I have a 2016 Superb L&K estate.  I would like to have a running coolbox in the boot and I bought a Dometic  Coolpower M50U voltage monitor to save the battery being run down,  however I  find that it kicks in after approximately 30 seconds after stopping the engine, even after a long run.  The dongle flashes showing that there is still current. It is meant to cut off at 11.6 volts. Stop/start works, so I think that the battery is fine. Can someone help please? The coolbox runs when plugged directly into the socket. 

Perhaps you need to test the voltage available and confirm the cut-out is indeed 11.6.....?

 

Will do, thanks. 

I was thinking of plugging 12v coolbox into boot today but wasn't sure if it would run the battery down if I left it plugged in by accident. Would be good to know how much these impact the battery when engine is turned off and also if they keep running indefinitely or if the car or even the coolboxes switch off after a certain period of time.. 

Basically this is just a long way of saying I'm watching this thread!! 

The voltage drop at the boot 12v socket is quite high when operating a coolbox, so you need battery protector that kicks in at a lot lower voltage than 11.6v, more like 11V.

Basically, with engine off and coolbox connected do not be surprised if you already have 11.5V there with an 7A coolbox. 

For continuously operating coolbox taking constant current, best would be battery protector that switches off at 11V and does not come back on until voltage recovers to 12.2V or so.

 

 

I run a Halfords 14ltr box that uses 40w and claims to draw 3.5amps - I'm happy letting it run up to 2 hours unattended - it's quite a small battery on the Karoq..........not a problem in my Golf inasmuch as the socket is ignition controlled but the box is poor at retaining any 'coolness' without constant supply.

 

Been looking at the highly regarded 12v compressor boxes but they are serious money, cost more than a domestic fridge!

 

Edited 14 August, 20214 yr by Berisford