[Fwd: Re: Charging a Neo battery in a Nokia charger or phone]

Michael Shiloh michael at openmoko.org
Thu Oct 2 23:34:47 CEST 2008

Andy Green wrote:
> Hash: SHA1
> Somebody in the thread at some point said:
> | Forwarded from the community list. Can anyone confirm that our code does
> | not care what brand the battery is?
> If there is suitable power available, the PMU will try to charge
> anything on the battery connector without trying to figure out what it
> is.  Because the charging algorithm is adaptive to how the battery is
> reacting, that isn't as dangerous as it sounds.

Hi Andy,

To further understand this, and to make sense of all the suggestions on 
the community list about how to charge a dead battery, I'd like to 
understand the PMU activity better.

At what point does the PMU start charging? I.e., if the phone is turned 
off and USB power is applied, will the PMU start charging? Or does it 
require some running code to enable the PMU?

If the latter, is this code in u-boot? Is the PMU enabled in either/both 
u-boot in NOR FLASH and NAND FLASH (depending on u-boot version, of course)?

Is it true that while in u-boot (version dependent?), the FR consumes 
less than 100mA, so that if powered by any USB source (prior to any USB 
negotiation for higher current), the FR can sit in u-boot and charge the 
battery with whatever current is left over after keeping the phone running?

Does any USB high current (500mA) negotiation take place in u-boot?

Do we sense the ID resistor in u-boot?

I presume that these two negotiations only occur after we boot into 
Linux, so that in u-boot the best we can do is draw 100mA, and charge 
with whatever is leftover.

I think you see what I'm trying to understand here. On the community 
list are various suggestions of sequences to get a dead battery charged. 
I want to understand the underlying process, so that I can document the 
correct sequence.


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