[ausev] Battery choices

[Brian Lasseter]

On Mon, Jul 7, 2008 at 12:23 AM, Mike Seningen <mseningen at austin.rr.com> wrote:
> 12v 20 Hr Rate AH = 100  -- so is this a 100AH battery at 12v -- or 1200AH at 12v?
>
> Li-ion 3.7v @1.7AH -- to get 100AH @ 12v is roughly 190cells?  (100/1.7)*(12/3.7)

Volts X Amp_Hours = Watt_Hours

12V x 100AH = 1200wh of energy for your AGM.
3.7V x 1.7AH = 6.29wh of energy for your Li-ion cell.

Your final count of 190 li-ion cells would give you the same energy though.

However, just to confuse you more, the peukert exponent comes into
play here.  Long story short... the li-ion cell can use nearly 100% of
it's energy, while the AGM cell will likely only be able to use 50% of
it's energy at the high rate of energy depletion used in electric cars
(depending on what it's peukert exponent is).

So... 95 li-ion cells should suffice to give you the same amount of
"useable" energy.  If you know the peukert exponents for each battery,
then you could calculate an exact number.

http://en.wikipedia.org/wiki/Peukert%27s_law
http://www.smartgauge.co.uk/peukert_depth.html

--
TTFN,
Brian "Lasso" Lasseter

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