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Subject: Re: I've done it : FM Recorder opened :-D
From: Andrew Jamieson (andrew.jamieson_at_projectlab.net)
Date: 2003-02-10


Hmmmmm ..... I've done a bit of googling, and your right. I stand
corrected. However, I reserve the right to still think it's kinda wierd,
and "something I would not do"(tm).

Andrew Jamieson

----- Original Message -----
From: "Joaquim Carvalho" <jdc_at_x64.com>
To: <rockbox_at_cool.haxx.se>
Sent: Monday, February 10, 2003 10:04 PM
Subject: Re: I've done it : FM Recorder opened :-D

> Many devices, including the Apple Powerbook Pismo use several (6)
> LI-Ion batteries in parallel so I don't believe there are any
> substancial problems with this solution. The Pismo batteries last
> for 5 hours which is surprisingly good even for a PPC notebook.
> Joaquim
>
> On Mon, 2003-02-10 at 10:43, Andrew Jamieson wrote:
> > Ive used Li-Ion batteries to power a device that drew ~2A peaks with two
> > cells in series. With cells in parallel I dont understand how you would
> > prevent them from draining each other due to slight differences in
internal
> > impedance and voltage, without external ciruitry to prevent cross flow
of
> > current.
> >
> > Which is probably what they have, but I still think its wierd :) Better
to
> > connect them in series and then use a step-down to reduce the high side
> > current draw.
> >
> > A
> >
> > ----- Original Message -----
> > From: "Stuart Tedford" <stuart.tedford_at_piresearch.co.uk>
> > To: <rockbox_at_cool.haxx.se>
> > Sent: Monday, February 10, 2003 8:36 PM
> > Subject: RE: I've done it : FM Recorder opened :-D
> >
> >
> > > > -----Original Message-----
> > > > From: Andrew Jamieson
> > > >
> > > > However, it's interesting to see it uses two Li-Ion batts,
> > > > but it looks like
> > > > they are connected in parallel ..... _very_ wierd. Very wierd
indeed.
> > > >
> > >
> > > No, its not that weird. I've got a data sheet for a MAX1684EEE DC-DC
> > > convertor IC (as used in PDA's etc) that states that a 1.5 Amp output
> > > requires the use of 2 Li-ion batteries, otherwise you only get 1 Amp.
It
> > > must have something to do with the batteries internal resistance - if
I
> > > remember rightly from my EE diploma some years ago :-)
> > >
> > > Stu.
> >
> >
>



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