Damn easy to set them up, just make an adapter to the rearend that comes with the chassis, and hit it with everything your electrons can muster. Place the battery to equal the weight bias and COG that the original car had, and its gona break world records.
Click to expand...

Do dragsters use gearboxes? Custom made or off the shelf? Differentials?

15.000$ is really affordable. I will defiantly make a dragster but I first have to finish the BMW and build the GTM

A 1000-1500 hp electric GTM won't be that bad too :D

Later we just swap the propulsion system into a dragster chassis
 
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