# [EVDL] Smaller footprint alternative to ThunderSky



## EVDL List (Jul 27, 2007)

Can anyone recommend some decent cells which take up less room than 
ThunderSky - even the lowest capacity TS cells (40Ah) won't fit in the 
space Ive got.

Andrew

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Can anyone recommend some decent cells which take up less room than ThunderSky - even the lowest capacity TS cells (40Ah) won't fit in the space Ive got.
> 
> Andrew


Headway 10ah cells
Kokam Pouches


----------



## EVDL List (Jul 27, 2007)

You need to state your objective!

But, have a look at electric bike batteries - 5-20AH prismatic LiFePo4
cells, or LiPoly for more capacity or power in the same space.





> Andrew Wood <[email protected]> wrote:
> > Can anyone recommend some decent cells which take up less room than
> > ThunderSky - even the lowest capacity TS cells (40Ah) won't fit in the
> > space Ive got.
> ...


----------



## EVDL List (Jul 27, 2007)

The batteries that use LiMnPO4 technology are 3.7 volts vs. 3.2 for LIFePO4
and would be smaller for the same energy. Life is supposedly less ( 800-1500
vs. 1000-3000 cycles ) but prices are less too so it might not matter.
Headway make 10AH cyl cells with terminals that can be connected in parallel
or series strings and these are LiFePO4. Size is smaller if you can take
advantage of the shape. There are also pouch LiFePO4 cells that are like TS
but no plastic case, these might be a good choice, these need support but
can be stacked. I think that the Leaf packs are made from these.
What voltage are you using.?

-- 
When all else fails, remember failure is the success of knowing what not to
do.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20100630/93446cd7/attachment.html 
_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Is it vertical or horizontal space that's constraining you? Headway cells
tend to be taller and thinner. So if you have a little extra height, you
can fit more of them into the same horizontal area.

Bill





> Andrew Wood <[email protected]> wrote:
> > Can anyone recommend some decent cells which take up less room than
> > ThunderSky - even the lowest capacity TS cells (40Ah) won't fit in the
> > space Ive got.
> ...


----------



## EVDL List (Jul 27, 2007)

Do you have more detail on these ones used by the Leaf?

I need a 120v pack at at least 40Ah, if bigger then great, but at a 
cost comparable to, or better than TS.




> ron doctors wrote:
> > There are also pouch LiFePO4 cells that are like TS
> > but no plastic case, these might be a good choice, these need
> > support but
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Andrew,

Have you considered Headway's - they're light and compact and a pretty good
match for the TS40AHA. Here is a comparison for you:
*
Thundersky LFP040AHA*
Voltage (nominal): 3.2
Nominal Capacity: 40AH
Continuous Discharge (continuous): 3C / 120A
Rated Max Discharge (burst): 10C/400A for 20ms
Actual Max Discharge (burst): 5C/200A for 15sec
Weight: 1.5KG
Price: ~$75.00 USD

120v (nominal) = 38cells in series
Continuous Discharge of pack: 120A
Actual Max Discharge of pack for 15s = 200A
Weight = 57KG
Pack Cost = $2,850.00 USD


*Headway 38120P 8AH*
Voltage (nominal): 3.2
Nominal Capacity: 8AH
Continuous Discharge (continuous): 5C/40A
Rated Max Discharge (burst): 25C/200A (as per product data sheet)
Actual Max Discharge (burst): 15C/120A for 4min
Actual Max Discharge (burst): 20C/160A for 3min
Actual Max Discharge (burst): 50C/400A for 15sec (as tested by Mike Willmon)
Weight: 0.35KG
Price: ~$19.00 USD

120v (nominal) = 38cells in series
Continuous Discharge of pack: 40A
Actual Max Discharge of pack for 15s = 400A
Weight = 13.3KG
Pack Cost = $722.00 USD

120v (nominal) = 2x 38cells in series (2P38S)
Continuous Discharge of pack: 80A
Actual Max Discharge of pack for 15s = 800A
Weight = 26.6KG
Pack Cost = $1,444.00 USD

120v (nominal) = 3x 38cells in series (3P38S)
Continuous Discharge of pack: 120A
Actual Max Discharge of pack for 15s = 1200A
Weight = 39.9KG
Pack Cost = $2,166.00 USD

120v (nominal) = 4x 38cells in series (4P38S)
Continuous Discharge of pack: 160A
Actual Max Discharge of pack for 15s = 1600A
Weight = 53.2KG
Pack Cost = $2,888.00 USD


So for less money then a 120v pack of Thundersky 40aha cells would cost you,
you could go with a Headway 3P38S pack and have better performing pack at a
lighter weight. Or you could go with a Headway 4P38S pack for only $38 more
then the Thundersky pack and have much better performing pack.

Food for thought.

Leslie






> Andrew Wood <[email protected]> wrote:
> 
> > Do you have more detail on these ones used by the Leaf?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Wait a minute. I think it depends whether you're going for instantaneous
discharge (performance) or capacity (range). The 4 parallel strings of
Headway packs offers better performance than Thundersky, but it is only a 32
AH pack instead of a 40 AH pack. If you're going for range, I think you
should find the Headway 4P (32 AH) pack would have 25% less range than the
Thundersky 40AH pack.

If the range in either case is sufficient, I definitely agree that the
Headway would offer better performance.

Mike

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of WRX STI
Sent: Wednesday, July 07, 2010 8:23 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Smaller footprint alternative to ThunderSky

Hi Andrew,

Have you considered Headway's - they're light and compact and a pretty good
match for the TS40AHA. Here is a comparison for you:
*
Thundersky LFP040AHA*
Voltage (nominal): 3.2
Nominal Capacity: 40AH
Continuous Discharge (continuous): 3C / 120A Rated Max Discharge (burst):
10C/400A for 20ms Actual Max Discharge (burst): 5C/200A for 15sec
Weight: 1.5KG
Price: ~$75.00 USD

120v (nominal) = 38cells in series
Continuous Discharge of pack: 120A
Actual Max Discharge of pack for 15s = 200A Weight = 57KG Pack Cost =
$2,850.00 USD


*Headway 38120P 8AH*
Voltage (nominal): 3.2
Nominal Capacity: 8AH
Continuous Discharge (continuous): 5C/40A Rated Max Discharge (burst):
25C/200A (as per product data sheet) Actual Max Discharge (burst): 15C/120A
for 4min Actual Max Discharge (burst): 20C/160A for 3min Actual Max
Discharge (burst): 50C/400A for 15sec (as tested by Mike Willmon)
Weight: 0.35KG
Price: ~$19.00 USD

120v (nominal) = 38cells in series
Continuous Discharge of pack: 40A
Actual Max Discharge of pack for 15s = 400A Weight = 13.3KG Pack Cost =
$722.00 USD

120v (nominal) = 2x 38cells in series (2P38S) Continuous Discharge of pack:
80A Actual Max Discharge of pack for 15s = 800A Weight = 26.6KG Pack Cost =
$1,444.00 USD

120v (nominal) = 3x 38cells in series (3P38S) Continuous Discharge of pack:
120A Actual Max Discharge of pack for 15s = 1200A Weight = 39.9KG Pack Cost
= $2,166.00 USD

120v (nominal) = 4x 38cells in series (4P38S) Continuous Discharge of pack:
160A Actual Max Discharge of pack for 15s = 1600A Weight = 53.2KG Pack Cost
= $2,888.00 USD


So for less money then a 120v pack of Thundersky 40aha cells would cost you,
you could go with a Headway 3P38S pack and have better performing pack at a
lighter weight. Or you could go with a Headway 4P38S pack for only $38 more
then the Thundersky pack and have much better performing pack.

Food for thought.

Leslie






> Andrew Wood <[email protected]> wrote:
> 
> > Do you have more detail on these ones used by the Leaf?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Yeah, very true Mike.

You'll sacrifice some range for performance if you go with any of the
Headway packs I suggested.

However, if you want equivalent range, you could go with 4P32S of the 10AH
Headways instead of the 8AH cells I listed. The 10AH Headways cost the same
as the 8AH cells, and a 4p32S will provide the same nominal 40AH, and the
pack will still perform better then a ThunderSky 40AHA pack.

Leslie







> Mike Nickerson <[email protected]>wrote:
> 
> > Wait a minute. I think it depends whether you're going for instantaneous
> > discharge (performance) or capacity (range). The 4 parallel strings of
> ...


----------



## EVDL List (Jul 27, 2007)

> WRX STI wrote:
> >
> > So for less money then a 120v pack of Thundersky 40aha cells would cost you,
> > you could go with a Headway 3P38S pack and have better performing pack at a
> ...


----------



## EVDL List (Jul 27, 2007)

I mis-cited in my previous email. It's China HiPower cells that are taller
and thinner. You can see the specs here: =


http://www.evequipmentsupply.com/LiFePo4.html

Bill

--------------------------------------------------------------------
mail2web.com =96 Enhanced email for the mobile individual based on Microsof=
t=AE
Exchange - http://link.mail2web.com/Personal/EnhancedEmail



_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Andrew,

How about 20ah Thundersky cells?

http://elitepowersolutions.com/products/product_info.php?cPath=16&products_id=74

Each cell is removable from the plastic box and you can get a better idea of what they look like with the lid removed here:

http://elitepowersolutions.com/products/popup_image.php?pID=122

Individual cells measure 70 x 41 x 150mm, call it 160mm with a bolt and washers on the terminal. 

We sell a lot of these for electric bike applications. I would say limit them to 2C continually though if you want them to have a good cycle life time. We have a customer near by who is building a prototype medium size electric dirt bike that wanted 40ah, but it wouldn't fit within the frame very well so they ended up using two 20ah cells in parallel. At 36 volts the little thing really moves.

Regards,
Ricky Suiter
Elite Power Solutions
92 Saturn SC Conversion
AZ Alt Fuel Plates "ZEROGAS"

> Message: 10
> Date: Wed, 30 Jun 2010 17:50:58 +0100
> From: Andrew Wood <[email protected]>
> Subject: [EVDL] Smaller footprint alternative to
> ThunderSky
> To: Electric Vehicle Discussion List <[email protected]u>
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> 
> Can anyone recommend some decent cells which take up less
> room than 
> ThunderSky - even the lowest capacity TS cells (40Ah) won't
> fit in the 
> space Ive got.
> 
> Andrew
> 
>




_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Hi Rick,

I didn't include cost of interconnects, as I was only comparing actual cell
costs and performance.

$1 isn't that bad a price though, especially when you consider some replace
the interconnects that come with the TS cells and pay several dollars each
for decent laminated or braided interconnects.

But yes, you are correct that interconnects will be an extra cost, and the
battery management will be more involved and generally more expensive.

I guess it comes down to what is really needed and what you will have to do
to meet those needs. If you wanted the lightest possible pack that still
offered good performance and didn't cost an arm and a leg, the headways are
a good option.

Basically the budget will be the limiting factor, and for whatever budget
you set for your pack, you'll have to choose either good performance or good
range. As you move towards one of those, you lose more of the other.

That is unless someone on this mailing list has found a well performing
bargain cell that I have missed and is holding out on us all 

Leslie






> Rick Beebe <[email protected]> wrote:
> 
> > WRX STI wrote:
> > >
> ...


----------



## EVDL List (Jul 27, 2007)

Hello,

I believe that many of us members of this forum are hobbyists building
single EV conversions.
Therefore, our criteria when selecting cells are different from the criteria
an auto manufacturer would use.

1) Chemistry: 
* Inherent safety is more important than energy density, and that's why we
tend to chose chemistries such as LiFePO4, as opposed to, say, Cobalt, even
though the latter has higher energy density. 
* Cycle life reported by manufactures may be moot to us, as we are likely to
need to replace cells sooner than that number of cycles: a) manufacturers
cycle cells under ideal conditions, which are _very_ different from the
conditions in which we will be using them (hard accelerations, the
occasional running down to very empty just to limp home); b) if your
initials are J.R., you will not use a BMS and therefore use the cells
outside their SOA (Safe Operating Range).

2) Format: 
For one vehicle it makes little sense to acquire the technical knowledge
required to weld cells together (therefore, not small cylindrical cells such
as A123's M1s) or how to clamp tabs without making short circuits
(therefore, not pouch cells such as Kokam). Pouch cells require a _lot_ of
know-how and mechanical design, so they are particularly to be avoided in
one-up projects by us hobbyists.
This leaves cells with bolts for terminals: prismatic cells (such as
Thundersky) and large cylindrical cells (such as Headway and PSI/Lifebatt).
Prismatic cells are easier to assemble into batteries, though they require
plates at either end to keep them from expanding; large cylindrical cells do
not require restraint against expansion, but you need to come-up with a
technique to assemble them together. So, neither is ideal for us, but both
are a heck of a lot easier to use than small cylindrical or pouch. The
easiest cell to use is not a cell but a battery: prismatic batteries from K2
(such as the LFP300EVS) have bolts and are rectangular, but also they do not
need restraining because, inside, they are made of small cylindrical cells.

3) Availability: sure A123 cells are great, but it's not like they'll sell
them to us, and, if they did, they are not exactly cheap. Look for cells
that you can actually get, and are affordable.

4) Ready made batteries:
Buy individual cells, not batteries. Stay away from 12 V batteries that have
only 2 terminals (such as K2's 12 V batteries): you can't connect a BMS to
the inner cells, which is essential. Even if regulators are included in the
battery, they only work when you use them in 12 V applications; they will
not work if you put multiple batteries in series (for reasons too complex to
get into here). 3.2 V prismatic batteries from K2 (such as the LFP300EVS)
are OK because, although they contain lots of cells, they are all in
parallel, so they work as if they were a single cell. GBS cell blocks from
Elite Power are also OK, because the BMS does have access to individual
cells (you can buy them with the BMS cell boards already installed).

So, I say, for a 1-up EV conversion, stick to Thundersky cells, LiFePO4
prismatic cells (such as Sky Energy / CALB, K2's 3.2 V batteries), or
LiFePO4 large cylindrical cells (such as Headway or LifeBatt). Improved
chances of success are more important than squeezing an extra Ah out of the
available space.



-----
Davide Andrea
http://liionbms.com/php/index.php Elithion 
-- 
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Smaller-footprint-alternative-to-ThunderSky-tp2274441p2283213.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Sounds good thanks. Wheres the best place to buy them?

Andrew



> WRX STI wrote:
> 
> > Hi Andrew,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Davide, This was a wonderfully clear and concise piece of advice, and I hope
you don't mind, that I have copied the entire one page dissertation for use
as a handout for my EV Tech trainees. Of course I have retained your name as
author at the bottom. As I am distributing your good advice, not stealing
it.
Regards
Dennis Miles



> Elithion <[email protected]> wrote:
> 
> >
> > Hello,
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Andrew,

I would prefer not to suggest any single EV parts vendor for your 
purchase as there as almost all EV parts stores sell Headway cels - I'd 
rather suggest that you do a search of the more popular forums as well 
as messages in this mailing list to accertain which of the EV parts 
vendors are more reputable and safe to purchase from.

Also, before you do make any purchase, it would be of benefit to you to 
detail what the goal of your EV is.

As has been pointed out, if you were after as much range for as little 
money as possible, then a Thundersky or CALB (Sky Energy) may be a 
better choice then a headway pack. Your pack will not have the same 
higher performance offered by a Headway pack, and won't be as light as a 
headway pack, but with the slightly higher AH rating of the Thundersky 
or CALB (Sky Energy) cells, they should provide more range for around 
the same cost.

Regards,
Leslie


On 11/07/2010 7:01 AM, Andrew Wood wrote:
> Sounds good thanks. Wheres the best place to buy them?
>
> Andrew
>
>


> WRX STI wrote:
> >
> >
> >> Hi Andrew,
> ...


----------

