Ben,
Why on the world would you need over 200kW unless you are doing a race
car?
Around 50kW gives you a system that keeps up with traffic and 100kW
gives you plenty power for all daily driving conditions and would not
put the Mustang to shame, even though you might not win off-the-line
from muscle cars - but I had the impression that was not your goal.

These days I am driving a truck that tops out at about 35kW. Certainly
not high performance by any measure, but I can commute with it, not
annoy too many people when I drive on the freeway and it give me the
utility that a truck has - all the load carrying capacity of the 7 foot
long bed.
The 20 Golfcart batteries are happy with the current limit so they are
not
over-extended to much pushing this heavyweight around - the only thing
that occasionally gets overextended is my patience, but it is a learning
process and until I get around to install a parallel pack of Lithiums
and BMS, I am
going to stay within the boundaries that keep these batteries happy.
Before this truck, I had a US Electricar that had 60kW power and
certainly could keep up with traffic even though it weight a total of
5,000 lbs (driver included)

My suggestion: use half your pack size (are there 90 Ah cells that you
can use instead of 3 strings of 60?) which gievs half the cost and
capacity,
as you indicated that is what you need.

Success making the trade-offs.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.com Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Ben Goren via
EV
Sent: Friday, July 25, 2014 2:59 PM
To: EVDL Administrator; Electric Vehicle Discussion List
Subject: Re: [EVDL] Hybrid Mustang: batteries

On Jul 24, 2014, at 9:57 PM, EVDL Administrator via EV
<ev@lists.evdl.org> wrote:

> I think Ben G can build this car.  However, I'm not sure he's going to
get 
> absolutely everything he wants (range, power, price).  
> 
> As with so many other things : go far, go fast, go cheap : pick two.
:-\

I'd love to pick just two! Sadly, it looks like "go fast" is coupled to
the other two....

Thanks to the people here, I've spent a lot of time today so far
searching and crunching numbers and the like -- dozens of batteries from
half a dozen vendors and as many manufacturers (including CALB, Enderel,
GBS, and more).

I'd appreciate if somebody can check my math on the current leading
candidate. It's a Voltronix 3.2V 60Ah 8C cell that EVWest sells for $78
/ ea:

http://www.evwest.com/catalog/product_info.php?cPath=4&products_id=266&o
sCsid=ph57045uael6qb57sjjaqi8cs3

If I have the math right, if I were to connect 45 in series, that would
make a 144V 60Ah cell. Three of those in parallel would make a 144V
180Ah battery capable of 1440A discharge and thus 207kW power with a
total capacity of 26kWh...at a total cost of $10,530 and a weight of
about 750 pounds.

Does that math sound reasonable?

That's twice the capacity I need, which obviously in and of itself isn't
a bad thing. But that's over twice the cost I had previously been
guesstimating -- and doesn't include a BMS or charger or the like. And
it's a *lot* of weight. But if I cut back on the number of cells, I cut
back on either voltage or amperage (or both)....

It looks like a GBS system in a kit with BMS and the like would likely
get similar performance with half the capacity and a third the
weight...for twice the money. Enderel looks to be about comparable to
GBS but maybe lighter and more expensive still.

So...um...am I missing anything?

Thanks again, everybody.

b&
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