L. Chris Hager wrote:
I have a British sports car from the 'microcar' era -- a 1959 Berkeley
SE 328...my Qs: If this were your project and you were opting for
lightweight batteries, what chemistry would you chose?
Li-Ion (like laptop cells) will provide the most power and range for a
given weight pack. But you would need a *large* number of cells, leading
to connection difficulties and reliability problems. They are also less
safe, and tend to have a shorter life expectancy.
Li-Fe cells will be physically bigger and weigh more for a given amount
of range. Higher amphour cells are available, so you don't need nearly
as many (much easier to wire up). They are safer (but still flammable).
Life is potentially longer, but it all depends on quality and how they
are used/abused.
Personally, I'd get the car working with a cheap set of lead-acid
batteries. Get things sorted out, and working well. This "trainer" pack
will probably get murdered, by being run dead, overcharged, or
something. When all is well, *then* spend the big bucks on a lithium
pack. Given your description, I'd probably try CALB Li-Fe cells.
Although another interesting possibility might be nimh (like 4 packs
from Prius hybrids).
And THEN: does that brand also offer a batt. management system that
is reliable? If not what BMS yould you buy?
I'm prejudiced. *Most* of the BMS I see are hastily designed by
amateurs, cheaply made, and barely work even when new. Then they get
old, and things break. A BMS that is supposed to protect the cells
becomes one that *destroys* the cells, either by failing to notify you
or stop a problem, or by actively causing the problem itself!
So, I build my own Balancers. You can copy it, or buy boards, kits, or
complete units. See http://www3.telus.net/nook/balancerland/ for details
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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