[BC]

Hi all,
Noticed another thread mentioned a cigarette lighter mounted voltmeter.
Has anyone had much to do with these? 
I thought they may be a worthwhile way of predicting a dying battery and save the grief of being stuck. 
They are only a few dollars each too.

Thanks . . .

[Phil №❶]

If you're not using the cig lighter for any other purpose, then it can't do any harm. I can't vouch for their accuracy though. Remember, the voltage is not a true indication of the health of your battery. A heavy load is placed on the battery at start up, especially Diesel's and engine cranking is a significant demand, so anything under 12.5 V indicated, after 12 hours off overnight is getting to end of life IMO.

[rustynutz]

I bought one just recently... 
From the specs it's not terribly accurate, something like +/- 1.2% error.
Cost was a whole $2.71

12 24V LED Display Cigarette Lighter Electric Voltage Meter FOR CAR Battery BY | eBay

[panthersteve]

It doesn't necessarily need to be accurate, just use it to indicate a trend.

[rustynutz]

I mostly just wanted to see how much it varied.

So far I've seen it peak at 14.4v....

[Just Rick]

I'd actually like a volt meter in Bruce and Cyril,not really anywhere you could fit a nice Aftermarket one in the FD's,do the GD's have them

[The Gonz]

Go on, Rick. I bought the body kit, time for you to get the voltmeter.

[The Gonz]

Has anyone done this yet? I'm about to test drive my new PayPal account for a few of these.

[Just Rick]

Gonz I have looked at so many of the after market,mounting kits,the driver pillar mounted ones are just unsightly and I don't particularly want to start drilling holes in my dash to run the required wiring,I have been looking at getting a mounting bracket molded up to replace the lower small glove  box door in front of the centre console,that's the only really decent place I can think of putting one and beside a decent oil pressure gauge,finding the rotor molding company is not the hard part the making of the mold and then once made the ownership of said mold is an issue,as I am paying for the making of it I think it should be mine(so if it took off I could make some money)but sadly they have the same idea

[The Gonz]

I hear you, Rick. I think I might get a half dozen or so (a few as novelty gifts) and try one in the cigarette lighter, which has gone unused since new. Even my GPS is hardwired from behind it so the socket can enjoy a purpose of its own.

Getting these is still a good idea for your needs. With access to a 3D printer, you can design your own new housing or panel shape in black plastic and then fit this to it without the ciggie plug behind it. That's probably where I'll go with it down the track if I decide on the right spot.

Edit:
I've just been browsing eBay and found a lot of alternative designs for panel mounting so it looks like once you decide on the mounting style, you'll have lots of options including little boxes made for flush mounting already.

[AlanHo]

I bought one of the cheapy cigarette mounted volt meters to monitor the volts under various conditions to try to see if it had any relation to the ISG having hiccups intermittently 

I first compared my cheapy cigarette socket volt meter with a professional Megger Multimeter and it is accurate rounding the output to the first decimal place. If the megger reads 12.65 it shows as 12.7 and 12.64 shows as 12.6.

The readings are as follows :-

Ignition key position 1 - voltage steady at 12.8

Ignition position 2 - steady at 12.5. Operate foot brake and it drops to 12.3

Start engine : volts fluctuate 13.7, 13.8 13.7 13.6, 13.8.
Switch all lights on it drops to 13.6 then gradually climbs to 14.1
Now switch A/C full blast and seat heaters on : drops to 12.9 then again climbs to 14.1 and stays there.

Whilst driving.

On level motorway. light throttle to maintain 65mph in 6th - 13.1 to 13.2

Slight incline demands more throttle - drops to 12.9 to 13.0 then increases to 13.8 and stays there until you back off on the throttle

Heavy throttle to accelerate : drops to 12.9 then increases to 13.8

On full over-run : quickly goes to 14.3 and stays there until you depress the throttle.

Knock it into neutral while on over run and coast - drops to 13.8.

Therefore my car does as I expected. The alternator charges at max when car is on over-run and seems to vary the charge volts depending on throttle opening. No throttle and car on over-run - max charge at 14.3 volts. Heavy engine load and the car relies on the battery until it drops to about 12.8 volts when the alternator kicks in slightly raising the volts to 13.8.

When the ISG stops the engine the volts drop to between 12.5 to 12.9 whilst the engine is off. As soon as the engine starts the volts rise to 13.7 or 13.8 and then after reaching cruising speed go up on light throttle to a max of 14.3 on over-run and down to as low as 12.8 on increased throttle.

[The Gonz]

That's great analysis for a $2.71 device. Thanks, Alan.

Was its display limited to 3 digits in total, as in 00.0?
If so, its accuracy as you describe it is as good as it can get for a 1 decimal place display - got to be happy with that.

[AlanHo]

Yes - the display is to one decimal place ie: 00.0

It could do with being buffered slightly because it changes very rapidly when the voltage oscillates above and below a particular value. the other small snag is that the power socket on the Venga is mounted  low in the central binnacle and I had to duck down to read the volt meter.  But I am being picky - overall it worked quite well.

The reason why I bought it is that my ISG does not behave according to "The Book" and I wanted to see if the voltage was a cause..

The normal complaint about ISG is that the engine fails to stop when it should - but my car cannot be faulted in this respect. It always stops in accordance with the specified conditions.

My problem is that after the engine is stopped by ISG it sometimes fails to start upon depressing the clutch and I have to start it with the key. I then get a peep on the horn from millisecond muggins behind me for failing to roar off instantly. I have not been able to determine any particular reason for the engine not starting as it should.  It is very intermittent and sods law will decree it will fail to happen if I take the car to the dealers.

Another anomaly is that when at ISG standstill - if I pump the foot brake a couple of times - it starts the engine without me touching the clutch.  This is a real mystery.

Guys on the KIA forum suggested that the latter behaviour may be because the brake lights cause a drop in volts below a safe limit which tells the engine to start and get the alternator charging. However, the voltmeter proved that this is not the case. Hitting the brake does not reduce battery volts value displayed.

[jsp1978]

This is not a great way to determine battery condition, but there is some info that would be useful. With engine off, state of charge is shown. 12.6 is fully charged, and 12.0 is flat. When cranking, the battery should not drop below 9.6v, but the battery needs to be fully charged to start with or the result will not be accurate. Charge rates should be between 13.6 and 14.8, but keep in mind most modern cars regulate the voltage to save fuel by reducing load on the alternator (like turning the alternator on and off).