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Subject: Re: FM Recorder battery?
From: Andrew Jamieson (ajamiesn_at_optusnet.com.au)
Date: 2003-02-08

There is virtually a whole industry in the design and manufacture of Li-Ion
battery monitor IC's. They prevent the battery from being overcharged
(above ~4.2V), undercharged (below 3V), or short circuited. In these
circumstances, it is possible for the Lithium in the cell to plate out to
the electrodes, and become explosively reactive to any contact with water.

Most Li-Ion cell manufacturers will not sell batteries to companies unless
they know what protection circuit they are using; this indemnifies them in
the case of an accident with the battery. I would be very surprised if the
Archos product does not have a protection IC in it, but it is a _REALLY_
good reason not to charge your batteries with rockbox until we have more
detailed circuit information, just in case it does not.

----- Original Message -----
From: "Maik Bühnemann" <M.a.i.k_at_gmx.de>
To: <rockbox_at_cool.haxx.se>
Sent: Saturday, February 08, 2003 11:43 PM
Subject: Re: FM Recorder battery?

> Hi!
> This ist a part of an interesting article about how to manage li-ion
> batteries:
>
> "Lithium ion batteries reach power densities of 230 Wh/l. As
> electrolytes organic connections or salt melts serve. A combination
of
> lithium with aqueous electrolytes is not possible due to the reactivity of
> the lithium. During the loading and discharge process ` ' the lithium
> ions between the metallic oxide cathode and the anode on carbon basis
> swing in electrolytes back and forth, why this system also lithium Swing
is
> called. The cell rated voltage of the system amounts to
> depending upon structure 3.6 or 3.7 V and cannot replace usual designs
> therefore so easily. Numerous recall actions shifted the call
> of lithium systems early a heavy impact. Thus Notebooks burned out
> proper, and Japanese Mobiltelefon Akkus got rid of with a flame impact of
> its positive pressure. Improved cell structure and
> sophisticated protection electronics led however in the meantime to a high
> security of this system. This necessary protective circuit is
also
> the reason, why ` naked ' left ion cells for the final consumer are not
> available.
>
> The optimal charge of the left-ion-Akkus is complicated and special
Akku
> Controllern reserved,
>
> which work usually in several phases: If the cell tension dropped
under
> 2,5 V, they load one hour with 0,1 C over 2,5 V with constant
> voltage and a maximum river by 1 C are loaded. The charging current drops
> then within 1,5 to two hours slowly. If the charging current does not
> sink any longer considerably, a timer starts. After one hour the
> cell received then its full capacity. Which the offerers of devices with
> lithium Akkus conceal gladly, the limited life span of left ion
> chemistry is independent, of the done cycle number. A meaningful use of
> left-ion-Akkus is limited because of the inevitable loss of capacity
to
> zirka three years."
>
>
> My Question: ist the charging done by archos hardware or does the firmware
> control this?
>
> MAik
>
>
>
> ----- Original Message -----
> From: "SeeSchloss" <SeeSchloss_at_zmail.pt>
> To: <rockbox_at_cool.haxx.se>
> Sent: Friday, February 07, 2003 9:51 PM
> Subject: RE : FM Recorder battery?
>
>
> > Hi,
> >
> > Hmm I dont think that the battery they put in the FM Recorder
> > is very bad... Most of the time I have to recharge my unit
> > after having used it for 12H...
> > But if your charged your FM Recorder with Rockbox I think
> > it may be damaged since Rockbox doesn't know how to manage a
> > LiIon battery...
> >
> >
> > SeeSchloß
> >
> >
> >
> > > So, when I first got my FM recorder, it got about 5
> > > hours of continuous play off the battery before it
> > > died. Now it only gets about 2-3 hours before it dies
> > > (after a full charge from the charger it came with).
> > >
> > > The only thing is, I did install a daily build of
> > > rockbox fm on jan 23 & jan 27 2003, but I have since
> > > removed the ajbrec.ajz file (but not the .rockbox
> > > dir). Is there any way that the rockbox could've
> > > damaged my battery/unit? Or is this just a really
> > > shoddy battery they put in it. It is now totally
> > > useless for any long flights or day trips away from my
> > > charger.
> > >
> > > The only other thing I will say is that I did buy a
> > > Radio Shack 6-volt/1000 miliAmp car charger (which
> > > works fine), but my battery problems started well
> > > before I started using the car charger.
> > >
> > > Any comments on the subject at all will be
> > > appreciated!!! Should I send my unit back to Archos?
> > > Thanks a lot!!!
> > >
> > > Andrew
> >
> >
>

Page was last modified "Jan 10 2012" The Rockbox Crew
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