Backup battery discharged -> GTA01 and GTA02 dead

Andy Green andy at
Sat Jul 19 15:59:39 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| Andy Green wrote:
|> Somebody in the thread at some point said:
|> | Are you 100% sure that a good backup battery level is not required for
|> | boot on a GTA02v5?  Who can answer that for GTA01Bv4?
|> Well, I have booted devices with very low backup battery level, during
|> the time we hunted down the reason for this
|> no-boot-with-low-or-no-battery issue I did check the battery state.  And
|> according to pcf50633 documentation, the effect of backup battery level
|> is mainly to act as a gateway into NOPOWER state of the PMU, which is
|> where we are at after manufacture anyway (and we evidently booted at
|> that time).
| OK, thanks.  I'll try "jump-starting" the backup battery tomorrow and
| see if I can get a boot that way.
| What's the normal voltage of the backup battery?  (i.e. what should it
| charge up to?)

I saw it at around 2V normally.  I'm not sure what the charging scheme
is without looking it up and it is time to cook tea, but I guess it is
something like 3.3V via a decent resistor.

| I'll try a 1.5V dry cell in parallel with the backup battery tomorrow to
| see if that will jump-start things.  Once I have a good boot I'll leave
| it on the wall charger to see if the backup battery recharges ok.

Should be OK if you don't leave it on too long without a series
resistor.  But you only need it on for your test while you are clicking
power button.

| Thanks for your help, Andy.

You're welcome, wish it was the kind of help that had got you up again

- -Andy
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