LiFe 18650 cells !!!

[Ypedal]

Here is a picture of a 144 cell 18650 48v 20ah pack

8 rows of 18 cells, 2 x 24v packs in series.

These may be available in October, i'm still waiting for more details, so sorry for the lack of specifics at the moment.

This baby weighs 15 lbs with bms etc.. 6" x 14" with bms at the end.

The cells are said to be available in 5C ( longer cycle life ) or 40C ( shorter cycle life )..

Aprox price at this time : 1100 to 1200 US $, includes BMS and 5 amp Charger and Shipping from Taiwan !

This would be Xysterific !

[xyster]

Xysterific indeed!

I'm having a hard time with the cell count math on this one.
Each of these cells should be 3.2V nominal and 1.1-1.4AH like the batteryspace 15C and 3C LiFePO4 18650s:
http://www.batteryspace.com/index.asp?P ... rodID=3071
http://www.batteryspace.com/index.asp?P ... rodID=3737

144 cells would contain about 3.2v X 1.2ah X 144 = 550 watt-hours of energy. But 48v X 20ah = 960 watt-hours -- about double.

I think the picture is showing an 8s18p 144-cell 24v 20ah pack, not two in series. A 48v20ah pack should consist of 288 cells in a 16s18p configuration.

Also, the weight of each cell should be about 40 grams -- like the B.S. cells. So 144 cells X 0.04kg X 2.2lbs/kg = 12.6 lbs.

Therefore, I also think that 15lb total pack weight is for a single 24v20ah pack, not two. If that wasn't the case, these cells would have to have a higher energy density than lithium cobalt 18650s -- which doesn't seem physically possible. Each of my 300 2.2ah 3.8v cells weighs 46 grams.

[Ypedal]

Yes, and i also just noticed that i count 17 cells in the picture, not 18, so that's also a bit strange !

I'll try to get more info and report back.

My intention is to get a box of cells for testing that i can assemble myself over the winter months, i'd love to have a bike frame packed with cells and have only a small amount of them outside the frame, ( would like to build a 72v 12+ ah pack of the 40C cells )

[patrick_mahoney]

Xyster beat me to it - while I was typing up pretty much the same thing.. he posted it.

Still, this is interesting stuff. I'd like to see datasheets, Ypedal, when you get them. And I'd like to hear more about them as you learn more.

Call me paranoid, but those look like burn marks on the solder joints on the cells on the left-side of the photo. Maybe they are really stress testing them.



Xy, why 3.2V nom? Most LiFePO4 cells that I have seen advertise 3V nom.

Like these:
http://www.all-battery.com/index.asp?Pa ... rodID=1014

[xyster]

Although LiFePO4 cells possess many advantages over standard lithium cobalt cells, this pack nicely illustrates the primary disadvantage: ~1/2 the energy density.

I calculate I'd need 576 of these cells in a 24s24p pack to approximately equal the 2000 watt-hours of energy actually available from my 300 cell lithium cobalt pack. Just those 576 cells alone would weigh 50lbs, compared to 30lbs for my pack's 300 cells.

[xyster]

Xy, why 3.2V nom? Most LiFePO4 cells that I have seen advertise 3V nom.

Like these:
http://www.all-battery.com/index.asp?Pa ... rodID=1014

"Nominal" is a very fuzzy, imprecise term in Battery Land. In this case, I was just quoting B.S.'s specs:
http://www.batteryspace.com/index.asp?P ... rodID=3071
http://www.batteryspace.com/index.asp?P ... rodID=3737

That all-battery page also cites a

Working Voltage:3.2V

Whatever the heck that means....I suppose just a guide for cell-count in battery packs, and usage in existing electronics?

[Ypedal]

Ok.. i got my pictures messed up... fixed the one above ( lol sorry guys )

[DeeL2003]

Doooooooooood! You just made my day. A 15lb LiFe pack?!?! Sold! (that's if they live up(or close) to their specs. Are these from FalconEV?

[Dingo]

Being that LiFe technology has pathetic market penetration, that could easily be the best deal around. We need more options. I can't find jack out there!

[BiGH]

Being that LiFe technology has pathetic market penetration, that could easily be the best deal around. We need more options. I can't find jack out there!

looks good very large though - energy density isn't the greatest on them, oh well that will only improve with technology eh?

one of those in each panny bag mmmm i can immagine it already hehe

[DeeL2003]

Sorry for my ignorance. But is the above pic the WHOLE 48v pack or is it just the 24v pack? But the whole 48v totals out to 15lbs right? Just checking

[Ypedal]

I count 17 cells in series.

17 x 1.15 ah = 19.55 ah at 20C * for the HI-Power cells
17 x 1.4 ah = 23.8 ah at 5 to 10C * for the Lo-Power cells


17x 8 = 136 cells x 38g = 5.17 kg = 11.4 lbs

11.4 lbs + bms + tape + box over bms= total pack is 15.4 lbs

Now..

I just got clarification, it's 15 lbs per 24v pack ( 3.2v x 8 = 25.6v )

And 1100 $ to 1200 $ per pack ( with bms/5 amp charger / shipping included )

[xyster]

And 1100 $ to 1200 $ per pack ( with bms/5 amp charger / shipping included )

For DIY cost comparison, a similar 8s17p pack of B.S.'s 15C LiFePO4 18650s would cost $756 for just the cells.
http://www.batteryspace.com/index.asp?P ... rodID=3737

[The7]

Seems battery is the main cost of running, not electricity.

Just image how many kWh of electricity one could buy for USD 1000-

If 1 unit cost USD 0.1,
then one could buy 10,000 units.
Assume ebike takes 1 unit per charge and the range is 30 km per charge.

Then the whole range = 300,000 km (200,000 miles).

How many km could an USD1000 battery last?
10,000km? 30,000km? 60,000km? .....?

[Dingo]

Being that LiFe technology has pathetic market penetration, that could easily be the best deal around. We need more options. I can't find jack out there!

looks good very large though - energy density isn't the greatest on them, oh well that will only improve with technology eh?

one of those in each panny bag mmmm i can immagine it already hehe

Now that's what I'm talkin about!

[DeeL2003]

I count 17 cells in series.

17 x 1.15 ah = 19.55 ah at 20C * for the HI-Power cells
17 x 1.4 ah = 23.8 ah at 5 to 10C * for the Lo-Power cells


17x 8 = 136 cells x 38g = 5.17 kg = 11.4 lbs

11.4 lbs + bms + tape + box over bms= total pack is 15.4 lbs

Now..

I just got clarification, it's 15 lbs per 24v pack ( 3.2v x 8 = 25.6v )

And 1100 $ to 1200 $ per pack ( with bms/5 amp charger / shipping included )

Ouch! What a bummer! 30+lbs AND $2400 for 48v. I guess I'll keep waiting.

[Dingo]

http://www.goldenmotor.com/batterypack.htm

This is one of the better deals I've found... at the bottom, the 36v. Can anyone beat it?

[OneEye]

At last report from the Goldenmotor users' forum, they are not currently shipping that battery. They ran into some supply or technical problems with the product they need to work out.

[Dingo]

Crap. Is there a place to post crazy deals on this thing? It seems pretty difficult to find outstanding deals in either ebike parts OR batteries.

[Ypedal]

I think it's because the prices are already as low as they can be....

The market is so small at the moment that there are very few levels before motors/batteries/etc..... go from factory to user.

With large production items you get Factory,Sales,Distributors,Vendors,Stores,Re-sellers,Mom and pop shops.. etc... by the time a product is sold to the consumer it has inflated many % .

Example, i purchased from Crystalyte, i build and sell the bikes, I base my prices on what the other dealers are asking as a general rule and there is very little profit to be made .. It has to be fun to make it worth the effort !

If the E-bike battery market is the same as this model, any less and the vendors will not be around for long before going bankrupt.

There is more to a battery pack than it's price !

[TylerDurden]

^^^Indeed.^^^

I'm dubious if anybody other than the manufacturers can break even on this stuff.

Be skeptical of anything sold in a sealed package. If it looks too good to be true... etc.

Cheating is par for the course in poorly regulated manufacturing zones. Look at the lead scare in childrens' toys... and the melamine in the food protein... I don't imagine it stops there. People now equate "Made in China" with "probably unsafe".

If I thought there was a decent buck in the ebike business, I'd jump in headfirst. But I really can't see where to make a reasonable profit.

[Doctorbass]

Here is another source for these 18650 LiFePo4 cells

https://s.p10.hostingprod.com/@www.voltphreaks.com/ssl/catalog/

Doc