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

Paul Fertser fercerpav at
Sun Aug 2 21:46:06 CEST 2009

Wolfgang Spraul <wolfgang at> writes:
>> Yes, i think that's the case. The only state where integrated power measurement
>> readings are unavailable is suspend and that's quite low level
>> already.
> You could measure the current when you wake up, couldn't you?

It's possible with bq27k because it works autonomously. But if you do
something similar to gta01 there's no way to measure current in
suspend without an external equipment.

>> bq27000 measures current accurately so it should be possible. I'm sure
>> there's some decent IC suitable for your task.
> bq27000 is a chip, right? You mean we should have that chip inside the device,
> instead of having it in every battery?

It would be a possible solution but it doesn't make much sense because
bq27k assumes it's connected to the same battery all the time. I meant
that since bq27k manages to measure the current accurately, there
should exist some other more simple IC (properly shielded to be immune
to noise) to measure the current inside a device. Also the charger IC
must know the current too, it's just that PCF50633 doesn't allow to
read it for some reason :(

There's also a possibility to use some other CC on device side, take
a look at
( $1.6 )

> That would make the batteries cheaper as well, I believe the CC batteries
> cost 2 USD or so more than without CC :-(

And also special batteries are always harder to source for
end-users. Especially if they're not located in EU or the USA.

Be free, use free ( software!
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