In rare cases, end users have reported a flat vehicle battery a while after installing a device like the Bolt2. Based on the Bolt2's current draw, the Bolt2 is not to blame. 

The numbers:

Bolt2 current draw from a 12V power supply, with the battery plugged in. 

• The average current while charging the battery is 38mA (note, this is worst case, the battery remains fully charged nearly always). 
• This is comparable to the typical car parasitic draw sits between 20-120mA
• When fully charged, the current drops off to about 0.85mA
• Every couple of hours the device 'refreshes' the GPS - which uses a little bit of power
  • A refresh in good signal bumps up the average current draw by 0.25mA
  • With no signal, about 0.5mA
• Hourly heartbeats add 25uA under normal conditions. If out of coverage about 3mA is added to the average draw. 

In context:

Most car batteries are about 40Ah (amp hours). Current draws in the region of mA have next to no effect on them.  

• In the worst-case current draw when out of coverage and with no GPS signal, the average current would be ~4.5mA. If the Bolt2 was the only thing connected to a small car battery (40Ah), it would last 1 year.
• In the case with a car parked in a garage with no GPS signal it would draw around 1.5mA. That would last 3 years on a small car battery.
• The typical case with good GPS signal and cellular signal would draw ~1mA on average and would last 4.5 years on a small car battery.

Conclusion:

If a car battery goes flat after installing a Bolt2 - it's just a coincidence. The device draws that little power it is essentially negligible. All car batteries age and eventually need replacement - for some this timing just occurs soon after a tracking device is installed!