# Cells Inbetween Haiyin & Headway or CALb



## Jordysport (Mar 22, 2009)

Hi Guys, i'm in a bit of a dilemma and i feel i need another set of eyes on a situation. I need a pack that is 220V circa +- for sag, but i've been asked the impossible..Performance AND Range, now for my other car i want to be using Haiyin cells as range is no issues whatsoever, but in this situation it needs to last a 15 min race around national UK circuits, 130mph top speed 0-60 circa 4 seconds, weight 400kg inc driver. the weight of the car without any ev or ice components is 140kg. 

Its hard to judge how many Ah i require, i've tried to basically map Silverstone (3 straights) estimating corner exit speeds and through other calcs ultimately Ah used, and for a 13 lap race (15 mins , 21.3 miles) but i'm coming out with a Ah figure required of 75ah (only using 80% of course) 

so assuming this calc is correct either the cells will be able to take 3600amps and 62ah (Haiyin-Cont) or 750A & 75ah (Headway-Peak). 

Question: Are there any cells in between? I really need a small compact pack. 

Thanks


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## DIYguy (Sep 18, 2008)

I've got some ideas... but why don't u talk to Steve (Jozzer) at Jozztek. He builds race pack for a living and has lots of experience, users, racers etc. He's one of the best and he's right in your backyard.... http://www.jozztek.com/shop/


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## Jordysport (Mar 22, 2009)

DIYguy said:


> I've got some ideas... but why don't u talk to Steve (Jozzer) at Jozztek. He builds race pack for a living and has lots of experience, users, racers etc. He's one of the best and he's right in your backyard.... http://www.jozztek.com/shop/


Please do divulge everyone's opinion matters, but jozzers costs . 

LifeBatt's are unsuitable


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## Bowser330 (Jun 15, 2008)

Turnigy A-Spec Lipo pack
3.7V (4.0Vcharge) 6AH (1s2p)
139g
65C constant (390A)
130C burst!!
24$

60 packs in series = 222V nominal, 240Vmax
10 packs in parallel = 60AH
600 packs = 13.3kwh, 184lbs, 3900A constant!, $14,440 cost....



Jordysport said:


> Hi Guys, i'm in a bit of a dilemma and i feel i need another set of eyes on a situation. I need a pack that is 220V circa +- for sag, but i've been asked the impossible..Performance AND Range, now for my other car i want to be using Haiyin cells as range is no issues whatsoever, but in this situation it needs to last a 15 min race around national UK circuits, 130mph top speed 0-60 circa 4 seconds, weight 400kg inc driver. the weight of the car without any ev or ice components is 140kg.
> 
> Its hard to judge how many Ah i require, i've tried to basically map Silverstone (3 straights) estimating corner exit speeds and through other calcs ultimately Ah used, and for a 13 lap race (15 mins , 21.3 miles) but i'm coming out with a Ah figure required of 75ah (only using 80% of course)
> 
> ...


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## Jordysport (Mar 22, 2009)

Bowser330 said:


> Turnigy A-Spec Lipo pack
> 3.7V (4.0Vcharge) 6AH (1s2p)
> 139g
> 65C constant (390A)
> ...


3.7V (4.2Vcharge) 6AH (1s1p)
170g
50C constant (300A)
65C burst (400A)
26$

is the Haiyin Cells, but thats still overkill seeing as my motor will take 700A peak. thats the point i am trying to get either its overkill of Discharge capacity or the capacity itself! nothing in between.

ideally i want a 60-80ah pack 700A cont & 1200A peak ish, and below $10,000 !


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## Jordysport (Mar 22, 2009)

zsnemeth said:


> 70s5p or 4p A123 pouch?


Indeed this seems one of the few alternatives, for value also but the ambiguity on the ACTUAL discharge capacities of non gen cells worries me but eg if i was to dual the motors (later on of course) upto the controller limit (1000A) 70S5P pack would be discharging at 10C or 200A per cell, which is possible, and of course cost is below $7k just building the packs, which i don't feel confident in, guess i will have to learn! IF this is the only alternative that is the route i will have to take.

the question also is how long are we going to be able to buy the A123 Pouch cells for? i might need future proof for 2800 cells!


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## GeoMetric (Aug 13, 2010)

You have to evaluate weight of the cells and pack. The Haiyin cells are the lightest 250 to 300amp cells we can buy. Kansas State Jayhawk eFormula team did very well using Haiyin cells.
__________________________________________
Hey Ron, 
My team and I just wanted to let you guys know how we did during our competitions. We competed in 2 different events. One was in Loudon, New Hampshire for Hybrid Electric category cars ad the other was in Detroit, Michigan as an promotion/exhibition/showcase electric vehicle. We achieved first place in the electric division: 1st in autocross, 1st in design, 1st in electric acceleration, 2nd in open acceleration, and 6th in sales. There were approximately 30 teams that competed in this event.

From the results of the New Hampshire competition, Jayhawk Motorsports was invited to bring the electric car, along with the internal combustion car, to Detroit, Michigan for the regular FSAE competition. FSAE is attempting to incorporate electric vehicles into the regular FSAE competition so we were invited, along with Munich (winners of FSAE Germany electric divisions). Our cars were used as promotion/exhibition/showcase cars, essentially showing the cars off and proving their performance.

In Detroit, we ran a 4.3 second 75 m acceleration run that put us at 10th place overall compared to all cars competing (approximately 120 cars). Munich ran the fastest time of the day at 3.9 seconds. We definitely didn't have enough time to produce a vehicle with traction control for controlled acceleration launches along with electronic differential control. In the endurance event we were running laps times within 0.7 seconds of the fastest combustion vehicles and on average 2-3 seconds faster than the fastest electric vehicle in Germany, Munich, for a 50-60 second lap time.

Needless to say, we created a car that will become a legacy to Jayhawk Motorsports and possibly the fastest electric car that has competed in FSAE events in the world. And we would like to thank you for that. The battery shop dedicated a significant amount of resources helping Jayhawk Motorsports produce this vehicle and we cannot express how much we appreciate that.

Here is the video of our endurance run in Detroit, Michigan
http://www.youtube.com/watch?v=EhfN5ZyWpOY

Here is a picture of the car and electric team.

Thanks!

Emily Dellwig
Jayhawk Motorsports
University of Kansas


http://www.nemrs.net/evroadcourseracing.html


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## Jordysport (Mar 22, 2009)

GeoMetric said:


> You have to evaluate weight of the cells and pack. The Haiyin cells are the lightest 250 to 300amp cells we can buy. Kansas State Jayhawk eFormula team did very well using Haiyin cells.
> __________________________________________
> Hey Ron,
> My team and I just wanted to let you guys know how we did during our competitions. We competed in 2 different events. One was in Loudon, New Hampshire for Hybrid Electric category cars ad the other was in Detroit, Michigan as an promotion/exhibition/showcase electric vehicle. We achieved first place in the electric division: 1st in autocross, 1st in design, 1st in electric acceleration, 2nd in open acceleration, and 6th in sales. There were approximately 30 teams that competed in this event.
> ...


yeah 2am last night i wasn't that sharp lol, 

A123 Pouch
70S3P 60Ah
discharge each cell at 233A peak  approx 10C
Volume: 0.06m^3
Mass: 106.92 Kg
Cell Cost: $3844.8 + delivery

Haiyin Cells
60S10P 60Ah
Volume: 0.047m^3
Mass: 102.00 Kg
Cell Cost: $15,600 + delivery

In terms of weight and volume they are pretty similar Haiyin being better but its over 4 times the price.


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> yeah 2am last night i wasn't that sharp lol,
> 
> A123 Pouch
> 70S3P 60Ah
> ...


You are way off in regards to pricing the A123 Pouch cells, Mavizan (the only US) dealer sells the A123 Amp20 Pouches for $65.00 to $68.00 each. If you are pricing Chinese A123 Pouch cells they are ALL defects and not original QC cells. There are over 30 cases (I know of) that these Chinese black market cells have gone bad. So, to buy real A123 cells your more in the range of $14,500+ for your needs, with a much heavier pack.


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## Jordysport (Mar 22, 2009)

GeoMetric said:


> You are way off in regards to pricing the A123 Pouch cells, Mavizan (the only US) dealer sells the A123 Amp20 Pouches for $65.00 to $68.00 each. If you are pricing Chinese A123 Pouch cells they are ALL defects and not original QC cells. There are over 30 cases (I know of) that these Chinese black market cells have gone bad. So, to buy real A123 cells your more in the range of $14,500+ for your needs, with a much heavier pack.


I am aware of the AMP20 cell situation. why is the pack much heavier? the difference in weight i less than 5kg from my calc above.


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## Bowser330 (Jun 15, 2008)

Jordysport said:


> 3.7V (4.2Vcharge) 6AH (1s1p)
> 170g
> 50C constant (300A)
> 65C burst (400A)
> ...


 If your motor can only take 700a peak then why have battery output of 1200a peak? If it's to limit sag, there are cells that sag less than others..
Calb CA cells 100ah 7.5 lbs 1000a peak 150$
67 in series = 221v
67cells = 500lbs,10k$,22.1kwh
10c sags a 3.3v cell to 2.8v
5c sags a 3.3v cell to 3.0v


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> I am aware of the AMP20 cell situation. why is the pack much heavier? the difference in weight i less than 5kg from my calc above.


You are correct on the weight issue, but why jeopardize burning your race car to the ground with defective A123 cells?

The decision is yours only, but I will say 6 teams will be racing the Hybrid eFormula Series in 2013. Good Luck!


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## GeoMetric (Aug 13, 2010)

Bowser330 said:


> If your motor can only take 700a peak then why have battery output of 1200a peak? If it's to limit sag, there are cells that sag less than others..
> Calb CA cells 100ah 7.5 lbs 1000a peak 150$
> 67 in series = 221v
> 67cells = 500lbs,10k$,22.1kwh
> ...


The Haiyin cells will have very little sag (if any) pulling such little amps. This will give faster acceleration with the straight high voltage line. You can pull 300amps from each Haiyin cell and deliver 3.3volts, you are barely getting the cells warm which will create enormous amounts of voltage.


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## Jordysport (Mar 22, 2009)

GeoMetric said:


> You are correct on the weight issue, but why jeopardize burning your race car to the ground with defective A123 cells?
> 
> The decision is yours only, but I will say 6 teams will be racing the Hybrid eFormula Series in 2013. Good Luck!





GeoMetric said:


> The Haiyin cells will have very little sag (if any) pulling such little amps. This will give faster acceleration with the straight high voltage line. You can pull 300amps from each Haiyin cell and deliver 3.3volts, you are barely getting the cells warm which will create enormous amounts of voltage.


you are right in that, and i did think that the sag would be minimal on the haiyin, its just the monumental cost of the cells, once the test bed is complete this year we will need at least 5 cars worth of cells! iirc Haiyin once sold their cells for $19.99 usd?? if i can get them for that its a signed sealed deal, will contact Erik this evening.


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> you are right in that, and i did think that the sag would be minimal on the haiyin, its just the monumental cost of the cells, once the test bed is complete this year we will need at least 5 cars worth of cells! iirc Haiyin once sold their cells for $19.99 usd?? if i can get them for that its a signed sealed deal, will contact Erik this evening.


Just imagine the costs and press after your A123 cells go pop! You want quality, you must pay for quality. Cutting costs should not go hand in hand with safety.


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## skooler (Mar 26, 2011)

I'm with bowser, 

100AH CALB CA's will be more than adequate probs 65-70?

If sag is an issue then just add another couple of cells.

By the time you have joined and housed the A123 or Haiyin cells the price and weight will have shot up.

70 CALB CA100AH cells should be about £7k after shipping, tax etc.

Cheers,

Mike


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## GeoMetric (Aug 13, 2010)

skooler said:


> I'm with bowser,
> 
> 100AH CALB CA's will be more than adequate probs 65-70?
> 
> ...


I totally disagree with the both of you. CALB 100AH only produces 300amps continuous and weighs 7lbs. My Haiyin 10P 60AH produces 3000amps continuous and weighs 4.5lbs with copper connections.


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## EVfun (Mar 14, 2010)

Hey Ron,

I bet you have leads on high amp cells. Do you have anything for the wicked street crowd? I'm thinking something that takes pretty fast discharges but is still in the LiFePO4 chemistry. I understand that watts per pound is king on the track, safety is somewhat secondary because discharges are short and charging is largely monitored. On the street a bit more capacity is needed (range "at least 1/4 mile" won't cut it) and the pack has to be a little more "hands off" for nightly charging.


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## Jordysport (Mar 22, 2009)

EVfun said:


> Hey Ron,
> 
> I bet you have leads on high amp cells. Do you have anything for the wicked street crowd? I'm thinking something that takes pretty fast discharges but is still in the LiFePO4 chemistry. I understand that watts per pound is king on the track, safety is somewhat secondary because discharges are short and charging is largely monitored. On the street a bit more capacity is needed (range "at least 1/4 mile" won't cut it) and the pack has to be a little more "hands off" for nightly charging.


Initially this was the backing for this thread, there seems to be cells for the extreme high powers such as Haiyin cells and prismatics for range but nothing in between, although i will end up using Haiyin cells EVfun and I are on the same wavelength there seems to be cells for high discharge and high capacity but nowt in between. 

A high performance cell for road use with limited range would be excellent whether it be LiFePO4 chemistry or otherwise.


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## major (Apr 4, 2008)

Jordysport said:


> Initially this was the backing for this thread, there seems to be cells for the extreme high powers such as Haiyin cells and prismatics for range but nothing in between, although i will end up using Haiyin cells EVfun and I are on the same wavelength there seems to be cells for high discharge and high capacity but nowt in between.


Sure there are. Take a look at this list: http://www.diyelectriccar.com/forums/showpost.php?p=327300&postcount=4 There is a lot of choice.

From post #1 it looks like you think you need a 20 kWh pack. The electric bikes run circuits like you describe at faster speeds, about the same distance, weighing 250 kg and have 12 to 14 kWh packs. Your 20 kWh might be in the ball park. A 15 minute race puts you at 4C average so 80 kW average power. Again, sounds in the ball park.

That isn't going to be a small pack. Or a cheap one.


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## skooler (Mar 26, 2011)

I thought the requirement was for 1200Amps and 220v?

If the above is correct then there is no need to spend ~4 times more on specialist cells. The off the shelf CA prismatics have been tested to 12c (evtv a few weeks ago).

If the requirement was to run a shiva then I can see your point!


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## GeoMetric (Aug 13, 2010)

skooler said:


> I thought the requirement was for 1200Amps and 220v?
> 
> If the above is correct then there is no need to spend ~4 times more on specialist cells. The off the shelf CA prismatics have been tested to 12c (evtv a few weeks ago).
> 
> If the requirement was to run a shiva then I can see your point!


My point was the weight, he want's the lightest cell that can deliver. Yes, the Haiyin cells are a bit "overkill" for the amps he needs, but having extra amps with a lighter pack makes more sense. The Calbs will only deliver 10 to 12C for a very short time, seconds before they drop to 3 to 5C.


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## Jordysport (Mar 22, 2009)

skooler said:


> I thought the requirement was for 1200Amps and 220v?
> 
> If the above is correct then there is no need to spend ~4 times more on specialist cells. The off the shelf CA prismatics have been tested to 12c (evtv a few weeks ago).
> 
> If the requirement was to run a shiva then I can see your point!





GeoMetric said:


> My point was the weight, he want's the lightest cell that can deliver. Yes, the Haiyin cells are a bit "overkill" for the amps he needs, but having extra amps with a lighter pack makes more sense. The Calbs will only deliver 10 to 12C for a very short time, seconds before they drop to 3 to 5C.


A Shiva wouldn't even fit in my chassis!! for this car i will need upto 1000A (Soliton 1) but for most of the cars a Jnr (600A) would be fine. 

But a 600A CA or Headway pack is the same size if not more than a Haiyin pack rated to 1800A cont & 2400A peak, and pretty much no sag at 600 or 1000A.

- Ron , I've emailed you about built pack sizes, as i need to update the cad model to confirm it will all fit! if its easier just measure your current pack and proportion the length relative to the number of cells in the pack. Thanks


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## Jozzer (Mar 29, 2009)

Jordysport said:


> Please do divulge everyone's opinion matters, but jozzers costs .
> 
> LifeBatt's are unsuitable


 I'm hurt - I spend many hours each week dishing out advice (and not getting paid for it!)

If you want >15 mins runtime the best bang for your buck would be the good old Turnigy 20C type packs. They fit your bill just right, easy to assemble, slightly better energy density than the Hayin cell (since it's NOT made for extreme discharge rates), cheaper, minimal sag at the power levels required (probably 5-10% in the size pack you'll need).
As Major states, 20kW/h pack might be a good place to start, giving you something like 100hp average power for the 15 mins race..

Calbs and Headway will sag far too heavily for 15 min race use (more like 35%) and take up nearly double the space..


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## Jordysport (Mar 22, 2009)

Jozzer said:


> I'm hurt - I spend many hours each week dishing out advice (and not getting paid for it!)
> 
> If you want >15 mins runtime the best bang for your buck would be the good old Turnigy 20C type packs. They fit your bill just right, easy to assemble, slightly better energy density than the Hayin cell (since it's NOT made for extreme discharge rates), cheaper, minimal sag at the power levels required (probably 5-10% in the size pack you'll need).
> As Major states, 20kW/h pack might be a good place to start, giving you something like 100hp average power for the 15 mins race..
> ...


I don't doubt you do!, but that's the first time i've seen your site, saw the 1hr of advice for £48.00 and thought oh no...just the impression i got from it. 

As for the Turnigy's i will look into them, but 20kWh pack is huge, at 222V (for the Turnigy's) its 90ah!! which would be 12S18P which is £9000+ ouch, i am expecting a lot but more like £6,000-£7,000 for the pack. 

I will look into it for sure though,


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## Jozzer (Mar 29, 2009)

Jordysport said:


> I don't doubt you do!, but that's the first time i've seen your site, saw the 1hr of advice for £48.00 and thought oh no...just the impression i got from it.
> 
> As for the Turnigy's i will look into them, but 20kWh pack is huge, at 222V (for the Turnigy's) its 90ah!! which would be 12S18P which is £9000+ ouch, i am expecting a lot but more like £6,000-£7,000 for the pack.
> 
> I will look into it for sure though,


 I doubt you will find a performance cell much cheaper than that (at least not without losing equivilent performance), but drop me a line anyway, I might be able to arrange a discount on a volume order...


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## Elithion (Oct 6, 2009)

I know little about Haiyin (no spec sheets out there), but I can tell you that, for your application, you could do far, far better than Headway, and somewhat better than CALB. 

I posted this in another thread, but here is is again. It is a comparison of a bunch of cell (as some batteries) from the point of view of using them for power packs (as opposed to energy packs). Top is best. 
Note that energy density and power density are not considered in this chart. All that is considered is the ability to put our power. The higher up a cell is in this chart the less it wastes heat and the least it sags.










This next chart does consider energy and power density:








You'll note that some of the best cells from all points of view are Kokam's super-high-power cells, the venerable A123 M1 (26650), and Boston Power's small oblong cylindrical cells.

Disclaimer: I am hoping to help, but I cannot vouch for any cell manufacturer; you are responsible for your own choice of cells.


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> I'm hurt - I spend many hours each week dishing out advice (and not getting paid for it!)
> 
> If you want >15 mins runtime the best bang for your buck would be the good old Turnigy 20C type packs. They fit your bill just right, easy to assemble, slightly better energy density than the Hayin cell (since it's NOT made for extreme discharge rates), cheaper, minimal sag at the power levels required (probably 5-10% in the size pack you'll need).
> As Major states, 20kW/h pack might be a good place to start, giving you something like 100hp average power for the 15 mins race..
> ...


I do agree with some of what Jozzer has posted, Turnigy is a very good product since they come from the same place. Anyways, Kansas State University Jayhawk Team ran a small Haiyin pack over twenty minutes and kicked everyones azz! Did you not read the article or watch the video?


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> A Shiva wouldn't even fit in my chassis!! for this car i will need upto 1000A (Soliton 1) but for most of the cars a Jnr (600A) would be fine.
> 
> But a 600A CA or Headway pack is the same size if not more than a Haiyin pack rated to 1800A cont & 2400A peak, and pretty much no sag at 600 or 1000A.
> 
> - Ron , I've emailed you about built pack sizes, as i need to update the cad model to confirm it will all fit! if its easier just measure your current pack and proportion the length relative to the number of cells in the pack. Thanks


Info coming, running on generators after the storm, give me a few days plenty of damage around here.


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## Bowser330 (Jun 15, 2008)

GeoMetric said:


> Info coming, running on generators after the storm, give me a few days plenty of damage around here.


hope everything is okay....


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## Bowser330 (Jun 15, 2008)

GeoMetric said:


> I totally disagree with the both of you. CALB 100AH only produces 300amps continuous and weighs 7lbs. My Haiyin 10P 60AH produces 3000amps continuous and weighs 4.5lbs with copper connections.


Yes, Lipo can burst more energy and weigh less, but the pack doesn't meet his total energy requirement OR his budget. At this point I've seen the Haiyin cells in high-end dragsters or cost-subsidized school projects...


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## GeoMetric (Aug 13, 2010)

Bowser330 said:


> hope everything is okay....


Thank you, still no power till Monday!


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## GeoMetric (Aug 13, 2010)

Bowser330 said:


> Yes, Lipo can burst more energy and weigh less, but the pack doesn't meet his total energy requirement OR his budget. At this point I've seen the Haiyin cells in high-end dragsters or cost-subsidized school projects...


His project is a high-end project and deserves the best and lightest cells he can get. The cell's energy will handle his needs. If you want to build a winner, it costs!


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## skooler (Mar 26, 2011)

Overkill is always appropriate but not always necessary....


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## GeoMetric (Aug 13, 2010)

skooler said:


> Overkill is always appropriate but not always necessary....


Maybe not, but overkill and light weight is always a winner!


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## skooler (Mar 26, 2011)

GeoMetric said:


> Maybe not, but overkill and light weight is always a winner!


True...

I agree 100% that Haiyin cells are the better technical solution. I just think that the CALBs are better bang for buck and plenty good enough for this application. 

Have you got any tech specs for the Haiyin cells? Never seen any info other than what you have posted.

Cheers,

Mike


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## Jozzer (Mar 29, 2009)

I've seen what 15 minite racing does to Calbs - they are not man enough for the job. They also take up a lot more space than LiPo - that the OP doesn't have to spare.

Calbs make more sense for a lower power road vehicle because they will last many many times more cycles. That said, there are other cells out there that offer much better cycle life AND better energy density than both of these - and still manage a decent discharge rate for a 15 min race - but they are more expensive (than Turnigy and Calb - only a little more than the Haiyin though).

Haiyin/Nano cells are great in drag vehicles where 10 second current is the most important thing..


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## Bags (Jun 20, 2010)

And the brands of those cells would be...?


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## Bowser330 (Jun 15, 2008)

Bags said:


> And the brands of those cells would be...?


Kokam......


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## rwaudio (May 22, 2008)

I'd look closely at the CALB CA cells. Buy a CALB, buy some Haiyin, and test them yourself under the conditions you will subject the battery to. With a 15 minute race that's an average of 4C, since you don't want to discharge 100% you get closer to 3C average with higher peaks for acceleration.

Talk to the guys at EV West, or EMW, both of them are using CALB's, and EV West's Pikes Peak car used CALB SE's and their new off road buggy uses CALB CA's.

For drag racing Haiyin or Kokam type cells are really the only choice, but the longer the race the more sense prismatics make. I've also built packs from both pouches and prismatics and the prismatic is so much easier to work with it deserves consideration.


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## Karter2 (Nov 17, 2011)

Jordysport said:


> i'm coming out with a Ah figure required of 75ah (only using 80% of course)
> 
> so assuming this calc is correct either the cells will be able to take 3600amps and 62ah (Haiyin-Cont) or 750A & 75ah (Headway-Peak).
> 
> ...


 Why have you ignored the Turnigy LiPo as proposed by Jozz ?

you could easily build up a 75Ahr pack from a string of 14 of the 4s, 5Ahr hard case packs, paralleled up 15 times = 210 packs
It would weigh 110 kg ( + interconnects)
and cost under $5k ( + shipping) ( $23 each)
Admittedly it still has way too much current capacity (1500 continuous), but that cannot be avoided and will minimize sag.

Why are you not considering these ??


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## Jordysport (Mar 22, 2009)

Karter2 said:


> Why have you ignored the Turnigy LiPo as proposed by Jozz ?
> 
> you could easily build up a 75Ahr pack from a string of 14 of the 4s, 5Ahr hard case packs, paralleled up 15 times = 210 packs
> It would weigh 110 kg ( + interconnects)
> ...


Because i am picking up 144 of these cells today for a 60Ah pack.......


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## Jozzer (Mar 29, 2009)

Bowser330 said:


> Kokam......


EiG and LGchem..


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## Jozzer (Mar 29, 2009)

rwaudio said:


> I'd look closely at the CALB CA cells. Buy a CALB, buy some Haiyin, and test them yourself under the conditions you will subject the battery to. With a 15 minute race that's an average of 4C, since you don't want to discharge 100% you get closer to 3C average with higher peaks for acceleration.


 Although the average is 4C, what really happens is that you hit it for 10C fifty times in a row with short breaks in between. The cell gets a much harder time than if you were to discharge it at 4C - which would already make the cell pretty hot.
The Calb will also sag by 30%+..


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## rwaudio (May 22, 2008)

Jozzer said:


> Although the average is 4C, what really happens is that you hit it for 10C fifty times in a row with short breaks in between. The cell gets a much harder time than if you were to discharge it at 4C - which would already make the cell pretty hot.
> The Calb will also sag by 30%+..


I don't disagree, I thought EV West was crazy to use CALB's in the pikes peak car, however the motors turned out to be the limiting factor. My early testing shows less than 30% sag from a CALB CA60FI. I'll be testing some CALB's in series with my A123 pack for comparison, it's not a race car but it will be in combination with a Soliton1 and Warp11HV. So it might make useful data for someone.


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## Jozzer (Mar 29, 2009)

rwaudio said:


> I don't disagree, I thought EV West was crazy to use CALB's in the pikes peak car, however the motors turned out to be the limiting factor. My early testing shows less than 30% sag from a CALB CA60FI. I'll be testing some CALB's in series with my A123 pack for comparison, it's not a race car but it will be in combination with a Soliton1 and Warp11HV. So it might make useful data for someone.


 A123 pouches sag a lot more than Turnigy too - I've got a 72v pack in series with my main Turnigy pack currently (testing for a client) and they drop way more voltage than the 230v turnigy pack does. (of course the A123 M1 cylindical cells are MUCH stiffer than the pouches - in case that's what your comparing against)
I've seen 2 seperate calb packs literally steaming and warped after a 15 min race. On the road though you would normally spend much less time with your foot down, and give much more time to cool between bursts (ie, you'd never discharge the whole pack in less than 15 mins) - a racetrack is very different - and racers are VERY hard on vehicles!

The fact that they take up nearly double the space as LiPo also doesn't bode well for race vehicles, or the fact that they are 30% heavier per capacity (or 70% heavier than NMC cells like EiG).
Calb offer good value for money in a more sensible road vehicle though. Every vehicle has different needs..


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## Bowser330 (Jun 15, 2008)

Jozzer said:


> A123 pouches sag a lot more than Turnigy too - I've got a 72v pack in series with my main Turnigy pack currently (testing for a client) and they drop way more voltage than the 230v turnigy pack does. (of course the A123 M1 cylindical cells are MUCH stiffer than the pouches - in case that's what your comparing against)
> I've seen 2 seperate calb packs literally steaming and warped after a 15 min race. On the road though you would normally spend much less time with your foot down, and give much more time to cool between bursts (ie, you'd never discharge the whole pack in less than 15 mins) - a racetrack is very different - and racers are VERY hard on vehicles!
> 
> The fact that they take up nearly double the space as LiPo also doesn't bode well for race vehicles, or the fact that they are 30% heavier per capacity (or 70% heavier than NMC cells like EiG).
> Calb offer good value for money in a more sensible road vehicle though. Every vehicle has different needs..


Well said.

However, are you not using 21kwh of turnigy cells in your daily driven Miata?

I don't wish to derail the topic too much, however can you share your experiences, good or bad, with using the turnigy lipo cells for daily driving? Hows the quality of the cells held up? Any replacements?
How many miles do you have on the pack? 
How has the energy density held up, any reduction in overall capacity?
Do you draw more peak amps than the continuous/constant rating of the cells? (Do you draw into the burst rating at all?)


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## Jozzer (Mar 29, 2009)

Bowser330 said:


> Well said.
> 
> However, are you not using 21kwh of turnigy cells in your daily driven Miata?
> 
> ...


Hi Bowser,
I have replaced 5kW/h of Turnigy with 72v/80ah of A123 just for the purposes of getting real road figures on the A123 over the winter months for a client - TBH I can't wait to ditch them and replace the Turnigy! They cost more than the 15kW/h turnigy remaining in the car, and took weeks to assemble (I built the Turnigy pack in one day - not including making the boxes of course).

Regarding every day use, I had gone a year with no problems whatsoever, and indeed still had 100% balance despite not a single balance charge in that year (4000 miles and around 80 cycles), but last month I lost a cell (and all it's parallel buddies). I'm kind of surprised that it didn't happen sooner, my pack contains alot of "B" grade cells that I didn't want to fit to race vehicles or sell (only very slight variations from "normal", but I'm very careful when building big packs out of small cells!). Had I been more careful I probably would have noticed that bank going down. I'd say that this fault is the biggest thing to watch out for - but I firmly believe that cells that are going to have this problem DO show anomalies when tested. I've never known it to happen with an "A" grade cell (I've processed/tested/used several thousand of them now, so am fairly confident about that).
I don't count on more than 4.5Ah from these cells (rated at 5Ah) even from new, but just last month after changing the bad cell I ran the pack down to 3.4v per cell and got 70Ah out - making 4.35Ah per cell. I might have got more, but didn't want to push it with an odd cell in the pack..
Interestingly, the A123's were down at 2.9v resting after this run (as good as flat), which either means that they have NOT cycled as well as the Turnigy, or that they don't like the cold weather (around 8 Centigrade that day).

I only hit the pack to around 12C - 80Ah pack with a 1000A controller, so no, I can't get near even the continuous rating (20C) with this vehicle. I wouldn't suggest they be used in an everyday vehicle at 20C though - cycle life seems to drop fast as you approach the limits.
Most of these LiPo will only manage some 60 cycles when hit with thier max rating every run (despite what some vendors will tell you), however used in my car where 12C is only seen very briefly and they are rarely discharged past about 70% I expect 300 cycles+ before I lose that magic 20%.
Of course, as the cells get older I suspect I might have to replace one or two for one reason or another, but that has also been the case with several LifePo4 packs I have experience with.
One thing I don't really know, is how well the calander life of these will be when used daily - I have some packs over 3 years old I have been saving for shelf life tests (they had lost some 10% last time I checked), what I want to know is whether the cells in use will lose 10% in addition to cycle life losses, or including (ie, maybe 150 cycles could have put on these cells over the 3 years and the end result would have been the same).

Hope that helps - tried to write as much as poss since there is so little info about using these in large packs online..

Steve


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## Karter2 (Nov 17, 2011)

Jordysport said:


> Because i am picking up 144 of these cells today for a 60Ah pack.......


 ??? ..Turnigy ??, CALB ,??


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## Jordysport (Mar 22, 2009)

Karter2 said:


> ??? ..Turnigy ??, CALB ,??


Turnigy


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## Karter2 (Nov 17, 2011)

144 Turnigy packs for 60Ahr ?
so is that 10 parallel strings of 14(4s, 5.8Ahr) packs ?
Or which packs & configuration have you planned for 60Ahr ?


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## Jordysport (Mar 22, 2009)

Karter2 said:


> 144 Turnigy packs for 60Ahr ?
> so is that 10 parallel strings of 14(4s, 5.8Ahr) packs ?
> Or which packs & configuration have you planned for 60Ahr ?


12S12P will be slightly under 60Ah as not quite what they are rated at. 

the individual packs are 18.5V nominal & 5Ah


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## Karter2 (Nov 17, 2011)

Any particular reason you went with the 5s packs ?
The 4s "hardcase" bricks give the same result ( capacity, weight, output etc) ..but work out a lot less dollars !. ( approx 25% less)
..and you have hardcase durability.


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## Jordysport (Mar 22, 2009)

Karter2 said:


> Any particular reason you went with the 5s packs ?
> The 4s "hardcase" bricks give the same result ( capacity, weight, output etc) ..but work out a lot less dollars !. ( approx 25% less)
> ..and you have hardcase durability.


firstly i can't find any Hardcase 4s 5800mah cells that exist. 

secondly i assume you are based in the USA, i am based in England, so generally you've gotta take what your offered here there is not a huge selection, hobbyking has a warehouse in the UK now but have very little stock and backorders last for upto 3 months!! these cells were tested on arrival and any duds (of many) were discarded, and for the price i can't really complain. Think it worked out about $51.95 per cell


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## Karter2 (Nov 17, 2011)

Jordysport, I am in Australia, so i understand your "availability" and shipping considerations, but obviously i dont know what is actually stocked in the UK.
So, please just consider my comments as "theoretical" if all other factors are equal !
The largest hardcase pack is a 4s , 5Ahr and is listed at $22.60 or equivalent to $5.65 per cell and $4.52 per Ahr
http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html

The 5s, 5.8 Ahr only show on my site as "Zippy" packs ??
..and at $51+ implies over $10 per cell and $8.80 per Ahr ! 

So you can see there are some good $$ savings to be had if you can get the 4s packs shipped economically.
I realize this is academic now for you, but worth bearing in mind for the future !
Good luck with your project .


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## Jordysport (Mar 22, 2009)

Karter2 said:


> Jordysport, I am in Australia, so i understand your "availability" and shipping considerations, but obviously i dont know what is actually stocked in the UK.
> So, please just consider my comments as "theoretical" if all other factors are equal !
> The largest hardcase pack is a 4s , 5Ahr and is listed at $22.60 or equivalent to $5.65 per cell and $4.52 per Ahr
> http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html
> ...


But also remember that if i bought from hobbyking i would have to get them shipped over here in 10kg batches as they refuse to send more than that, at $125 each shipment, thats $1,250 in delivery for 100kg of cells, plus import duty which i think is 2.7% + VAT 20% plus you have to account for cells being duds out of the factory so and an extra third on to the purchase. 

So with that in mind take the Hardcase 4s 5ah for $22.60 each as there not supplied to the UK would have to buy from the HK warehouse. 

Cell Price $22.6 * 180 *1.3 = $5,288
Delivery (12) $125*12 = $1,500
Customs $6,788 *1.027 = $6,971.28
VAT 20% Total = $8,365.54 

Which equates to over £500 more than i paid, plus the lead time was crucial, I am building to a tight schedule and can't mess around with china and dud cells. 

So in theory yes you are right the hardcase 4s is a better option but when you take into all considerations (which i have over 6 months) this seemed the best option. considering also that the cells are guaranteed to be good and bought from a reputable supplier. It may of cost me a bit more but that is worth it for me for peace of mind as I won't be racing the car only testing it, so got to think of other peoples safety not just mine. 

As I gain further experience with future cars, I am sure i will buy a few cells from hobbyking as and when they come in stock here in the UK. But just need to get this first one off the ground.


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## Karter2 (Nov 17, 2011)

No problem, ..i follow your reasoning !
.. Except the hardcase 4s packs have proven to be very consistent with very few duds, ..So more like a 1-5% max contingency required.
AND it looks like HKUK do list them as a stock item @ $25.68..but on backorder.
..Watch for restock date !
+ dont overlook the benefit of that protective hardcase !


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## Jozzer (Mar 29, 2009)

Karter2 said:


> No problem, ..i follow your reasoning !
> .. Except the hardcase 4s packs have proven to be very consistent with very few duds, ..So more like a 1-5% max contingency required.
> AND it looks like HKUK do list them as a stock item @ $25.68..but on backorder.
> ..Watch for restock date !
> + dont overlook the benefit of that protective hardcase !


 As far as I am aware, volume increases a fair bit with the hard cases - and the cases are just wasted since you have to make a secure housing for such a large pack anyway.
I'd also want to actually check thier weights - they list 2 weights on the HC page, the higher of which would make them heavier cell for cell than the 20C 5s packs. Both these criteria are very important when fitting large packs to race vehicles - Jordy for example has a few MM of headroom for his case..

Has anyone actually tested a large volume of the hardcase packs yet that you know of? I for instance was completely unaware of the high failure rate until I had to test my first batch of 1000! When you ask people who buy just 4-10 packs they don't have a clear indication of the real picture..
I would only ever stock cells that I had tested very carefully in high quantities - I have lost count of the number of times I have been let down or surprised and left with boxes of something no-one can use!


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## Jordysport (Mar 22, 2009)

Jozzer said:


> As far as I am aware, volume increases a fair bit with the hard cases - and the cases are just wasted since you have to make a secure housing for such a large pack anyway.
> I'd also want to actually check thier weights - they list 2 weights on the HC page, the higher of which would make them heavier cell for cell than the 20C 5s packs. Both these criteria are very important when fitting large packs to race vehicles - Jordy for example has a few MM of headroom for his case..
> 
> Has anyone actually tested a large volume of the hardcase packs yet that you know of? I for instance was completely unaware of the high failure rate until I had to test my first batch of 1000! When you ask people who buy just 4-10 packs they don't have a clear indication of the real picture..
> I would only ever stock cells that I had tested very carefully in high quantities - I have lost count of the number of times I have been let down or surprised and left with boxes of something no-one can use!


Out of interest, what is the dud cell rate you have had? 10%, 20%, 50%??


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## Jozzer (Mar 29, 2009)

Jordysport said:


> Out of interest, what is the dud cell rate you have had? 10%, 20%, 50%??


 5% on arrival, another 4% showed up as self dischargers after a month, another 2% (slower dischargers) a few months later. THis was the last batch we ordered - which HC claimed they would run trhough extra testing before they sent them (because we lost so many of the first two batches we had). There was not much improvement over the "untested" first batches TBH.


I wonder about recycling the hardcase ones too - are they easy to take apart? If not it might add a significant cost onto the disposal/recycling fee when the day comes to retire them (which is already expensive - a few pounds (£) per pack depending on volume and location).


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## Karter2 (Nov 17, 2011)

HK always list 2 weights for every pack.. a unit net weight and supposedly a higher, gross packed, weight.
Reports from the guys on ES who have bought large quantities of the hardcase packs suggest they are of equal if not better quality and reliability as the conventional Turnigy packs.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=35263&hilit=turnigy+hardcase
from the HK site data,they are certainly slightly bigger in volume ( different shape ?) by about 15% compared to a similar "soft shell" 4s pack , with no weight difference, but are simply better value for some odd reason ? ( 25% cheaper)
At the end of the day.. you have to go with what suits your application , circumstances, budget and availability, best.


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## winzeracer (Apr 3, 2012)

Thanks for the write up on your Turnigy's Steve. And thank you for taking that controller back. What is the max C rating you feel comfortable running the 20C non-nano Turnigy's at? I have been testing my Turnigy Nano-tech 35-70C, and have been pleased so far not much in the way of abnormalities, though after reading your build thread on the Miata over at ES, I am tempted to retest and do the 6 weeks shelf (self discharge) test. I have also been testing some old Electrovaya LiPo that had been improperly stored ( 30-45% cell fatality), these are large format 35ah LiPo rated for 10C, my PL8 shows about a 15-20% higher IR than the Nano techs.

How important do you think the 6 week self discharge test is?


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## DIYguy (Sep 18, 2008)

Jozzer said:


> 5% on arrival, another 4% showed up as self dischargers after a month, another 2% (slower dischargers) a few months later. THis was the last batch we ordered - which HC claimed they would run trhough extra testing before they sent them (because we lost so many of the first two batches we had). There was not much improvement over the "untested" first batches TBH.
> 
> 
> I wonder about recycling the hardcase ones too - are they easy to take apart? If not it might add a significant cost onto the disposal/recycling fee when the day comes to retire them (which is already expensive - a few pounds (£) per pack depending on volume and location).



Great info on the RC lipo in larger packs Steve, thanks. What is the "bogey" for classifying as a "dud"? Of course you are looking at capacity and IR for initial testing and self discharge (again capacity) for ones on the shelf.... just wondered if there is a significant gap in the good vs bad or where/how u draw the line.

Thanks.


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## Jozzer (Mar 29, 2009)

DIYguy said:


> Great info on the RC lipo in larger packs Steve, thanks. What is the "bogey" for classifying as a "dud"? Of course you are looking at capacity and IR for initial testing and self discharge (again capacity) for ones on the shelf.... just wondered if there is a significant gap in the good vs bad or where/how u draw the line.
> 
> Thanks.


 Hiya,

The "good" ones are all very close in IR and capacity (and of course get further "evened out" when put together in parallel) - the bad ones are all well outside the norm - we never have a tough choice deciding if a cell is "good enough"..
Usually we find a few cells actually DOA, find a few more that have obviously very different IR (and often poor capacity as well), and a small number that are only low in capacity.
A 5C discharge cycle shows most of the problems straight off - the self discharge problem is a bitch though, because it can take a few months to find them all. They very often get worse after a few cycles, so if you aren't patient enough can find yourself with a bank of cells in your car that can discharge itself over just a few short weeks (much less if the pack is left in a low state of charge).


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> Turnigy


Turnigy are great cells, but should not be used for your application. How will you balance your cell packs when charging? If you claim balance wires, then you have a rued awaking coming. You will have to parallel the balance wires, but because of the size, your charging (if works) will be very slow. Good Luck, 8 other teams have purchased the Haiyin cells.


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## Jordysport (Mar 22, 2009)

GeoMetric said:


> Turnigy are great cells, but should not be used for your application. How will you balance your cell packs when charging? If you claim balance wires, then you have a rued awaking coming. You will have to parallel the balance wires, but because of the size, your charging (if works) will be very slow. Good Luck, 8 other teams have purchased the Haiyin cells.


Hi Ron, thank you for your input. If i had gone for Haiyin i would be waiting into 2014 for them, I never received an Email back from Eric hence why I went for the Turnigy cells as they seemed better suited. 

Steve runs the cells in his personal car and has no issues with charging, the cells seem to rarely go out of balance unlike other cells, I will balance them when building the packs and the HVC will prevent overcharge during charge cycles and if capacity is reduced on a cycle I can easily access the pack and balance a cell up if necessary. Am i along the right lines steve? as you've had the most experience with these cells. 

No offense Ron but saying 8 other teams have purchased the cells means absolutely nothing to me, I assume you are talking about Formula Student Teams in which case the application is entirely different the FS cars are built for the tests not circuit racing.


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## Jozzer (Mar 29, 2009)

Thanks Ron - though we have been using these cells for several years now and I believe we know what we are doing by now They have seen MUCH more track use than Haiyin cells have to date - there were at least a dozen bikes built using these during 2011 and 2012 on the race track seeing MUCH more use than a 10s blast down the track

We can charge much faster than we can get power from the wall socket at every track we've ever been too..




GeoMetric said:


> Turnigy are great cells, but should not be used for your application. How will you balance your cell packs when charging? If you claim balance wires, then you have a rued awaking coming. You will have to parallel the balance wires, but because of the size, your charging (if works) will be very slow. Good Luck, 8 other teams have purchased the Haiyin cells.


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## Karter2 (Nov 17, 2011)

GeoMetric said:


> ....., 8 other teams have purchased the Haiyin cells.


 That seems to suggest that they are typical novices who dont know much about battery technology, dont bother to do very thorough research, and are content to believe anything they read on web sites !


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Turnigy are great cells, but should not be used for your application. How will you balance your cell packs when charging? If you claim balance wires, then you have a rued awaking coming. You will have to parallel the balance wires, but because of the size, your charging (if works) will be very slow. Good Luck, 8 other teams have purchased the Haiyin cells.


BTW Ron, am curious to know how many other kinds of cells you have actually used in a vehicle? What are you basing your opinions on?


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> BTW Ron, am curious to know how many other kinds of cells you have actually used in a vehicle? What are you basing your opinions on?


The truth is Turnigy are great cells, but there is no way to properly balance them after more than 6P, no way. The only person on this planet that has built a proper custom BMS for series cells is LithiumStart. I have seen your applications and website, you do not have the proper BMS to build for large applications. Yes, in some motorcycles they will work because they use minimum amps compared to a racing vehicle.


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> Hi Ron, thank you for your input. If i had gone for Haiyin i would be waiting into 2014 for them, I never received an Email back from Eric hence why I went for the Turnigy cells as they seemed better suited.
> 
> Steve runs the cells in his personal car and has no issues with charging, the cells seem to rarely go out of balance unlike other cells, I will balance them when building the packs and the HVC will prevent overcharge during charge cycles and if capacity is reduced on a cycle I can easily access the pack and balance a cell up if necessary. Am i along the right lines steve? as you've had the most experience with these cells.
> 
> No offense Ron but saying 8 other teams have purchased the cells means absolutely nothing to me, I assume you are talking about Formula Student Teams in which case the application is entirely different the FS cars are built for the tests not circuit racing.


You would not be waiting until 2014, maybe 2013 Jan. I have just placed a order for the Haiyin cells that will be delivered in just over 45 days when the new batch has aged.

I find it interesting that you and Jozzer are from UK, hmmmmn....nice sales pitch!


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> That seems to suggest that they are typical novices who dont know much about battery technology, dont bother to do very thorough research, and are content to believe anything they read on web sites !


No, it shows they did their DD. This team used our Haiyin cells! 
_____________________________________________

Hey Ron,

My team and I just wanted to let you guys know how we did during our competitions. We competed in 2 different events. One was in Loudon, New Hampshire for Hybrid Electric category cars ad the other was in Detroit, Michigan as an promotion/exhibition/showcase electric vehicle. We achieved first place in the electric division: 1st in autocross, 1st in design, 1st in electric acceleration, 2nd in open acceleration, and 6th in sales. There were approximately 30 teams that competed in this event.

From the results of the New Hampshire competition, Jayhawk Motorsports was invited to bring the electric car, along with the internal combustion car, to Detroit, Michigan for the regular FSAE competition. FSAE is attempting to incorporate electric vehicles into the regular FSAE competition so we were invited, along with Munich (winners of FSAE Germany electric divisions). Our cars were used as promotion/exhibition/showcase cars, essentially showing the cars off and proving their performance.

In Detroit, we ran a 4.3 second 75 m acceleration run that put us at 10th place overall compared to all cars competing (approximately 120 cars). Munich ran the fastest time of the day at 3.9 seconds. We definitely didn't have enough time to produce a vehicle with traction control for controlled acceleration launches along with electronic differential control. In the endurance event we were running laps times within 0.7 seconds of the fastest combustion vehicles and on average 2-3 seconds faster than the fastest electric vehicle in Germany, Munich, for a 50-60 second lap time.

Needless to say, we created a car that will become a legacy to Jayhawk Motorsports and possibly the fastest electric car that has competed in FSAE events in the world. And we would like to thank you for that. The battery shop dedicated a significant amount of resources helping Jayhawk Motorsports produce this vehicle and we cannot express how much we appreciate that.

Here is the video of our endurance run in Detroit, Michigan
http://www.youtube.com/watch?v=EhfN5ZyWpOY

Here is a picture of the car and electric team.

Thanks!

Emily Dellwig
Jayhawk Motorsports
University of Kansas


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## Jordysport (Mar 22, 2009)

GeoMetric said:


> The truth is Turnigy are great cells, but there is no way to properly balance them after more than 6P, no way. The only person on this planet that has built a proper custom BMS for series cells is LithiumStart. I have seen your applications and website, you do not have the proper BMS to build for large applications. Yes, in some motorcycles they will work because they use minimum amps compared to a racing vehicle.


Ron, my vehicle will be using less peak amps than the motorcycles. and have you ever got your hands on the cells and actually balanced them, hands on experience? 
And my pack is around 13kwh the same size as most of the race bikes.



GeoMetric said:


> You would not be waiting until 2014, maybe 2013 Jan. I have just placed a order for the Haiyin cells that will be delivered in just over 45 days when the new batch has aged.
> 
> I find it interesting that you and Jozzer are from UK, hmmmmn....nice sales pitch!


you really think myself and Jozzer are the same person to make a sales pitch for Turnigy, just look at my history on here, would Jozzer really ask some of the stupid questions i have asked a few years ago? 

As for the Haiyin cells its been nearly a month since i last received an email from Eric, previous to that a further couple of months trying to get through to him! If that's how long it takes to send a quick email then i'd be worried how long the delivery time would take! its just a logical deduction. 



GeoMetric said:


> No, it shows they did their DD. This team used our Haiyin cells!
> _____________________________________________
> 
> Hey Ron,
> ...


You still don't get the point, Formula Student Cars have no point in the world after the year they run, and a test around some cones and a few endurance runs isn't what i would call a race car. hey i've worked in FS before didn't like how it was run and left. 

And an FS car is totally different to my application so how can you say bluntly and boldly that Turnigy cells are not the right cells for the application when you have no hands on experience of the cells (from what you've said). 

I Like the Haiyin cells they seem to be a good cell but issues with building the pack, the low capacity and the overkill on discharge rates make it not applicable for my vehicle, for your drag car it may be perfectly suited, but i can't comment on that because i have no hands on experience of the Haiyin cells likewise you with the Turnigy cells.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> The truth is Turnigy are great cells, but there is no way to properly balance them after more than 6P, no way. The only person on this planet that has built a proper custom BMS for series cells is LithiumStart. I have seen your applications and website, you do not have the proper BMS to build for large applications. Yes, in some motorcycles they will work because they use minimum amps compared to a racing vehicle.


 Actually we developed fully fledged BMS in 2009-2012, but find the LVC setup protects better and doesn't risk killing cells. And of course, when connected up we can balance just the same as you can (ANY bms that can be fitted to a Haiyin pack could also be fitted to a Turnigy pack, or any other LiPo chemistry). It is our customers choice whether they want to use a full balancing BMS setup..


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> Ron, my vehicle will be using less peak amps than the motorcycles. and have you ever got your hands on the cells and actually balanced them, hands on experience?
> And my pack is around 13kwh the same size as most of the race bikes.
> 
> 
> ...


I built the largest Turnigy pack in history, check "Warp Factor II", so I know first hand how the cells work.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> You would not be waiting until 2014, maybe 2013 Jan. I have just placed a order for the Haiyin cells that will be delivered in just over 45 days when the new batch has aged.
> 
> I find it interesting that you and Jozzer are from UK, hmmmmn....nice sales pitch!


 Interesting in what way Ron? Lots of people live in the UK you know..


My observation stands Ron, you've got a few teams with very limited experience THIS year with Haiyin, I know of many times more vehicles fitted for much longer with Turnigy that do not have problems (and have won many races, have stayed balanced, have been charged with ZERO problems).
You cannot offer a balanced opinion if you have only ever tried one product..

I've driven on Turnigy cells in a number of vehicles every day for the last 3 years, have done thousands of miles in real world conditions, and have also built and owned vehicles using at least 8 other battery manufacturers and several different chemstries in the years preceeding.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> I built the largest Turnigy pack in history, check "Warp Factor II", so I know first hand how the cells work.


 In a drag car for 10 seconds...


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> Actually we developed fully fledged BMS in 2009-2012, but find the LVC setup protects better and doesn't risk killing cells. And of course, when connected up we can balance just the same as you can (ANY bms that can be fitted to a Haiyin pack could also be fitted to a Turnigy pack, or any other LiPo chemistry). It is our customers choice whether they want to use a full balancing BMS setup..


I am curious, can you show us all how you would balance say 10P of Turnigy cells?

"ANY bms that can be fitted to a Haiyin pack could also be fitted to a Turnigy pack"
That is not correct, now you are scaring me. You need specially design BMS boards, the only company on the planet that has produced such as BMS board is LithiumStart for John Metric's car. Prove me wrong and show me your BMS that fits series made packs?


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## Jozzer (Mar 29, 2009)

You connect each cell tap to the BMS of course. 
Only one BMS in the whole world - are you serious?

This is V4 of a project I worked on (with Patrick Schindler) for 3 years..
http://endless-sphere.com/forums/viewtopic.php?f=14&t=6602&start=315

There are many many other BMS's that will work fine with these cells - as I said, ANY bms that can balance and manage any other LiPo cell can do it. THere are a large number of manufacturers, as well as lots of homebuilt projects that do the job fine.
If I even thought you would understand how a BMS works Ron...

Anyway, I just wanted to balance your opinion (that no other cell apart from the Haiyin can possibly ever be used in a vehicle of any kind)... from here I'll let everyone make up thier own minds! Certainly got better things to do than argue the toss with you! 





GeoMetric said:


> I am curious, can you show us all how you would balance say 10P of Turnigy cells?
> 
> "ANY bms that can be fitted to a Haiyin pack could also be fitted to a Turnigy pack"
> That is not correct, now you are scaring me. You need specially design BMS boards, the only company on the planet that has produced such as BMS board is LithiumStart for John Metric's car. Prove me wrong and show me your BMS that fits series made packs?


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> You connect each cell tap to the BMS of course.
> Only one BMS in the whole world - are you serious?
> 
> This is V4 of a project I worked on (with Patrick Schindler) for 3 years..
> ...


Will not work properly with a large 10P+ pack. The other issue is the cell tabs and the soldering of wires. The series packs work well for smaller applications, but when you need to pull over 1500amps you will need to parallel extra series packs to compensate for the tab size or the tabs will act like fuses.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Will not work properly with a large 10P+ pack. The other issue is the cell tabs and the soldering of wires. The series packs work well for smaller applications, but when you need to pull over 1500amps you will need to parallel extra series packs to compensate for the tab size or the tabs will act like fuses.


 
Works fine Ron - all packs are paralleled. If yours wern't, then you built it wrong.
At the end of the day, I've got more vehicles out there working correctly under higher duty cycles than you do - and they all still work and are all still balanced..

In your pack, you will connect small wires too each cell interconnect, then plug that into the BMS. That is exactly what we do.
As I say, since I doubt you even know how a BMS really works it's not worth arguing with you about it..

1500A? Look around you Ron - exactly what percentage of cars here are drag cars? I'm not suggesting you don't use Haiyin in a drag car... just that not everyone else reading this page wants drag car. Perhaps the thread title would give that away...


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> Works fine Ron - all packs are paralleled. If yours wern't, then you built it wrong.
> At the end of the day, I've got more vehicles out there working correctly under higher duty cycles than you do - and they all still work and are all still balanced..
> 
> In your pack, you will connect small wires too each cell interconnect, then plug that into the BMS. That is exactly what we do.
> ...


So, you stand corrected, you cannot safely use series cells in a large parallel pack pushing over 1500amps . I do look around me, many need and use battery packs over 1500amps.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> So, you stand corrected, you cannot safely use series cells in a large parallel pack pushing over 1500amps . I do look around me, many need and use battery packs over 1500amps.


I didn't say that at all Ron, the amps pulled are irrelevant - as long as the pack is made larger to give more power then the current at any one place will be the same..
I run at 1000A often, my pack would easily do 1500A peaks, and if I increased capacity it would do more.
That's why we use "C" ratings - it is uselss to talk about amps unless the pack size is specified. A 20C turnigy pack would have to be twice the capacity to safetly run 1500A than a Haiyin pack would need to be...but that's only important if you need less than 2 mins runtime in your vehicle - something that's ONLY useful to drag racers..
You could get 1500A from a Calb pack if you placed enough cells in series..

Many? Funny, I only know of one 1500A+ controller in production, and they have only sold a handful! On this forum 95% of users are using less than 1000A, and 70% less than 600A as far as I can see..


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> I didn't say that at all Ron, the amps pulled are irrelevant - as long as the pack is made larger to give more power then the current at any one place will be the same..
> I run at 1000A often, my pack would easily do 1500A peaks, and if I increased capacity it would do more.
> That's why we use "C" ratings - it is uselss to talk about amps unless the pack size is specified. A 20C turnigy pack would have to be twice the capacity to safetly run 1500A than a Haiyin pack would need to be...but that's only important if you need less than 2 mins runtime in your vehicle - something that's ONLY useful to drag racers..
> You could get 1500A from a Calb pack if you placed enough cells in series..
> ...


Amps pulled does matter when you need 370volts @ 1500amps. You can only bring your voltage up to your controller limits, so amps per cell does matter. Your method of balancing will work on smaller applications, but it takes much longer to charge. And tab size matters when your continuously pulling amps or volts, they will melt, no doubt about that.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Amps pulled does matter when you need 370volts @ 1500amps. You can only bring your voltage up to your controller limits, so amps per cell does matter. Your method of balancing will work on smaller applications, but it takes much longer to charge. And tab size matters when your continuously pulling amps or volts, they will melt, no doubt about that.


 You seem to be confused on a few points..

You can put as many cells in parallel as you need to reach the desired output current, this has nothing to do with number of cells in series.
You could build a pack of 1C cells that can give 370v and 1500A that sags the exact same amount as your Haiyin pack - but it would have to be a very high capacity pack!

Charging speed depends on the power of the charger connected to the pack.
The only possible reason that you would be able to charge a Haiyin pack faster is that the C rate is higher than Turnigy (though the Nano can charge exactly the same speed as the Haiyin- regardless of pack size, dependant only only upon the chargers current output).

Tab size, again is to do with C rating of the cell, if you put more cells in parallel then your tabs pass less current each. The main difference between Turnigy Nano cells and Haiyin racing cells for instance is tab size (which incidentally, doesn't help if your connection methods are worse than the Nano packs connections - which judging by the sag in your pack they are!).

No more time to give you lessons though Ron - I'm off to do some work!


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> You seem to be confused on a few points..
> 
> You can put as many cells in parallel as you need to reach the desired output current, this has nothing to do with number of cells in series.
> You could build a pack of 1C cells that can give 370v and 1500A that sags the exact same amount as your Haiyin pack - but it would have to be a very high capacity pack!
> ...


I am definitely not confused, I know how to build EV battery packs. You touched on what I explained, with series packs you will need more in parallel to compensate for the small thin tabs. That is a fact. Here is your example:

Say you need 4000amps, some series built packs are 100C 5AH = 500amps per cell. You can build a 4000amp pack using series cells (small tabs) 8 in parallel. But, the tabs would melt and you might have a fire. To compensate for the small tabs, you would need to add extra in parallel say 15P (added weight) so your pack will survive.

In regards to the Haiyin cells, it was not my silver coated bus bars that caused the sag. At 400amps each cell dropped to 2.2 volts. At around 300amps each they hold voltage above 3 volts. The cells tabs never get hot, so we are not worried about the tab issue series cell carry.


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## Jozzer (Mar 29, 2009)

Yes - except tabs are not the biggest problem, if the cell is pushed beyond its C rating (which was decided INCLUDING the tab connections in the first place), then the cell itself will get hot and catch fire..
Turnigy do not have "small thin tabs", they have tabs rated for the current they are supposed to provide.

So, I say again, there is not a problem using these in large packs, as long as you use them at a safe C rating. They can be charged and used just as any other cell can be.

The ONE thing that you consider important is having as small a pack as possible for as much power, whereas the main thing 95% of EV'ers need is having as much energy onboard as possible to cover the distance they require, and only a high enough C rating to ensure they are not pushing the pack too hard.

Also, 99% of the people here want more than 100 cycles at thier rated current - which yours will have trouble providing if you are pushing them too the limit at 4000A!







GeoMetric said:


> I am definitely not confused, I know how to build EV battery packs. You touched on what I explained, with series packs you will need more in parallel to compensate for the small thin tabs. That is a fact. Here is your example:
> 
> Say you need 4000amps, some series built packs are 100C 5AH = 500amps per cell. You can build a 4000amp pack using series cells (small tabs) 8 in parallel. But, the tabs would melt and you might have a fire. To compensate for the small tabs, you would need to add extra in parallel say 15P (added weight) so your pack will survive.
> 
> In regards to the Haiyin cells, it was not my silver coated bus bars that caused the sag. At 400amps each cell dropped to 2.2 volts. At around 300amps each they hold voltage above 3 volts. The cells tabs never get hot, so we are not worried about the tab issue series cell carry.


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## Jozzer (Mar 29, 2009)

So Ron, to be clear, YOU stand corrected? You CAN charge a Turnigy pack up fast, and you CAN draw more than 1500A from a suitably sized pack?


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> Yes - except tabs are not the biggest problem, if the cell is pushed beyond its C rating (which was decided INCLUDING the tab connections in the first place), then the cell itself will get hot and catch fire..
> 
> So, I say again, there is not a problem using these in large packs, as long as you use them at a safe C rating. They can be charged and used just as any other cell can be.
> 
> ...


Boy oh' boy, you seem to have a learning issue. We had Turnigy series cells tested by Thomas Cook (Lithium Start), Thomas works for NASA and builds the most advanced packs in the World. If you pushed Turnigy cells for more than 10 seconds at their published C-Rating you would burn the tabs off. That is why "Warp Factor II" needed to build our Turnigy pack much larger than needed. Turnigy are great cells, low resistance, etc.....but not designed for large KW applications.


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## skooler (Mar 26, 2011)

GeoMetric said:


> Boy oh' boy, you seem to have a learning issue. We had Turnigy series cells tested by Thomas Cook (Lithium Start), Thomas works for NASA and builds the most advanced packs in the World. If you pushed Turnigy cells for more than 10 seconds at their published C-Rating you would burn the tabs off. That is why "Warp Factor II" needed to build our Turnigy pack much larger than needed. Turnigy are great cells, low resistance, etc.....but not designed for large KW applications.


...And the solution to that is to build a much larger pack and not push the c ratings.

What is it you don't understand about what Steve is saying?


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> Boy oh' boy, you seem to have a learning issue. We had Turnigy series cells tested by Thomas Cook (Lithium Start), Thomas works for NASA and builds the most advanced packs in the World. If you pushed Turnigy cells for more than 10 seconds at their published C-Rating you would burn the tabs off. That is why "Warp Factor II" needed to build our Turnigy pack much larger than needed. Turnigy are great cells, low resistance, etc.....but not designed for large KW applications.


 Oh dear Ron - I give up - brick wall!

Lucky you had someone else test them, since your idea of testing for sag was at 0C!
Once again, this thread in NOT about drag packs. If having the absolute minimum weight for a 2 min run is important then Haiyin is indeed the best cell I know for the job - for anything else there are better choices - some cheaper, some better energy density, and most having MUCH better cycle life than the HAiyin (or Turnigy - though that wasn't important in this race build).

The question was "cells between Haiyin and Calb" - Turnigy fits that bill, and will do a good job for Jordy, despte you saying he will not be able to charge it fast enough or that it is going to catch fire because the tabs are too small

He spent less money and waited less time than if he had waited for Haiyin, and got to experience what they felt like in a real roadgoing vehicle that has done a lot of miles doing all the things you claim are impossible..


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## Jozzer (Mar 29, 2009)

skooler said:


> ...And the solution to that is to build a much larger pack and not push the c ratings.
> 
> What is it you don't understand about what Steve is saying?


 Lol - thanks Mike!

Watch it though, your from the UK too, he'll likely think we are all partners against him!


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## rwaudio (May 22, 2008)

GeoMetric said:


> I am definitely not confused, I know how to build EV battery packs. You touched on what I explained, with series packs you will need more in parallel to compensate for the small thin tabs. That is a fact. Here is your example:
> 
> Say you need 4000amps, some series built packs are 100C 5AH = 500amps per cell. You can build a 4000amp pack using series cells (small tabs) 8 in parallel. But, the tabs would melt and you might have a fire. To compensate for the small tabs, you would need to add extra in parallel say 15P (added weight) so your pack will survive.
> 
> In regards to the Haiyin cells, it was not my silver coated bus bars that caused the sag. At 400amps each cell dropped to 2.2 volts. At around 300amps each they hold voltage above 3 volts. The cells tabs never get hot, so we are not worried about the tab issue series cell carry.


Hi Ron, please take this as constructive criticism and not an attack...

Ron are you really trying to school these people with much more experience than you on batteries when in the other threads you talk about building a new pack because your first one failed horribly due to voltage sag. You wouldn't take anyone's advice on how to properly parallel cells for the lowest connection resistance? Sure make your cells available as an option, put it out there and let people make their own decision. Don't force it down their throats.

Making turnigy cells work at 4000A is just as possible it would take careful design and assembly in proper connection and termination, but it can be done just as well. 

I won't even comment on your absurd BMS comments, it just shows how little you actually know about the subject.

You went through this the first time around and left the site because you were an ass, make some friends, share and learn from others. Just because you threw the most money at a car doesn't make you the authority on anything. You have come a very long way and I'm very impressed with what you have put together and where you are going with the car, what you lack in experience you make up with determination and enthusiasm. (Take that as a compliment it really is one).

Early in this thread I suggested CALB CA cells, and they were ruled out with reason and explanation due to the application. It's a fair answer that I and anyone should be able to reasonably accept. You should do the same.


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## skooler (Mar 26, 2011)

Just gave you positive rep for that, well said.



rwaudio said:


> Hi Ron, please take this as constructive criticism and not an attack...
> 
> Ron are you really trying to school these people with much more experience than you on batteries when in the other threads you talk about building a new pack because your first one failed horribly due to voltage sag. You wouldn't take anyone's advice on how to properly parallel cells for the lowest connection resistance? Sure make your cells available as an option, put it out there and let people make their own decision. Don't force it down their throats.
> 
> ...


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## GeoMetric (Aug 13, 2010)

skooler said:


> ...And the solution to that is to build a much larger pack and not push the c ratings.
> 
> What is it you don't understand about what Steve is saying?


I understand it 100%, that why I stated it. What is it that you don't understand that adding packs to compensate for small tabs in no solution? It adds weight, it adds cost, it adds addition wiring to control. The max C-Rating of a cell is based on only a few seconds of draw. Series built packs are NOT designed for large applications, that is why OEM, racers, solar, etc...use a different cells or parallel single cells first.


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## skooler (Mar 26, 2011)

Yes its not ideal,

Not everyone needs to do a quarter mile in < 10 seconds, so why would anyone pay ~4 times for something they really don't need?

Its all about compromise, and turnigy is one of the better compromises.


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## Karter2 (Nov 17, 2011)

GeoMetric said:


> No, it shows they did their DD. This team used our Haiyin cells!
> _____________________________________________
> 
> Hey Ron,
> ...


 how does that prove any DD ???
It sounds like they relied on your advice !


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## Karter2 (Nov 17, 2011)

Jozzer said:


> ...... If having the absolute minimum weight for a 2 min run is important then Haiyin is indeed the best cell I know for the job.....-


Sorry Jozz,.....but i cant agree with that.
The evidence to date suggests otherwise.

I can think of cells that would give higher output, less sag, with less weight,
.... and be much cheaper too !!

Ron's original reason for changing packs from the Turnigy pack he ran last year was to reduce the weight..
Well he has gone from about 110kg of Nanotech, to 130 kg of Haiyin ( with sag).
..... But now he is building more similar packs such that he will end up with best part of 300kg pack of Haiyin cells! ( 10P, 65s x 2 packs)

I can understand Ron using & standing by these cells as they are a sponsor... ( at least i hope Ron is not having to pay for these packs !)... but he should know better than to try to spin that sales pitch to guys on here who know better.

This was Ron a few months ago ..


EVDragRacer said:


> Guys,
> 
> Some here remember my battery build the World's Largest Turnigy nano-tech pack in history. 14 (5S) packs in parallel, connected to a busbar 70ah. 10 parallel rows in series to create 185n. I have drag raced this pack all over the East Coast (Team Haiyin EV Racing) (http://www.ECEDRA.com), so far I have charged this pack with NO BMS and all cells have stayed very balanced. I will have to admit, I was suprised they all stay balanced. I have charged this pack over 20 times already and check with the meter each 5S pack, balance is fine, it must be the busbars keeping everything inline. My pack punches 6300amps and 210 volts! The only downfall is the weight (14 - 5SP) because of the tab size. These Turnigy nano-techs are perfect for motorcycles and small EV's. :lol:


Also in May 2011....


EVDragRacer said:


> ... the Turnigy nan-tech Lipo's give you 45C to 90C. They have proven themselves to be worthy. ...
> ....I have built the largest Lipo EV Racing Pack to date, 14P 50S and have beat the crap out of the Lipo's and never had a problem....


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## drgrieve (Apr 14, 2011)

Nice to see some heated discussion!

I'm planning a DD / track car. I'll have around a 24 KWh pack.

Was going to do A123 20ah but with the new Calb cells thinking of taking the weight and power hit for ease of build.

However will they work for heavy acceleration for 5 1.5 minutes laps ( 7 to 8 minutes) and 4 to 5 times over a day?

What is the life cycle loss, density, and extra cost (in rough numbers) to go to a different cell? I haven't seen much information on other cell types.

Thanks


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## Karter2 (Nov 17, 2011)

Drgrieve,
you will have to give a few more details for anyone to comment on your battery choice.
Vehicle weight, motor type, controller, planned system voltage & max amps, etc etc
Initial thought is that 24kWhr pack will need quite a big charger to keep you racing all day !
Where do you plan to run it ? ...E Creek ?


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## major (Apr 4, 2008)

drgrieve said:


> Nice to see some heated discussion!
> 
> I'm planning a DD / track car. I'll have around a 24 KWh pack.
> 
> ...





Karter2 said:


> Drgrieve,
> you will have to give a few more details for anyone to comment on your battery choice.
> Vehicle weight, motor type, controller, planned system voltage & max amps, etc etc
> Initial thought is that 24kWhr pack will need quite a big charger to keep you racing all day !
> Where do you plan to run it ? ...E Creek ?


Hi Karter2,

Drgrieve gives enough info to comment, but obviously shy of being able to quantify cycle life, loss, density, etc. Using a 24 kWh pack, I suspect, means he would not have to charge at the track to accomplish the sessions outlined. Let's look at it.

1.) Each session is five laps where the lap time is 90 seconds. So the session is 7.5 minutes. Four sessions is a total of 30 minutes. If he used all the energy in the battery without any recharge at the track, his rate would be 2C (1/2 hour). So the average power would be 48 kW. Is that sufficient power to yield his desired performance? 

In this scenario he carries the "big" 24 kWh battery in the vehicle all the time but only uses one forth of its energy each session. The battery is used at a 2C rate and therefore does not have to be a "high power" or "high C-rated" type of cell and probably less costly.

2.) Same session of five laps but now uses the entire battery energy during a single session. Now the rate would 8C and average power is 192 kW. He would need to charge 3 times during the day to make the 4 sessions. If you allow 2 hours for a recharge, you charge at C/2 or 12 kW. Not terribly high but considered a fast charge by some.

He carries the same "big" battery as in scenario #1 but has considerably more power to play with. The battery or cell type would have to move into the "power" classification or high C-rate; more expensive and shorter life expectations.

3.) Same day at the track, but let's take a different approach. Use the cell type from scenario #2 but alter the energy to accomplish a single session of 5 laps. Now you have a 8C rate and 48 kW average power. The battery is only 6 kWh, so there is a lot smaller battery mass to carry around the track.

The trick here is to make the 6 kWh pack "swappable" so that it can be removed from the vehicle after the session and replaced with a fully charged battery for the next session. You could travel with a total of 4 battery packs and do no charging at the track, or perhaps 2 battery packs and charge one as the other is being used.

This is just an example and I did not attempt to include details you would need to consider such as minimum SoC and such. I just wanted to show different approaches to pack sizing. For circuit racing, you try to minimize the mass you carry around the track so theoretically want to cross the finish line at zero SoC (and in first place). 

Regards,

major


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## Jozzer (Mar 29, 2009)

Karter2 said:


> Sorry Jozz,.....but i cant agree with that.
> The evidence to date suggests otherwise.
> 
> I can think of cells that would give higher output, less sag, with less weight,
> ...


 As far as I know, the Haiyin cells that Ron is touting are actually Nano cells with slightly larger tabs - which other cells did you have in mind that were lower resistance? 
Note I didn't say that Rons pack was the best - just that I didn't know of any cells that had better power density..

Lol at those old Ron quotes - thanks for that - I try not to read too many of his posts! (actually, come to think of it, he used to be on my ignore list but sneakily started a new profile!).


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## Karter2 (Nov 17, 2011)

Jozz,
Those Haiyin cells may be "nano", but their test results and performance dont seem to represent what we have come to expect from "nano" tecnology.
A quick "paper spec" comparison of published data shows that the new Tunigy Nanotech cells have more capacity ( 6.6Ahr) , less weight (137gms), lower resistance ( 1.2mOhm), and higher "C" rating (65-130)..
Better in every respect than Haiyin ......on paper !
Power density obviously follows suit at 175 Whrs/kg for Turnigy vs 141Whrs/kg for Haiyin
BUT.. the most important factor for the drag strip is that "C" rate...
..and we know,..and Ron has accepted , that the Haiyin can only supply burst rates of 250 A ( 42C) in practice... what we dont know is what the Turigy can do in a real high load situation...
..other than Rons pack from last year with "Gen 1 nanotech ", that powered his previous ( heavier) car , down the track quicker than the Haiyins in this years lighweight version.
The "Tab size" debate is a bit of a distraction in my view since
A) ..i have not seem any reports of tab failure in Nanotech's operating within their spec.
B) Heavy tabs are not an advantage if the cell cannot generate the amps to make use of the thicker tabs.


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## Jozzer (Mar 29, 2009)

Karter2 said:


> Jozz,
> Those Haiyin cells may be "nano", but their test results and performance dont seem to represent what we have come to expect from "nano" tecnology.
> A quick "paper spec" comparison of published data shows that the new Tunigy Nanotech cells have more capacity ( 6.6Ahr) , less weight (137gms), lower resistance ( 1.2mOhm), and higher "C" rating (65-130)..
> Better in every respect than Haiyin ......on paper !
> ...


 Very interesting - thanks. Though who's test results for the Haiyin cell are you basing this on? Ron's Lab, or is there another source with similar results?

I didn't mean to imply that the thicker tabs were an improvement, since I have not tested tha Haiyin OR seen tab heating problems I can't really comment. Just a difference..

TBH I've given up searching for higher power density, Turnigy have more than satisfied me in that respect (I'd always want at least 15 mins runtime on any vehicle worth driving!) - what I seek these days are higher energy density cells. After all - if you can fit more Wh in the vehicle without weight or space penalty then you don't NEED such a high C rating.

Ease of assembly is also very important to most DIY'ers - one reason why Calb/TS type cells are so popular. Working with Turnigy type packs can be fairly easy too - a 20kW/h pack can be connected up in a long days work. Constructing a pack from single cells, coming up with a connection method, packaging and compressing the cells is extremely time consuming - I've got an A123 pouch pack sitting around here that cost more in engineering time than it did to buy the cells! Most DIY'ers don't want to face that..


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## skooler (Mar 26, 2011)

Karter2 said:


> Power density obviously follows suit at 175 Whrs/kg for Turnigy vs 141Whrs/kg for Haiyin


You mean 'Energy density'


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## Karter2 (Nov 17, 2011)

Jozzer said:


> Very interesting - thanks. Though who's test results for the Haiyin cell are you basing this on? Ron's Lab, or is there another source with similar results?..


 Which Haiyin test results ?
..Ron has published the "paper" ( nominal) specs several times.
Ron also posted a Data download from his last run.
Actual load tests results were also posted on the Warp3 thread in the "EV Performance" forum...showing the voltage sag at various loads..250A, 300A and 400+ A
http://www.diyelectriccar.com/forums/showthread.php/warp-factor-iii-now-alive-74864p17.html
Those were from an independent test requested by Ron i believe.


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## GeoMetric (Aug 13, 2010)

rwaudio said:


> Hi Ron, please take this as constructive criticism and not an attack...
> 
> Ron are you really trying to school these people with much more experience than you on batteries when in the other threads you talk about building a new pack because your first one failed horribly due to voltage sag. You wouldn't take anyone's advice on how to properly parallel cells for the lowest connection resistance? Sure make your cells available as an option, put it out there and let people make their own decision. Don't force it down their throats.
> 
> ...


Seems like I have some catching up to do. Rwaudio, the sag from my pack was NOT caused from the connection method, it was caused from the cell's performance. I underestimate the amount of time the Shiva would keep pulling amps from the pack. The connection method is fine and works well.

Now, on the other shoe, you have been bloating for months how your connection method and the Chinese A123 cells were so great. We all now how that worked out for you, so please keeps your comments to yourself, you are no specialists.


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## GeoMetric (Aug 13, 2010)

Jozzer said:


> Very interesting - thanks. Though who's test results for the Haiyin cell are you basing this on? Ron's Lab, or is there another source with similar results?
> 
> I didn't mean to imply that the thicker tabs were an improvement, since I have not tested tha Haiyin OR seen tab heating problems I can't really comment. Just a difference..
> 
> ...


You must have a large stock of Turnigy cell packs just sitting around, keep trying someone will bite.


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> how does that prove any DD ???
> It sounds like they relied on your advice !


They raced Dow Kokam's the year before and had their azz handed to them, they researched all cells produced and made a desicion the Haiyin cells fit their needs best. Thats called DD. And you see the results!


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> Sorry Jozz,.....but i cant agree with that.
> The evidence to date suggests otherwise.
> 
> I can think of cells that would give higher output, less sag, with less weight,
> ...


The main reason for requesting a new cell design was to reduce the number of cells in series. Like I said, Thomas Cook (LithiumStart) tested the Turnigy cells and said the tabs would not last under drag racing conditions, he said they would burn off because of heat. He recommended I over build "Warp Factor II" pack to compensate the stress on tabs. What part of that do you not understand?

Haiyin was made aware of the tab issue and produced the new Haiyin cells with large tabs. 

The other issue was balancing 14P 5S series packs. I used Luke's recomendation on adding large bus bars which helped a little, but the Turnigy cells never balanced correctly. This phony BMS set-up you use on bikes, scooters, and your little car, would not work on a large 4000amp 300+ volt pack, no way impossible. You would have wires everywhere.

One very well known car running series built packs "Black Current" burnt to the ground from this nonsense way of build a large pack. You can call me a bad guy, say I don't know sheet, but you guys know you are wrong for saying to the public building a large EV pack from series cells is safe.


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## rwaudio (May 22, 2008)

GeoMetric said:


> Seems like I have some catching up to do. Rwaudio, the sag from my pack was NOT caused from the connection method, it was caused from the cell's performance. I underestimate the amount of time the Shiva would keep pulling amps from the pack. The connection method is fine and works well.
> 
> Now, on the other shoe, you have been bloating for months how your connection method and the Chinese A123 cells were so great. We all now how that worked out for you, so please keeps your comments to yourself, you are no specialists.


As a matter of fact the connection method is great and I've had minimal sag on good cells. I couldn't be happier with how it turned out and how reliable it has been in use. There is a method that can be used with full tab cells that improves on what I did and would work very well in a racing pack giving minimal sag at ultra high currents. However as you say "I'm not specialist" so you couldn't possibly learn anything from what I've learned, or what everyone else on this forum has learned.

There is something unrelated to the connection method that you were right about.... some of these A123 cells are questionable, I've had big problems with 6 or so cells and loss of capacity in over a dozen others. So from that point of view you were correct in warning people against using them. Most of the pack is still working perfectly but it is a ton of work to reconfigure everything to make it work again.

Good luck with your car Ron I hope you do well with it next season, even though you ignore or dismiss most of the valuable information that that people on this board give you for free you apparently know more and have more experience than all of us combined.


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## GeoMetric (Aug 13, 2010)

rwaudio said:


> As a matter of fact the connection method is great and I've had minimal sag on good cells. I couldn't be happier with how it turned out and how reliable it has been in use. There is a method that can be used with full tab cells that improves on what I did and would work very well in a racing pack giving minimal sag at ultra high currents. However as you say "I'm not specialist" so you couldn't possibly learn anything from what I've learned, or what everyone else on this forum has learned.
> 
> There is something unrelated to the connection method that you were right about.... some of these A123 cells are questionable, I've had big problems with 6 or so cells and loss of capacity in over a dozen others. So from that point of view you were correct in warning people against using them. Most of the pack is still working perfectly but it is a ton of work to reconfigure everything to make it work again.
> 
> Good luck with your car Ron I hope you do well with it next season, even though you ignore or dismiss most of the valuable information that that people on this board give you for free you apparently know more and have more experience than all of us combined.


I read and learn good info and bad info when listening to folks on these forums. Yes, I will agree, some info is very good, but this thread has taken a dangerous turn trying to get EV's to use series built packs. And it seems you put your stamp on it. I thought you knew better. I have nothing against you and look forward to more topics, but this time I know I am correct. Ever hear the term "been there, done that", well enough said.


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## Karter2 (Nov 17, 2011)

GeoMetric said:


> ...., they researched all cells produced and made a desicion the Haiyin cells fit their needs best. Thats called DD. And you see the results!


 Presumeably their research amounted to relying on your specifications...or did they test them ? and decide that they were happy with that sag ?
Either way..they ended up with a 45C cell that is heavier and costs way more than equivalent compettitors cells.
Thats good DD is it ??
The point is, that FS car doesnt need high C cells, or thick tabs..they would have been better off focusing on reducing pack weight !


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> Presumeably their research amounted to relying on your specifications...or did they test them ? and decide that they were happy with that sag ?
> Either way..they ended up with a 45C cell that is heavier and costs way more than equivalent compettitors cells.
> Thats good DD is it ??
> The point is, that FS car doesnt need high C cells, or thick tabs..they would have been better off focusing on reducing pack weight !


You are wrong, for the Hybrid Formula Competition using less amps the sag was very little. The cells are much lighter than most brands, 170g. They made a good choice, they did whip everyone elses azz didn't they?

Now take a hike, your like a pimple on my azz. I have nothing more to say to you. Unless you are building EV race cars, or bikes, WTF is your business posting here?


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## Karter2 (Nov 17, 2011)

GeoMetric said:


> The main reason for requesting a new cell design was to reduce the number of cells in series. Like I said, Thomas Cook (LithiumStart) tested the Turnigy cells and said the tabs would not last under drag racing conditions, he said they would burn off because of heat. He recommended I over build "Warp Factor II" pack to compensate the stress on tabs. What part of that do you not understand?
> Haiyin was made aware of the tab issue and produced the new Haiyin cells with large tabs. .


 The part i do not understand, is how come the "overbuilt" 70Ahr Turnigy pack weighed less than your improved 60Ahr Haiyin pack ??
How heavy will your Haiyin pack need to be before it gives similar performance (results) to the old Turnigy pack ?


GeoMetric said:


> The other issue was balancing 14P 5S series packs. I used Luke's recomendation on adding large bus bars which helped a little, but the Turnigy cells never balanced correctly. This phony BMS set-up you use on bikes, scooters, and your little car, would not work on a large 4000amp 300+ volt pack, no way impossible. You would have wires everywhere..


 Again you are showing your limited experience with pack design and operation. Ballancing is straight forward and you should not have a BMS on that pack at all.



GeoMetric said:


> One very well known car running series built packs "Black Current" burnt to the ground from this nonsense way of build a large pack. You can call me a bad guy, say I don't know sheet, but you guys know you are wrong for saying to the public building a large EV pack from series cells is safe.


 Obviously you have the inside track as to what caused BC to go up in flames..i have seen no details of the actual cause.
But ..those series RC packs sure did make it fast and lightweight..eh Ron ?


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## Karter2 (Nov 17, 2011)

GeoMetric said:


> ... Unless you are building EV race cars, or bikes, WTF is your business posting here?


 "building EV race cars, or bikes" ?.... I thought this was the Batteries and Charging forum ?
And i thought i was answering a question about finding alternatives to Haiyin cells ?
..What exactly are you trying to do on this thread Ron ?


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## winzeracer (Apr 3, 2012)

Actually Jozzer( Steve) does not push any of his products around here or otherwise, i have dealt with him a few times and he is stand up guy. When I requested info from Hayin and the Battery Shop as well as PM'ing you Ron I got no answer from all three despite your attempt to sell your batteries outside of the "marketplace" on this forum.


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## rwaudio (May 22, 2008)

GeoMetric said:


> I read and learn good info and bad info when listening to folks on these forums. Yes, I will agree, some info is very good, but this thread has taken a dangerous turn trying to get EV's to use series built packs. And it seems you put your stamp on it. I thought you knew better. I have nothing against you and look forward to more topics, but this time I know I am correct. Ever hear the term "been there, done that", well enough said.


I do agree that an unskilled person trying to make a high current pack out of Turnigy packs has a good chance of going up in flames. It doesn't mean that it can't be done, or that it would be easy. I'm never going to build a pack like that, but if I were it would be through a systematic approach after testing a pack or two to destruction, first find the limits of the wiring and cell tabs. Test connection methods on the small scale to make sure it works at high currents and then scale it up to full size. I don't believe in active balancing every charge cycle, but I do believe in monitoring at the cell level while charging/discharging. So the balance wires would need to be connected in parallel and brought out safely, that is probably one of the more difficult parts to do while avoiding spaghetti.

My offer still stands to make you a prototype cell connection that would let you compare it to whatever method you plan to use on your next pack. With the scale and cost of your car what do you have to lose? All it takes is comparing a 2S version of your method to a 2S version of my method using Haiyin cells from the same batch, or to be more fair if possible a 3S group with 1-2 connected your way and 2-3 connected my way and you load it down measuring the voltage drop across each set of connections at as close to the same load you would have in the car on the track. I have nothing to gain or lose from this offer but for the EV community and the evolution of electric racing I would love to see you succeed and go well beyond everyone's expectations.


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## GeoMetric (Aug 13, 2010)

Karter2 said:


> The part i do not understand, is how come the "overbuilt" 70Ahr Turnigy pack weighed less than your improved 60Ahr Haiyin pack ?? How heavy will your Haiyin pack need to be before it gives similar performance (results) to the old Turnigy pack ?
> 
> Again you are showing your limited experience with pack design and operation. Ballancing is straight forward and you should not have a BMS on that pack at all. *
> 
> ...


*The "overbuilt" pack was very dangerous and almost caught fire because of out of balance cells.*

*Not much, I decided to add additional copper to cool and carry large amounts of current, something the series cell packs do not have.*

*Then you are a fool. Any large size packs should have the proper BMS.*

*The light series packs did save weight, but the whole car only weighed 1600lbs. The series packs with NO BMS and thin tabs is what caused the fire. I hope you learned something today, I will have to start charging soon! *


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## drgrieve (Apr 14, 2011)

Karter2 said:


> Drgrieve,
> you will have to give a few more details for anyone to comment on your battery choice.
> Vehicle weight, motor type, controller, planned system voltage & max amps, etc etc
> Initial thought is that 24kWhr pack will need quite a big charger to keep you racing all day !
> Where do you plan to run it ? ...E Creek ?


Looking at getting a BMW E30, finished weight will be around 1150 KG (plus driver) if I use Calbs.

Waiting to see results from scott drive or the netgain AC motors, otherwise K11 Alpha and Solition 1.

Would use a 10 KW charger, but unsure of charging facilities on tracks. 

Thinking of replacing stock manual trans with powerglide.

Yeah E Creek, Wakefield park but just for fun, not overly serious - but of course I don't want to look like an idiot with a golf cart.

Hopefully will get a good running car this weekend, so I can try to work out the energy requirements and the gearing I'll need to operate 0 to 200 km/h.

Other choice is a car with blown engine which is much cheaper, but then I lack testing with the ICE.

Does anyone have any data from track racing?

I guess another ceiling limit is motor temp, obviously you can't run 10x continuous power for long ... Is there a rough guide for converting continuous rating to 10 minutes rating?


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## Jordysport (Mar 22, 2009)

Firstly Ron you said earlier at how surprised you were how in balance the cells kept, and now contradicting yourself saying they didn't! 

Anyway for MY application the Turnigy cells are the most suitable, they are the most energy dense in terms of Volume and Mass than Haiyin and other cells. the packaging of them fits nicely into my application for very easy upgrades and or reconfigurations. 

Furthermore unlike the yank tanks the car is what we call over here "light" weighing in at under 615lbs, so to accelerate that requires very little force and with a peak controller current of 600A discharging the cells at 10C is hardly challenging for them, that is 1/2 their contin rating.

I would like this to be the end of this argument as the thread has got way out of hand, and off topic. At the end of the day the question was what cells are in between the performance of Haiyin Cells and Headway cells, and I got my answer Turnigy cells with a C rate in between the two, making it the ideally specc'd pack for my application. Every application is different and one has to accept that some cells are not going to be applicable for all.


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> Firstly Ron you said earlier at how surprised you were how in balance the cells kept, and now contradicting yourself saying they didn't!
> 
> Anyway for MY application the Turnigy cells are the most suitable, they are the most energy dense in terms of Volume and Mass than Haiyin and other cells. the packaging of them fits nicely into my application for very easy upgrades and or reconfigurations.
> 
> l.


If I ever quoted that series packs stayed balanced it was before the complete 14P line caught fire on the dyno. We never used series cells again after watching a 4" flame shoot out of the lexan box, the only thing that saved the car and pack was G10 and our quick response. 

I wish you all the best with your Turnigy cells, they are the best of quality, but not designed for large applications or racing.


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## DIYguy (Sep 18, 2008)

All packs are series connected. If they weren't, you would be using 3 - 4 volts. 

Tab size is only relevant when pushing the C rating to max. Paralleling enough cells of any chemistry reduces the amp per cell requirement. So, u can make it a non issue depending how u design the pack.

John Metric pushed his 45 - 90 C rated Enerland RC Lipo to 150 C in testing. Failure occurred at the discharge to wire solder joint. . . not the regular tabs. 

Any BMS can be used on RC Lipo. . as long as it is designed for lipo chemistry.

Large pack vs small when talking about Lipo has no relevance other than the sheer number of connections etc that goes with any pack build. Discharge current vs C rate and # number of paralleled cells will determine how "stressed" the cells get.

I think that the key to having success with RC lipo in performance applications is to do what Jozzer does. Test, sort, test, sort. Weeding out the weak cells is key to making a reliable pack. Secondly, keeping from stressing them to max C rate will help them live longer and probably stay in better balance. Goes back to design. Other than that, paying attention to sound practices like keeping wires short and using buss bars that can draw some heat away from wire conductors has got to help. 

I would listen to Steve, he has more experience with RC Lipo racing pack building than anyone I know of. Motorcycle size vs car size pack is irrelevant. 

I think you made a good choice Jordy. As long as you weed out the weak ones, use, at minimum LVC/HVC and do a good initial balance (and keep an eye on it), you should have no issues.


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## Jordysport (Mar 22, 2009)

Thank you mate, that means a lot. 

The Cells came through Steve and they were all tested like you said the weak ones weeded out.

Secondly the max i am running them at is 10C (rated at 20C cont 30C peak) and my maximum wire length is 8 inches!!! and i'm using busbars as well. 

I've got methods HVC/LVC boards so on that side of things is all controlled and they have been balanced already but i will double check them when building the pack. 

Its reassuring to hear the points you've covered are ones that have been covered in my pack design. 

  





DIYguy said:


> All packs are series connected. If they weren't, you would be using 3 - 4 volts.
> 
> Tab size is only relevant when pushing the C rating to max. Paralleling enough cells of any chemistry reduces the amp per cell requirement. So, u can make it a non issue depending how u design the pack.
> 
> ...


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## GeoMetric (Aug 13, 2010)

DIYguy said:


> All packs are series connected. If they weren't, you would be using 3 - 4 volts.
> 
> Tab size is only relevant when pushing the C rating to max. Paralleling enough cells of any chemistry reduces the amp per cell requirement. So, u can make it a non issue depending how u design the pack.
> 
> ...


John Metric had Thomas Cook (the same guy that tested my cells) test his A123 RC Lipo's, the tabs are much much larger on John's cells than Turnigy cells. You guys keep attacking me like this is my info, I told you Thomas Cook from LithiumStart tested the Turnigy Cells and posted data. He found the tabs were too small for any large pack using the cells published current. When you use Turnigy in a car, YOU CANNOT get the maximum amps published or you will burn the tabs. If you build a small pack and keep the amps under the published C-Rating they will work fine. Yes, any BMS can be MODIFIED to use series packs, the ONLY true BMS system ever built for series packs is on John Metric's car.


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## GeoMetric (Aug 13, 2010)

Jordysport said:


> Thank you mate, that means a lot.
> 
> The Cells came through Steve and they were all tested like you said the weak ones weeded out.
> 
> ...


Go to the Endless Sphere forum for true insight on how to use bus bars with series packs. Ask Luke. Good Luck.


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## Jozzer (Mar 29, 2009)

GeoMetric said:


> John Metric had Thomas Cook (the same guy that tested my cells) test his A123 RC Lipo's, the tabs are much much larger on John's cells than Turnigy cells. You guys keep attacking me like this is my info, I told you Thomas Cook from LithiumStart tested the Turnigy Cells and posted data. He found the tabs were too small for any large pack using the cells published current. When you use Turnigy in a car, YOU CANNOT get the maximum amps published or you will burn the tabs. If you build a small pack and keep the amps under the published C-Rating they will work fine. Yes, any BMS can be MODIFIED to use series packs, the ONLY true BMS system ever built for series packs is on John Metric's car.


A123 make RC LiPo?
Actually Ron, you are doing the attacking - and actually we think you don't UNDERSTAND the info you are trying to push.


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## DIYguy (Sep 18, 2008)

Jozzer said:


> A123 make RC LiPo?


Ya, I believe Enerland was owned by A123 in the earlier days. Sometime shortly after John got his pack, they bailed out of Enerland. 

For what it's worth, a while before Olly's BC III burnt, he was getting fires after every run. He had balance wires that were all paralleled that would overheat and start burning. (he may have had other issues also). This would indicate the imbalance between cells. . . which could have come from the lack of a good "sort-test-sort-test" weeding out . . . or perhaps were getting aged enough and pushed to the limit enough that they became so poorly balanced. To the best of my knowledge, he hasn't detailed what caused the last major burn where his car was severely damaged. I suspect its related. (by the way, he has a sophisticated BMS also) I believe, but could be wrong, that Ron's Turnigy pack did not undergo the rigorous test-sort methodology either. At least I don't recall ever any mention of it. I did follow all the discussions also, including on ES (which didn't end well). 

Thomas Cook and Derek Barger are also very knowledgeable and competent race pack builders of lithium in multiple formats. I'm not sure that they have used a lot of the RC packs though. Derek has sourced his own pouch lithium similar to what Ron uses and has a lot of race records out there. If Thomas has concerns about Turnigy tab size at it's max discharge rate. . . I would definitely believe it and take that into consideration when using this brand (can we get a look at that publication? I think it would have value to many people). That said, i haven't seen it (doesn't mean it doesn't exist), also, most competent pack builders do not push max C-rate in design stage. Steve, Derek and Thomas are in a different snack bracket when it comes to pack building. I would pay heed to all of their feedback/input without question. It just so happens, we have one of them sharing some info on this thread. Personally, I would soak it up.

No attacks from my side. I'm just watching and learning. I like to say what I think occasionally too. (I have two PL8's and a laptop full of test graphs also ) I think we are all on the same side . . . unfortunately we have a hard time focusing on the technical stuff some times.

Edit; oh, I just wanted to mention, Olly's pack is built from FlightPower (note; Julian Cox issues). Shawn Lawless has a pack of FP also.


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## Jozzer (Mar 29, 2009)

Ahh, so enerland cells not A123. Indeed I tested these years back and rejected them, inconsistant IR was a big problem.

Current flowing over balance taps would indeed indicate that the pack wasn't well matched - different IR cells pushed too hard. Also possible that he was running lots of long series strings in parallel (rather than having each pack paralleled on a heavy bussbar)? I've seen several people attempt this and ALL have had similar issues..

Regardless of which setup you go with, if you want to push a pack full of small cells to the extreme edge of thier capabilities then all cells MUST carefully vetted. All cells are not equal out of the any factory. Of course, if you don't find out before you build your pack you will never have a clue what was the cause of failure, once it's gone bad it's too later to be sure of anything!

THe main thing in this thread though - it's NOT about a drag vehicle - the cells will NEVER see thier rated current of 20C.

Another point - Ron gives a blanket statement saying that the "tabs will fail when pushed to the rated current" - but he is talking about packs that are rated for 2 or 3X higher C rating than the packs we are currently discussing. The tabs of the 20C packs are almost of the same size as the 50C+ Nano packs, and are NOT pushed when supplying 20C (as they may be when trying to push 50C+). 

Personally I have never tested Nano packs too the max - because I am not interested in building vehicles with <1 minute runtime! I have tested the 20C packs too thier rated current, and have found tab temperature to be stable (generally a few degree's above cell temp - which stays within safe limits also).


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## DIYguy (Sep 18, 2008)

Jozzer said:


> Ahh, so enerland cells not A123. Indeed I tested these years back and rejected them, inconsistant IR was a big problem.


A123 Aquired Enerland back in 2008 and dumped them in early 2011. I know Metric pushed the factory for matching IR, perhaps he got a decent batch. His pack seems to be doing ok so far.



Jozzer said:


> Current flowing over balance taps would indeed indicate that the pack wasn't well matched - different IR cells pushed too hard. Also possible that he was running lots of long series strings in parallel (rather than having each pack paralleled on a heavy bussbar)? I've seen several people attempt this and ALL have had similar issues..
> 
> Regardless of which setup you go with, if you want to push a pack full of small cells to the extreme edge of thier capabilities then all cells MUST carefully vetted. All cells are not equal out of the any factory. Of course, if you don't find out before you build your pack you will never have a clue what was the cause of failure, once it's gone bad it's too later to be sure of anything!
> 
> THe main thing in this thread though - it's NOT about a drag vehicle - the cells will NEVER see thier rated current of 20C.


Yes exactly. . . getting on the real topic, precisely why I think he made a good choice. Especially after getting the packs after your sorting process.


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