Re volt meter, yes ok plugged in permanently as long as it’s not in a socket that’s always live like the boot one.  Plus there will be a voltage drop through the cabling so it will under read.  When using one I read the battery volts directly using a multimeter, then read off the ciggie lighter read out, maths gives you what to add to the ciggie lighter readout to get whet the battery is.  Re where to get one, I just use the cheap ones from eBay. As below, right of the cable spaghetti.  Pls excuse the mess.  

 

1. Yes it will drain the battery if permanently on.

 

On 29/11/2020 at 00:50, anombres said:

There were some earlier discussions on that, there might be some risk of affecting some of the electronics and might cause more damage.

 

Can you link to these? Sounds very, very unlikely to me.

I have a voltmeter permanently plugged in the cigarette lighter socket, which is permanently live on my 2019 Karoq.

Mine draws 8 mA, but I have seen other models drawing much more.

 

It's imperative that you mount the voltmeter so that you can read the no-load voltage through the closed window, as opening the door starts some car's systems and the voltage reading isn't relevant any more.

 

Keeping a sharp eye on battery no-load voltage is important today for two reasons: less driving due to lockdown and the tendency of modern start/stop cars to only charge the battery on gravity (going downhill) or inertia (decelerating/breaking) to save fuel. Thus we more often than in the past return home with the battery still not fully charged. And letting the battery stay below 12.4 V for longer periods induces sulfation, i.e. battery deterioration

 

The round model (bottom) is the one I settled on, while the direct-plug models were grossly inaccurate and drew up to 40 mA.

 

 

Edited 2 December, 20205 yr by agedbriar

10 hours ago, agedbriar said:

I have a voltmeter permanently plugged in the cigarette lighter socket, which is permanently live on my 2019 Karoq.

Mine draws 8 mA, but I have seen other models drawing much more.

 

It's imperative that you mount the voltmeter so that you can read the no-load voltage through the closed window, as opening the door starts some car's systems and the voltage reading isn't relevant any more.

 

Keeping a sharp eye on battery no-load voltage is important today for two reasons: less driving due to lockdown and the tendency of modern start/stop cars to only charge the battery on gravity (going downhill) or inertia (decelerating/breaking) to save fuel. Thus we more often than in the past return home with the battery still not fully charged. And letting the battery stay below 12.4 V for longer periods induces sulfation, i.e. battery deterioration

 

The round model (bottom) is the one I settled on, while the direct-plug models were grossly inaccurate and drew up to 40 mA.

 

 

Can you clarify exactly what you’ve done here ab, you say it’s permanently plugged into the cigarette lighter but you also say the bottom one (13.8v ?) is the one you’ve settled on yet it appears to be a panel mount device.........Are you saying the bottom device is wired into the cigarette lighter circuit permanently?

1 hour ago, Berisford said:

Can you clarify exactly what you’ve done here ab, you say it’s permanently plugged into the cigarette lighter but you also say the bottom one (13.8v ?) is the one you’ve settled on yet it appears to be a panel mount device.........Are you saying the bottom device is wired into the cigarette lighter circuit permanently?

Exactly.

The bottom model (displaying 13.8 V) is mounted on a  piece of aluminium sheet and resides raised just above the vane edge beneath the central armrest, turned laterally towards the driver's window. It's connected to the cigarette lighter by a short cable and standard 12 V plug.

55 minutes ago, agedbriar said:

Exactly.

The bottom model (displaying 13.8 V) is mounted on a  piece of aluminium sheet and resides raised just above the vane edge beneath the central armrest, turned laterally towards the driver's window. It's connected to the cigarette lighter by a short cable and standard 12 V plug.

Ah, I see, thanks.

Here's how it looks.

The wooden block is part of the support I'd made for my former Octavia. I figured it would look more solid than panel mounted directly to the aluminium sheet without any protection on the backside.

The car is currently connected to the battery charger, hence the reading. 

 

Edited 3 December, 20205 yr by agedbriar

LCD display is a more appropriate technology for this, which is why it's used for permanently displayed info on dash panels. It only uses current when the reading changes, so is very much less draining. On the other hand, unless backlit by LEDs (defeating the low-current aim) it's not visible in low light or darkness without a torch. It's rare that my phone torch is unable to do this job from outside drivers door though, so not really an impediment.

 

Mine  - in my 9N Polo - is cobbled together in an ugly fashion as seen below. (I'm a function over fashion type person).

The switch chooses between a wire going directly to battery + and one going to D+ of the alternator, both have fuses inline just in case. The negative connection goes direct to battery negative.  It uses just 0.5mA.

 

 

 

 

The one I use has a switch so consumes no current when its switched off, I leave it on so that I can see the state of charge through the passenger window, it was more visible in the console of the Octavia but this is the best location in the Yeti.

 

It has a USB port as well, accuracy of this one spot on, the last under-read by 0.2v which is still pretty good.

Interesting, I've been having issues with my Karoq lately its almost a year old and I was stopped at a traffic lights today and the stop/start must have kicked in and about a minute later I pressed on the accellerator and nothing the engine didn't reignite so I had to put it in park and start it again and it took about 30 seconds to get it going again not sure why but I suspect its related to the battery.

The stop start will not engage if the battery is down on volts, so it is unlikely?