My Gta02s wont charge

steve steve at
Mon Jun 23 20:43:23 CEST 2008


  micheal will get back in town and I will go visit him on Thursday.

  Since I don't know a volt from an ohm, he will do the testing.
  ( I do, but he is the better man for the job) 

  The biggest issue is not me getting a charged battery. The big issue
  is how does the total system respond when you drain the battery to dead
  and then jack it in? 



-----Original Message-----
From: Werner Almesberger [mailto:werner at] 
Sent: Sunday, June 22, 2008 1:39 PM
To: Andy Green
Cc: Joerg Reisenweber; openmoko-kernel at; Sean McNeil;
Subject: Re: My Gta02s wont charge

Andy Green wrote:
> This will also solve the "no charging when PMU left on its own if 
> charger off was the last order" issue as a side effect.

That's one of the things I'm not convinced about. If the PMU manual is to be
believed, there's no active current path to the battery or Vsys in that

Furthermore, if the battery is below the Vsys detection threshold voltage,
Vth(sysmin) = 2.5V, and there is no other current path to Vsys, the system
shouldn't come up for whatever reason.

Heh, just tried that setup, and this time it really didn't come up when I
plugged in USB. Finally something works as expected ;-)

There's the procedure:

- make sure MBCC1.chgena isn't set (e.g., disconnect USB, power up, then
  remove the battery)

- discharge a battery through a resistor until the internal protection
  circuit cuts it off. This happens around 2.5V with GTA02 batteries,
  2.2V with GTA01 batteries.

- insert the battery

- plug in USB

Steve, can you please measure the voltage of your "dead" battery ?

Steve, if your battery reads 0V, there's something you could try:

- find a power source that delivers roughly 4-5V

- briefly (for a second or so), connect that power source to the battery,
  such that + connects to + and - to -, i.e., like jump-starting a car.

With a little luck, this little jolt will have convinced the protection
circuit that the battery can stand some more use, and the battery will now
deliver >2.5V, enough to bring up the Neo and charge from USB.

- Werner

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