Substitute batteries

Michael Shiloh michael at
Thu Aug 21 08:03:42 CEST 2008

Joel Newkirk wrote:
> On Wed, 20 Aug 2008 22:49:05 -0700, Michael Shiloh <michael at>
> wrote:
>> Joel Newkirk wrote:
>>> My guess is that it incorporates some constants that depend on the
>> actual
>>> battery pack.  Note that I don't actually KNOW that it's in the battery,
>>> but previous ML posts by folks at Openmoko refer to it as 'in the
>> battery',
>>> and with a bl-5c installed almost all battery-related entries in sysfs
>> are
>>> unpopulated.
>> This is to confirm that the coulomb counter is in the battery pack. Why?
>> Because it stores the count, and if you swap batteries, you need to know
>> the count for the battery in the device, not for the one you removed.
> Makes perfect sense. Is it a custom IC, something off-the-shelf, or what? 

That I don't know. Joerg, any reason we don't open source this 
schematic, since we did all of GTA02?

> Could it be cheaply retrofitted by a hobbyist into a BL-5c clone battery? 

There is the space issue of course.

> I'm quite happy to crack one open, just not my Openmoko battery... ;)  
> Barring the workability of that idea, I'm hoping we can adapt the battery
> management/monitoring software to fallback to the 'dumb cellphone' approach
> and let us safely charge, and have some idea of remaining capacity of,
> non-Openmoko batteries if it detects a battery present without the coulomb
> counter circuit.

Yes, this should be done in any case, so that a "dumb" battery can 
always be used.

> j
>>> j
>>> On Thu, 21 Aug 2008 00:13:00 -0400, "Charles Pax"
>> <charles.pax at>
>>> wrote:
>>>> On Wed, Aug 20, 2008 at 11:29 PM, <freerunner at> wrote:
>>>>> OK, I have a few Nokia batteries laying around, BL-5c and BL-6c, and
>>>>> desktop chargers.  They power the Freerunner fine, and seem to charge
>>>> when
>>>>> they're in the FR plugged in.  But the Freerunner doesn't know what to
>>>> do
>>>>> with them apart from that, presumably since they lack the Openmoko
>>>> coulomb
>>>>> counter circuit.
>>>> The coulomb counter circuitry is in the battery? Why isn't this on the
>>>> board
>>>> itself?
>>>> -Charles
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