Possibly one for Vic S

[sunquest]

Bit of a quandary! I disconnected and separated my batteries to check the voltages after 3 or so days as I suspect one or more is not holding a charge. With no power going to the distribution panel the voltmeter read 3volts. After about 5 minutes, the voltmeter dropped to zero.
Any ideas? Thanks Geoff

 

[neil_s]

If you have a digital voltmeter, it's input impedance is likely to be very high. your 12v system might also have enough capacitance and suitably excellent insulation so that the voltmeter will continue to read a voltage for some time. The reading would decay slowly over time. I noticed this effect in a test site at work only last week.

If you have a moving coil voltmeter, the needle might be just plain stuck!

 

[AngusMcDoon]

If you have a digital voltmeter, it's input impedance is likely to be very high. your 12v system might also have enough capacitance and suitably excellent insulation so that the voltmeter will continue to read a voltage for some time. The reading would decay slowly over time.

It could be energy stored in the power supply capacitors of devices on your 12V system, for example radios. They usually have some pretty hefty capacitors in them. Or maybe there's a smoothing capacitor in your charging system that remains connected even when the batteries are disconnected. As neil_s says, it will be capacitance somewhere.

 

[VicS]

Bit of a quandary! I disconnected and separated my batteries to check the voltages after 3 or so days as I suspect one or more is not holding a charge. With no power going to the distribution panel the voltmeter read 3volts. After about 5 minutes, the voltmeter dropped to zero.
Any ideas? Thanks Geoff

Not much to add.

You don't say what sort of meter. The rate at which it discharges a capacitor will depend on the type .An analogue one will draw a small but significant current that will quickly discharge a capacitor.

Not something to loose any sleep over.

Check your batteries as you intended.

 

[sunquest]

Thanks for your thoughts, the voltmeter is an analogue type and I should have added the panel lights of switches that were on also lit dimly. But as you say, nothing to worry about.