# A123 vs K2 Energy



## efan (Aug 27, 2009)

hey, I am not a raced but aren't the headways good enough??

i just ran into this web page so I dont know how credible it is..but...

http://www.bmsbattery.com/index.php?main_page=product_info&cPath=1_10_11&products_id=9


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## LithiumaniacsEVRacing (Oct 9, 2010)

I know nothing about these K2 batteries? Headway's seem to have a bad reputation from what I read. 



efan said:


> hey, I am not a raced but aren't the headways good enough??
> 
> i just ran into this web page so I dont know how credible it is..but...
> 
> http://www.bmsbattery.com/index.php?main_page=product_info&cPath=1_10_11&products_id=9


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## efan (Aug 27, 2009)

well...I am just throwing different battery companies here, but have you looked at lifebatt

http://www.lifebatt.com/application-kit-battery.html

http://www.lifebatt.co.uk/power_cells.html

to be honest they seem very similar to headway to me...


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## jeremyjs (Sep 22, 2010)

So the K2's are roughly equivalent to A123? Interesting; because you can actually buy 72ah 3.2v packs of these from at least one EV parts distributor I've seen. They come at a pretty steep cost though, but if they're really that good they should work well for a no compromises performance EV build if you've got the scratch to spend.


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## Jozzer (Mar 29, 2009)

When you buy K2 in numbers and test them you will not find the same level of QC and consistency as you will with A123's. When your going to make a pack from that many cells this is important.

Steve


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## LithiumaniacsEVRacing (Oct 9, 2010)

Thanks, has anyone done this? Where can I find the link? 



Jozzer said:


> When you buy K2 in numbers and test them you will not find the same level of QC and consistency as you will with A123's. When your going to make a pack from that many cells this is important.
> 
> Steve


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## LithiumaniacsEVRacing (Oct 9, 2010)

K2 Energy has their own store, what EV parts distributor is selling them?



jeremyjs said:


> So the K2's are roughly equivalent to A123? Interesting; because you can actually buy 72ah 3.2v packs of these from at least one EV parts distributor I've seen. They come at a pretty steep cost though, but if they're really that good they should work well for a no compromises performance EV build if you've got the scratch to spend.


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## LithiumaniacsEVRacing (Oct 9, 2010)

http://www.peakbattery.com/projects.html

Using our high performance 26650P cells with a 240V 300hp electric engine produces an astounding 1,000 lb/ft of torque!!! Leaving even most expensive supercars in the dust! 

The Shelby brand, like K2 Energy Solutions, is synonymous with big power! When we teamed up with APT Automotive to build a custom battery system to power their Shelby Cobra EV, we knew the results would have to be impressive for such a legendary car but when we ran 3.2 second 0-60 time, we were all blown away. Imagine a classic like the Cobra flying by without a plume of exhaust fumes trailing behind.


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## DIYguy (Sep 18, 2008)

man... I've always wanted to build an AC Cobra kit car.... in the past year, I've dreamed of building an electric one like this. drooling here....


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## jeremyjs (Sep 22, 2010)

LithiumaniacsEVRacing said:


> K2 Energy has their own store, what EV parts distributor is selling them?



They have absolutely no details on their site, but there's one I've seen.
http://currentevtech.com/Lithium-Batteries/K2-Battery-Packs-c60/
They have absolutely no details about the packs on their site though, other than saying they're similar in specification to a123 26650m1 cells, and they are pricey.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Yes, it is sweet! 

I am interested in seeing this car and its battery pack, but I cannot find it anywhere? I will keep looking. 



DIYguy said:


> man... I've always wanted to build an AC Cobra kit car.... in the past year, I've dreamed of building an electric one like this. drooling here....


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## LithiumaniacsEVRacing (Oct 9, 2010)

Very interesting:

"They are great building block to build a larger battery pack for those who want the power of the small cylindrical cells and the ease of the larger prismatics" 



jeremyjs said:


> They have absolutely no details on their site, but there's one I've seen.
> http://currentevtech.com/Lithium-Batteries/K2-Battery-Packs-c60/
> They have absolutely no details on the packs though, other than saying they're similar in specification to a123 26650m1 cells, and they are pricey.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I will call Dave and get his opinion on these cells. It seems much easier if these hold the cylider cells? 



jeremyjs said:


> They have absolutely no details on their site, but there's one I've seen.
> http://currentevtech.com/Lithium-Batteries/K2-Battery-Packs-c60/
> They have absolutely no details on the packs though, other than saying they're similar in specification to a123 26650m1 cells, and they are pricey.


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## jeremyjs (Sep 22, 2010)

I'd assume it's just a pack with a bunch of 26650's in parallel. It's anyone's guess just how good they are, how well the cells are matched, etc. When I first saw them I searched around for any reviews or tests on those actual packs. I wasn't able to find anything myself. So it looks like someone with some bank will have to be a guinea pig before we know anything concrete.


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## LiFe (May 24, 2010)

Be very careful in any dealings with K2 (formerly Peak battery).

They have repeatedly understated the internal impedance of their previous 26650 cell offerings  to say it nicely.

The prior model cells were sampled, tested using professional instrumentation, and returned room temp I/R numbers in excess of 20mohms @50% SOC. Many cells were tested, with similar results.

Their salesman skirted the I/R results when confronted with the numbers.

Now take on the other hand; LifeBatt 

What you have here is a 3x overpriced Taiwanese assembled cell, that may contain some percentage of Phostech licensed powder  the remaining could be dandruff for all we know. The pricing, as we've surmised, has to do with the three year warranty offered (as long as you buy their BMS). The problem is that you'd be required to deal with a person named Don Harmon (douchebag extraordinaire) in the event of a problem, and that's where it will go south  There is some history on this noted on this at another EV forum.

These are very good performing cells, delivering well within their stated impedance and capacity numbers. Isn't it funny? the product appears great, it's the company pitchman who is a trainwreck and can't keep his stories straight.


My advice? go with Headway cells from Victoria. They're relatively cheap, they appear to meet their cycle life numbers, and there is plenty of published data about various builds using them. The I/R numbers are somewhat high for EV use, so put a few more in parallel.


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## Jozzer (Mar 29, 2009)

HEadway's will not work well in a drag car (in fact, I believe Crodriver tried them and found this out).
Unless you can get hold of A123's I would suggest looking into LiPo for light weight and extreme discharge rates..

Steve


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## LithiumaniacsEVRacing (Oct 9, 2010)

You speak of LifeBatt, what is the highest C-rating batteries they produce? 

Now the US batteries are not the batteries of the past sold in UK.



LiFe said:


> Be very careful in any dealings with K2 (formerly Peak battery).
> 
> They have repeatedly understated the internal impedance of their previous 26650 cell offerings  to say it nicely.
> 
> ...


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## jimberry3 (May 11, 2009)

We had the ability a while ago to utilize A123's in our packs but they just got so damn hard to deal with and decided to sell only to the big guys (or girls) that we went with [email protected] for a while and had no problems as long as we ordered from the same production run but we got a lot better price, great service and someone willing to align themselves with us and support us in the manufacturer Molicel. We utilize them exclusively now. I also have a post under Li-ion batteries about manufacturing packs. Jim @ ethos electric vehicles.com


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## LithiumaniacsEVRacing (Oct 9, 2010)

What cell do you prefer from Molicel? I see none with decent AH, maybe I am missing something, i will review their site again. 

http://www.molicel.com/ca/products_data.html



jimberry3 said:


> We had the ability a while ago to utilize A123's in our packs but they just got so damn hard to deal with and decided to sell only to the big guys (or girls) that we went with [email protected] for a while and had no problems as long as we ordered from the same production run but we got a lot better price, great service and someone willing to align themselves with us and support us in the manufacturer Molicel. We utilize them exclusively now. I also have a post under Li-ion batteries about manufacturing packs. Jim @ ethos electric vehicles.com


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## jimberry3 (May 11, 2009)

We utilize the IBR26700, don't know if they have put it on the site yet. It has a capacity of 2800Mah, an energy rating of 10Ah, A volumetirc density of 26wh/l and a gravimetric density of 100wh/kg. It may not fit your needs but the Molicel fills the need for our custom electric two seat sports car we are bringing to market this fall. We can achieve 0-60 in 4.9 seconds and can drive the haleakala highway (30 miles at 6-8% grade) utilizing only a little over 1/2 charge (great regen on the way down). But if you are a drag racer it may not fit your needs


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## frodus (Apr 12, 2008)

how can it have a 2800mAh rating AND a 10Ah rating? (and make sure you watch unit capitolization, M is mega, m is mili and u is micro, so Mah would be Mega-Ampere-Hour)

do you mean 10Wh? what is the nominal cell voltage?


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## DIYguy (Sep 18, 2008)

jimberry3 said:


> We utilize the IBR26700, don't know if they have put it on the site yet. It has a capacity of 2800Mah, an energy rating of 10Ah, A volumetirc density of 26wh/l and a gravimetric density of 100wh/kg. It may not fit your needs but the Molicel fills the need for our custom electric two seat sports car we are bringing to market this fall. We can achieve 0-60 in 4.9 seconds and can drive the haleakala highway (30 miles at 6-8% grade) utilizing only a little over 1/2 charge (great regen on the way down). But if you are a drag racer it may not fit your needs


Hi Jim,

Energy is typically rated in Watt-hours and capacity in mAh or Ah. Cheers


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## LiFe (May 24, 2010)

frodus said:


> how can it have a 2800mAh rating AND a 10Ah rating? (and make sure you watch unit capitolization, M is mega, m is mili and u is micro, so Mah would be Mega-Ampere-Hour)
> 
> do you mean 10Wh? what is the nominal cell voltage?


Good one!
When you point out the inaccuracies of scale by others, check spelling before hitting send. "capitolization"


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## frodus (Apr 12, 2008)

LiFe said:


> Good one!
> When you point out the inaccuracies of scale by others, check spelling before hitting send. "capitolization"


Not as concerned with spelling as I am with units. 

"my bad"


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## jimberry3 (May 11, 2009)

Aloha guys,

I apologize for the delay in getting back to you, small business can get sick busy from time to time. I also apologize for the wrong scale, the wrong initials, anything wrong I might have typed in. I was in the midst of speaking with clients about their lithium packs we are building for them, getting six of our kit cars together to go out the door for shipping and trying to get our next kit car package to the manufacturer as well as find a proper building in Ohio for us to begin manufacturing and shipping out of in August. So, I was not paying as much attention as I should have been to the post reply. In order to not print anything that does not sit well with you, if you let me know your email I will send you the PDF straight from Molicel so that there is no confusion. But and I will put this to you, I made the recommendation of Molicel because they function like a charm for us, never had a problem with stability, or excessive sag, or not delivering what they need to deliver performance wise. With that said, we utilize them for high performance and everyday vehicles but do not drag race them, yet! We do have a design on the board for an all wheel drive open class hill climber for possibly 2011 Pikes Peak if we get some sponsorship.

Mahalo,

Jim


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