SatNav in lighter socket and 'surge' risk before engine running?

Hello

I have a Navitel SatNav. The instruction book advises: To protect the device from sudden surges in the on-board power supply, always connect the car adapter only when the engine is on.

Is this a common piece of advice from manufacturers? I presume it means do not plug the satnav into the cigar lighter socket until the engine has started or you risk frying something in the circuit board. Unfortunately, neither my car's socket nor the satnav's plug come with an on-off switch/button, so this means mechanically plugging and unplugging the unit which in my experience wears things out and eventually leads to a bad connection.

I know there are on-off lighter socket accessories out there, and it looks like that's the only option.

 

Thanks for the reply. I think so -- it's this one: (page 2 and 7)

Code:

https://findinstructions.com/instructions-for-navitel-re900-lifetime/download/

But the thing is that the instruction book gives that warning, so I am a bit worried.