12v memory saver ... Have you used?

[Jev88]

I will soon be changing my RV engine battery but the fact it is an RV is hopefully irrelevant.

I have an alarm and immobiliser that I am not yet fully familiar with (Year 2000 vehicle and alarm fitted in UK after import but fobs look quite new/modern with multiple buttons). I know I could wrestle with jump leads to a spare battery or if my 12v cig socket was live without ignition I could use that (it isn't) but discovered this little widget..... See below. Anyone with experience and is the OBD port always live?

 

[Richard n Ann]

Looks like pin 16 is always +12v

 

[Popty]

Hi, obd port has permanent live, without ign switched on, if you plug in any obd reader, it lights up, without the ignition on