Hello @Otofoto
are the aforementioned 25 minutes from a fully charged TailBat? That seems a bit short.
I've measured the power consumption of the Atom GPS kit (w/o sd card) and it takes about 100 mA. So it should not suffer from a premature shutdown due to consuming too little power as the shutdown current limit in the TailBat is about 45 mA.
The TailBat has a 190 mAh battery - so theoretically you should get close to 2 hours out of it.
Thanks
Felix