This question comes up from time to time where there is a suspicion that the GNX unit is draining the vehicle's battery although there has yet to be a case where that was found to be true.
The facts are as follows:

• A GNX device will only charge its internal battery while "napping"
• A standard car battery is normally rated at about 48 Ah or 48000 mAh
• The GNX is most likely to be averaging around 50 mA when the vehicle ignition is off (parked) which would mean that it would take 40 days to completely discharge the battery
• Complete discharge is only possible if the parameters POWER_OFF_TIME (105) and/or POWER_DOWN_VOLTAGE (136) are not set as these can reduce consumption to near 0 (< 1mA). Default settings for these are to power down if the voltage drops below 8000 mV or after 1 week

To summarize, it is highly unlikely that the GNX would be responsible for draining a vehicle battery unless the vehicle is parked an extraordinarily long time and no power management parameters are set.