Keeping your instrument panel simple? You probably already have a voltmeter 🙂

[danny_galaga]

I noticed this too late for my build. My radio has a voltage display. That could have saved me some wiring. Mind you, my voltmeter is a USB port with built in voltmeter and USB seems useful nowadays. So I don't regret putting it in.

 

But especially if you are building something really small and light, worth seeing if your radio, or other instrument has this function before you get a voltmeter.

 

 

 

[Area-51]

Be aware the usb volt meter may not read accurate; the one i installed reads a whole volt higher than actuals; confirmed with external test meter.

[danny_galaga]

14 minutes ago, Area-51 said:

Be aware the usb volt meter may not read accurate; the one i installed reads a whole volt higher than actuals; confirmed with external test meter.

Already tested before I installed. Within 0.1V of my voltmeter. The radio of course is even more accurate 🙂

Edited March 25 by danny_galaga

[RFguy]

I was working on a plane recently , without a working voltmeter, and a USB car voltmeter plugged into the "cigarette lighter" is what we used .....

It's showing master bus voltage of course, not battery. Could be maybe half a volt different from battery voltage depending how it is wired

However it does work to  tell you if you are charging, or in discharge .  > 13V probably charging. <13V. probably discharging.  . ==13V ? wait another minute .

[danny_galaga]

Totally agree, although if all the wiring is good the difference is negligible - no need to have wires going separately all the way to the battery.

 

Like you say, you want to know if it's charging or not. Even area 51s faulty one would be fine as long as it's consistent. Doesn't even have to read as volts. 

 

825 bananas- battery at rest.

 

990 bananas- battery charging (a few minutes after start). 

 

Over 990. Overcharging.

 

Somewhere between 825 990- something's going on (alternator not working fully, an unknown extra load has occurred etc). Monitor situation.

 

825 bananas or less in flight. No charge, battery going flat.

[kgwilson]

The Dynon D6 I installed in 2014 has a voltmeter built in. I only wanted a turn co-ordinator & balance ball but got a VSI, ASI, ALT, AoA, Compass, AH, & rate indicators for everything as well. Duplicates all my steam gauges.

[facthunter]

Don't go Banana's. Just use an ammeter,  Same gauge with a low impedance wire (or two) in Parallel.  Reads Plus AND Minus. Nev

[IBob]

Danny, you may want to check the current output of that USB port: I have seen an aircraft equipped with them initially, but subsequently replaced with good quality conventional USB charging ports. I can only assume either that the output was inadequate for whatever they were driving (tablet?), or that they were electrically noisy.

[danny_galaga]

15 hours ago, IBob said:

Danny, you may want to check the current output of that USB port: I have seen an aircraft equipped with them initially, but subsequently replaced with good quality conventional USB charging ports. I can only assume either that the output was inadequate for whatever they were driving (tablet?), or that they were electrically noisy.

Totally agree. I was building a linear power supply for that purpose but realised mucking around with little side projects wasn't getting my plane in the air. My USB is really just for the voltmeter 😄

 

You know what's really dumb of me? I recently installed a battery isolator switch in the instrument panel.  I put the isolator where the USB was. I had already seen I had a voltmeter in the radio some  before, but completely forgot and REINSTALLED the USB next to the isolator, instead of just leaving it out 🤣

 

DOH!

[facthunter]

Those who never made a mistake never made anything. BUT" everybody makes mistakes" doesn't cut it with flying. Thats why we CHECK everything.  (Boring as it might appear).   Nev