[winzeracer]

Originally Posted by rwaudio

If you were the one legit reseller of these cells but they could be had all over the place for 1/5 - 1/3 the price wouldn't you try to scare people away from buying them?
No guarantee the cells are perfect, but for the price it's worth the risk to some people.

Jack Rikard on evtv.me has done lots of testing with the "grey market" A123 Amp20's he has several rather long videos on testing these cells. He says they are good for 375 amps (23C) and he is selling them http://evtvshop.projectooc.com/products.php?cat=10

I was contemplating using these for my high current eKart build, but I needed a little more so I will be going with the Haiyin 6ah 3.7v calls which claim 50C ( voltage drops to 3.3v) constant draw. http://www.ecedra.com/thebatteryshop.html
These are what Lithuimmanics Drag racer runs \, but you have to be comfortable making you own pack. Make sure when you are taking voltage drop into account when calculating your max Kw rating. There are TONS of threads about this so I will not go into it here.

Happy Hunting.

[Ziggythewiz]

With most smaller cells you'll need a series-parallel pack, so if you see a headway that only does 1/5 what you need, you just need 5-6 in series. I think some do up to 30C though, so you shouldn't need that many.

[frodus]

If you built a pack of Headway batteries with 16s5p for a 48V 50Ah pack with the 10Ah batteries, you'll have absolutely no problem getting 200A. That's only 40A per cell or ~4C. That barely gets these cells warm. 125A would be around 25A a cell, or right about 2.5C, which they'll readily do.

US distributors with warranty, they're affordable and easy to replace.....

not that A123 is bad, they're just more risky, and assembly can be a PITA.

[lkcl]

hi travis, thanks for the idea... let's think it through, though, from both a cost and a weight perspective. the Headway cells are £12 each (about $18) from a UK supplier, and they're 0.346kg each. whereas evassemble.com is doing Thundersky 40Ah 1.6kg packs for $52 each (ok excluding shipping and tax) - but still, to make up 40Ah with 8Ah Headway cells that's $18 x 5 x 16 = $1440! whereas Thundersky cells, $52 * 16 = $832.

weight-wise, it's a close call: .346 x 5 x 16 = 27.68kg, and the thunderskys are 1.6 x 16 = 25.6kg.

in some ways i would actually be better off with those A123 cells - 0.6kg (or so?) x 16 = 9.6kg but they're 20Ah so half the capacity, pricing $30 (or so) x 16 = $496 - double those numbers and they're good on weight and reasonable on price.

so, making it all 40Ah, it's

• thundersky: 25.6kg, $832
• A123: 20kg, $1000
• headway: 27.68kg, $1400

looks to me like the thundersky cells are the best price/weight/performance option.


/peace

[rwaudio]

Originally Posted by lkcl

hi travis, thanks for the idea... let's think it through, though, from both a cost and a weight perspective. the Headway cells are £12 each (about $18) from a UK supplier, and they're 0.346kg each. whereas evassemble.com is doing Thundersky 40Ah 1.6kg packs for $52 each (ok excluding shipping and tax) - but still, to make up 40Ah with 8Ah Headway cells that's $18 x 5 x 16 = $1440! whereas Thundersky cells, $52 * 16 = $832.

weight-wise, it's a close call: .346 x 5 x 16 = 27.68kg, and the thunderskys are 1.6 x 16 = 25.6kg.

in some ways i would actually be better off with those A123 cells - 0.6kg (or so?) x 16 = 9.6kg but they're 20Ah so half the capacity, pricing $30 (or so) x 16 = $496 - double those numbers and they're good on weight and reasonable on price.

so, making it all 40Ah, it's

• thundersky: 25.6kg, $832
• A123: 20kg, $1000
• headway: 27.68kg, $1400

looks to me like the thundersky cells are the best price/weight/performance option.


/peace

That is all correct, the thing to watch out for is continuous and peak currents, it will be much higher for the A123/Headway option (if you need those current levels) if you don't go thundersky. It's pretty much the same choices that EV builders make, if TS/CALB will give enough current go with them, they are so much easier to use. If that won't give enough current the choices move to a higher current cell like A123/Headway.

You need to add one more column to make it more relevant continuous and peak currents. That should help you make the final decision on the best cell for your application.
Given equal current loads the A123/Headway would have the lowest sag at a given current output vs TS, take that into account and see if the sag from a TS cell is acceptable.

[winzeracer]

Originally Posted by lkcl

hi travis, thanks for the idea... let's think it through, though, from both a cost and a weight perspective. the Headway cells are £12 each (about $18) from a UK supplier, and they're 0.346kg each. whereas evassemble.com is doing Thundersky 40Ah 1.6kg packs for $52 each (ok excluding shipping and tax) - but still, to make up 40Ah with 8Ah Headway cells that's $18 x 5 x 16 = $1440! whereas Thundersky cells, $52 * 16 = $832.

weight-wise, it's a close call: .346 x 5 x 16 = 27.68kg, and the thunderskys are 1.6 x 16 = 25.6kg.

in some ways i would actually be better off with those A123 cells - 0.6kg (or so?) x 16 = 9.6kg but they're 20Ah so half the capacity, pricing $30 (or so) x 16 = $496 - double those numbers and they're good on weight and reasonable on price.

so, making it all 40Ah, it's

• thundersky: 25.6kg, $832
• A123: 20kg, $1000
• headway: 27.68kg, $1400

looks to me like the thundersky cells are the best price/weight/performance option.


/peace

Rw is correct you are not cimparing apples to apples. The TS cels will max at 5C burst and sag to ~2.7v underload so 2.7vX40ahX100vX5C=~50kw
The headways may sag to 2.5v under thier max 10C load
2.5vX40ahX100VX10C= 100kw
A123.amp 20 I guess sag to be down to atleast 2.5v at 23C
2.5X40X100X23=230kw

All.very different numbers. You.are also comparing 2 different chemistrys, and 3 different levels of difficultly for install. All things that must be entered into the equation.

[frodus]

Agreed.... best to look at what power you need, and work that way. TS isn't a great choice for something that needs high C-ratings. If you do, consider double or even tripling the Ah rating (i.e. go with 100Ah TS cells).

Weight and price they may have others beat, but they've got a ways to go on performance.

[skooler]

Originally Posted by lkcl

hi travis, thanks for the idea... let's think it through, though, from both a cost and a weight perspective. the Headway cells are £12 each (about $18) from a UK supplier, and they're 0.346kg each. whereas evassemble.com is doing Thundersky 40Ah 1.6kg packs for $52 each (ok excluding shipping and tax) - but still, to make up 40Ah with 8Ah Headway cells that's $18 x 5 x 16 = $1440! whereas Thundersky cells, $52 * 16 = $832.

weight-wise, it's a close call: .346 x 5 x 16 = 27.68kg, and the thunderskys are 1.6 x 16 = 25.6kg.

in some ways i would actually be better off with those A123 cells - 0.6kg (or so?) x 16 = 9.6kg but they're 20Ah so half the capacity, pricing $30 (or so) x 16 = $496 - double those numbers and they're good on weight and reasonable on price.

so, making it all 40Ah, it's

• thundersky: 25.6kg, $832
• A123: 20kg, $1000
• headway: 27.68kg, $1400

looks to me like the thundersky cells are the best price/weight/performance option.


/peace

Hi,

Who is the UK supplier of headway cells?

Cheers,

Mike

[lkcl]

Originally Posted by skooler

Hi,

Who is the UK supplier of headway cells?

Cheers,

Mike

http://eclipsebikes.com/headway-life...ah-p-1011.html

seems like they sell electric bikes (and offer parts), some of the parts being those cells, it looks like they got a bunch in. good for them.

l.

[lkcl]

okok sorry they have the 10Ah, 12Ah and 16Ah versions, their system says they have 180 of the 16Ah cells in stock, they're not the higher current 8Ah ones though.