Switch Panel 423 volt meter not working properly 2001 B34

[Bill]

The digital voltmeter on the 423 switch panel is giving wrong and variable readings of both the house batteries and starter battery. Does anyone have experience or comments here. The voltages at the back of the 2 switches that select the battery sources to measure (on the panel) read correctly on a multimeter.

Any information appreciated.

[Lyra]

Don't know this panel but if the voltage at the switch terminals are OK and the reading wrong I would check for:
1. Defective switch - disconnect the wires and check resistance between in-out terminal when the switch is at the connected state - at least on my panel with an analog meter the reading sometimes is jumpy while pressing the switch.
2. Corroded wires between switch and meter - check the resistance of the wires
3. Defective meter - connect directly to its terminals a known voltage

[Salty]

Bill,
You don't say which boat you have, and I think this makes a considerable difference where specific knowledge of the boat, the location of the panel, proximity of openings that might give rise to water leakage etc., would all play a part in helping to determine the problem.
One thing that Lyra mentioned was in regard to corrosion, and certainly on the older boats, Bavaria used to use ordinary copper wire rather than tinned wire. The copper is particularly prone to corrosion from salt water leakage say from leaking deck stanchion mountings as well as from salt laden sea air, and so the older your boat is the more likely that this could be the problem. Owners of boats similar to yours would be better placed to advise of problems known to them, and from which specific boat problems can be identified. I'd also be looking at any crimped on connectors, particularly though not limited to spade type, as these can also suffer from corrosion which would result in erratic meter readings.

[Bill]

Thanks for the comments so far.
Regarding the boat the panel belongs to: it is a 2001 Bavaria 34 sail boat. The panel and printed circuit board looks OK and there is no visual evidence of water leaks. The whole concept of a printed circuit board with sophisticated electronics seems to be a bit over-complicated to me.

thanks
Bill

[Nigel]

Subject updated.

Are you measuring across the meter terminals, or each positive input and a ground point?

[MarkTheBike]

Bill

I've also got a B34/2001 although with a 420/421 board. Like yours, mine are digital. All the wiring is in good clean shiny condition and there's no corrosion that I can find but my voltage readings for starter and house batteries read about .8v over actual voltage (measured at batteries and terminals). No idea why although I suspect there's smoothing circuitry in there, which might be a factor. I keep a multimeter attached to the domestic bateries for accurate readings. The binnacle has an ST4000+ and ST60 Wind / Tri & Multi + a Multi repeater below. Voltage on the Multi is usually about .1 - .2V under, which is to be expected at the end of a cable run. I've used 2 x multimeters and they tend to agree with each other. Wish I still had my Dad's AVO.

[Impavidus]

Bill, Hi. Are there two little potentiometers on the rear of the panel that adjust with a small screwdriver? I seem to remember that there are on your type of panel? They are there to calibrate the reading to the true battery voltage. If so mark the position of the driver slot with a sharpie pen and turn the pot up and down a few times. Then return it to the marked position +/- a degree or two so that you have the same reading at the panel as you do at the battery. The pots get dirty or contaminated and give a false reading. Good clean contact all through the circuit is a must.

Couple of points to watch for;

Multi-meters need to be calibrated to a known voltage, some of the cheaper digital ones can be 10% out or more. Analog ones also need to be calibrated too, but any error can be added to if your not reading the scale directly at 90 deg to it. This is called the parallax effect. Make sure you can only one needle in the little mirror on the scale.

Or it may just be busted 

Best regards.