voltage gauge

[Mel Griffin]

Upon starting my engine, Cat 3126-B, my voltage gauge almost pegs, it reads approx. 17 volts and stays there. I took voltage reading across the chassic batteries, which are brand new, and get 13.4 and about the same reading across the coach batteries, these readings are with engine running My monitor panal says batteries are about that same voltage as above. I'm wondering whats going on?  Is it safe to drive it with that much charging?

[Edward Buker]

The wire gauge going to the battery is a heavy gague which means there is little voltage drop from the wire coming from the alternator and I assume that the meter you are using is a digital meter that is accurate. Those readings at the battery are normal and would indicate that the voltage gauge at the dash is incorrect. Measure the output of the alternator at the isolator center lead to see if it is a few tenths of a volt higher than at the battery. If so the alternator and isolator is also working properly. You may be able to get a measurement at the back of the voltage gauge and conform that it is in normal range, probably about a volt  lower value than at the battery allowing for harness wire voltage drop. My assumption is that the house charging system is not involved and shore power is disconnected. Your battery voltage readings would indicate that to be true. If you confirm these measurements are normal and your dash gague is out of calibration it is safe to drive.

Regards Ed

[Gerald Farris]

The voltage readings on your Silverleaf monitor are accurate. The analog voltage gauge in your dash is notoriously inaccurate, and therefore it is said to be for "entertainment purposes only".

Lift the access panel on the top of the dash, and measure the voltage at the two studs on the back of the voltmeter with a good digital meter. These readings should agree with your Silverleaf monitor.

If your digital meter agrees with your Silverleaf, you can replace your dash gauge, or just ignore it and use the Silverleaf as your voltmeter.

Gerald

[Bill Sprague]

I don't think any of my dash guages are accurate, including the speedometer that does not agree with the GPS.  But, all of them are consistant and useful as indicators of "normalcy".  Some use tape, stickers or grease pencil to mark the spot where the needle is supposed to be.  Then it can be a quick scan to see if everything is OK.

I used to fly P-3s with four 3,000 hp turboprops.  They had lots of guages.  Some clever engineer figured out that the guages should be rotated in the dash so that when things were normal the needles were vertical.  I've been tempted to try the same to my Beaver dash!