My Gta02s wont charge

Werner Almesberger werner at
Wed Jun 25 06:17:12 CEST 2008

steve wrote:
> For completeness let's review the steps you want michale and I to go
> through.

1) Measure the voltage across the terminals of the "dead" battery
   and post the result. Expected result: either no measurable
   voltage, or somewhere in the 2.4V-3.6V range.

2) If the voltage measured in 1) was very low (<1V), take a power
   supply in the 4V-5V range (*) and connect briefly (~1s) to the
   "dead" battery, such that + goes to + and - goes to -.

   Then measure the battery voltage again.

(*) Examples, in increasing degree of fanciness:
    - one of those ancient 4.5V batteries, e.g., the leftmost in
    - some wall adapter that emits 4-5V DC
    - another Neo battery (charged)
    - lab power supply, e.g.,

If the voltage measured in 1) was significantly above zero or 2)
doesn't help, you may consider charging it in an external charger or
from a lab power supply (if Michael has any of these).

For the latter, set the voltage limit to 4.2V, the current limit to
0.8A, connect + to + and - to -, and enjoy some beers while waiting.
You should see the voltage rise to 4.2V with the current constantly
at 0.8A, and then the voltage remains at 4.2V while the current drops
towards 0A. Your battery is charged when the current drops below 0.1A.

Please be careful not exceed the 4.2V. A bit less (e.g., 4.0V) is
okay, but will charge the battery only partially.

If also external charging doesn't restore the battery to a working
condition, then it may have suffered some permanent damage.

- Werner

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