# Turnigy LiFePo4 batteries with high C rating? Will this setup work?



## Tomdb (Jan 28, 2013)

4.5 ah x 6 x 16 x 3.6 =1555 Wh = 1.55 Kwh
capacity pack x *series* cells x *series* packs x cell voltage = energy capacity

8 packs in parallel gives you 1.55 x 8 = 12.44 Kwh
in Amp Hours that is 4.5 x 8 = 36 ah


Thing is you need to take the qouted specs of these batteries with a grain of salt, especialy the burst discharge so pulling more then 20C will be the max, before serious thermal issues.

Power would then be 12.44 x 20c = 250 Kw pack discharge.

Still I would stay away from these cells and look into a chevy volt pack. Take a look at EV-album to see what it takes to do a conversion, some RX-7's there too.


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## riba2233 (Apr 29, 2015)

These cells are greatly overrated, they are barely 3C continuous. Also, they are hobby grade, so I would stay away from them.


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## dcb (Dec 5, 2009)

rp0029 said:


> ...My calculations indicate that if I put 16 in parallel *series* packs I will get 320(ish) volts, and if I make 8 packs *in parallel*...


8 * 4.5ah=36ah

36ah * 320v = 11.5kwh (energy)

320v * 1080a =345.6kw(power, 463hp)

8 * 16 * 900g=254 lbs

8 * 16 * $56.74 = $7262.72


transwarp max v is 288V fyi, I know nothing about overvolting/overcurrenting them.

I have read the turnigys were used in some drag bikes, and I think they are currently using the 100C+ batteries, but I don't really have any first hand experience, so I would love to see if/how they perform for you and how long they last. 

463hp, even if it is just from the battery would be sweet if the motor can handle it.

throttle, contactor, charger, cables/crimper/lugs, dc converter, 12v batt, custom driveshaft, motor mounts, battery mounts, misc mounts, bms is nice, etc. plus possibly a new rear end if the mazda unit doesn't last.


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## rp0029 (Jun 8, 2015)

Just looking for a battery that doesn't weigh down the car. I don't need a 100 mile range, just want like 20-30. I don't need the extra capacity. So I would like a high C rating. I heard LiPo is dangerous (wife will be mad if I burn down house). Are there any LiFePo4 batteries that have a high burst rating?

What are the volt batteries C ratings?


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## dcb (Dec 5, 2009)

rp0029 said:


> What are the volt batteries C ratings?


The only point of reference I have on that is from here:
"The lithium ion battery in the Chevy Volt has a peak output of 136 kW and a total capacity of 16 kWh."

@355v nominal, 136000w/355v=~383 amps. (C rating is a little too abstract to be useful, but it is 383a/45ah=8.5C )

and there are 746 watts in 1 hp, so 136kw = 182 hp (before controller/motor/driveline losses)

But you do get something of a transformer effect with a motor and controller, so if the motor is limited to 288v, you should be able to buck the 355v battery down to an equivalent of 475 motor amps (383a*355v/288v), maybe... but you still need to limit current draw from the battery to 383a.


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## dcb (Dec 5, 2009)

I was curious, so I looked at the specs on the transwarp 11 hv
http://www.evsource.com/tls_transwarp11_HV.php

they suggest an upper weight of 2200lbs for direct to rearend drive, which an rx7 would easily exceed.

also it lists 75 ft lbs @300A, so assuming you could wring out 475 motor amps, that would be 118 ft lbs, * 4.1 rear ratio =487 ft lbs to the rear wheel.

assuming your tires are 12" radius for simplicity, that is 487 lbs of force accelerating the car, which isn't a lot in a 3000+ car (batteries/people/etc). Plus it starts falling off once the rpms start coming up.

If I figure it right, with that setup, you *might* be able to crawl up a 9 degree slope, till it overheats. sin(9)*3000=469


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## rp0029 (Jun 8, 2015)

Do you think that 136kw peak capacity is burst or sustained? Think I can eke out a 20c burst from one of those suckers? 8.5 C is less than the calb batteries, and to get 1000 amps out of it would require, what, like the equivalent of three complete chevy volt batteries in series, which would take me 150 miles? I don't need that. I would like to have my cake and eat it. 

I would like to find a battery that will give me 1000 amps and 30 miles of range. That is all I need. The Turnigy batteries with the advertised 40c rating would be a dream, if that is accurate. Would there be a way I could test their claims by just buying one of those batteries?

Are there any other batteries that will do this?

Thanks so much.


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## rp0029 (Jun 8, 2015)

dcb said:


> I was curious, so I looked at the specs on the transwarp 11 hv
> http://www.evsource.com/tls_transwarp11_HV.php
> 
> they suggest an upper weight of 2200lbs for direct to rearend drive, which an rx7 would easily exceed.
> ...


I'm showing FD 13b motor with peak torque at 263 ft lbs, with a 3.0 first gear/4.1 final drive, about 3100 ft lbs in first if you dump the clutch at peak torque. Surely that would spin the wheels, and I'm sure torque is about 100-150 or so at 2000 RPM with a normal spirited take off.

So I guess something like 2000 foot/lbs would do? 1500 amps might do it direct drive. Will the warp 11 HV not take 1500 amps at 320 volts for a five second 0-60 burst? If not, can it be modified, or is there another motor that will?
Also, the car doesn't have a transmission in it. I could always add a powerglide.


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## Tomdb (Jan 28, 2013)

https://www.youtube.com/watch?v=HYrhykqpyj4
https://www.youtube.com/watch?v=_dTmndAXsTs


some good data from running it. He states 300 Kw. so go figure 300/16 = 18.75c with a not so bad sag, would say very hard to beat performance per dollar or performance in general. 

Plus price for a volt pack is unbeatable and it comes *assembled * (often not calculated into the build).


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## dcb (Dec 5, 2009)

Tomdb said:


> https://www.youtube.com/watch?v=HYrhykqpyj4
> https://www.youtube.com/watch?v=_dTmndAXsTs


That is encouraging stuff, I assume we have long been into needing some liquid cooling for the pack though (really bad idea to leave it hotter than necessary). Pump, reservoir, 
radiator, hoses, fittings, etc. And we are well into short term power demand territory.



rp0029 said:


> I could always add a powerglide.


you do need either a lot more motor amps or gears I think to have it streetable. if you can get ~2x the power out of the battery then you might have a short term climbing limit of 18 degrees. Which probably won't win any races, but will get you most places.

also from my previous link, it listed 3000 rpm continuous, redline 5000.
with 12" radius tires, and 4.1 diff, you will be doing 60mph @ 3447 rpm, so consider the speed ratio as well.


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## dougingraham (Jul 26, 2011)

rp0029 said:


> I am still analyzing what to do with my RX-7 (FD3S).
> So say I got a Zilla 2k EHV, with a transwarp 11 HV - Direct driven, 4.1 final drive ratio, about 2700 lb car.


I can relate to this pretty well as I have been driving an FB with a WarP9 for over 4 years now. Differences between your proposed setup and mine.

WarP9 vs Warp 11HV. Your motor has a little bit more torque per amp than mine. You can run almost twice the voltage and the peak power is close to twice that of the WarP9. But it is the Torque that matters most. You have a little more torque. I have 277 ft-lb at 1000 amps and I believe the 11 HV has about 300 ft-lb. For comparison this is 0.923. 

I still have the transmission and the car is comfortable to start out in 3rd but feels sluggish in 4th which is 1:1. My final drive is the 3.909 while you have the 4.1 (4.076?) diff ratio. The final drive of 4.1 vs my 5.55 (3rd gear is 1.419 * 3.909). 5.55/4.1 = 1.35

I think the FD's have larger diameter tires than the FB. The circumference of the stock FB is 72.87 inches and of the stock FD is 78.09. A ratio of 1.07

My car weighs 2424 lbs without me in it. Yours weighs 2700 without you. this is a ratio of 1.114.

0.923*1.35*1.07*1.114=1.485

This means my third gear performance will be about half again better than your direct drive performance. If I went to direct drive then the ratio changes to 1.049 so just slightly in my favor.

Based on that the acceleration performance from a stop of your direct drive and my 4th gear should feel similar. Which is the whole point of all the math. And as I said up front it feels wimpy off the line. On the flip side it feels great once you get to 30 mph as the acceleration stays pretty constant all the way to 70 mph.



rp0029 said:


> For batteries, I want to use Turnigy 4500mAh 6S2P 30C LiFePo4s, 120 or so of them.
> http://www.hobbyking.com/hobbyking/store/__10311__Turnigy_4500mAh_6S2P_30C_LiFePo4_Pack.html
> My calculations indicate that if I put 16 in parallel in packs I will get 320(ish) volts, and if I make 8 packs, I will be able to discharge at 30C = 1080 amps. I'm showing that with a 250Wh/mile calculation, that equates to 36Ah, and that allows about 46 mile of range, excluding depth of discharge and peukert effect.
> First, is my math correct?


You said 16 in parallel but I think you meant Series and then later you mention 8 of these so I am basing my analysis on that.

16 in series would give a full charge voltage of 403.2 volts. Too high for the current Zilla. I believe Manzanita says something like 368 volts. This is 14.6 packs so you are stuck with 14 in series. Peak voltage is 352.8 and a nominal voltage of 310.8. 8 packs in parallel gives 36 AH for a total of 11189 kwh. With you in the car at a weight of ~2900 lbs expect 290 wh/mile if you drive sanely. Giving a drop dead range of 38 miles. This would translate into a reasonable range of 30 miles.

If their 30C rating were real you could expect a continuous current of 1080 amps. If you treat this as your never to exceed current you might be ok. Those are not very good batteries. I've tested a few from Hobby King and except for the A-SPEC cells they don't do very well.

The biggest problem with these is they don't last. You might get 300 cycles out of them. If you drop the charge cap to 4.1 volts per cell and never take them down too low you might get 1000 cycles. What are they for price? Around $60 per pack? And you need 112 pack which works out to $6720. 



rp0029 said:


> Second, aside from batteries, controller, motor, what is everything else I need to buy?
> Thanks in advance.
> Ryan


DC-DC converter to keep the 12 volt battery charged that powers the vehicle systems alive. Battery charger. Cables and contactors. Lugs and heavy duty terminal strips. Vacuum pump for the brake assist. Power Steering pump if you want to keep that. Depending on where you are you might want a heater or some kind of air conditioner. Water pump and radiator for motor controller and charger cooling. I used the oil cooler from the GSL-SE for this on mine.


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## rp0029 (Jun 8, 2015)

What about a123 batteries?
http://hobbyking.com/mobile/viewproduct.asp?idproduct=48783

These say they have a 60c burst. Is that accurate?
Seems you could make 7 cells of 100 for 320v over 1000 amps. Would that work?


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## rp0029 (Jun 8, 2015)

Or what about A123 - AMP20M1HD-A - they say 1200 watt discharge - is that accurate? 60 c rating? If so, that is the ticket, unless they don't give you many cycles. Anyone have experience with them?


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## bigmotherwhale (Apr 15, 2011)

i actually bought some of these turnigy batteries when they were half price, i wouldn't buy them at full price, they were being sold off because they couldn't live up to their rated specs even in hobby use people were puffing cells.


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## Yabert (Feb 7, 2010)

rp0029 said:


> I would like to find a battery that will give me 1000 amps and 30 miles of range. That is all I need.


Stop hesitate. Go to the scrap yard and pick up a Volt battery for 2K$.
You don't know at the moment, but you want a Volt battery for your project.
This one is very well build, cheap and powerful.
http://www.diyelectriccar.com/forums/showthread.php/power-capability-chevy-volt-battery-109698.html

Depending of your drive train set up, you will have extreme torque from start (relate to motor/controller) and way enough peak power (relate to battery) to reach insane speed in few second.


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