Lithium Iron Phosphate LIFEPO4 technology

[marty]

Still working on electric bike project # 2. Called EV Tech http://www.texaselectricbikes.com ready to buy 2 batteries - Lithium Polymer 36V 15Ah. Out of stock :-(
------------------------------------------------------------------------------------------------------------------------------
What do you all think of LIFEPO4?
Copy from http://www.iloveebikes.com/batteries.html
We can custom design your LiFePO4 battery to fit your needs.

Each of our LiFePO4 cells comes in 3.0volt configuration. Thus from there we can build your own customized cell in 5 Ah, 10 Ah, 20 Ah, 40 Ah, 80 Ah, 16 Ah, etc.

To fit your specific needs, you can can make 24 volt -- 8 x 3 volt, 36 volt -- 12 x 3 volt, 48 volt -- 16 x 3 volt, etc.

Customized pricing is easy.

It is easy to understand our pricing. Each 3 volt cell is $3.50 per Ah. So if you need 10 Ah, it is $35 for each cell and you need 12 cells (12 x 3 - 36) = $420 each (includes our most advanced battery managment system that handles all current flow, high and low level controls, etc)

This calculation can be done for any different type of LiFePO4 battery configuration. We can even customize size and shape to fit your needs.

------------------------------------------------------------------------------------------------------------------------------
I could build a rocket ship with proper instruction. But I am not a electrical wizard. What V?, Ah? would I need for electric bike with Crystalyte 409 rear hub motor in 26" wheel. Want top speed of about 30 MPH and range of about 20 miles. Faster and farther would be OK. Batteries must be light.

Thanks all, for your help with Electric Bike Project # 2

 

[Ypedal]

From what i know.. and i'm learning about them now.. 2 ways to look at them .. Hi power and Lo..

Hi power will deliver the amps with a reduced cycle life.

Lo will provide longer cycle life but you need to size the pack to not exceed 2 C rating..


Example>> Running a 20amp controller.. minimum 10 ah pack ( lighter- less range), if you run a 40 amp controller.. you need a 20ah pack ( heavier - more range)

Cycle life is all " Theoretical " right now.. as no one has put a real 2000 cycles into a pack in every day use, that i know of..... this will take a while to happen.

I should receive mine soon, can't wait.. my main concern is not the cycle life but rather the calender life.. If i can use 150 cycles per year, i'll only be at 600 in 4 years..

 

[Lowell]

For 30mph you'll want at least 72V. ~1100 input watts should get you 30mph on flat ground easily, so you'll need 730 useable watt hours to travel 20 miles. Of course that doesn't take into account stop and go, hills, headwinds and 100kg passengers. :lol:

80% DOD means 910Wh or 12.6Ah @ 72v. A little extra never hurts, so a 72v 13Ah pack will fit your needs with ~20% reserve. If you want to go faster, add more volts. More range, add Ah.

 

[Lowell]

I should receive mine soon, can't wait.. my main concern is not the cycle life but rather the calender life.. If i can use 150 cycles per year, i'll only be at 600 in 4 years..

If the pack works as good as they say, I bet you'll be putting a lot more cycles on it. I'm putting an average of 8 cycles per week on my packs.

 

[marty]

OK.... 72V 12Ah
24 x 3 = 72V
$3.50 per Ah x 12 = $42
$42 x 24 = $1008

Am I thinking correctly?
How are these LIFEPO4 wired together? My battery knowledge is limited to series and parallel.

 

[Drunkskunk]

OK.... 72V 12Ah
24 x 3 = 72V
$3.50 per Ah x 12 = $42
$42 x 24 = $1008

Am I thinking correctly?
How are these LIFEPO4 wired together? My battery knowledge is limited to series and parallel.

Looks like the battery would be both series and parallel. If thats the case, it might be easier from a charging standpoint to have your 72V, 12Ah built as 2, 36v 12Ah, or 3 24v 12Ah, or 6 24v, 6Ah, depending on what kind of chargers are available.

BTW, anyone know what the choices are for chargers?

 

[patrick_mahoney]

How about using a regular lithium ion charger and one of these:
http://www.batteryspace.com/browseproducts/Smart-Cable-for-converting-37V-Li-Ion-Charger-into-10-Cells-LiFePO4--Li-Fe-PSO4-Battery-Pack-(32V).html

 

[eP]

it is very expensive for $3.5 per ah

So what price per Ah is unexpensive for over 1000 cycles durable cells ?

 

[Battboy]

Here’s how a 36 V / 20 Ah pack works:

There are (4) cylindrical cells in the module case. Each cell is 3.3V/10Ah.
Series Connection - will be 3.3V x 4 = 13.2 (marked 12V), and the current hour remains in 10Ah = (12V/10Ah module)

For the 36V/20Ah Pack, we can add (2) sets of series connected modules and form a 36V/10Ah stack set, and these stack sets are parallel connected.

The cells can handle continuous 10C discharge or charging, therefore, a 40-60 Amps Continuous draw is still inside the range of the 36 V / 20 Ah Pack.

Overall dimensions of this pack would be Length: 12.6â€￾, Width: 6.3â€￾, Height: 6.3". The 36V/20Ah battery pack with BMS is approximated 12kgs, (26 lbs.) and the charger is around 2kgs. (4.4 lbs.)

Technically, our LiFePO4 batteries are lithium ion. It is just that the Olivine batteries (such as iron phosphate) choose not to use the term, "lithium ion" to distinguish them from the more dangerous cobalt and manganese oxide batteries. The difference is in the propensity toward forming metallic lithium deposits, not in the use of lithium ions to store energy. NOTE: All Lithium batteries are considered “hazardous cargoâ€￾ and must be shipped by ocean freight – even those that fall in the LiFePO4 classification.

You may be familiar with the power tool batteries which are 18650 LiFePO4 batteries made in China and commonly used in De Walt power packs and the Tesla Roadster. Ours are 40138 format cells - rated 3.3V/10Ah, much larger than the 18650 format cells, and are made in Taiwan. Our factory manufactures the raw cells and the complete battery packs including a “balancingâ€￾ BMS and charger for these packs. The larger cells require fewer of them and a much simpler BMS to manage them in straight talk. Perfect for the e-bike application!

I know pricing is on everyone’s mind, but we have to wait a little longer for this to shake out. If you have been searching the internet looking for LiFePO4 packs you know there is very little or no inventory available at any price at the moment.
Our factory is telling us they will finish the tooling and be able to furnish test packs by the middle of June now. I read this to mean that by August or September the new LiFePO4 battery packs will be landing by ocean freight ready to ship to a hungry market. At 1,500 Life Cycles and 1/3 the weight of Lead Acid with a 2 Hr. charging time, one can see why these will be in high demand.

Don Harmon

 

[Lowell]

Are you saying that the A123/Dewalt M1 cells are made in China? Is this true?

 

[Battboy]

All 18650 cells are as far as I am aware of. Why does this surprise you?

Don

 

[Lowell]

I wouldn't have guessed they were made in China considering the price A123 charges. Emoli is a short bike ride away from my shop, and manages to be significantly cheaper than A123, although the Emoli cells don't have the high C rating or ultra quick charge ability of the A123. I doubt either are an issue for EV's except for drag racing.

http://www.rcgroups.com/forums/showthread.php?t=594726

 

[eP]

it is very expensive for $3.5 per ah

So what price per Ah is unexpensive for over 1000 cycles durable cells ?

I can get it for $2.5AH PER ah.

How many cycles are guarantee at what dod percentage ?
Would you like to give as full technical specification ?

$2.5 per Ah for what quantity ?
What is the freight/delivery cost ?

Have you any business partners in Poland ?

 

[Dingo]

At this point I feel as though I've decided to use LiFePo4. I was going to go SLA so I could afford my kit like tomorrowish, but I want range with my volts without having a 100+ lb bike, and I don't want to go dumping 6 buckets of lead into the ground every year, either. I'm doing this to save the world after all

As someone who hasn't got a kit yet and is trying to find the pitfalls before he buys (and don't be afraid to speak g33k w/ me, I'm sorta into DC): if you were to have 4 lifepo batts in the 36v x 15ah denomination, would you be able to easily swap them from a 72v x 30ah to a 36v x 60ah for a long ride, or would you have to swap controllers, etc? I'm speaking specifically about crystalyte's 35a 36-72v 5 series controller.

I guess my question is... with these 36-72v controllers... is changing your voltage really as easy as rewiring your batts? I'd love to make a 3 way switch that had three settings: balls, distance, and charge. The easier this is to make convenient, etc, the more I'll use it instead JEEP.

Thanks guys... I'm glad I found a collective brain out there... e-bike documents are sorta few and far between.

 

[Ypedal]

Yes, the clyte controller can take from 36 to 72v ( 29v low voltage cutout ) to about 95v fully charged pack, as simple as un-plug.. re-plug. no switches or jumpers involved etc...

 

[xyster]

As someone who hasn't got a kit yet and is trying to find the pitfalls before he buys (and don't be afraid to speak g33k w/ me, I'm sorta into DC): if you were to have 4 lifepo batts in the 36v x 15ah denomination, would you be able to easily swap them from a 72v x 30ah to a 36v x 60ah for a long ride, or would you have to swap controllers, etc? I'm speaking specifically about crystalyte's 35a 36-72v 5 series controller.

I guess my question is... with these 36-72v controllers... is changing your voltage really as easy as rewiring your batts? I'd love to make a 3 way switch that had three settings: balls, distance, and charge. The easier this is to make convenient, etc, the more I'll use it instead JEEP.

72v30ah provides the same range as 36v60ah -- total watt-hours of energy is the same in both cases.
So long as you can control yourself as far as the throttle and speed goes, there's no reason to rewire.
As a real-life example: I have an 80volt 33ah pack, 72v35a controller, and a 5304 motor in a 20" wheel. At the normal 80 volts, cruising on level ground at 20mph requires 5 amps of current (400 watts since 80v X 5amps = 400 watts). When I've ridden with half the pack (40volts 33ah), cruising over the same ground at the same speed required 10 amps (again 400 watts since 40v X 10amps = 400watts).
More voltage allows you the option of riding faster. Riding faster will drain the batteries much faster. But just because you can, doesn't mean you have to.

 

[Ypedal]

But most people do !

 

[xyster]

But most people do !

Dingo has a hydroponic veggie garden -- he's definitely not 'most people'.

 

[Ypedal]

" veggie garden " is that what they call it these days ? 8)


But i agree with X on this one.. if you have high-voltage potential on board.. just pump the volts to it and have fun ! switching to lower voltage is a drag in more ways than one.

 

[xyster]

" veggie garden " is that what they call it these days ? 8)

I wouldn't know.

But i agree with X on this one.. if you have high-voltage potential on board.. just pump the volts to it and have fun ! switching to lower voltage is a drag in more ways than one.

I do know the throttle is already a voltage divider. The only reason I see for series/parallel switches, jumpers and such is if the throttle is too sensitive at high voltages and very low speeds. The only complaint of such throttle hypersensitivity I've read is a recent post from a member here using 115 volts with a modified 20 amp controller.

 

[Jozzer]

Are you saying that the A123/Dewalt M1 cells are made in China? Is this true?

They may well be made in china, but they are not 18650 cells, they are 26650. http://www.a123systems.com/newsite/pdf/ANR26650M1_Datasheet_FEB2007-1.pdf

 

[Dingo]

Brilliant, brilliant. Thank you very much for the replies... I see it's obvious I, (and maybe the industry, too?), should be speaking in watt hours. Lesson well learned; you're not a teacher are you, xyster?

I think you're right that I'm not most people, too, hehe. In fact that's what I respect about you guys, (nods head to safe, et al), you're not afraid to think in ways that make you stand out. The world needs more people like that.

I guess I would use the balls if they were there on short and daily runs, but when on a distance ride I would ride for distance, yes. That means this project just got easier and more feasible. Thanks guys!

 

[xyster]

Brilliant, brilliant. Thank you very much for the replies... I see it's obvious I, (and maybe the industry, too?), should be speaking in watt hours.

Yes, electrical energy capacity should be reported in Watt-hours, not amp-hours. Amp-hours are not even a measure of energy. Just one of those dumb things that got baked into the system....

Lesson well learned; you're not a teacher are you, xyster?

No, not unless you count all the stuff I've taught myself.

I guess I would use the balls if they were there on short and daily runs, but when on a distance ride I would ride for distance, yes. That means this project just got easier and more feasible. Thanks guys!

Yep, just wire for the highest voltage you're interested in using, then if you find you need more range:
-slow down
-accelerate more gently
-pedal more
-add a fairing, or ride in a more aerodynamic tuck or semi-tuck.

You mentioned a 72v30ah pack. That's over 1700 watt-hours if you run it down to 80% or so (so the batteries live longer and you don't run the risk of killing any by fully depleting any).

20mph on an upright bike on level pavement typically requires about 400 watts to maintain; 25mph requires about 800 watts to maintain. So if you ride 20mph on the level and don't pedal, with that pack you should be able to ride over 80 miles in 4 hours time; at 25mph, range will drop to a bit over 50 miles and 2 hours. Of course, most of the world isn't level...but that should provide an idea of the outside range limits.

 

[TylerDurden]

The issue of partial throttle at a higher voltage may be worth reviewing:

The7's testing of 48V at 67% duty cycle seemed to produce a loss of about 15%

http://endless-sphere.com/forums/viewtopic.php?p=25069&#25069

Makes me wonder...

:?

 

[xyster]

I'd be interested to see that test done under various load conditions.

The 6 W extra loss at 50% duty cycle and no load probably does not extrapolate to a 20% extra loss under load -- which would be extreme, and something I or other people would have noticed -- but only a ~6 W loss no matter the load. A loss of 6 W out of, say, 1600 W would not be unexpected, or probably noticeable. I personally wouldn't bother rewiring my batteries for only 6 watts difference.

Power input = 29.3 W for 24V battery; 100% duty cycle
Power input = 33.1 W for 36 V battery; app 67% duty cycle
Power input = 35.5 W for 48 V battery; appr 50% duty cycle