My Gta02s wont charge

Werner Almesberger werner at
Sun Jun 22 22:39:17 CEST 2008

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 state.

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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