Document with answers to most popular battery-related questions is ready

Wolfgang Spraul wolfgang at qi-hardware.com
Sun Aug 2 20:27:58 CEST 2009


Paul,

> > We will ship our first NanoNote with a BL-4C compatible battery, without
> > Coulomb counter (middle pin unused) [1].
> Hm, can BL-5C fit there? Because it'd be much nicer as modern 5Cs have
> quite some capacity.

It fits, but it's a bit too thick so it's hard to close the battery cover with
a BL-5C (or gta02 battery) inside. Not recommended.

> The only problem so far with using a dumb battery on FR is that
> there's no way to know the current from inside the device. On gta01
> there's a resistor shunt supposed to be used to measure the current
> but readings are too noisy to be useable. So if you have a good way to
> measure current already i'd not go for CC.

Hmm, that's a pretty strong statement.
At Openmoko we spent _a lot_ of money combined to get this CC thing to work.
The theory was that you have it in most notebook batteries so it's 'a good
thing to have'.
But if it's not actually used, then it would be one of those many things
we did that should have been better thought through.

I will check with Adam about precise current measurements for the NanoNote,
and still I would appreciate any feedback from other people who are using the
CC data for something other than proving that we have it :-)

Any Coulomb fans out there?

Wolfgang

On Sun, Aug 02, 2009 at 10:02:42PM +0400, Paul Fertser wrote:
> Wolfgang Spraul <wolfgang at qi-hardware.com> writes:
> > this is an excellent document, obviously I cannot spot anything
> > wrong!
> 
> Thanks for you kind words. :)
> 
> > I didn't know that some external chargers would not charge gta01 or gta02
> > batteries because of the thermistor check you are writing about.
> 
> I'm not sure i saw any charger like that myself or seen reports
> (except on our wiki). But i suspect the probability of that for nokia
> brand charges is quite high.
> 
> > All the cheap external chargers we bought in Taiwan or China for testing can
> > charge both gta01 or gta02 batteries without a problem.
> 
> Proves my point :D
> 
> > I have a question for all:
> > We will ship our first NanoNote with a BL-4C compatible battery, without
> > Coulomb counter (middle pin unused) [1].
> 
> Hm, can BL-5C fit there? Because it'd be much nicer as modern 5Cs have
> quite some capacity.
> 
> > How are people really using the Coulomb counter in gta02?
> > Theoretically I would think that it provides far superior power measurement
> > options for actual software development, just as you write.
> > For example when playing with power saving codes, whether in the kernel,
> > middleware or applications, I would think over the course of several hours or
> > days the Coulomb counter data is the primary means for efficient
> > development.
> 
> To me it seems that CC readings are almost unused except for
> presenting the user with a bit more accurate capacity data. And when
> someone is developing something lowlevel he could as well connect and
> external ampmeter, much more reliable and flexible approach.
> 
> > So we are considering shipping the next version of the NanoNote with Coulomb
> > counter batteries same as the Neo FreeRunner.
> > But if nobody is actually using the data from the Coulomb counter, then it's a
> > wasted effort.
> 
> I'm not sure you'll get much for using CC.
> 
> The only problem so far with using a dumb battery on FR is that
> there's no way to know the current from inside the device. On gta01
> there's a resistor shunt supposed to be used to measure the current
> but readings are too noisy to be useable. So if you have a good way to
> measure current already i'd not go for CC.
> 
> -- 
> Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software!
> mailto:fercerpav at gmail.com



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