look them up, they’re LiFePo, they just call them Lithium Ion. If you look up their MDS datasheet (chemical), it says inside it that its LiFePo.
great news, thanks for the info frodus
No problem. I’ve been following this topic since it started… I’m interested in the group buy for batteries for my motorcycle project
and
pics.evfr.net for pictures
Greetings. I linked to your site (and registered) from ‘EV Finder’. I’d be interested in replacing the seven 12-volt lead-acid bricks in my EV with lithium substitutes at a reduced price.
I’m a newbie who might be interested as well. I’m sort of in alex’s position - still trying to figure out what I need. I have a donor vehicle (jeep cherokee), and have decided on AC drive. But I have not sized or selected a motor and controller. I have also been trying to get up to speed on the energy/power density issue, economic life, drive cycle requirements, etc. Please keep me in mind on the order; I’ll try to follow the thread.
Glad to see so many people are interested!
A few things to keep in mind when selecting your battery pack:
-Range
You can calculate your approximate range by finding a car with similar weight, size, motor etc from the list below, it will have a WH/Mile rating. To use this number, you first need to decide how many miles you want your EV to go. So theoretically I will have a car that should get 350 WH/M, I multiply this number by the milage I want (100 miles) so I get 35,000 WH. Now you must divide this number by your system voltage. A little not about voltage, make the voltage as high as your system will allow. I want a voltage of 348 V so I take 35,000 and divide it by 348V to get my AH rating wich is about 100.5 AH. So I need a pack that has 348V and 100 AH. Li-Ion comes in 3.2v cells so I need 109 cells to get me to 348.8V. Although there is no 100 AH cell, there are 60AH cells that I can use twice the cells for to get me a total of 120AH. (a little extra range never hurt)
Ford Ranger (Production) 400 WH/Miles, AC, 4,750 lbs, 312V
Toyota Rav4 (production) 250 WH/Miles, DC, 3,500 lbs, 288V
Small truck (4wd) 366 WH/Miles, DC 9", 4,060, 192V
Small truck (eff. 2wd) 300 WH/Miles, AC, 4,880, 312V
Medium Sedan 345 WH/Miles, DC 9", 3,650, 228V
Micro car 133 WH/Miles, DC, 1,750, 120V
Small Car 250 WH/Miles, DC 8", 3,280, 114V
Aerodynamic Small car 180 WH/Miles, DC 9", 2,725, 240V
Small SUV 200 WH/Miles, AC, 1,650, 600V
-Discharge rate
Another aspect to take into concideration is your discharge rate. If you have a single DC motor, like a 9" or less, you should not draw enough current to have to worry about this with these perticular cells. However, if you have a much more powerful system, you will have to. These thundersky cells have a constant rating of 3C and an impulse rating (about 10 sec) of 10C. This means that a 90 AH cell will put out 270A constantly and can peak its output to 900A for 10 seconds. But do not think that lowering your voltage to increase your AH will get you a higher discharge rate. If you are lowering the voltage of the pack, you will need to increase the discharge rate from the batteries. In other words, the higher the voltage, the lower the amperage. An Ideal EV system has very High voltage and low amperage. There is really no way I can help you calculate how much current your EV will draw. However if you find that you need more power after you have purchased your lithium pack, you can always add a capacitor stack along with your battery pack. I can explain this later if anyone thinks they will need more amperage than their pack can dish out.
-Time scale
I am hoping to have an order in by late February, early March. Does this seem like a feesable time scale?
-Latest pricing
The pricing on the thunder-sky website is now saying that if we get more than 510,000 AH it will only cost $1 per AH. So that is 50% off! Recalculate and let me know!
Keep us updated!!
Thanks! Feb/March would give me about the right motivation. I need to select & purchase motor/controller as well (3xx V AC).
Question: Why divide your W.h/mi by what I think I understand to be your full-charge voltage of 348? Wouldn’t you want to divide by the nominal operating voltage, or some voltage that represents the “average” voltage over the typical discharge cycle? That would give you a higher A.h needed.
Before you jump into that bucket of fish;
You better ask everspring about;
Charger (s)
impedance of cell
battery mgmt system
why only 1000 cycle life ?
recommended 1C discharge ?
And… why is no major EV company or [B]any [/B]other U.S. EV outfit using them ? They are the cheapest for a reason. Try and find out why.
And…would’nt a cell w a higher C rate give you the power you need with fewer total Ah, thus costing much less…hmmm ?
Hi there,
This is a very interesting discussion. Here is a link to another forum that might interest you: http://visforvoltage.org/forum/batteries-and-chargers/1758
You can also check out this link included in the thread: http://zeva.com.au/tech/LiFePO4.php Here is a test that might interest you. Cheers,
Daniel
[QUOTE=roadrailer;1256]
Question: Why divide your W.h/mi by what I think I understand to be your full-charge voltage of 348? Wouldn’t you want to divide by the nominal operating voltage, or some voltage that represents the “average” voltage over the typical discharge cycle? That would give you a higher A.h needed.[/QUOTE]
I am sorry, was not thinking correctly. That is what you want.
[QUOTE=Lectrol;929]So i found out that there is a lot of money to be saved when purchasing batteries in bulk. So here are the prices of THunder sky batteries are the best for EV conversion…
Nominal Nominal Max Discharge Cycle Life Dimension Weight List Price
Voltage capacity Current (80%DOD) (mm) (Kg) US$
@ 0.3C (Continuous)
TS-LFP40AHA 3.2V 40AH 120A 1000 190x116x46 1.5kg $80
TS-LFP60AHA 3.2V 60AH 180A 1000 215x115x61 2.5kg $120
TS-LFP90AHA 3.2V 90AH 270A 1000 220x145x68 3.0kg $180
TS-LFP160AHA 3.2V 160AH 480A 1000 285x182x71 5.6kg $320
TS-LFP200AHA 3.2V 200AH 600A 1000 285x182x100 7.6kg $400
TS-LFP400AHA 3.2V 400AH 800A 1000 452x288x71 13kg $800
TS-LFP800AHA 3.2V 800AH 800A 1000 850x288x71 25kg $2000
The discount goes:
Volume (Ah) Discount on List Price
Per Order Discount %
less than AH
200 0.00%
1,000 5.00%
3,000 7.00%
5,000 10.00%
10,000 15.00%
15,000 20.00%
20,000 25.00%
40,000 28.00%
60,000 30.00%
80,000 30.00%
100,000 32.00%
200,000 33.00%
400,000 34.00%
600,000 36.00%
800,000 38.00%
1,000,000 40.00%
So since I am getting 48x 400AH packs, thats $19,200, so i am only saving 20% I am hoping to get to 1,000,000 AH. But i think that is unlikely. So if anyone would like to go in on a group purchase, let me know. I will be placing the order within a year.
Other links:
Thundersky webpage: http://www.thunder-sky.com/products_en.asp?fid=66&fid2=70
Supplier: http://www.everspring.net/txt/product-battery-pricing.htm
-Leif[/QUOTE]
Correct me if i’m wrong but you say you are getting 48x 400 amp packs . This would mean that your total amphours ordered would be 19,200 (400 x 48). That would put you in the 20% discount bracket (although I’d say go ahead and the the extra 2 pack to make it 25% discount).
Now the price is (48 x $800 ) - 20% = 48 x $800 * .8 = $30,720 (not $19,200 as you typed. Hope this helps)
I have actually changed my plans for what, and how many cells I am planning on using. I am using 160AH cells and using 95 of them. that is 15200AH
I was until today interested by Thundersky batteries. But please check these two things out:
http://www.electric-echo.com/blog/
and
[ame]http://www.youtube.com/watch?v=FB1iKYgKSqo[/ame]
Maybe you should consider other options.
That video talks about ThunderSky Lithium Cobalt batteries. The ones we’ll order are Lithium Iron Phosphate (LiFePo4).
And about that blog post:
I notice that for their 160Ah cells they specify a maximum constant discharge current of 480A (3C) yet a “standard” discharge current of 48A (0.3C), presumably to get >2000 cycles (80% DOD). 48A is barely enough to maintain my EV at 40km/h on the flat. So how many cycles do you get when you need much more than 48A for normal driving? I don’t know and as far as I know neither does anybody else.
All batterie capacities advertised are what you’d get with a slow discharge. Have a look at other manufacturers, it’s the same I think.
I read somewhere that the first amercian batch of LiFePo4 cells had alot of problems, but that ThunderSky had fixed them…not sure though…anyway you’re always taking a risk buying something at half the market price
I have a feeling that the a123 offers much better quality then Thunder-Sky, and much better performance(higher c span and w/kg). I did some calculations and came up with the following:
You can buy the Dewalt DC9360 and get 10 of the fantastic ANR26650M1 cells from a123.
I would appreciate if someone would comment:
a123 v.s. TS
cellvatt 3.6 3.2
packs 2319 100
ah 2.3 60
wh 19200 19200
kg/pack 0.072 2.5
Total kg 167 250
price/pack 5 120
Total USD 11’594 12’000
What is not clear yet is how to manage the pack you build with BM. Here are some thoughts: http://endless-sphere.com/forums/viewtopic.php?t=2498&highlight=&sid=d10f1706d5a55c2650c09cfb97471b46
[QUOTE=dangie;1460]I have a feeling that the a123 offers much better quality then Thunder-Sky, and much better performance(higher c span and w/kg). I did some calculations and came up with the following:
You can buy the Dewalt DC9360 and get 10 of the fantastic ANR26650M1 cells from a123.
I would appreciate if someone would comment:
a123 v.s. TS
cellvatt 3.6 3.2
packs 2319 100
ah 2.3 60
wh 19200 19200
kg/pack 0.072 2.5
Total kg 167 250
price/pack 5 120
Total USD 11’594 12’000
What is not clear yet is how to manage the pack you build with BM. Here are some thoughts: http://endless-sphere.com/forums/viewtopic.php?t=2498&highlight=&sid=d10f1706d5a55c2650c09cfb97471b46[/QUOTE]
The a123 batteries are almost certainly quite superior, and if you have the money, I would defiantly suggest buying them over the Thunder Sky, but when I looked up the prices the A123 batteries were 4-5 times the price of Thunder Sky.
Where did you get the price in your post from, I sure like the looks of that, if it’s correct.
I’m looking to buy a 156volt 90ah pack for my car, for Thunder Sky I get $7200, for A123 $25,000 Thanks, Eric
Hello,
I am sorry that I forgot to give a reference to the a123 prices, and I guess that I might have been a bit unrealistic. I have seen them on ebay for 50USD/pack but that excludes shipment and sometimes they sell for more then twice this amount. http://cgi.ebay.com/DeWalt-DC9360-36V-NANO-Lithium-Ion-36-Volt-Battery-NEW_W0QQitemZ230198418296QQihZ013QQcategoryZ20794QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
My idea was that perhaps it will be possible to make a large bulk purchase via an ebay reseller for a price in the range of 50-100 uds per pack?
how many AH are the dewalt packs anyway?
A guy at work has a deal that puts the LiFePo at about 1.95 an Ah. I’ll need twenty 50Ah cells, so about 1000Ah. Still not bad. But then you have to put into acount, the BMS needed.
I have not found anything bad about the LFP cells we are planning on getting. I just sent an email to TS regarding cycle life and dsicharge rate. I also asked a few questions about the warrenty. I will keep the thread updated when i get a response. ITs too bad that there werent a lot of companies making the same cells. that would give us great company competition as well as choices! oh well, we have to work with what we have…
do they have a BMS already designed for their own batteries?
I’m helping a company test/build/design one, but its a ways off. we’re working on the 500A DC controller first.