# Sky Energy LiFepo4 cells



## FalconEV (Aug 21, 2007)

Bulk buy being shipped out 1st of June
order by May 25th to receive them end of June
$1.10 per Ah, plus expenses bringing to USA to west coast
100 Ah or 180Ah cells
add your domestic shipping onto that
contact falconev at gmail dot com


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## Stunt Driver (May 14, 2009)

looked up details, and turns out LiFe batteries are still 5 times the cost of Lead batteries, comparing same voltage-A/H
As for myself, may not afford it yet.

Or am I missing something?


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## dimitri (May 16, 2008)

You are missing the lifecycle of these cells, they are 7-10 times more charge cycles than Lead Acid, and they weigh half as Lead Acid. Also, if you compare AH listed for LA and LiFePo4, then you must reduce LA numbers in half, to accound for Puekert loss.

So, when you adjust everything to compare apples to apples, LiFePo4 batteries are much cheaper than LA, although the initial cost may be prohibitive, so I give you that....

Think of it as investment in energy independence for next 7-10 years....


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## Technologic (Jul 20, 2008)

Stunt Driver said:


> looked up details, and turns out LiFe batteries are still 5 times the cost of Lead batteries, comparing same voltage-A/H
> As for myself, may not afford it yet.
> 
> Or am I missing something?


You are missing something... 

Let's take the Trojan deep cycle (often used in conversions these days)
http://solardyne.stores.yahoo.net/trojdeepcycb.html

$199 for 225AH x 6v... These will last anywhere from 20,000-40,000 miles (with about half of that in useable energy due to Peukert effect and general safety zone so your batteries won't die after a couple weeks). so roughly that lead acid, which weighs about 8 times as much as LiFePO4, has about 6v x 100AH to use... safely (though you might see even less than this if you're pulling significant amperage), someone who has more experience with a high amperage draws on lead acids could help here.

Sky Energy prices are $1.1/AH for proven batts. or $99 for a 3.2v nominal x 100AH with roughly 90% of usable energy (safety voltage) and no Peukert effect so... two of them in series means a 6.4v x 100AH battery with 90AH useable... for $198.

Roughly the same price as lead acid, 1/8th the weight, and last anywhere from 150,000-400,000 miles depending on storage temp, charge during storages, etc.

There's several examples of Lithium battery car systems getting 100 miles of range on 10kwh or so... I'm not aware that there are any lead acid cars, even with 28kwh+ that can do 50 miles of range... Lead acid is a huge huge diminishing return kinda thing.

You start trying to gain range, then you need bigger and bigger motors to power the weight, higher and higher amperage controllers etc.


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## grayballs (Aug 27, 2008)

dimitri said:


> Think of it as investment in energy independence for next 7-10 years....


 
Well said,,,, now I hope their track record proves out. They haven't been around long enough to prove expectations. That is the only downside that I see.

'Just one old guy's opinion


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## dimitri (May 16, 2008)

grayballs said:


> Well said,,,, now I hope their track record proves out. They haven't been around long enough to prove expectations. That is the only downside that I see.
> 
> 'Just one old guy's opinion


That's what most skeptics say, and I don't blame you, but every single record I found and I read many reports from people who bought first batches of TS cells ( with exception of their disasterous run of LCP cells, lets not confuse those with LFP cells ), all LFP cells that have been used for 3-4 years by now pretty much behave like the day they were made. Also, details of the chemistry and production process led me to believe there are no reasons why these cells can't handle promised 3000 cycles if they are used properly and kept above 20% DoD.

I truly believe this technology is the breakthru for EVs that we all been waiting for. Lower energy density is their only drawback, but it can be managed with proper EV design.


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## Technologic (Jul 20, 2008)

dimitri said:


> I truly believe this technology is the breakthru for EVs that we all been waiting for. Lower energy density is their only drawback, but it can be managed with proper EV design.


I don't forsee the density as an issue in conversions or common cars.

Generally a car's size is limited to the actual parts to make it run (such as engines, electric motors, any transmissions, etc) and the size of people.

Generally lithium fits into a smaller compartment than ICE engines for a 100-150 mile range. (even if the car weighs 2000lbs and gets a poor 250 w-h/mile).

The advantage, to me, is how simple a car can be with lithium over lead acid. Due to the possibility of making ultra safe 2-4 seaters in the 1000lb and 150 mile range (simply by the use of aluminum and composites), you can use motorcycle sepex motors and/or small cheap AC drives. 

The advantages of such a design are immense and almost entirely unavailable with lead acid builds. 

You start getting into lead acid and you need something rather large for anything substainal over 20 miles of range... ie. 500amp and 144v controllers, no regen (at least no controllers yet exist for AC drives at this range).

Once you start factoring in associated costs... Lead acid isn't cheaper range, faster builds, or even cheaper overall costs. It hasn't been since the market for lifepo fell out in china last year.

Once lithium reached <0.40/wh last year, it was sorda over for lead acid conversions IMO...

a $4000 battery pack will make your average sedan (with some good planning and transmission removal) go like 80-100 miles... you can even use a cheap $1500 controller/motor combo for the job.

I don't think you can beat that... especially if you go fully custom ground up... you could see double or triple that range off the same 16kwh of lithium.

I hope in the coming months, now that there seems to be a lot of people with their hands diving into these prismatic lithiums, we see Lead Acid resigned to scrounger builds from junk heaps... no new builds should be pulling lead acid batteries anymore.

the days of $10,000 packs are gone... in many circumstances for $5000-6000 you're looking at 20kwh... enough to make full size pickup go about 150 miles or enough that the Aptera could go 240 miles (and it's absurd 1500 lb weight now).

There's already $100, 24 Cell BMS's that monitor charging, discharge and keep every cell completely safe during usage... Chargers are $220 for the max out of 110v (1600w)... what more can someone ask for?

You're looking at a parts cost, for a fully ground up composite build vehicle with 150 miles of range, of less than $10,000... <$7000 for a 70-80 mile range EV that's converted from a steel sedan.


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## FalconEV (Aug 21, 2007)

So... when will we get an order ?


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## grayballs (Aug 27, 2008)

You guys are preachin' to the choir,,,, I already spent my money on LiFePo4's and am getting ready to spend some more for another project.


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## AmpEater (Mar 10, 2008)

Technologic said:


> There's already $100, 24 Cell BMS's that monitor charging, discharge and keep every cell completely safe during usage... Chargers are $220 for the max out of 110v (1600w)... what more can someone ask for?


Could you provide links to the aforementioned bms and charger?


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## EVComponents (Apr 20, 2009)

grayballs said:


> Well said,,,, now I hope their track record proves out. They haven't been around long enough to prove expectations. That is the only downside that I see.


Sky Energy was a contract factory for ThunderSky manufacturing cells to TS specs. That was going on for years. So they are not exactly new. I think the only new part is that they are building their own brand name and their SE batteries have a slightly better discharge of 4C vs 3C.

We have both ThunderSky and Sky Energy cells on our website.

http://www.evcomponents.com/SearchResults.asp?Cat=28


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## Technologic (Jul 20, 2008)

AmpEater said:


> Could you provide links to the aforementioned bms and charger?


http://visforvoltage.org/forum/5192-4-24cell-battery-management-system-bms

http://www.bmsbattery.com/product_info.php?cPath=2_18&products_id=38

People at Endless sphere have reported extremely good results...

That charger can be had with 220v etc outlets (and higher wattages)


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## Stunt Driver (May 14, 2009)

Well, thanks everyone for good insight!

I may still use a few LAs for proof of functionality, but possibly in 5-6 months, when i get it all ready - i'll switch.
Hopefully LiFePo become even cheaper by then.

I am only looking for 10-15 miles range yet, and would not want to invest thousands in batteries.

How it is possible with existing LiFePo elements to get 10-15 miles range with under 40mph speed? Possibly 48-72 volts?


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