FreeLists / 18650 / [18650] Re: My LiIon Cells - LGQ863448H

["Davide Andrea" <1davide@xxxxxxx>]

> I could send you 50.  Do you want me to go ahead and
> send them to you?

50 is OK, but I am buried right now, so you might as well wait.
(That job that I thought would happen in one month? It's here.)

> And, during discharge, its
> voltage bounced back immediately after the load is removed.

As if there were a high series resistance?
Please see page 6 of:
http://eprints.soton.ac.uk/338/01/draft_sent_in_2.pdf

Davide


----- Original Message -----
From: "Edward Ang" <EdAng@xxxxxxxxxxxxx>
To: "Davide Andrea" <1davide@xxxxxxx>
Sent: Tuesday, August 17, 2004 2:28 PM
Subject: My LiIon Cells - LGQ863448H


> Davide,
>
> I finally got a chance to measure the current draw on my scooter.  It has
a
> 30A fuse.  But, max current measured is about 20A.  This is about twice my
> expectation.  I have always used 250W max.  Apparently, it is 250W
cruising
> at max speed.  When accelerating, it is able to draw closed to 500W.
>
> In this case, I will need at least 13 cells in parallel to keep it under
2C
> rate.  13 x 7 = 91.  I only have 150 cells.  I would not be able to send
you
> half as I thought.  I could send you 50.  Do you want me to go ahead and
> send them to you?
>
> Also, I did some charge/discharge tests on a single cell.  It was very
> interesting.  The most interesting part is that its voltage stayed at 4.2V
> (at full charge) even after I stop charging it.  And, during discharge,
its
> voltage bounced back immediately after the load is removed.  No slow
rising
> or dropping of voltage like we see on Lead Acid.  This got me thinking
about
> hybrid pack again.  This behavior make doing a hybrid pack much easier.  I
> pasted the voltages below for a possible hybrid pack.  Also, we might be
> able to use small automotive starter batteries.  They are cheap.  And,
with
> this system, they should die first before the LiIon.
>
>                 Standing     Discharging    Charging
>                 VL    VH      VL    VH      VL     VH
> # of LiIon Cell 46    46      46    46      46     46
> LiIon cell      3.5   4.1     3     4.1     3.6    4.2
> Liion Pack      161   188.6   138   188.6   165.6  193.2
> Per PbA (13)    11.5  13.47   9.86  13.47   11.83  13.8
>
> I attached the spec for these cells.  Also, this page contain actual test
> data of various LiIon cells.
> http://www.definity-systems.net/Transportation/EV/efficiency/Li-ion/
>
>
> Ed Ang
>